United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Proceedings

RMRS-P-7

March 1999

Rio Grande Ecosystems:

Linking Land, Water,

and People

Toward a Sustainable Future for

the Middle Rio Grande Basin
Abstract

Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey, F.; Loftin, Samuel R. 1999. Rio Grande ecosystems: linking land,

water, and people. Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5; Albuquerque, NM.

Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

245 p.

These proceedings are an outcome of a symposium and workshop held June 2-5, 1998 in Albuquerque, NM. Hosted

by the USDA Forest Service, Rocky Mountain Research Station and the U.S. Fish and Wildlife Service’s Bosque

Improvement Group, in collaboration with numerous partners from a variety of sectors, the symposium was designed

to report on current research and development activities in the Middle Rio Grande Basin. The purpose of the meeting

was to share information and develop ideas for sustaining and conserving Middle Rio Grande Basin ecosystems,

especially those from Cochiti Dam to Elephant Butte Reservoir. Experts were invited to contribute oral presentations,

posters, and papers that addressed five Basin themes. Theme one’s session was designed to identify methods and

opportunities to enhance communication and collaboration among researchers, managers, and communities. A

second theme explored ideas and approaches for conserving water and riparian resources in relation to human needs

and population growth. Theme three discussed how watershed processes form linkages and influence management

of upland and river resources. A fourth session identified methods and strategies for restoring and monitoring basin

ecosystems and discussed project successes and failures. Theme five reported on status of endangered and sensitive

species, biological diversity, and opportunites for restoring and managing habitats to recover species. Management

and understanding of the Middle Rio Grande Basin’s natural resources and ecosystems require communication and

cooperation of partners across cultural, landowner, and organizational boundaries. To produce a shared understanding

of the current state and desired future state of the Middle Rio Grande Basin and to outline the steps needed to move

toward the desired future, a facilitated workshop was held the last day of the conference. The results of this workshop

are reported in the concluding section of this proceedings. The technical coordinators of the symposium and

proceedings wish to acknowledge all the partners who have contributed to the research, restoration, technology

development, educational outreach, and special events and activities designed to improve human and ecosystem

conditions in the Basin. We hope this volume captures at least some of the excitement, ideas, and productivity

generated by Basin projects over the past several years.

Key words: Rio Grande Basin, conservation, watershed, endangered species, sensitive species, restoration

Sponsors and Partners

U.S. Fish and Wildlife Service, Bosque Improvement

 Group

USDA Forest Service, Rocky Mountain Research Station

Bosque del Apache and Sevilleta National Wildlife

 Refuges

USDA Forest Service, Southwest Region

Cibola and Santa Fe National Forests

City of Albuquerque and Open Space Division

Bureau of Reclamation

USDA Plant Materials Center

Natural Resources Conservation Service

U.S. Geological Survey Desert Research Laboratory

U.S. Army Corps of Engineers

Bandelier National Monument

New Mexico Department of Game and Fish

Rio Grande Nature Center

Bureau of Indian Affairs, Southern Pueblos Agency

Pueblo of Santa Ana

Pueblo of Sandia

All Indian Pueblo Council

University of New Mexico (UNM)

New Mexico State University

New Mexico Institute of Mining and Technology

University of Arizona

Arizona State University

University of Southern Mississippi

Texas Tech University

UNM Natural Heritage Program

Oklahoma State University

New Mexico Riparian Council

Partners in Flight

Sweetwater Reclamation, Inc.

Bosque Hydrology Group

Save Our Bosque

Tides Foundation

Earthwatch

Rio Grande Bird Research, Inc.

Paleoresearch Laboratories

Wingswept Research

Bat Conservation International

Publisher’s Note: Most papers in this report were

reviewed and edited only for format and style. Pages

were composed from copy supplied by authors.
You may order additional copies of this publication by sending your mailing information in label form

through one of the following media. Please specify the publication title and Research Paper number.

Ogden Service Center Fort Collins Service Center

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FAX (801) 625-5129, Attn: Publications (970) 498-1660

E-mail pubs/rmrs_ogden@fs.fed.us rschneider/rmrs@fs.fed.us

Web site http://www.xmission.com/~rmrs http://www.xmission.com/~rmrs

Mailing Address Publications Distribution Publications Distribution

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324 25th Street 3825 E. Mulberry Street

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The use of trade or firm names in this publication is for reader information and does not

imply endorsement by the U.S. Department of Agriculture or any product or service

CAUTION:

PESTICIDES

Pesticide Precautionary Statement

This publication reports research involving pesticides. It does not

contain recommendations for their use, nor does it imply that the

uses discussed here have been registered. All uses of pesticides

must be registered by appropriate State and/or Federal agencies

before they can be recommended.

CAUTION: Pesticides can be injurious to humans, domestic

animals, desirable plants, and fish or other wildlife—if they are

not handled or applied properly. Use all pesticides selectively

and carefully. Follow recommended practices for the disposal of

surplus pesticides and pesticide containers.
Federal Recycling Program Printed on Recycled Paper

Contents

Page

Introduction

Deborah M. Finch Rio Grande Ecosystems: Proceedings Introduction ...................................................... 3

Jeffrey C. Whitney

People, Culture, and Communication

Joseph A. Tainter Rio Grande Basin and the Modern World: Understanding Scale and Context .............. 7

Richard D. Periman Dynamic Human Landscapes of the Rio del Oso: Restoration and the

Simulation of Past Ecological Conditions in the Upper Rio Grande Basin ............12

José A. Rivera Water Democracies on the Upper Rio Grande, 1598-1998 .........................................20

Jim Winder Resolving Resource Conflict: a Bigger Pie ..................................................................29

Steve Harris How Great a Thirst? Assembling a River Restoration Toolkit......................................32

Carol Raish Española/Canjilon Pilot Study: Economic, Social, and Cultural Aspects of

Public Land Grazing on the Santa Fe and Carson National Forests.....................35

Steve Kluge “Southwest Strategy” Update .......................................................................................39

Sarah Kotchian Rio Grande/Rio Bravo Basin Coalition .........................................................................42

River and Riparian Issues

Jeffrey C. Whitney Watershed/River Channel Linkages: The Upper Rio Grande Basin

and the Middle Rio Grande Bosque ......................................................................45

J. S. O’Brien Simulation of Rio Grande Floodplain Inundation Using FLO-2D .................................52

W. T. Fullerton

Gail Stockton Upper Rio Grande Water Operations Model: a Tool for Enhanced

D. Michael Roark System Management ............................................................................................61

Jan M. H. Hendrickx Salinity Management in the Rio Grande Bosque .........................................................68

J. Bruce J. Harrison

Jelle Beekma

Graciela Rodriguez-Marin

Michael D. Marcus Albuquerque’s Constructed Wetland Pilot Project for Wastewater Polishing ..............72

Shannon M. House

Nathan A. Bowles

Robert T. Sekiya

J. Steven Glass

Ross Coleman Methods for Increasing Biodiversity in Wetland Creation and

Restoration Efforts.................................................................................................79
Watershed Issues

Carleton S. White Response of Vegetation, Soil Nitrogen, and Sediment Transport to a

Samuel R. Loftin Prescribed Fire in Semiarid Grasslands ................................................................83

Steven Hofstad

Bill Fleming Watershed Health: an Evaluation Index for New Mexico............................................. 93

Dave Pawelek A Constructed Wet Meadow Model for Forested Lands in the Southwest ..................97

Roy Jemison

Daniel Neary

Teresa L. Newberry Effect of Spatial and Temporal Variablilty on Water Relations and

Growth in Pinyon Pine: III. Whole Tree Response ................................................ 99

Alan R. Johnson Analysis of Change in Piñon-Juniper Woodlands

Bruce T. Milne Based on Aerial Photography, 1930’s-1980’s .....................................................106

Peter Hraber

Deborah Ulinski Potter Applications for Predicting Precipitation and Vegetation Patterns at

Landscape Scale Using Lightning Strike Data ....................................................112

Restoration and Monitoring Issues

Samuel R. Loftin Trial by Fire: Restoration of Middle Rio Grande Upland Ecosystems........................119

James R. Thibault Effects of Livestock Grazing on Morphology, Hydrology and Nutrient

Douglas L. Moyer Retention in Four Riparian/Stream Ecosystems, New Mexico, USA ..................123

Clifford N. Dahm

H. Maurice Valett

Michael C. Marshall

Mark D. Ankeny Establishing Riparian Vegetation Through Use of a Self-Cleaning

L. Bradford Sumrall Siphon System ....................................................................................................129

Kuo-Chin Hsu

Joanne Mount Vegetation Classification on the Middle Rio Grande .................................................135

Ondrea C. Linderoth Restoration Efforts in the Rio Grande Valley State Park ...........................................136

Esteban Muldavin River Bar Vegetation Mowing Response in the Middle Rio Grande ..........................139

Elizabeth Milford

Yvonne Chauvin

David R. Dreesen Establishment of Rio Grande Cottonwood Seedlings Using Micro-irrigation

Gregory A. Fenchel of Xeric Flood Plain Sites ....................................................................................151

Joseph G. Fraser

Clifford S. Crawford Restoration and Monitoring in the Middle Rio Grande Bosque:

Lisa M. Ellis Current Status of Flood Pulse Related Efforts ....................................................158

Daniel Shaw

Nancy E. Umbreit

Page
Robert R. Parmenter Sevilleta Long-Term Ecological Research Program:

Measuring Ecosystem Reponses to Environmental Change ..............................164

Todd R. Caplan Influence of Mycorrhizal Source and Seeding Methods on Native Grass

Heather A. Pratt Species Grown in Soils from a Disturbed Site.....................................................170

Samuel R. Loftin

Joy Rosen Using GIS Technology to Analyze and Understand Wet Meadow Ecosystems ........ 175

Roy Jemison

David Pawelek

Daniel Neary

Maria L. Sonett Integrated Surface Management for Pipeline Construction:

the Mid-America Pipeline Company Four Corners Project.................................. 180

Biodiversity and Endangered Species

Alice Chung-MacCoubrey Maternity Roosts of Bats at the Bosque Del Apache

National Wildlife Refuge: a Preliminary Report ...................................................187

Michael D. Means Bird Migration Through Middle Rio Grande Riparian

Deborah M. Finch Forests, 1994 to 1997 .........................................................................................191

Deborah M. Finch Status and Migration of the Southwestern Willow Flycatcher in New Mexico ...........197

Jeffrey F. Kelly

Peter B. Stacey Biological Diversity in Montane Riparian Ecosystems: the Case of the

Angela Hodgson Mexican Spotted Owl ..........................................................................................204

Jean-Luc E. Cartron Riparian Dependence, Biogeographic Status, and Likelihood of

Scott H. Stoleson Endangerment in Landbirds of the Southwest ....................................................211

R. Roy Johnson

Linda S. DeLay Arthropods of Native and Exotic Vegetation and Their Association with

Deborah M. Finch Willow Flycatchers and Wilson’s Warblers ..........................................................216

Sandra Brantley

Richard Fagerlund

Michael D. Means

Jeffrey F. Kelly

Jeffrey F. Kelly Use of Saltcedar Vegetation by Landbirds Migrating Through the

Deborah M. Finch Bosque Del Apache National Wildlife Refuge .....................................................222

Bob Calamusso Native Montane Fishes of the Middle Rio Grande Ecosystem: Status,

John N. Rinne Threats, and Conservation ..................................................................................231

Workshop Summary

Barbara A. Coe Future of the Middle Rio Grande ...............................................................................241

Page
Rocky Mountain Research Station

324 25th Street

Ogden, UT 84401

Rio Grande Ecosystems: Linking

Land, Water, and People

Toward a Sustainable Future for the

Middle Rio Grande Basin

June 2-5, 1998

Albuquerque, New Mexico

Technical Coordinators:

Deborah M. Finch

Rocky Mountain Research Station

2205 Columbia Southeast

Albuquerque, NM 87106

Jeffrey C. Whitney

U.S. Fish and Wildlife Service

New Mexico Ecological Services

2105 Osuna Northeast

Albuquerque, NM 87113

Jeffrey F. Kelly and Samuel R. Loftin

Rocky Mountain Research Station

2205 Columbia Southeast

Albuquerque, NM 87106

Introduction

People, Culture, and

Communication

River and Riparian 

Issues

Watershed Issues

Restoration and 

Monitoring Issues

Biodiversity and 

Endangered Species

Workshop Summary

Introduction

USDA Forest Service Proceedings RMRS-P-7. 1999 3

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Deborah M. Finch is with the Ecology Diversity, and Sustainability of

Soil, Plant, Animal, and Human Resources of the Rio Grande Basin Research

Work Unit, USDA Forest Service, Rocky Mountain Research Station, Albuquerque, NM. Jeffrey C. Whitney is with New Mexico Ecological Services

Office, U.S. Fish and Wildlife Service, 2105 Osuna Rd. NE, Albuquerque, NM

87113.

These proceedings are an outcome of a symposium and

workshop of the same title held June 2-5, 1998, in Albuquerque, New Mexico. Hosted by the USDA Forest Service,

Rocky Mountain Research Station and the U.S. Fish and

Wildlife Service’s Bosque Improvement Group, in collaboration with partners from a variety of public and private

sectors, the symposium was designed to report on current

research, development, and educational activities in the

Middle Rio Grande Basin. Participants shared information

and developed ideas for sustaining and conserving Middle

Rio Grande Basin ecosystems, especially those from Cochiti

Dam to Elephant Butte Reservoir.

In 1994, the Rocky Mountain Research Station in Albuquerque developed and implemented a 5-year research program to evaluate ecological conditions of Middle Rio Grande

Basin ecosystems. This Forest Service Research program

addressed four problem areas: (1) ecology and restoration of

upland basin ecosystems, (2) watershed analysis and stream

quality, (3) riparian habitats and species, and (4) human

history and culture. More than 25 cooperating organizations

have been participating in this program, either by conducting research through contracts and agreements, by matching funds and sponsoring new research, or by cooperating

through various land use agreements. Simultaneously, the

U.S. Fish and Wildlife Service developed a program of

research, monitoring, management, and education focusing

on improving ecological conditions and communications

along the Middle Rio Grande. This program, implemented

through the Bosque Improvement Group, was also initiated

as a 5-year effort. Combined, both programs have sponsored

over $1 million per year of Rio Grande Basin activities from

1994 to 1998. This includes cost-share and matching dollars

contributed by collaborating organizations such as Bureau

of Reclamation, U.S. Geological Survey, Army Corps of

Engineers, State of New Mexico, City of Albuquerque, National Forests, National Wildlife Refuges, University of New

Mexico, and several other universities, private institutions,

environmental organizations, and public agencies.

Specially designated funds allocated to these two programs have been used to develop partnerships, conduct

research, and expand knowledge for managing the Rio

Rio Grande Ecosystems: Proceedings

Introduction

Deborah M. Finch

Jeffrey C. Whitney

Grande and its associated natural resources and ecosystems. After prioritizing, sponsoring, and conducting projects

for the past 5 years, we have convened this symposium to

report relevant results, describe progress, and document

outcomes of joint ventures. The research results, technology,

and partnerships described in these proceedings attest to

the many achievements and products these programs have

helped to generate in the Basin. Viewed by some as the “river

of life,” the Rio Grande’s past, present, and future are

captured in this volume. Success stories are worth telling

and worth reading about.

We invited experts to contribute oral presentations, posters, and papers that addressed five Basin themes. Theme

One’s session was designed to identify methods and opportunities to enhance communication and collaboration among

researchers, managers, cultural groups, and communities.

Historical overviews from different cultural perspectives

were presented that helped to lay the groundwork and

direction for communication about current environmental

conditions, conflicts, and options. Theme Two participants

explored ideas and approaches for conserving water and

riparian resources in relation to human needs and population growth. Theme Three focussed on how watershed processes form linkages and influence management of upland

and river resources. Theme Four participants identified

methods and strategies for restoring and monitoring basin

ecosystems and discussed project successes and failures.

Theme Five was a report on the status of endangered and

sensitive species, biological diversity, and opportunities for

restoring and managing habitats to recover species. The

written papers that resulted from the symposium are grouped

along similar lines.

An evening poster session and social was held at the

Albuquerque Aquarium. Symposium participants, accompanied by friends and family members, viewed scientific

posters, chatted with presenters, toured exhibits of sea life,

and exchanged ideas and information with strolling colleagues. Poster papers were assigned to theme categories

using an ad-hoc basis.

Management and understanding of the Middle Rio Grande

Basin’s natural resources and ecosystems require communication and cooperation of partners across cultural, landowner, and organizational boundaries. To produce a shared

understanding of the current state and desired future state

of the Middle Rio Grande Basin and to outline the steps

needed to move toward the desired future, a facilitated

workshop was held the last day of the conference. The

workshop was designed to enable participants to plan some

joint actions for improving environmental conditions in the

Rio Grande watershed and river corridor and at the same

time learn a new way to increase their success rate in
4 USDA Forest Service Proceedings RMRS-P-7. 1999

achieving goals when working together. Participants were

first asked to find areas of “common ground” regarding their

desired future of the Rio Grande Basin. Then they were

asked to examine their views of the current status of the

Basin so as to be able to determine what the appropriate

actions would be. During these exercises we saw a positive

release of “structural tension,” a phenomenon defined by

Workshop Facilitator, Dr. Barbara Coe of Daystar Associates, as energy that generates action toward the goal. The

written results of this workshop are reported in the concluding section of this proceedings. Additional outcomes included: (1) increased understanding of the similarities and

differences in participants’ desires for the future of the Rio

Grande, (2) increased understanding of the current state of

the Rio Grande Basin, (3) preliminary action plans for

elements of the desired future, and (4) increased knowledge

of a new way to achieve goals collaboratively.

In conclusion, the technical coordinators of the symposium and proceedings wish to acknowledge all the partners

who have contributed to the research, restoration, technology development, educational outreach, and special activities designed to better human and ecosystem conditions in

the Basin. A comprehensive list of those organizations that

helped to make this symposium successful is included in the

beginning of the proceedings. We hope this volume captures

at least some of the excitement, ideas, and productivity

generated by Basin projects over the past 5 years.
People, Culture, and

Communication

USDA Forest Service Proceedings RMRS-P-7. 1999 7

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Joseph A. Tainter is Project Leader, Rocky Mountain Research Station,

U.S. Department of Agriculture, Forest Service, Albuquerque, NM.

Abstract—Environmental problems are social issues, embedded in

economic and political contexts at the local, regional, national, and

global levels. Placing environmental issues on the scale from local

to global clarifies conflicts between the level at which problems

originate and the level at which they must be addressed. Local

issues today often originate in sources distant in time and space,

increasing the difficulty of discerning and addressing them. Conflicts in environmental management can be approached by understanding their broader context and the appropriate level at which to

manage them.

Scaling and Social Context _______

Environmental problems are really social issues. Environmental matters do not exist on an independent plane in the

biophysical world. Ecosystems, being systems, adjust automatically to what we call disturbances, and cannot care

about such matters as species composition, ground cover, or

water flow. An environmental phenomenon becomes a problem only because people perceive it to be. Variation in human

perception gives rise to environmental concerns, the research by which we comprehend them, and the confrontations or negotiations by which we resolve them.

To understand that environmental problems are really

social issues is also to understand that they have scalability

that is characteristically fractal. As we consider environmental issues ranging from local to national to global, we

find that the problems fundamentally retain the same form,

the same parts, and the same relations among parts. Always, for example, there is conflict between immediate

human livelihood and long-term environmental resiliency.

The fact that the problematical relationship between humanity and the environment tends to repeat the same

patterns and issues helps us to develop a context to understand both what we experience in the Rio Grande Basin

today and the broader processes in which we participate. A

perspective that is comparative and historical helps to

clarify both the situation of the Rio Grande Basin and the

meaning of the ecosystem approach to management. The

discussion is far-ranging, and is meant to illustrate the

diversity of the knowledge that we need to understand any

region today.

Rio Grande Basin and the Modern World:

Understanding Scale and Context

Joseph A. Tainter

The era since World War II has been particularly transformative in many places, of which it is useful to relate one

example. Until World War II communities in this area were

relatively isolated and closed. Within a community everyone

knew everyone else, the information pool was homogeneous,

and decision-making was primarily consensual. There were

few differences among people, either technical, social, or

economic. The system of land use had been in operation for

a very long time. People knew the area intimately, and their

subsistence practices were suitable to the environment and

sustainable over the long term.

Roads were introduced in the period just after the war,

leading to increased contact between villages and with

the outside world. This brought new influences and information about the world at large, and new opportunities and

ways of doing things. Within villages both the pool of information and community organization began to differentiate.

Villages lost some autonomy as they came to be embedded in

larger systems at the regional and national levels. As urban

ways of living penetrated the countryside, people began to

acquire manufactured goods and cash became increasingly

important.

The last 50 years have seen much emigration from the

villages, as people have moved to the outside world to find

work. Social and economic differentiation accelerated, so

that no longer could everyone know everything about everyone else. Personal and group interests began to conflict.

Subsistence practices changed also. Transformations in

cattle grazing meant that fire stopped being used to keep

upland pastures clear of competing vegetation. This led to an

overgrowth of undesirable woody plants and to erosion.

The natural environment, and how it is used, have been

central to the people’s cultural heritage. Yet forests in the

region are now controlled by the government, and there is

frequent conflict between forestry officials and local residents. Organizations external to the area now promote

projects to develop the local economy. The great beauty of the

area is to be marketed by far-off urban residents to other

urban residents. These outsiders bring an ethos in which

heritage is to be preserved rather than lived. Forests are to

be maintained largely for urban values. The architectural

style is to be preserved even though local people can no

longer afford it, and no longer have free access to raw

materials in the forests.

As local self-sufficiency declined, the region has become

more and more dependent on the commercial economy and

the government. Today many people, particularly older

ones, are supported by government payments. Being embedded in larger systems means that the transformation from

autonomy and self-sufficiency to dependency and environmental deterioration is probably irreversible in the near

future (Green and others 1998, van der Leeuw and others

n.d.).
8 USDA Forest Service Proceedings RMRS-P-7. 1999

This is a description of changes, not within the Rio Grande

Basin (though it could almost be), but in the region of Epirus

in the northwest of Greece. We recognize the account and

respond to it because, with a few changes in minor details, it

could easily describe what has happened in the Basin over

the past 50 years. How is it that two distant and unrelated

places could exhibit such strikingly parallel developments?

The answer lies in understanding the scalability of economic and environmental change. The description of Epirus

sounds not only like the Rio Grande Basin, but also like

many other places that have been transformed in recent

decades. These places tend to change along parallel courses

because they have become embedded in a global economic

system in which participation is rarely optional. To a degree

that is generally not understood this system guides the

development of localities that were previously unconnected.

Places like the Rio Grande Basin or Epirus, once largely

autonomous and self-sufficient, may never again control

their own destinies.

Social Memory, Hierarchy, and

Heterarchy _____________________

Epirus exemplifies the problem of scaling in environmental management. The problem concerns the levels at which

environmental problems arise, and the levels at which we

consider and devise solutions to them. Often these levels

exist in blissful ignorance of each other. Take climate change

as an example. The Intergovernmental Panel on Climate

Change (IPCC) periodically issues reports synthesizing scientific information on this topic. Its most recent report in

1995 was in three volumes, one of which concerned the social

and economic dimensions of climate change (Bruce, Lee, and

Haites 1995). It is a remarkable compilation, which addresses such pressing matters as adaptation and responses,

equity, decision-making frameworks, and economic considerations. Yet within its learned chapters one looks fruitlessly for discussions of scaling, or for sensitivity to the

matter, or even, at the very least, for awareness of it.

Scaling in this case concerns the level at which humans

respond to environmental change, or attempt to manage it.

As befits an organization chartered by the United Nations,

IPCC considers adaptation and responses primarily at the

level of nations, and within nations, at the level of cities.

Discussions of equity, for example, usually turn on relations

of developed nations to those in transition. Adaptation is

discussed in terms of responses that nations might undertake, such as steps to protect coastlines and low-lying areas.

Certainly these matters are important, but they are not the

considerations of most people who will be affected by climatic or other environmental change. The major part of

humanity’s adaptation will come at the local level, at a

community or regional scale, among people who do not

participate in international deliberations and who know

nothing of such concepts as international or intergenerational

equity, opportunity costs, return on investment, or net

present value.

Environmental responses at the local or regional level,

including the Rio Grande Basin, reflect the accumulated

knowledge of people who have occupied a territory for

generations, and who have learned through long experience

how to respond to change (McIntosh, Tainter, and McIntosh

n.d.). Environmental responses at this level are based on

knowledge of which national governments, and international organizations such as IPCC, are typically unaware.

Carole Crumley, for example, has studied traditional farming and gardening practices in the Burgundian region of

France (Crumley n.d.). Millennia of experience with local

conditions have given these people knowledge to farm

sustainably. Yet as the French government accedes to international demands for open markets, local production systems are being destroyed. The result for the French government is tractor parades of angry farmers through Paris. In

Burgundy the consequences are more serious: to compete in

international markets these farmers must expand their

scale of production. Hedgerows are being destroyed to allow

for larger fields, and centuries-old conservation practices

are being abandoned. Closer to home, similar problems

generated by the North American Free Trade Agreement

have damaged subsistence farmers in southern Mexico, and

contributed to the grievances fueling the rebellion in Chiapas.

Meanwhile, in the Rio Grande Basin, we seem increasingly

to worry about farmland preservation less as a fundamental

aspect of our lives, and more as a quaint curiosity, part of our

conception of a picturesque landscape.

In a world that has become globally interconnected we will

increasingly experience conflict between action at the local

level and actions at higher levels. Environmental action at

the local level, among people who have occupied a region for

much time, is initiated on the basis of what has been termed

social memory (McIntosh, Tainter, and McIntosh n.d.). Social memory is the mechanism by which local-level societies

retain, transmit, and modify knowledge of the environment,

its past changes, and successful responses to those changes.

Social memory is encoded in the very things that form the

basis of life in small communities: cosmology, myths, rituals,

stories, and drama. Social memory is active in all communities, even those that are part of nations with scientific

traditions. The Burgundians studied by Carole Crumley

(n.d.), for example, encode knowledge of environmental

variation in sayings and aphorisms that guide how they

prepare and tend vegetable gardens. Gardening in turn

serves as a repository of knowledge and experience about

broader environmental variation. On the other side of the

world, China possess perhaps the oldest continuous tradition of social memory (Hsu n.d.). Proverbs predict how one

state of weather leads to another, while pragmatic observations on the environment are encoded in poems and songs.

These traditions have been transmitted for centuries. The

people of the Rio Grande Basin have had a similarly rich

tradition of environmental knowledge, extending over a

century in the case of Anglo-Americans, for several centuries

among Hispanos, Apaches, and Navajos, and even longer

among Puebloans.

A physical remnant of this tradition can be found south of

Tijeras Canyon, along an old state highway that runs parallel to but largely hidden from the current road. It was a

narrow, curving road, meant to be driven at slow speeds.

Amidst rock art of the 14th century there is a sign from

earlier this century, hand painted on a limestone cliff. It

advertises, in a characteristically New Mexican combination of Spanish and English, that “Curandera cures all.”

Whoever this curandera was, she carried a long tradition
USDA Forest Service Proceedings RMRS-P-7. 1999 9

about the medicinal use of local plants. It is an example of

what we call social memory. Her tradition still exists, though

many New Mexicans, newly arrived and working for some

modern institution, will be unaware of it. It is a tradition

that can no longer galvanize social action to the extent that

it once did.

Responses to environmental challenges can be categorized by the channels through which they are initiated. In

broad terms these channels can be termed hierarchical and

heterarchical. The meaning of hierarchy is widely understood. In a social context it refers to people or institutions

that are ranked relative to each other, and connotes authority and power. Heterarchy, a term coined by Carole Crumley

(1979: 144), means just the opposite: a social condition in

which people or institutions are unranked relative to each

other, or can be situationally ranked in a number of ways. Of

course most societies today incorporate elements of both

hierarchy and heterarchy. The communities of central and

northern New Mexico in the 18th century could be viewed as

a heterarchy, but they were in turn linked hierarchically

through Santa Fe to the government in Mexico City, and

ultimately to the Spanish Crown. The villages of Epirus in

the 1930s similarly formed a local heterarchy, linked weakly

to the national government in Athens.

Hierarchy and heterarchy differ in the speed and scale at

which they respond to challenges, in the rates at which they

change, and in their appropriateness for different situations. We usually think of hierarchies in an active sense:

passing laws, setting policies, issuing orders, or establishing

budgets. Higher levels do constrain lower levels in this way,

but much of the time they do so in ways that are not

intuitively obvious. Higher levels often constrain those further down by not acting, or by acting slowly (Allen and Starr

1982, Allen and Hoekstra 1992, Ahl and Allen 1996). Elites

limit the behavior of subordinates by being unresponsive.

While the lower levels in a social hierarchy go about the

high-frequency business of daily life, the higher levels slowly

issues edicts or grant appeals.

In human societies as in most living systems, information

flows to higher levels and controls operate downward. Higher

levels respond not to the primary forces felt by lower levels,

but to information about those forces. Information flowing

upward is always filtered, becoming ever more abstract and

disconnected from its source, while at the same time higher

levels are notoriously unresponsive to signals from below.

What hierarchies do respond to is horizontal social signals—

messages from or about other elites. A Russian colleague, for

example, once described to me how Mikhail Gorbachev

behaved in the waning days of the Soviet Union. As the union

crumbled about him, and its citizens and security forces

battled in the streets, the information that mattered to

Gorbachev was not the needs of lower levels but his reputation in the minds of Western leaders. Along analogous lines,

in August 1996 there was much discussion of establishing a

high-speed rail line between Moscow and St. Petersburg. At

the same time the local rails within St. Petersburg were so

dilapidated that in places they ran over mud. The upper

levels of civil administration in St. Petersburg responded to

horizontal signals from civic elites in Moscow, while responding callously to local distress.

This may sound like hierarchy is merely a useless parasite, utterly unsuited to solving local problems. In fact

hierarchy has distinct advantages that heterarchy can never

match. The advantages of hierarchy are that it can act

quickly, uniformly, and over large areas. Hierarchy conveys

the authority to mobilize communities to act, and to act

expeditiously. Hierarchy can mobilize resources for an effective response, and can ensure that resources are distributed

equitably. What hierarchy typically cannot do is to respond

quickly and effectively to signals from below about new or

unusual problems. Our own disaster-relief agencies, for

example, have become adept at responding to flooding in the

Mississippi Basin, but take excruciatingly longer to address

a more unusual problem such as a catastrophic snowfall in

southeastern New Mexico. National governments may unwittingly undermine traditional production systems, such

as in Burgundy, because they respond to horizontal social

signals, while information from below must always struggle

upstream.

Heterarchy, while not so effective at mobilizing quick,

large-scale responses, is better able to acknowledge and

incorporate varieties of experience. Heterarchical systems

work either by consensus, or by ad hoc consensual leadership. While the process of adjusting to new circumstances in

a heterarchy is unavoidable slow, it derives legitimacy from

consensus. It is based on local experience and social memory.

Those who have developed a heterarchical consensus are

intrinsically committed to implementing it. Yet heterarchy,

like hierarchy, is by itself incomplete. While heterarchy has

the advantage of incorporating diverse experiences and

ensuring legitimacy of decision-making, it falters where

conditions call for rapid or uniform responses, or where

problems arise from outside a local context. Social memory

is also far from faultless. Fekri Hassan relates a story of an

advisor to the Egyptian government, who insisted that he

had detected a pattern to the Nile floods of seven years of

high water, seven years of low, and six years of intermediate

levels. In fact the advisor had detected no such thing, and

admitted privately that his model was inspired by the

Koran. The inspiration is actually far older than the Koran.

The advisor, probably unknowingly, perpetuated a long

tradition of Egyptian social memory, which has a documented history of over four thousand years, and which is

reflected in the Biblical tale of seven years of plenty followed

by seven years of famine (Hassan n.d.). Local social memory,

formed through heterarchies, may sometimes be a suitable

guide for action, but it can also be nothing more than fable.

Scale, Context, and Landscape

Change ________________________

This meandering discussion has come in a roundabout

fashion to one of the fundamental dilemmas of our time:

whether to confront our problems top-down, through our

national government or even international conventions, or

from the bottom up, based on local experiences. This dilemma, as we know, frames much of our national debate, and

in various guises dominates our headlines. The dilemma

becomes poignant as we realize that for the most part there

are no answers or solutions that are unambiguously right or

wrong. Neither hierarchy nor heterarchy is invariably appropriate or misguided. Their usefulness depends on circumstances. In a world that is interconnected at many
10 USDA Forest Service Proceedings RMRS-P-7. 1999

levels—in which the air of Albuquerque can be turned to

haze by fires in southern Mexico, (such as in the third week

in May, 1998), in which warming of equatorial waters

increases profits for Mesilla lettuce farmers while it increases disease in the San Juan Basin—we realize that evercloser scrutiny of our problems will likely reveal only finer

and finer shades of gray. This underscores again the centrality of scaling and context, and particularly the problems that

inevitably arise when there is a contradiction between the

level at which problems are generated and the level at which

they must be addressed.

My colleague Tim Allen is fond of saying that if fish were

scientists, the last thing they would discover would be water

(for example, Allen, Tainter, and Hoekstra n.d.). His point is

that the most difficult matter to comprehend is the context

that constrains us. It is always difficult to understand

something larger than ourselves, and that is what context is

(Allen and Hoekstra 1992). In a global marketplace in which

the fiscal crisis in Asia may influence the level of water use

in microprocessor manufacturing, and ultimately how long

farmers in the Rio Grande Basin will be able to irrigate

alfalfa, trying to understand our context is surely one of the

most important things we can do.

The dilemma we ultimately face is that our context is

increasingly distant, impersonal, unaware of us, and uncaring. In the eighteenth century the Spanish Crown probably

also seemed distant, impersonal, unaware, and uncaring,

but it also had little influence in the day-to-day lives of New

Mexicans. Today New Mexico may be affected by decisions

made on Wall Street, in Tokyo, or in the Persian Gulf, or even

by the actions of angry mobs in Indonesia. The control of our

local affairs is more and more in external hands.

Although the universality with which this is happening is

peculiar to our era, there are precedents for it. It is worth

reviewing one of these precedents briefly, for it allows us to

see the long-term consequences of a locality losing control of

its destiny. In the civilizations of the ancient Mediterranean,

agriculture was the basis of wealth and power. The ideal

landscape was one of peasant farmers producing food for the

cities, sons for the armies, and taxes for the state. This was

the energetic basis of the Greek city-state, and it formed a

landscape in which events and processes were substantially

under local control.

This began to change when Alexander the Great conquered the Near East toward the end of the fourth century

B.C. The large Hellenistic kingdoms that formed in the wake

of his conquests hired large armies of Greek mercenary

soldiers. Suddenly Greek peasants had opportunities on an

unprecedented scale to earn gold and silver serving as

soldiers in Syria or Egypt, rather than farming laboriously

for meager subsistence in the poor soil of Greece. The Greek

countryside began increasingly to lose population from the

second century B.C. When the Romans came to Greece they

expropriated so much treasure that for small farmers there

was a liquidity crisis. They could not earn money to pay their

debts and began to lose their lands to the wealthy. The Greek

landscape of peasant proprietors changed to one of ostentatious villas, owned by oligarchs who used the land less

intensively—for exportable cash crops such as olive oil,

wine, or livestock, and to raise prize horses and cattle. By the

second century A.D. writers described the Greek countryside as unkempt and underpopulated—a sad reflection of its

former productivity. Ironically, cities flourished in this era,

as oligarchs put their wealth into building public monuments. The magnificent ancient cities of the Mediterranean

Basin, which we admire so much today, were partly built on

the basis of rural depopulation. Greece has, in some ways,

never recovered from this.

By the third century A.D. the Roman Empire was fighting

for its own survival against Germanic peoples from the north

and the Persians from the east. It financed its wars largely

from taxes on land. It came to require that taxes be paid

whether a plot of land was cultivated or not, and so tried to

force underutilized lands back into production. The Greek

landscape came to be repopulated, but not by a free peasantry. Farmers from the fourth century on were legally tied

to their lands, or attached as tenants to great estates. These

obligations were hereditary, a foretaste of the social conditions of the Middle Ages (Alcock 1993, Allen, Tainter, and

Hoekstra n.d.).

The unfortunate story of the Greek landscape is one of

changing context. In the era of city-states the Greek landscape developed under local control, responded to local

needs, and supported the local population—much as the

landscape of the Rio Grande Basin did until recently. Developments far off brought Greek independence to an end. As

political units grew in size and scale, the context for the

Greek landscape shifted first to the entire Near East, then

to the Roman Empire and the Mediterranean Basin, then

beyond the borders of the empire to the pressures exerted

from central Europe and central Asia. Similarly we participate now in a Rio Grande landscape that came in the 19th

century to be embedded in distant processes at national and

continental scales, and in the 20th century in the international arena. We might wonder whether we have any more

power to control our landscape today than the Greeks did

2,000 years ago.

Ecosystem Management:

Understanding Context __________

As the context for the Greek landscape shifted to everlarger arenas, in a process that extended over centuries, the

Greeks lost the ability to understand what was happening to

them. To lack comprehension of one’s context, or the ability

to influence it, makes for a depressing tale. It is also a

common tale. In the first century B.C. (to give a final

historical example) the Romans financed their continuous

foreign and civil wars with very high production of silver

coins. The metal was produced from silver-bearing lead ores,

and the smelting process caused atmospheric lead pollution

that circled at least the entire northern hemisphere and left

a signature in the Greenland ice cap (Hong and others 1994).

It is a remarkable story of context. As Marc Antony and

Cleopatra dallied in the eastern Mediterranean, the silver

coins they minted to pay their armies caused American

Indians in the Rio Grande Basin to breathe air polluted by

levels of lead not seen again until the Industrial Revolution.

The prehistoric New Mexicans of that era could not, of

course, have understood this process, if they were even

aware that something in their air was wrong. They could not

know their context. I relate this story, and that of the Greek

landscape, to show how fortunate we actually are in the
USDA Forest Service Proceedings RMRS-P-7. 1999 11

midst of all our challenges. As we have lost direct connection

with our context we have also gained the ability to understand it, and that is the first step toward influencing it. We

have the capacity, more than the people of any previous era,

to know where we are in long-term historical processes

(Tainter 1988, 1995), in the international economy, and in

global environmental concerns.

We face, as I have sketched, contradictions between the

levels at which problems are generated and at which they

must be addressed. Many of us would no doubt prefer that

local environmental problems be addressed on the basis of

local experience, social memory, and heterarchy, and be

resolved sustainably on the basis of local resources. Yet

challenges arising from such things as atmospheric circulation patterns or international monetary flows bring us to a

world of problem-solving where we depend on hierarchy,

centralized solutions, and external subsidies. In such a

world we will always face conflict between local and centralized problem-solving. Our approach to this conflict should

start by taking advantage of the remarkable levels of knowledge that are available about our national and international

context. Resolving problems locally requires equal doses of

knowledge about the Basin itself and about the world at

large. It is unrealistic to expect that our context will ever

know us sufficiently well to avoid the sort of problem that the

French government caused in Burgundy. It is our responsibility to understand our context.

As the processes at work in the world call for broader and

broader realms of knowledge, most of us specialize in narrower and narrower pursuits—this or that species, or watershed, or cultural group. Accordingly we fail to see connections that ultimately we must understand, connections that

form the essence of ecosystem management. How many of us

would recognize that welfare reform, to take one example, is

pertinent to ecosystem management? How many of us realize that for rural areas there is a fundamental contradiction

between welfare reform and environmental conflict? As

judicial decisions deprive rural people of their livelihoods,

more and more will move to cities. Rural traditions of local

knowledge, social memory, and heterarchy will decline,

while the hierarchical, centralized cities will grow larger,

more congested, and more polluted. Environmental protection in one area may simply shift environmental problems

elsewhere.

To have the capacity to understand our context is meaningful only if we take advantage of it. We are challenged not

only to develop the ability to see connections between disparate things, but more fundamentally, to change how we think

so that it becomes normal and unremarkable to do so. This

is the only way that the problems of the Rio Grande Basin

will be understood, the best way that conflicts can be resolved, and the only way that we can discern the appropriate, ever-shifting balance among local, national, and international solutions. As the Forest Service and other agencies

have developed the concept of ecosystem management in

recent years, many have wondered what the term means. I

suggest that it should mean precisely these matters of scale,

context, and interconnection. These link the biophysical and

social realms in a bond that we can dissolve artificially in

specialized scientific analyses or in environmental litigation, but which can never be dissolved in actuality.

Acknowledgments ______________

I am pleased to express my appreciation to Dr. Deborah

Finch for the invitation to present this paper as a plenary

address in the symposium “Rio Grande Ecosystems: Linking

Land, Water, and People” (Albuquerque, 2-5 June 1998),

and to Dr. T. F. H. Allen and Dr. Dale Brockway for comments on an earlier draft.

References _____________________

Ahl, Valerie; Allen, T. F. H. 1996. Hierarchy Theory: A Vision,

Vocabulary, and Epistemology. New York: Columbia University

Press.

Alcock, Susan E. 1993. Graecia Capta: The Landscapes of Roman

Greece. Cambridge: Cambridge University Press.

Allen, T. F. H.; Hoekstra, Thomas W. 1992. Toward a Unified

Ecology. New York: Columbia University Press.

Allen, T. F. H.; Starr, Thomas B. 1982. Hierarchy: Perspectives for

Ecological Complexity. Chicago: University of Chicago Press.

Allen, T. F. H.; Tainter, Joseph A.; Hoekstra, Thomas W. n.d.

Supply-Side Sustainability. New York: Columbia University Press

(in preparation).

Bruce, James P.; Lee, Hoesung; Haites, Erik F., eds. 1996. Climate

Change 1995: Economic and Social Dimensions of Climate Change.

Cambridge: Cambridge University Press.

Crumley, Carole L. 1979. Three locational models: an epistemological assessment of anthropology and archaeology. In: Schiffer,

Michael B., ed. Advances in Archaeological Method and Theory 2:

141-173. New York: Academic Press.

Crumley, Carole L. n.d. From garden to globe: linking time and

space with meaning and memory. In: McIntosh, Roderick J;

Tainter, Joseph A.; McIntosh, Susan Keech, eds. The Way the

Wind Blows: Climate, History, and Human Action. New York:

Columbia University Press (in press).

Green, S. F., G. P. C. King, V. Nitsiakos, and S. E. van der Leeuw.

1998. Landscape perception in Epirus in the late 20th century. In:

S. E. van der Leeuw, ed. The Archaeomedes Project: Understanding the Natural and Anthropogenic Causes of Land Degradation

and Desertification in the Mediterranean Basin, pp. 329-359.

Luxembourg: Office for Official Publications of the European

Communities.

Hassan, Fekri. n.d. Environmental perception and human responses

in history and prehistory. In: McIntosh, Roderick J; Tainter,

Joseph A.; McIntosh, Susan Keech, eds. The Way the Wind Blows:

Climate, History, and Human Action. New York: Columbia University Press (in press).

Hong, Sungmin; Candelone, Jean-Pierre; Patterson, Clair C.;

Bouton, Claude F. 1994. Greenland ice evidence of hemispheric

lead pollution two millennia ago by Greek and Roman civilizations. Science 265: 1841-1843.

Hsu, Cho-yun. n.d. Chinese attitudes toward climate. In: McIntosh,

Roderick J; Tainter, Joseph A.; McIntosh, Susan Keech, eds. The

Way the Wind Blows: Climate, History, and Human Action. New

York: Columbia University Press (in press).

McIntosh, Roderick J.; Tainter, Joseph A.; McIntosh, Susan Keech.

n.d. Climate, history, and human action. In: McIntosh, Roderick

J; Tainter, Joseph A.; McIntosh, Susan Keech, eds. The Way the

Wind Blows: Climate, History, and Human Action. New York:

Columbia University Press (in press).

Tainter, Joseph A. 1988. The Collapse of Complex Societies. Cambridge: Cambridge University Press.

Tainter, Joseph A. 1995. Sustainability of complex societies. Futures 27: 397-407.

van der Leeuw, S. E.; ARCHAEOMEDES Research Team. n.d. Land

degradation as a socio-natural process. In: McIntosh, Roderick J;

Tainter, Joseph A.; McIntosh, Susan Keech, eds. The Way the

Wind Blows: Climate, History, and Human Action. New York:

Columbia University Press (in press).
12 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Richard D. Periman is Research Archaeologist, USDA Forest Service,

Rocky Mountain Research Station, Cultural Heritage Work Unit, located in

Albuquerque, NM.

Abstract—The successful restoration of riparian ecosystems to

sustainable conditions requires that we understand the dynamic

historical relationships between humans and the environment.

Research is needed that measures the continuing effects of past

human activities on contemporary ecosystem structure and function. An interdisciplinary approach is needed that incorporates

expertise from archaeology, paleoecology, plant ecology, and geology. In this paper, I discuss how prehistoric peoples have altered

ecological processes and changed the vegetation and overall physiography of northern New Mexico’s Rio del Oso Valley. In the Rio del

Oso study, we are using paleobotanical, sedimentary, archaeological, and historical data sets to reconstruct past vegetational structure and function, and to identify the cumulative influences of past

human activities on today’s ecosystems. This information is used to

generate three dimensional simulations of environmental conditions through time. These computer reconstructions and analyses of

past landscapes will give land managers a greater range of information for use in planning, decision making, and restoration.

Historical Information and

Restoration ____________________

The landscapes of the Rio Grande and its tributaries have

been modified, shaped, and domesticated by humans for at

least twelve millennia. Yet the myth of the pristine wilderness prevails among those intent on restoring or preserving

this land in its so-called “pre-settlement conditions” (cf.

Grumbine 1992). Often, “pre-settlement” refers to pre-A.D.

1850, seemingly negating thousands of years of Native

American land use and environmental influence (Quigly

and others 1996). Not only does this lack of ecological

understanding limit our knowledge of past ecosystem dynamics, it also restricts the future range of restoration

efforts possible in the Basin.

The National Resource Council defines restoration as the

return of an ecosystem to a close approximation of its

conditions before disturbance (1992). Before the objectives of

Dynamic Human Landscapes of the Rio del

Oso: Restoration and the Simulation of Past

Ecological Conditions in The Upper Rio

Grande Basin

Richard D. Periman

a restoration effort can be established, the ecosystem needs

first to be evaluated. Appropriate reference conditions need

to be established as goals for restoration of various ecosystem components. The interactions between biotic and abiotic

components of the ecosystem must be identified. Additionally, the significant linkages between biotic communities for

reestablishing historic ecosystem structure must be understood. Christensen and others emphasize that ecosystem

management needs clear long-term operational goals and

sound ecological models. Understanding ecological complexity and interconnectedness, recognizing the dynamic character of ecosystems, and acknowledging humans as ecosystem components is crucial for successful restoration, as well

as sustainability (Christensen and others 1996:669-670).

Evaluation of an ecosystem’s historic structure and function for the purposes of restoration, as indicated above,

needs to include study of long-term anthropogenic processes. However, our understanding of how landscapes

have developed under cumulative human influences remains limited, and assumptions, rather than the systematic

study of past conditions, perpetuate myths about ecosystem

development. For example, degradation by over-grazing and

other extractive processes may appear obvious. However, we

often know little about how a specific ecosystem may have

been manipulated, altered, and maintained by humans

before such degradation took place. What were the dynamic

historical conditions of landscapes we now consider degraded? What long-term processes, including human processes, contributed to this pre-grazing environment? Although historical documentation from personal journals

and photographs seem to answer these questions, such

sources provide only a glimpse of past landscapes from a

synchronic visual, spatial, and temporal perspective. For

restoration to be successful, a more comprehensive and

diachronic knowledge of past ecosystem dynamics that includes anthropogenic processes needs to be developed.

Addressing this lack of information, Rocky Mountain

Research Station’s Cultural Heritage Research Work Unit is

developing an interdisciplinary approach for quantifying

anthropogenic influences on ecosystem structure and function. Our first study area is located in northern New Mexico’s

Rio del Oso Valley where a variety of cultures have shaped

and changed the landscape for at least 7,000 years. In this

paper, I first provide a short discussion of how humaninduced environmental change has been identified in various areas world-wide. Then I describe the Rio del Oso study

and our use of paleoenvironmental information to construct

visual models of past vegetational landscapes. Finally I offer

a refinement to our conception of restoration.
USDA Forest Service Proceedings RMRS-P-7. 1999 13

Identifying Past Anthropogenic

Ecological Change ______________

Human-induced environmental change has been identified in environments around the globe. In a review of pollen

and charcoal studies from around the world, Walker and

Singh discuss a broad range of data from Western Europe,

Africa, Asia, Australia, and North and South America. They

suggest that the event most detectable in the pollen and

microcharcoal record is deforestation, and that this was

caused and aided by human-set fires (1993:108). Additionally, increases in microscopic charcoal, changes in fossil

pollen assemblages, and faunal extinctions also indicate

human occupation (Burney 1993 and 1997; Chambers 1993a).

Paleobotanical research in the Peruvian Andes shows that

human-caused deforestation for agricultural purposes took

place at least 4,000 years ago (Chepstow-Lusty and others

1998). Throughout the British Isles as early as 10,000 B.P.

(before present) reduced arboreal pollen, with a corresponding increase in microscopic charcoal and archaeological

evidence, indicates that human activity was responsible for

the transformation of forest into peatlands (Caseldine and

Hatton 1993; Edwards 1988; Simmons 1988). On the island

of New Guinea forest clearing is suggested by changes in

pollen assemblages and significant increases in microscopic

charcoal dating before 30,000 B.P. The human role in this

environmental change is corroborated by the presence of

stone axes and adzes (possibly used for forest clearing), from

archaeological sites that date to the same period. Indeed,

such clearing of vegetation may have begun much earlier in

New Guinea, as suggested by the discovery of ground-stone

axes, complete with grooves for hafting to a handle, dating

to at least 40,000 B.P. (Hope and Golson 1995:821-823).

In the Americas, ethnographical accounts, historical

records, and archaeological information show that people

directly affected ecosystems by manipulating vegetation.

Landscape patterns in native California were altered by

human activities such as sowing and broadcasting seeds,

transplanting shrubs and small trees, and pruning a variety

of plants to induce greater productivity (Blackburn and

Anderson 1993:19). Fire was used to clear vegetation and

increase the productivity of plants and animals important

for human survival. By 1492 agricultural fields were common, as were settlements with networks of roads and trails,

all of which had local impacts on soil, microclimate, hydrology, and wildlife 1992:370). Subsequently, the introduction of

Old World livestock, intensive agriculture, and industrial

development into existing Native American land-use systems resulted in a combination of anthropogenic influences

producing hybrid landscapes (Whitmore and Turner

1990:416).

Human actions of one century have a cumulative environmental effect when combined with human actions from

another century. Succeeding occupation and abandonment

causes a landscape’s developmental trajectory to evolve in a

new direction (see Tainter and Tainter 1995:28). Over the

course of generations, repeated and changing levels of human disturbance become part of the ecological processes in

an ecosystem (Allen and Hoekstra 1992:272). Each new

anthropogenic landscape is built upon an antecedent landscape. Such is the case in the Rio Grande Basin of New

Mexico where Puebloan agricultural landscapes were constructed upon those created by earlier foragers, and Spanish

colonial landscapes were built upon Puebloan farming

landscapes.

Rio Del Oso Study _______________

The Rio del Oso is an eastern-flowing tributary of the

Rio Chama that drains the northern portion of the Jemez

Mountains of north central New Mexico (fig. 1). Most of the

Rio del Oso watershed is administered by the Santa Fe

Figure 1—Rio del Oso study location.
14 USDA Forest Service Proceedings RMRS-P-7. 1999

National Forest. I selected the Rio del Oso as my study area

because of its complex richness of recorded archaeological

sites. More than 280 archaeological sites including four

large pueblos have been recorded in the lower portion of the

drainage (Anschuetz 1995). Although the anthropogenic

qualities of the Rio del Oso landscape may not be readily

discernable, this place has been shaped into the landscape

we see today by thousands of years of human activity. The

archaeological data of the Rio del Oso valley covers the

Archaic period (5500 B.C. to A.D. 600), the Coalition period

(1200-1325), the Classic period (1325-1600), and the historic

Hispanic period (beginning c.1600).

During the Archaic period hunter-gatherers occupied the

valley and likely affected the Rio del Oso landscape by

burning its vegetation, dispersing seeds, and selectively

harvesting plant and animal species. So far, archaeologists

have found little evidence for human occupation of the valley

between the late Archaic and the Coalition periods. However, from A.D. 1200 through 1600, the Puebloan groups

greatly altered the valley by creating villages, agricultural features and other systems of land and water use

(Anschuetz 1995).

When historic Hispanic groups moved into the Rio del Oso

they constructed small settlements and farms, built roads

and water ditches, and produced their own unique landscape

patterns in the valley (Wozniak and others 1992). During

the first part of this century the Forest Service assumed

administration of the area, creating yet another pattern of

human-use and environmental change by restricting grazing, building roads and fences, and attempting to restore

vegetation.

Data Sources and Methods

The primary goal of our research is to develop an integrated, interdisciplinary approach to identify and measure

cumulative anthropogenic effects on landscapes. Data in

the Rio del Oso project ranges from historical and ethnographic records to archaeological and paleobotanical data.

The Santa Fe National Forest has provided digital vegetation data, land type, watershed coverages, and Digital Elevation Models (DEMs), and has made all archaeological site

records and field maps available. Additionally, I am using

Forest Service administrative records, 1935 aerial photos,

and 1991 color infrared aerial photos to reconstruct the

valley’s environmental history and document vegetational

change for this century.

With these data map layers have been developed including vegetation, landform, watershed, and archaeological site

coverages. All four data sets will be used, either individually

or in combination, to develop visual models of the existing

vegetational environment. In this interdisciplinary study,

we are using archaeological, paleobotanical, sedimentary,

geomorphological, and historical data to identify past

human-induced ecological change through time. Our research questions include:

1. What interdisciplinary data sources, research methods, and analytical approaches can be used to develop

GIS data layers of past and cumulative human-created

landscapes?

2. Using the above methods, can we identify and quantify

the extent of human-induced vegetational change for

specific periods relative to the different technologies

and economies of the cultures that occupied the land

during those times?

3. Using data from the above sources, is it possible to

produce three-dimensional landscape models that accurately illustrate the environmental history of an

area? Which sources of information are the most useful? Do the resulting landscape simulations provide a

useful model for understanding human and environmental interactions?

4. Is it possible to develop a set of methods and techniques

that can be applied to ecosystems different from those

in northern New Mexico?

Fieldwork and Paleobotanical Analysis

Fieldwork began during the summer of 1996 with the

collection of soil samples from an exposed, 5 m stratified

section of alluvial sediments. Pollen, phytoliths, microscopic

charcoal, and radiocarbon samples were extracted from each

stratum. Four prehistoric human hearths, or ash-stain features, were uncovered while preparing the vertical surface of

the cutbank for sample collection. During sampling, geologist Dr. Stephen A. Hall (geologist and research partner,

Department of Geography, University of Texas at Austin)

identified seven distinct paleosols in the profile (Hall personal communication 1996).

In 1997 pollen, phytoliths, and microscopic charcoal were

extracted from the samples by paleobotanist Dr. Linda Scott

Cummings (paleobotanist and project collaborator, Paleo

Research Inc., Denver, CO). Radiocarbon dates were produced, ranging from 3515 B.C. to A.D. 1350, for the 24 strata.

The pollen analysis, when matched with the radiocarbon

dates, suggests fluctuations in vegetation and microcharcoal levels over the past 5,512 years. During her analysis

Dr. Scott Cummings identified corn pollen in three of the

levels dating between 1360 and 1225 B.C., associated with

hearths. Although presently inconclusive, this may be some

of the oldest evidence of corn in the Rio Grande Basin (see

Minnis 1992).

Additionally, surface samples for pollen, phytoliths, and

microscopic charcoal were collected from areas near our

stratified section. The data from those samples are being

used to develop control ratios of pollen frequencies to treesand shrubs-per-acre. These ratios will be used with the

three-dimensional GIS to reconstruct the hypothetical tree

and shrub densities of past landscapes.

During reconnaissance of the valley in 1997, other stratified deposits containing buried soils were identified, and

sediment samples were taken from newly discovered

cutbanks as well as from a peat bog located at the head of the

drainage. New surface samples were also collected from the

Rio del Oso’s riparian habitat. We conducted additional

analysis and developed new methods for analyzing opal

phytoliths during 1998. Dr. Scott Cummings identified an

abundance of phytoliths that appear to be from woody

plants, possibly from tree species. Appropriate phytolith

comparative collections being unavailable in the United

States, she took the phytolith samples to Israel where they
USDA Forest Service Proceedings RMRS-P-7. 1999 15Figure 2—Hypothetical simulations of Rio del Oso landscapes.
16 USDA Forest Service Proceedings RMRS-P-7. 1999

were compared to tree phytoliths identified by Israeli scientists (Scott Cummings personal communication 1998).

In 1999 we will excavate backhoe trenches at the first

sample location and at three of the localities identified in

1997. Additional samples will be taken from those locations

and the trenches will enable further study of the geomorphology of the Rio del Oso Valley. Future research will

include the calculation of areas affected by prehistoric

activities, the identification of zones around archaeological

sites and features representing levels of land use, and the

refinement of interdisciplinary methods for application to

other types of landscapes. We also will continue to establish

indices of surface pollen, phytolith, and microscopic charcoal, which represent different habitat types in the Rio del

Oso drainage.

Simulation of Past Landscapes

The Rio del Oso landscape simulations are based on

vegetational assemblages reconstructed from paleobotanical, ecological, archaeological, and historical data. Analyses,

of the paleobotanical samples by Dr. Scott Cummings will

identify variations in absolute and relative pollen and

phytolith frequencies, assemblages representing specific

habitats, past fire frequencies, and human-induced vegetational change through time. The quantities of vegetation

(for example, trees-per-acre) will be derived from the surface

and subsurface data as described above. This information

will be used to produce three-dimensional simulations of

past vegetational landscapes (fig. 2) from a variety of

viewsheds within the Rio del Oso drainage for each stratigraphic level. The simulations are grouped according to

their radiocarbon dates into corresponding archaeological

periods.

The simulations are created using a visual simulation

system designed by Resource Analysis Systems for natural

resource management. This software, called Visual F/X,

produces three-dimensional landscape perspective scenes

as if seen through a 35mm camera with a 50mm lens. It

allows the user to define up to 14 basic tree forms and control

the crown width, height, and trunk diameter. A DEM

(digital elevation model) is used as the base map and

vegetation density is derived from estimated trees- and

shrubs-per-acre figures. Additionally, we utilize digital vegetation, soil, timber, and watershed map data. The paleobotanical data (for example, pollen) are grouped by ecological

or phytogeographic categories to help illustrate how

plant distribution and ecological conditions have changed

through time (Pearsall 1989:286). These data will be used to

help identify temporal and spatial fluctuation of vegetation type areas, for example, riparian cottonwood-willow

habitat.

Linking Past Vegetational Patterns

to Ecological Processes __________

Along with compiling paleobotanical data that show ecological change, and represent that change graphically, we

also need to identify reliable indicators of past humancaused environmental change (see Birks and others 1988).

How does analysis of pollen and other organic particles

indicate human manipulation and change of the environment? The answer to this question may depend on the

“sensitivity of an ecosystem to human exploitation and the

degree to which this is reflected in the pollen analytical

signal” (Walker and Singh 1993:104). In order to discern

“natural” paleobotanical change from that caused by human

manipulation, Walker and Singh suggest four criteria:

1. It [the paleobotanical record] should reflect ecological

processes operating at levels and rates that are unprecedented under ‘natural’ conditions but are readily

explicable as resulting from human actions of defined

kinds.

2. The necessary human activities should be within the

technological capacity of prehistoric peoples of the

relevant age and region.

3. There should be some acceptable reason why the

humans might have taken the hypothesized action

(ideally exemplified by the pollen itself, for example,

crop pollen).

4. There should be strong evidence (ideally artifacts

stratified into the pollen-analyzed deposits) for human

occupation at the appropriate time within the pollen

catchment (Walker and Singh 1993:104-105).

When these criteria are applied to the pollen and charcoal

records of Europe, there is striking evidence for an anthropogenic influence resulting in the transformation of western

European forests between 7000 and 6000 B.P. This ecological change is attributed to clearing land for agriculture

(Walker and Singh 1993:106-107). Although the Rio del Oso

project includes the study of landscapes created before and

after the introduction and use of agriculture, these criteria

will be used to help determine human-induced environmental change from that caused by climate change and other

natural occurrences. However, I have added another criterion to help with the identification of anthropogenic change:

Two or more paleobotanical indicators, for example, pollen,

phytoliths, macrobotanical remains, packrat middens, ethnographic information, or historical photographs should

correlate when data sets are analyzed and compared.

An essential part of this analysis involves bridging the gap

between the paleobotanical record and interpretation of

vegetational landscapes. This interpretation is very important for producing the simulations discussed above. Pollen

and phytolith analysis identifies pollen producing plants

inside and outside an ecosystem. The paleobotanical record

accounts for a generalized sample of vegetation from a large

area (Pearsall 1989).

Designating a group of species that represents a specific

vegetation community will help describe the vegetational

variation of specific habitats within the Rio del Oso landscape. For example, an assemblage of species may represent

riparian areas while another group may represent species

growing mainly in upland habitats. It should be possible to

estimate vegetation density by comparing representative

species groups to the index surface of samples and then

compare the variation in pollen frequencies for each species

and each habitat assemblage. Such densities would be calculated as trees and shrubs per acre for spatially discrete

habitats. From this record a specific group of plant species

may be identified within a given range of pollen frequencies
USDA Forest Service Proceedings RMRS-P-7. 1999 17

which would identify human alteration of vegetational patterns. Comparing the fossil habitat assemblages and their

associated species frequencies to an index of current habitat

pollen frequencies gives us an estimate of the expansion and

contraction of individual habitats through time (Berglund

and others 1996; Pearsall 1989).

However, vegetational reconstructions are only the first

step in understanding how the Rio del Oso landscape developed under human influence. As stated earlier, we also need

to understand ecological processes. The following definitions for ecosystems, ecological landscapes, anthropogenic

landscapes can be used to link landscapes, ecosystems, and

human influences. Using Lindeman’s definition, an ecosystem is “the system composed of physical-chemical-biological

processes active within a space-time unit of any magnitude,

i.e., the biotic community plus its abiotic environment”

(1942:400). An ecological landscape is the spatial matrix in

which organisms, populations, and ecosystems are set

(Allen and Hoekstra 1992:56). Anthropogenic landscapes

are formed within and become integral to ecological spatial

matrices; they include process as well as form. Such landscapes are “land shapes,” areas which are made up of a

distinct association of forms both physical and cultural

(Sauer 1925:25-26). Landscape is the way we produce or

Figure 3—Model of long-term human influences in landscape development. Humans affect landscapes at all levels (a, b, and c).

reconstruct our physical, material world; a kind of human

sculpting of the natural universe (Wilson 1992).

In figure 3, ecosystem processes occurring through time

(a) are represented as cyclical, components, while the three

surfaces represent the landscape spatial matrix (b). Change

in landscape vegetation and geomorphology occurs within

the spatial matrix and is represented on the landscape

surfaces as differing vegetation (c). Human activities like

burning vegetation or practicing agriculture affect ecosystem processes. Over time these human-induced processes,

or changes in processes, affect plant community composition, habitat size, as well as carbon, nutrient, water, and

decomposition cycles. Changes in function (ecosystem processes) and structure (vegetation patterns and geomorphology) result in variations in the placement of landscape

components (see Hobbs 1997). Changes in technologies result in changes in ecological processes. As new, human landuse practices change vegetational patterns (for example, the

introduction of agriculture), new anthropogenic landscapes

are created within and are part of the ecosystem and spatial

matrix. Over thousands of years, this complex relationship

between humans and the environment has had a cumulative

effect on landscape development.
18 USDA Forest Service Proceedings RMRS-P-7. 1999

Restoration

In places like the Rio del Oso Valley human influence is

inextricable from the other components and processes that

created the landscape we see today. The relationships among

ecological and cultural processes can be important for restoration. An alternative to merely restoring vegetative structure (replanting etc.) using reference conditions would be to

identify a set of multidimensional reference dynamics (natural and anthropogenic). These reference dynamics should

include an understanding of the: (1) paleoecological evidence

of natural and human-induced change including change in

biodiversity and abundance of specific species; (2) technologies and processes responsible for specific environmental

change; and (3) temporal and spatial intensity and extent of

such change to the ecological-spatial matrix. By understanding these components, a land management agency has

more options for restoring and sustaining an ecosystem

within a range of ecological, climatic, and sociological

constraints.

Conclusions____________________

Public demand for the restoration of ecosystems degraded

by grazing, logging, and other extractive uses, daily challenges the ingenuity and resourcefulness of land management agencies. The landscapes we manage today have been

modified, shaped, and domesticated by humans for at least

twelve millennia. The concept of ecological restoration involves human intervention in ecological processes. Indeed,

the word “degradation” reflects human values and varies

among cultures (see van der Leeuw 1998). Just as past

cultures played an integral role in creating the landscapes

we see today, restoration involves the manipulation of ecological processes to achieve landscape conditions desired by

society. Current conflicts over public land management is

to some degree based on differing definitions of degradation

and what ecological conditions are considered desirable

(see Raish this volume).

Models of past landscapes like those being produced for

the Rio del Oso can help managers to understand better the

dynamic processes required for restoring ecosystems to

desired conditions. Creating landscape simulations based

on paleobotanical, archaeological, and geological data will

enable decision-makers to view their restoration options

within a range of dynamic processes leading to sustainable

conditions.

Acknowledgments ______________

I thank Joe Tainter whose support and guidance have

been inestimable. I wish to thank Liz Kaplan, Karin Periman,

Nora Altamirano, and Madelyn Dillon for their editorial

suggestions. I extend my sincere gratitude to Brian Kent

and Deborah Finch for supporting this research. From this

study’s beginning they have recognized the importance of

understanding that humans have been integral to the development of Rio Grande Basin landscapes for thousands of

years.

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20 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

José A. Rivera is Associate Professor of Public Administration, University

of New Mexico, Albuquerque, NM.

Some sections of this paper appeared in a recent book by the author,

“ACEQUIA CULTURE: Water, Land, & Community in the Southwest,”

University of New Mexico Press, Fall 1998.

Abstract—The acequia irrigation systems of northcentral New

Mexico and southern Colorado are the oldest, continuously functioning water management institutions in the United States. For a

period of four hundred years, 1598-1998, the acequias have sustained the agropastoral economies of the region while protecting the

watershed resources on which downstream water stakeholders

depend. The acequia customs of sharing and system of self-government provide a framework for sustainable resource use into the

twenty-first century in a time of changing and often conflictive

values. Continuance of these traditional institutions, however,

depends on how successfully they adapt to the new realities of the

emerging water markets in the region.

This year marks the cuarto centenario or 400th anniversary of the establishment of the first Spanish colony in El

Reino del Nuevo México, the northern border province of

Nueva España in the New World. On July 11, 1598, Capitán

General Juan de Oñate arrived at present day San Juan

Pueblo and established the first European colony in this

northern Spanish frontier, calling it San Juan de los Caballeros (Simmons 1991). During the early period of Spanish

exploration and expansion, Nuevo México loosely encompassed the territory north of Nueva Viscaya (Chihuahua)

with no fixed boundaries west or east (D. Cutter and

Engstrand 1996). From the start, Oñate and his party

conducted expeditions in both directions; but they expended

the majority of their efforts at establishing a permanent

colony and seat of government, initially at San Juan on the

eastern banks of the Río del Norte, as the Río Grande was

known at the time. Here, according to Oñate biographer

Marc Simmons (1991), Oñate planned to build a new municipality he intended to call San Francisco de los Españoles.

With the help of 1500 laborers from the nearby Indian

Pueblos, construction of a ditch was begun to support this

new town site and eventual capital city of El Reino del Nuevo

México (Simmons 1991; Hammond and Rey 1953).

For unknown reasons, Oñate abandoned his plans for

the building of a Spanish municipality in the vicinity of

San Juan, and instead he moved the colony to the west bank

of the Río del Norte directly across from the original site

(Simmons 1991). This settlement was called San Gabriel,

Water Democracies on the Upper Rio Grande,

1598-1998

José A. Rivera

itself built on a partially abandoned Tewa Pueblo. Here,

too, one of the first tasks of the Oñate party was to construct

an irrigation ditch sufficient to support the expansion of

cultivated fields essential for the permanent occupation of

the Spanish colony (Baxter 1997). San Gabriel (now known

as Chamita) remained as the capital of the fledgling province

throughout Oñate’s term as governor. In 1610 a subsequent

governor, Pedro de Peralta, moved the capital to a more

strategic location at Santa Fe, where once again, the construction of a municipal irrigation system was a primary and

early public works project. Two acequia madres (main canals)

were dug to irrigate fields on both sides of the Río de Santa

Fe, the river that passed through the center of the new and

permanent capital city (Simmons 1972; Twitchell 1925).

The occasion of the cuarto centenario anniversary provides

an opportunity to recognize the cultural, historic, political,

economic and ecological importance of the acequia-based

irrigation systems constructed at San Gabriel, Santa Fe,

and other later sites. Following Spanish laws, the acequia

appropriators long ago evolved customary rules for the

administration and equitable distribution of water resources,

traditions that have continued in force but that differ in

some respects with modern legal systems in the western

states. Though acequias are built systems carved into the

natural landscape, these earthen ditches in a sense mimic

the physics of the natural watercourses in the surrounding

area as much as alter them, relying as they do on the

relatively benign technology of gravity flow. Acequias contribute to the diversity of the landscape by extending the

biotic environment beyond the narrow confines of the river

channels from where they take water for the purposes of

irrigation.

In the semiarid environment of the uplands region, the

external effects of these ditches are largely beneficial, a

characteristic of acequia watercourses that needs to be more

widely recognized by other water stakeholders and the

general public. In most uplands river valleys, the acequia

communities are the first points of diversion of headwaters

streams. Their location in the area of origin upstream makes

them central to the maintenance of pure and clean stream

waters for all categories of uses downstream. Sustainability

of these communities, thus, coincides with values that acequia

irrigators hold in common with the multitude of other users

throughout the watershed: healthy forest ecosystems and

benign upstream uses preserve water quality for everyone.

In this sense, the historic stewardship role of acequia communities should be recognized, validated and supported in

modern water planning, state policies and laws.

Acequia agriculture also should be credited for providing

the social organization critical to the goals of Spanish colonization in the high altitude region which at the time formed

the northern borders of the vast Spanish empire in the New

World. This accomplishment makes the acequias of present
USDA Forest Service Proceedings RMRS-P-7. 1999 21

day northcentral New Mexico and southern Colorado the

oldest, continuously functioning water management institutions in the United States. For centuries the irrigators

have operated their acequias as water democracies, governing their own water affairs, electing their officers, and

enforcing their own rules. Functioning as they have under

three sovereigns (Spain, Mexico, and the United States),

these local acequia institutions have thus far survived the

test of time with only minor adjustments in their customary

practices, traditions and system of self-government.

Also, we should recognize that the first water laws of

New Mexico were based on customary usage and local

traditions passed on from generation to generation. These

acequia practices were crystallized into law by the New

Mexico territorial assemblies of 1851 and 1852. In southern

Colorado, the San Luis People’s Ditch holds the oldest water

rights in the entire state, a distinction commemorated by

way of a state monument which marks the location of this

“oldest continuously used ditch in Colorado, with court

decree priority right no. 1.” For centuries the acequias in

both states have carried on a tradition of resource stewardship and can be credited with adopting the first environmental laws to protect water quality and to promote water

conservation and public health. The remaining sections of

this paper demonstrate these and many other contributions

of the acequia waterworks located on the valley bottomlands

of the Río Grande watershed and other river systems in the

region. The paper concludes with a discussion of a few

contemporary issues impacting the acequia communities in

a time of changing realities and the emerging water markets

that challenge the continuance of the historic acequia institution into the 21st century.

Evolution of Watershed

Communities ___________________

Since the establishment of the first Spanish colony at

San Juan de los Caballeros, the upper Río Grande has

served as a continuous homeland for hispano mexicanos, a

mixed race of people who migrated as colonists from central

Mexico in order to occupy and settle the northern borders of

New Spain. Watersheds have long defined the boundaries of

community in this semiarid environment, not only as hydrologic units that support local agropastoral economies, but

also as the basis for social and political organization (Rivera

and Peña, 1998). Nestled within the canyons and valley

floors, tiny rural villages dot the spectacular and enchanting

landscape. These settlements survive due to the infrastructure of earthen ditches, native engineering works known

locally as acequias, that divert the precious waters from the

river systems to extend life into every tract and pocket of

arable bottomland. (Rivera 1996; Carlson 1990). In the

uplands physiography of northcentral New Mexico and

southern Colorado, these watercourses of rivers, streams,

creeks and acequias are the single most critical resource

needed for the survival of all forms of life: biotic, animal and

human.

The acequia-based farming methods that are still utilized

extensively in the upper Río Grande have Roman, MoorishIberian as well as indigenous, Pueblo Indian roots. The

Spanish and Mexican settlers who occupied the river corridors

of the northern frontier melded the Roman and MoorishIberian customs transplanted from Spain to Mexico with the

irrigation practices they observed at many Pueblo Indian

villages during their expeditions of the late sixteenth century (Simmons 1972). As to their own contributions, these

pobladores adapted and expanded irrigation farming

throughout the region, including diversions built on the

mightiest stretches of the Río Grande, the Río Chama, the

Río Pecos, the Mora and Gallinas rivers, and others. Constructed of locally available materials, the acequia irrigation works included an earthen presa (dam), the acequia

madre (main canal), and a network of sangrías or lateral

ditches that irrigated the individual parcels of farmland.

Together, the system of rivers, streams and acequias dominated the natural and rural landscape of the region, demarcating land uses and defining places of human occupation

and settlement.

Spanish Settlement Policies

The general region designated as El Reino del Nuevo

México was expansive and its boundaries indeterminate, but

the first Spanish communities were established along the

more confined Río del Norte corridor north and south of

Santa Fe from Taos to Socorro either on the present day Río

Grande or some of its tributaries (C. Cutter 1995). These

settlement practices concerning location generally adhered

to the ordinances set out in the Laws of the Indies and issued

by the Spanish crown to colonial officials as instructions

governing the pacification, development and permanent

occupation of newly discovered lands, the Ordenanzas de

Descubrimiento, Nueva Población de las Indias dadas por

Felipe II en 1573 (Crouch, Garr, and Mundigo 1982). Codified in 1681, the ordinances in the Laws of the Indies

provided the framework for colonists and provincial governors to follow when selecting sites for occupation and

development.

An important element in the ordinances was that fact

that Spanish settlement planning through these instructions was environmentally guided from the outset (Arellano

1997; Carlson 1990). The ordinances, for example, instructed

officials and colonists to establish settlements in sites with

access to plentiful supplies of clean and pure waters for

irrigation and domestic uses. In addition, the lands and the

surrounding environments should be replete with the natural resources necessary to sustain permanent colonies: forests to supply fuel wood and building materials, abundant

pasture lands for the grazing of livestock, lands with healthy

and fertile soils for the cultivation and harvesting of crops,

and a sky with clean, benign and pure air without impediments or alterations (Arellano 1997; Crouch, Garr and

Mundigo 1982).

Throughout the period of Spanish settlement, colonial

officials for the most part complied with the necessity of

locating villages in places where reliable water supplies

could support the permanent occupation of the province and

thus secure the northern Spanish borders. As noted by

Carlson (1990), agrarian planning reflected strongly the

environmental realities of the settlement region, where

rough terrain, aridity and high altitude limitations on the

growing seasons necessitated an integrated approach to

colonization. Spanish officials overcame these physical
22 USDA Forest Service Proceedings RMRS-P-7. 1999

barriers, Carlson and others argue, by implementing a wide

array of land grant policies on the Río Grande watershed and

its short but numerous perennial streams. In the case of

communal land grants, for example, settlers petitioning for

lands were required to specify the physical boundaries of the

desired grant of land. Significantly, the boundaries of the

land grants were not predetermined according to any

formal grid plan, and instead were established according to

the natural contours of the land, resulting in irregular

shapes highly adaptive to local topography, vegetation,

soils, hydrology and mircrobasin climates (MacCameron

1994; Van Ness 1987; Scurlock 1998).

In the next step, the governor would order an inspection of

the boundaries to be conducted by the alcalde mayor of the

jurisdiction. This official had to ascertain that the land in

question was not already settled nor prejudicial to the

welfare of any existing Indian Pueblo or other Spanish land

grants in the vicinity. Part of the investigation on-site also

included an evaluation of the water supply needed for

irrigation and domestic uses, and for the watering of livestock (Baxter 1997). Further, the alcalde mayor made sure

that the land, water and other natural resources within the

boundaries of the grant would encourage tilling of the land,

the grazing of cattle and other elements essential for permanent occupation (Keleher 1929). Absent any legal protests

from adjacent Indian Pueblos or other neighboring communities with potential claims on the existing resources of the

area, the governor would then be free to confirm the grant

and authorize that the alcalde place the settlers in possession of the designated lands.

As part of the possession activities, each petitioner would

be allocated a solar de casa for a homesite and an accompanying suerte, an irrigable parcel with boundaries laid out in

a spatial arrangement consistent with the topographical

and hydrological character of the watershed. The width of

these individual tracts varied from site to site, dependent on

local physical conditions and an estimation by the alcalde as

to the size and configuration of bottomlands necessary for

successful cultivation (Carlson 1990; Wozniak 1987). This

unique farming landscape integrated each farm unit into

the lay of the land and the watercourses for irrigation. The

tiras, elongated long lots that resulted from partitioning,

provided each land grant family with access to the fertile

bottomlands and river banks, an essential aspect of gravity

flow, communal equity and social organization (Rivera and

Peña 1998; Carlson 1990). Similarly, all families would have

access to the ejidos or common lands in accordance with the

Spanish laws and local customs of the times. In these open

lands, native pastures and forested areas typically surrounding the land grant community, villagers could freely

graze their livestock, gather wood, harvest native plants and

berries, hunt for wild game, and engage in other collective

use privileges (Tyler 1989).

After the partitioning of the land, the settlers began the

process of forming their community. Though the Spanish

planning precepts for town layout and physical design were

followed loosely—adapted to local conditions and resources—

the upstream boundaries of each village were usually designated according to the place where the stream source was

diverted and a dam installed. As part of the initial inspection, when needed, the alcalde would help locate suitable

places where one or more ditch diversions could feasibly be

built to take water from the river source (Carlson 1990;

Wozniak 1987). Once determined, this saca de agua (the

diversion dam) was the first public works construction

project undertaken in the formation of most communities,

begun even before the building of the local mission or church.

On larger streams, such as the Río del Norte, the settlers

built wing dams protruding into the river from one of the

banks; these simple structures were usually sufficient to

channel water into ditches during the irrigation season

when natural flows were highest. Streams with intermittent flows, on the other hand, required the construction of

dams across the width of the watercourses in order to

impound portions of the flows and form small reservoirs. The

presas (diversion dams also called atarques) were constructed

of forest timbers, juniper brush, boulders, rock slabs, earth

and other local materials, resulting in structures that often

resembled beaver dams. These building materials were

placed on the streambed in a layered fashion gradually

raising the level of impounded water closer to a ditch

headgate constructed on the banks of the stream. Containment of the water by the presa would accomplish the rest of

the task, with gravity flow pushing the water into and

through the main irrigation ditch or acequia madre.

To complete the infrastructure for irrigation, the pobladores

excavated the acequia madre off one or both banks of the

river, thereby extending the irrigable lands adjacent to the

watercourse for several miles downstream. Typically, each

acequia madre was cut perpendicular to the stream source

at the upper end of the community in order to then convey

water downstream, parallel to the river alongside the foothills or natural slope of the terrain, all the while enclosing

the practical limits of irrigable land. Then, at the bottom end

of the community the ditch was made to return to the

original stream source through a desague channel.

Each commons ditch, described in the Spanish of the times

as the “acequia de común,” was the main force that established a distinct place, defined the community boundaries,

and bonded the irrigators obligating them all to the collective management of the local water system and their village

enterprise as a whole. The idea of a common property ditch

for all irrigators in any new settlement was replicated time

and again in the province and, in fact, was the key to both

the development and economic survival of local communities. As Tyler (1989, p. 26) vividly describes, the officials who

placed the grantees in legal possession of the community

grants made sure that the settlers acknowledged their

rights and responsibilities to the common welfare “by swearing de mancomún or de mancomunidad,” meaning that they

agreed to “work together for the benefit of the community

and jointly manage their common property.”

Land and Water Petitions

Spanish colonization policy, thus, resulted in the building

of communities alongside the Río del Norte and its tributaries in both westerly and easterly directions, further and

further from the main stem of the river, eventually dispersing the population into numerous plazas, ranchos, villas,

and other water-based colonies. Access to irrigation water

served as the guiding principle, a continuation of land policy

implemented from the outset since the founding of the early

villas: San Gabriel in c.1600, Santa Fe in 1610, Santa Cruz

de la Cañada in 1695, and Albuquerque in 1706.
USDA Forest Service Proceedings RMRS-P-7. 1999 23

When Governor Don Diego de Vargas proclaimed Santa

Cruz in 1695 as the next villa after Santa Fe, for example, he

did so because of the known fertile soils and plentiful supply

of irrigation water available at the valley area known as La

Cañada (Baxter 1997). By 1696, newly arrived families from

Zacatecas and Mexico City could no longer be supported by

the acequias and cultivated fields irrigated by the Río de

Santa Fe at the capital city. Additional water and land

resources would be needed to accommodate the growing

population of the province. In his 1696 decree allowing a

second group of Spanish-Mexican families to move to the

Santa Cruz land grant, De Vargas assigned to them the use

of the agricultural lands, irrigation ditches and dams, built

at his expense, as well as access to the natural resources

within the La Cañada environs. The decree by De Vargas

illustrates the Spanish colonial precepts for town site planning, common lands use, and the reciprocal interdependence

of land grants, irrigation, and the formation of community in

the acequia culture that was emerging in the fledgling

province:

Having recognized that in this villa of Santa Fe there is not the

supply of water which is requisite to insure the irrigation of the

cultivated fields, in order to maintain the families domiciled

thereon; and having recognized that this said villa [of Santa Cruz]

has better accommodations ... I assign them to said villa for the

aforesaid reason.

I, the said Governor and Capitan General, have decided to go

personally to the said Villa Nueva de Santa Cruz ... to examine the

lands, whose sections are uncultivated, being naturally fertile,

and being under irrigation as they are, and able to use the water

which the rest have had generally in great abundance, assured by

their ditches, clean and running, which have been established at

my own expense, as I have also repaired and made their dam

secure.

...likewise this will serve them as a patent to be residents belonging and assigned to the said Villa Nueva de Santa Cruz, and as

such will further their use of the said lands, and their right to the

pastures, woods, waters and minerals, as it appears in the [land]

grant made to the said Mexican residents of said Villa Nueva, and

that the said order made in their favor will be sufficient title for the

privileges derived from the grant that I, the said Governor and

Capitan General, have assigned to them in the name of his majesty

(De Vargas Decree 1696).

Expansion of settlements to the upper reaches of the

Río del Norte and to other basins frequently resulted from

petitions by groups of restless colonos (colonist settlers) for

more land and water to support the growing population in

the uplands region. These petitions enabled the pobladores

to respect the carrying capacity of the land and watershed

streams they believed were already fully developed and

appropriated. Repeatedly, groups of settlers took initiative

to branch out in search of new territories just when the local

natural resources, especially irrigation water from the rivers and creeks, began to show signs of stress. By around

1800, there were some 164 community ditches in the province, a number that would continue to grow at an even faster

rate during the late colonial and the start of the Mexican

period of land grant concessions (Hutchins 1928). Population growth and policies in support of colonization prompted

hispano mexicanos to seek new lands for development well

into the Mexican period. Availability of water was always of

paramount concern. In 1837, for example, a group of vecinos

(citizen residents) from the Valle de Santa Gertrudis (Mora)

petitioned the alcalde at Las Trampas for additional lands a

few miles to the east, permitting them to take possession of

the Guadalupita Valley on the Río del Coyote, a tributary of

the Mora River. The petitioners proclaimed that new cultivable lands were necessary to sustain themselves and their

families due to the scarcity of water at their current location

in Mora:

We, the citizen colonists, among your Lordship’s proven subjects,

upon finding ourselves very cut back in water supply at this

current place of residence, appeal to your kindness in the name of

God and his divine laws, if you could be magnanimous and grant

us the right to take possession of the Valley of Guadalupita, at the

Coyote River, to cultivate and sustain a settlement there.... [To

sustain] our families and in all reverence to the nation, with

dignity, please accept our stated need with the list [of petitioner

names] attached so that you may know the number of individuals

that we submit for your kindness, and that is why we place this

request to see if you can serve in the name of Justice to decree your

wishes (Petition to Take Possession of Valle de Guadalupita,

1837).

The alcalde of the jurisdiction, Juan Nepumuseno Trujillo,

acknowledged their petition and requested that the colonos

appear before him within a few weeks of that same year,

clearing the way for the eventual approval of the new

settlement at Guadalupita and subsequent river communities downstream on the Río del Coyote (Lower Coyote,

Lucero, and El Llano del Coyote, now Rainsville).

Social, Political and Ecological

Values _________________________

Besides performing their irrigation function, the acequia

waterworks have served other equally important roles:

social, political and ecological. As a social institution, the

acequia systems have preserved the historic settlements

and local cultures spanning four major periods of political

development: Spanish Colonial (1598-1821), Mexican (1821-

1848), Territorial (1848-1912), and New Mexico Statehood

(1912-Present). Politically, most acequia villages continue

as unincorporated entities. In most places, the irrigators

and their acequia associations serve as the only form of

local governments below the county level. In the New Mexico

portion of the region, these associations have been recognized time and again as political subdivisions of state government, a legal status similar to that of counties, townships

and school districts (Report of the Attorney General of NM,

1963-64). More recently, the federal government has also

recognized the acequia associations as public entities. In the

Water Resources Development Act of 1986, Congress directed the Army Corps of Engineers to help restore and

preserve the acequia engineering works and to enter into

agreements with the acequias themselves as the local sponsors of the projects (Public Law 99-662). By 1996 these

cooperation agreements had resulted in fifty-two contracts

with local acequias for the financing of forty-nine ditch

rehabilitation and diversion projects amounting to 14.2

million dollars in federal funds (Annual Report, SEO/ISC,

1996).

General maintenance of the community ditches continues

to be a responsibility of the acequia officers and parciantes

(the irrigators). The annual limpia (cleaning) of the acequia

not only marks the beginning of the agricultural season in

early spring, it is also an occasion for the vecino irrigators to
24 USDA Forest Service Proceedings RMRS-P-7. 1999

address local issues, reconfirming the traditions and values

that undergird the social and political life of the community.

During this ritual event, the ditch officers and irrigators,

informally or in small groups, may address a broad range of

topics such as the condition of the presa in the river, any

repairs that might soon be needed, the amount of projected

water flows based on the winter snowpack at the sierra

headwaters, and other items of importance to the ditch or to

the community as a whole. By the end of the ditch cleaning

process, the irrigators have dutifully renewed their attachment to the land base of their own particular locality,

assuring the continuance of place for yet another cycle of

irrigation.

Recently, bioregional studies have documented that these

earthen waterworks serve ecological and other purposes

that should also be recognized by the public. Acequias, for

example, extend the riparian zone, preserve farmland and

rural open space, increase local biodiversity and protect the

hydraulic integrity of the watershed. According to research

conducted by Devón Peña and his colleagues, acequia landscapes in the San Luis Valley of Colorado and throughout the

upper Río Grande double as important biological corridors

and habitat islands for many species of plants and wildlife

(Peña 1997) Conservation biologists, per Peña’s analysis,

might say that the acequia human community becomes the

“keystone” species in the bioregional environment because

numerous other life forms, wild flora and fauna, become

dependent on the expanded habitat made possible by the

ditch watercourses (Peña 1997; Noss 1994).

The beneficial impacts of acequia irrigation methods on

the landscape, hydrology and the local ecology are many. For

example, the earthen acequia watercourse itself helps to

recharge the local acquifer through the natural process of

seepage. Aided by gravity flow, water that continues to flow

through the ditch extends the stream to a new, wider

landscape; meanwhile, the water moves gently through the

ditch and its sangrías, a process that spreads water slowly

through the long-lot fields, helping to retard soil erosion.

Water that percolates down to the aquifer aids in the

cleansing of groundwater. Seepage throughout the ditch

system nourishes the cottonwood bosques as well as native

shrubs such as plum, chokecherries, willows, and other

native plant species which, in turn, provide corridors of

shelter, cover and food sources for wildlife (Peña 1997). Any

unused waters are returned to the stream as sobrantes, or

surplus waters, destined for other beneficial uses downstream.

Putting stream waters to beneficial use through acequiabased farming can also help to maintain instream flows for

the protection of fish habitats. Both of these uses need not

be viewed as conflictive, one at the expense of the other.

Instead, they can be viewed as relatively compatible in the

sense that they each require a minimum flow or otherwise

sufficient hydraulic head of water in the river, as long as

there is adequate quantity for both uses. Other water use

alternatives, especially water-rights transfers from surface

use to groundwater pumping, deplete hydrologically connected stream flows. This application can result in the

lowering of the flows to levels potentially adverse to fish

and other wildlife dependent on river systems that are wet

year round. Acequia systems, on the other hand, contribute

to the health of the river by flushing silt and taking surface

water in the season when it is available, as opposed to

groundwater pumping, which most often creates deficits of

water quantity by depleting the aquifers well into future

years.

Stewardship and Environmental Ethics

The Spanish institutional framework for arid-lands irrigation has survived essentially intact into the modern era of

agropastoral farming on the upper Río Grande. Unlike the

fate of the community ditches in San Antonio, Texas, where

the once indispensable network of mission acequias has

been destroyed or reduced to tourism sites as remnants of

the past, the acequias of northcentral New Mexico and

southern Colorado continue to function in the traditional

manner. Around the globe, the traditional and political

rights of land-based peoples are increasingly threatened by

demands placed on the limited resource base critical to the

survival of local cultures. But there is growing evidence

that countries in both the Third World and the West are

giving serious attention to alternative models of development that emphasize community-based conservation and

the utilization of the many reservoirs of indigenous and

traditional knowledge. In the field of development administration, for example, planners and other officials now propose that cultural diversity itself is a global resource that

should be preserved alongside the need to maintain and

protect biodiversity (Kleymeyer 1996; Berkes and Taghi

1989; Redclift and Sage 1994). Customary rights and local

traditions need not be regarded as impediments to rational

water management; instead, modern legal systems should

be redefined to co-exist with customary practices and thus

achieve optimum resource utilization.(S. Clark 1990).

After four hundred years of successful adaptation, the

acequias of the upper Río Grande are model institutions

worthy of further research. A good starting point is to

consider the conservation ethics and environmental values

that acequia irrigators inherited and transplanted from

Old World irrigation systems. In his study of medieval

Valencia, Spain, Glick (1970) found that the basic irrigation

unit in the society was the comuna, a unit he defined as a

group or community of irrigators all irrigating from a single

main canal. These comunas were instruments for selfgovernment in the water affairs of local society; and by way

of ordinances, they provided for the maintenance of the

canal, authorizing the local cequier (official similar to the

ditch boss or mayordomo in New Mexico and Colorado) to

impose fines in cases where water was being wasted or

polluted through unauthorized uses (Glick 1970).

Water quality protection and conservation were likewise

taken seriously in the acequias de común that flourished

centuries later in the upper Río Grande, carrying forward

the water ethic evident in the irrigation societies of medieval

Spain. In his review of customary practices transplanted

from Spain to New Mexico, Malcolm Ebright (1994) noted

that the environmentalist ethic was woven directly into the

very fabric of custom and public law in the Spanish and

Mexican land grant communities. A 1705 decree by Governor Francisco Cuervo y Valdez, Ebright points out, mandated that villagers of Santa Fe should not drive their

livestock onto a marshy wetland and public commons known

as the cienega; anyone who violated this order would face a

jail sentence. These orders were repeated by subsequent
USDA Forest Service Proceedings RMRS-P-7. 1999 25

governors such as in 1717 when the village pigs and other

loose animals were rounded up to prevent damage to the

planted fields and the grass meadows found at the cienega

commons (Ebright 1994).

Guided initially by Spanish and Mexican water laws, the

early settlers were mindful of conserving the resource base

for themselves and for future generations, especially when

the existing water supply could no longer support additional

community growth. As mentioned earlier, petitions for additional land grants were submitted to the authorities with

admirable regularity as population densities and the need

for increased agricultural productivity outstripped the carrying capacity of the land base. After the new lands were

occupied, irrigation practices were regulated in a manner

designed to conserve the scarce water supply in each farm

village. During the Mexican period, the Provincial Statutes

of 1824-26 authorized local alcaldes to impose a one peso

fine, plus the costs of repairs, on any irrigator who caused the

flooding of roads and fields by not closing off his ditches

when they overflowed (Provincial Statutes 1824-26). The

first comprehensive acequia statutes were adopted in 1851

and 1852 at the start of the territorial period in New Mexico

(Laws of 1851-52). Here again, water conservation was

mandated. Section thirteen of these water laws stipulated

that the mayordomo (ditch boss or superintendent) should

apportion the available waters to each particular irrigator,

but not only according to the amount of cultivated land he

owned; the mayordomo should also take into consideration

“la naturaleza de las semillas, cosechas y de las legumbres

que se cultivan...” (the nature of the seeds, crops and plants

to be cultivated...). Furthermore, each irrigator was entitled

to retain all native plants of any description growing naturally on the ditch banks bordering and running through his

property (Laws of 1851-52).

Other territorial laws specifically addressed the need to

maintain water purity and quality in local ditches. In some

ditches, mayordomos were authorized to levy fines against

persons who befouled acequia waters by washing dirty

clothes, bathing, or allowing swine to wallow inside the ditch

(Laws of 1868 and 1872, cited in I. Clark 1987). By the turn

of the century, a series of general, anti-pollution water laws

had been enacted (1880, 1897, and 1899) that applied to all

acequias of the territory. These laws prohibited the pollution

of streams, lakes, and ditches by any number of means or the

discarding of objects that would endanger the public health

of the community. The penalties, upon conviction, were

gradually made more severe, up to one hundred dollars and/or

a sixty-day jail sentence in the 1897 laws (cited in I. Clark

1987).

Dividing and Sharing the Waters

Water conservation became a frequent concern in the late

nineteenth century as the number of ditches and irrigators

increased in some of the more densely populated valleys. The

solutions and arrangements for the sharing of available

water were primarily of local design, either by custom or

legal agreements on how to divide the water, practices that

continue to the present either intact or in some modified

form. Some localities divide the water according to fractions

where each ditch is entitled to its prorated amount of water,

such as a one-third share in the case of three acequias

sharing the water in equal parts out of a common compuerta

or headgate at the stream source. Other arrangements

divide the water based on a scheduled time rotation, as in an

1895 example where ditches located in two Taos precincts

agreed to take water from four streams in their area according to a predetermined weekly schedule. One precinct would

be entitled to all the available water flowing in the four

streams for their exclusive use and benefit from Friday of

each week at sunset until the following Sunday at twelve

noon; the second precinct thus, would take the water the rest

of the time, from Sunday at noon until sunset on Friday. Per

the terms of the agreement, this rotation plan would be

repeated through the remainder of the irrigation season,

lasting until the fifteenth of September every year (Agreement to Divide Irrigation Waters 1895).

During periods of drought or low water flows in the river

source, most local acequias strongly value their customary

practices of sharing, setting aside any legal rights based on

prior appropriation. In many watersheds, acequia irrigators prefer the repartimiento system of dividing water according to local customs and traditions, where water is

shared by all users, regardless of priority dates. Under these

arrangements of customary usage, irrigators divide water

based on historic practices of sharing and the need to provide

auxilio (emergency mutual aid) during times of shortage or

drought. This time-honored system of reciprocal assistance

runs counter to the prior appropriation doctrine which

forces a system of hierarchy among acequias and users who

share the same stream source. Acequia officials and the

parciantes as a whole are aware of this conflict, but most opt

to ignore the strict system of priority calls on the river and

would rather continue to share the water in the traditional

manner (see Adjudication Hearings 1991).

This obligation to offer auxilio in times of special need and

to share water during conditions of drought continues to be

a deeply held belief of the acequia irrigators, an influence

perhaps from the Moorish traditions evident in Spanish

water law. According to I. Clark (1987), the Islamic law of

thirst granted free access of water for all living things to

satisfy their needs in the aridity of the north African homeland. “Islam not only subscribed to a belief in the purifying

character of water ... but also the moral obligation of each to

help all others of the community in the time of need” (I. Clark

1987, p. 9). Or in the words of a Taos parciante at the

adjudication hearings on customs and traditions held in

1991 by Special Master Frank Zinn: “When [the flow is] low,

nobody has any. When it’s high, everybody has some. That’s

the way it was too. If there’s a cup of water there, we will

share it” (Adjudication Hearings, Testimony of Esequiel

Trujillo, May 20, 1991).

Repartimiento, water rotation schedules and other devices of sharing water have continued as local practices into

the contemporary period, evidence of the persistent conservation ethos among acequia parciantes. Often, water rotations are established where individual irrigators from a

single ditch are assigned certain days and hours of the week

when it is their turn to take water from the ditch to irrigate

their fields and gardens. Ditch rules provide for stiff penalties should an irrigator take water out of turn. Rules have

also been crafted by the users themselves to protect and

enforce water quality standards in the ditch. Just before

statehood in 1911, for example, the parcionistas (landowner
26 USDA Forest Service Proceedings RMRS-P-7. 1999

irrigators) of the Margarita Ditch in Lincoln County charged

the mayordomo with enforcing the “Reglas de Limpiesa,”

(Rules for Cleanliness). The Margarita Ditch Rules prohibited anyone from discarding junk in the community ditch,

namely, “garras, cajetes, puercos cueros, barriles o otras

porquerillas que sean en prejicio de la saludbridad de los

ha[b]itantes” (rags, tubs, pig hides, barrels, or other filthy

objects which might endanger citizen health).

Acequias and Contemporary Public

Policy _________________________

The goal of Spanish settlement during the colonial period

was to inhabit the vast reaches of the province based on

agropastoral economies, a land use practice resulting not in

the establishment of municipios (municipalities) but in the

dispersal of the population throughout the rural jurisdictions of the region (Tyler 1990; Simmons 1969). Within the

confines of available resources, some physiographic limitations, and many opportunities for creative engineering, the

early pobladores proved adept at implementing the goals of

colonization expressed in royal Spanish ordinances and

subsequent Mexican land grant concessions. With the active

encouragement of government officials who liberally implemented Spanish and Mexican land-distribution policies,

the hispano mexicano settlers established permanent communities throughout the narrow valley bottomlands of

La Provincia del Nuevo México. Acequias have withstood the

test of time and insured the survival of a unique regional

culture into the twenty-first century. These water institutions have operated with a few basic rules based on customs

and traditions managing communal property resources with

minimal government interference or assistance, features

they share with other small-scale irrigation organizations

around the world: the subaks of Bali, the zanjeras of the

Philippines, the sociedades de riego in the Tehuacan Valley

of central Mexico, and the huertas of Valencia, Spain. (Ostrom

1990; Berkes and Taghi 1989; Whiteford and Henao 1980;

Maass and Anderson 1978).

In the upper Río Grande, the benefits of acequia-based

farming extend well beyond the consumptive needs of the

irrigators themselves. Watershed studies have established

that acequias also help to maintain other important social,

cultural, economic and environmental values that should

be recognized by downstream water stakeholders, policymakers and the general public:

1. The acequia culture of the region promotes tourism and

economic development;

2. Protection of the acequia system of agriculture also

protects the health of rivers, forests and the watershed

headwaters in the sierra peaks;

3. Acequias promote a land ethic supportive of responsible stewardship of the watershed ecosystem in a high

altitude, arid lands environment;

4. Acequias double as wildlife habitat and travel corridors, and therefore promote both wildlife and plant

biodiversity; and

5. Acequia associations are democratic institutions that

are dynamic, self-reliant and sustainable forms of local

government (Rivera and Peña 1998; Rivera 1996).

Comparatively, the upper Río Grande community acequias

of southern Colorado and New Mexico stand apart from the

fate of many other irrigation canals in the western United

States. In Worster’s historical study (1985), most irrigation

systems in the American West have succumbed to the forces

of the new hydrologic society, where water has been reduced

to a simplified, abstracted resource, separated from the

earth in a manipulative relationship with nature:

The modern ditch is lined along its entire length with concrete to

prevent the seepage of water into the soil; consequently, nothing

green can take root along its banks, no trees, no sedges and reeds,

no grassy meadows, no seeds or blossoms dropping lazily into a

side-eddy. Nor can one find here an egret stalking frogs and

salamanders, or a red-winged blackbird swaying on a stem, or a

muskrat burrowing into the mud. Quite simply, the modern canal,

unlike a river, is not an ecosystem (Worster 1985, p. 5).

The earthen acequias of the upper Río Grande are unique

in the western states. The acequias de común continue to

function much as before, as model institutions of water

management in environments where water is not plentiful

and where reciprocal relationships of mutual aid are increasingly necessary if the human, animal and plant communities are to survive in balance and harmony. These

keystone acequia villages perpetuate cultural continuity, a

sense of place, and an indigenous system of participatory

democracy that is worthy of public support as we enter the

twenty-first century and already are confronting the challenges and opportunities of a pluralistic, diverse society of

competing and often conflictive values.

Fortunately, values and perspectives concerning water

resources policy are changing, especially in the American

West where the era of large scale water development projects,

meant to harvest and channel water destined for urbanizing

regions or to reclaim desert lands for agribusiness welfare,

is rapidly ending. Most river streams are fully appropriated

or committed to the delivery requirements of interstate

compacts and binational treaties. Thus, a new conservation

ethic is taking root, but so are water markets and other

mechanisms to transfer water away from historic or traditional uses in order to accommodate population growth,

industrial development, recreational uses and other demands. These “higher use” values increasingly threaten the

ability of acequia irrigators to compete on even terms. In

Colorado and New Mexico water rights can be severed from

the land and sold in the marketplace much like other

property commodities. Some of the competing stakeholders

perceive the acequia institution as antiquated and an obstacle to growth and development. To the critics, the acequia

methods are wasteful and too primitive for the needs of a

modern economy based on new industries, corporate agriculture, municipal growth and recreational tourism.

The challenge to acequia users is to retain ownership of

their ancestral water rights in the face of mounting pressures to sell or otherwise transfer water rights out of the

community. Not only must they continue to put their water

to beneficial use, to avoid forfeiture, but in most cases they

must also increase production, raise incomes and generate

economic returns sufficient enough to discourage sales and

transfers. Already, some ditch associations experience difficulties when it comes time to clean or repair the ditch

waterworks. Maintenance of the system requires full and

sustained participation from all parciantes, whether they
USDA Forest Service Proceedings RMRS-P-7. 1999 27

farm or not. Acequia officials fear that one water transfer

from within the group of irrigators will lead to others,

creating a domino effect, leaving fewer and fewer parciantes

to maintain the ditch, raise funds for the seasonal repairs,

enforce and administer the rules, and generally keep up with

the chores of organizational maintenance. A collapse of the

acequia institution would be catastrophic to the community

and perhaps the surrounding area (Rivera 1996).

The event of the cuarto centenario provides an opportunity

for all stakeholders and public officials to reflect on the

historic and cultural values intrinsically connected to traditional water uses in both the Hispanic and Pueblo Indian

communities. In the long run, sustainability of water quantity and quality may depend more on democratic and social

processes than on technological or regulatory fixes. Understanding, dialogue and new ways of sharing are imperative.

The four hundred years of acequia customs, traditions and

values have endured and passed the test of time thus far.

The pressures of the water markets in the bioregion have

surfaced new realities creating tensions and conflicts across

the myriad of users and stakeholders, and within the acequia

communities themselves. Survival of the acequia institution

depends on how adeptly the irrigators and their officers

respond to these challenges and chart a course of action into

the 21st century.

References _____________________

Adjudication hearings on customs and traditions, transcripts. 1991.

In: State of New Mexico vs. Eduardo Abeyta and Celso Arellano,

and others, United States District Court for the District of

New Mexico, May 20, 21, and June 11, 1991.

Agreement to divide irrigation waters, Acequia Madre del Cerro and

Latir Ditch. 1895. In: Rivera, José A. 1998. Acequia Culture:

Water, land, and Community in the Southwest. University of

New Mexico Press, Albuquerque, pp. 178-180.

Annual report of the New Mexico State Engineer Office/Interstate

Stream Commission. 1996. Santa Fe, NM: Office of the State

Engineer, p. 47.

Arellano, Juan Estevan. 1997. La querencia: La Raza bioregionalism.

New Mexico Historical Review 72(1): 31-37.

Baxter, John O. 1997. Dividing New Mexico’s waters, 1700-1912.

University of New Mexico Press, Albuquerque, pp. 1-2, 5-6, 12.

Berkes, Fikret; Farvar, M. Taghi. 1989. Introduction and overview.

In: F. Berkes, ed., Common Property Resources: Ecology and

Community-based Sustainable Development. Belhaven Press,

London, pp. 3-5.

Carlson, Alvar W. 1990. The Spanish American homeland: four

centuries in New Mexico’s Río Arriba. Johns Hopkins University

Press, Baltimore, pp. 4, 7-11, 23-37, 203-204.

Clark, Ira G. 1987. Water in New Mexico: a history of its management and use. University of New Mexico Press, Albuquerque,

pp. 9, 30-31.

Clark, Sanford D. 1990. Tensions between water legislation and

customary rights. Natural Resources Journal 30(3): 503-520.

Crouch, Dora P.; Garr, Daniel J.; Mundigo, Axel I. 1982. Spanish

city planning in North America. MIT Press, Cambridge, pp. 1-23.

Cutter, Charles R. 1995. The legal culture of northern New Spain,

1700-1810. University of New Mexico Press, Albuquerque, p. 19.

Cutter, Donald; Engstrand, Iris. 1996. Quest for empire: Spanish

settlement in the Southwest. Fulcrum Publishing, Golden, CO,

pp. 7-8, 54.

De Vargas Decree. May 8, 1696. State Archives of New Mexico I,

Translations, Archive No. 817. Santa Fe, NM: State Records

Center and Archives. (For the De Vargas Proclamation, April 19,

1695, see Archive No. 882)

Ebright, Malcolm. 1994. Land grants and lawsuits in northern New

Mexico. University of New Mexico Press, Albuquerque, pp. 88-90.

Glick, Thomas F. 1970. Irrigation and society in medieval Valencia.

Harvard University Press, Cambridge, pp. 31, 35-37, 54-55

Hammond, George P.; Rey, Agapito. 1953. Don Juan de Oñate,

colonizer of New Mexico, 1595-1628. University of New Mexico

Press, Albuquerque, Vol. 1, pp. 17, 320-23, 346.

Hutchins, Wells A. 1928. The community acequia: its origins and

development. Southwestern Historical Quarterly, 31 (July 1927-

April 1928): 278, 261-284.

Keleher, William A. 1929. Law of the New Mexico land grant.

New Mexico Historical Review 4(4): 352, 350-371.

Kleymeyer, Charles D. 1996. Cultural traditions and communitybased conservation. Grassroots Development: Journal of the

Inter-American Foundation 20(1): 27-35.

Laws of 1851 and 1852. Territorial Assembly of New Mexico. N.M.

Revised Statutes and Laws (Studley 1865).

Maass, Arthur; Anderson, Raymond L. 1978. ...And the desert shall

rejoice: conflict, growth, and justice in arid environments. MIT

Press, Cambridge, pp. 11-45.

MacCameron, Robert. 1994. Environmental change in colonial

New Mexico. Environmental History Review 18(2): 27, 17-39.

Margarita Ditch Rules. 1911. In: José A. Rivera collection, No. MSS

587 BC, Center for Southwest Research, Zimmerman Library,

University of New Mexico, Albuquerque, NM.

Noss, Reed F. 1994. A sustainable forest is a diverse and natural

forest. In: DeVall, Bill, ed. Clearcut: The Tragedy of Industrial

Forestry. Sierra Club Books/Earth Island Press, San Francisco,

p. 37.

Ostrom, Elinor. 1990. Governing the commons: the evolution of

institutions for collective action. Cambridge University Press,

New York, pp. 69-88.

Peña, Devón. 1997. Cultural landscapes and biodiversity: the

ethnoecology of a watershed commons. In: Cabeza de Baca,

Vincent, ed. Hispanic Life and History. Colorado Historical Society, Denver. Also see Devón Peña and Rubén Martínez, coprincipal investigators, Upper Río Grande Hispano Farms Study,

research project supported by the National Endowment for the

Humanities, Grant No. RO 22707-94, Colorado College, 1994-

1998. The documents and files resulting from this study will be

archived at Colorado College.

Petition to take possession of Valle de Guadalupita. 1837. In:

Rivera, José A., Acequia Culture: Water, Land, and Community

in the Southwest. 1998. University of New Mexico Press, Albuquerque, pp. 22-24.

Provincial Statutes. 1824-26. Trans. Perrigo, Lynn I. 1952. New

Mexico Historical Review 27(1): 66-72.

Public Law 99-662. 1986. Water Resources Development Act of

1986, Section 1113, Acequias irrigation systems. Washington,

D.C.: United States Congress

Redclift, Michael; Sage, Colin, eds. 1994. Introduction. Strategies

for Sustainable Development: Local Agendas for the Southern

Hemisphere. John Wiley & Sons, New York, p. 11.

Report of the Attorney General of New Mexico. 1963-64. Santa Fe,

NM: Office of the Attorney General of New Mexico, Vol. 1: 247-252.

Rivera, José A. 1996. Irrigation communities of the upper Río

Grande bioregion: sustainable resource use in the global context.

Natural Resources Journal 36(4): 743-44, 731-760.

Rivera, José A.; Peña, Devón G. 1998. Historic acequia communities in the upper Río Grande: policy for cultural and ecological

protection in arid land environments. Draft manuscript on file at

the Julian Samora Research Insititute, Michigan State University, Lansing, MI.

Scurlock, Dan. 1998. From the río to the sierra: an environmental

history of the middle Río Grande basin. USDA General Technical

Report RMRS-GTR-5, pp. 105-119.

Simmons, Marc. 1969. Settlement patterns and village plans in

colonial New Mexico. Journal of the West 8(1): 7-21.

Simmons, Marc. 1972. Spanish irrigation practices in New Mexico.

New Mexico Historical Review 47(2): 135-150.

Simmons, Marc. 1991. The last conquistador: Juan de Oñate and

settling of the far southwest. University of Oklahoma Press,

Norman, pp. 109, 114, 117, 148-49, 182.

Twitchell, Ralph Emerson. 1925. Old Santa Fe: the story of New

Mexico’s ancient capital. Santa Fe, New Mexico Publishing Corporation, pp. 20-21.
28 USDA Forest Service Proceedings RMRS-P-7. 1999

Tyler, Daniel. 1989. Ejido lands in New Mexico. In: Ebright,

Malcolm, ed. Spanish and Mexican Land Grants and the Law.

Sunflower University Press, Manhattan, KS, pp. 24-35.

Tyler, Daniel. 1990. The mythical pueblo rights doctrine: water

administration in Hispanic New Mexico. Texas Western Press,

University of Texas, Southwestern Studies Series, No. 91, El

Paso, pp. 12-13.

Van Ness, John R. 1987. Hispanic land grants: ecology and subsistence in the uplands of northern New Mexico and southern

Colorado. In: Briggs, Charles L. & Van Ness, John R, eds. Land,

Water, and Culture: New Perspectives on Hispanic Land Grants.

University of New Mexico Press, Albuquerque, pp. 192-195.

Whiteford, Scott; Henao, Luis E. 1980. Irrigación descentralizada,

desarrollo y cambio social. In: América Indígena 40(1): 57-72.

Worster, Donald. 1985. Rivers of empire: water, aridity and the

growth of the American West. Pantheon Books, New York, p. 5.

Wozniak, Frank E. 1987. Irrigation in the Río Grande valley, New

Mexico: a study of the development of irrigation systems before

1945. Santa Fe, NM: New Mexico Historic Preservation Division,

pp. 24-25, 64-65.
USDA Forest Service Proceedings RMRS-P-7. 1999 29

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Jim Winder is Chairman, Quivira Coalition, HC 66, Box 38, Deming, NM

88030.

Abstract—One of today’s critical questions for ranchers is how to

gain economic benefits from natural resources without damaging

biodiversity. Ranchers today face declining beef prices, escalating

resource prices, and taking on costs once covered outside the

industry. Ranchers join environmentalists and agency personnel in

the struggle to meet evolving needs of the American people.

Change is inevitable but so is resistance to change. Ranchers, environmentalists and agency personnel are wrapped in

a struggle over the changing management focus on public

lands. Although this debate has many facets, the fundamentals lie in the evolving needs of American society. Lands once

valued only for commodity production are now valued by a

well fed public more for recreation and conservation. These

changing needs and values have found their way into the

market place where the real price of beef has declined

precipitously and environmentalists are asking ranchers to

pay the cost of past resource abuse. Paradoxically, the forces

which seem to be destroying ranching on public lands offer

the one legitimate opportunity for ranchers to survive on the

land.

Ecology of Business _____________

Just as plants and animal are subject to the laws of

ecology, humans are subject to the laws of economics. A

living organism must be able to out compete other organisms

for natural resources in order to grow and reproduce. If that

organism uses more energy than it captures, degrades its

ecosystem, or is unable to compete for resources then it is not

sustainable and will disappear over time. Business failures

result from an inefficient process which uses more monetary inputs that it produces, degrades the resource or is at

a competitive disadvantage with other businesses. To remain solvent a business must be sustainable in terms of

Nature and in terms of the needs of society.

As the debate over proper uses of public and private

rangelands continues in and out of the courts, only one thing

is certain, economics will have the final word. Those uses of

the land which are sustainable when all costs are considered

will remain viable, however non-sustainable users will be

pushed from the land. Far more ranchers will continue to

leave the land because of economic reasons than because of

the courts.

Resolving Resource Conflict: a Bigger Pie

Jim Winder

Brief History of Ranching _________

To nineteenth century Americans, this country’s vast

rangelands held no value outside of commodity production.

Domestic livestock grazing, at its core, is only a method to

harvest and refine native vegetation which is indigestible to

human beings. Grass had no value in and of itself, it was only

when that grass was converted to beef that the value was

realized. And thus the beef industry took root as a method of

refining the vast natural resources in the American west.

The history of the western beef industry is not unlike that

of many other industries, rapid growth and large profits

which recruit additional producers which in turn lead to

industry maturation. In the case of the beef industry, this

aging process was escalated by a government policy of cheap

food which encouraged further production through investment in research. On one level the research was successful

as production per cow more than doubled. But on another

level it was disastrous for those ranchers it professed to help,

as production improvements only tended to flood the market

with more tons of beef selling at lower prices. This policy was

good for society and politicians as real food prices declined

but devastating to the rancher as beef prices failed to keep

up with inflation.

In 1960 it took 8 finished steers to buy a new pickup truck,

today it takes 34. This shows us that the real price of beef has

declined precipitously while the price of inputs has continued to climb. In real terms, American society values beef

relatively less today than it has in the past. At that same

time, society has begun to place value upon other, noncommodity, uses of natural resources such as conservation

and recreation.

New Uses of Natural Resources ___

When my grandfather ranched, the price of a parcel of land

was determined by its productivity in terms of livestock,

timber or mining. In financial terms this meant that the

price was approximately equal to the present value of the

expected net income stream from these enterprises. In my

father’s time the price of land began to reflect a new value,

recreation. A ranch would be valued higher if it had greater

recreational potential, such as deer hunting, even though

commodity production was comparable to other ranches.

Today our society has found a third value for natural resources, that of conservation. Organizations and individuals

purchase ranches with no intent of grazing cattle, instead

they are focused on habitat production. Individuals value a

parcel of land for its health, and are willing to fight for land

that they have never even walked upon. It is the conservation value of our lands that fuels the entire environmental

movement.

The ranching community which is suffering through the

fall in real beef prices is now faced with escalating resource
30 USDA Forest Service Proceedings RMRS-P-7. 1999

costs due to the competition from non-commodity users. In

other industries faced with maturation, the strategy is

consolidation in order to reap economies of scale. Ranchers

are denied this option because they are unable to pay for

additional land through production centered on only one

land value, when the land price reflects all three values.

Scarcity _______________________

Damage to the environment resulting from business activity is often not paid for by the business but born by society.

Economists call this an external cost. Costs such as riparian

deterioration or species extirpation do not show up on the

financial statements of any company but instead are thought

to impoverish society, especially future generations, through

reduced resource productivity and the direct cost of

remediation. The major strategy of the environmental movement is the reversal, or internalization of these external

costs. That is to make the business pay for the true costs of

production, not just labor and materials but the present and

future cost of keeping the land healthy.

At a time when profits in the mature livestock industry are

at a low ebb, ranchers are unable or unwilling to shoulder

additional costs, whether real or perceived. Thus the heart

of the debate for ranchers is economic survival. Proposals to

restore riparian habitat or reintroduce wolves are feared for

their perceived effect of reducing production and increasing

costs. This attitude is one of scarcity, there is only room for

commodity based businesses on the land, anything involving

recreation and especially conservation will deplete commodity production.

An Alternative __________________

Ranching is a capital extensive industry, that is it takes a

lot of capital in the form of land, livestock and equipment to

produce beef. Often a rancher has invested in excess of $4000

for each animal unit grazed. Traditionally, the net return on

asset (ROA) for ranching has hovered around 2-3 percent in

the best of years. This is very low, considering the risk

involved with a ranching investment and the fact that one

could usually earn a higher return with a risk free government bond. When we view the simple equation for return on

assets:

ROA = Net Returns/Total Asset Value

it is apparent that there are only two ways to improve ROA,

increase the productivity of the assets in terms of net returns

or decrease the cost of the assets required for a given level of

production. We have seen the results of the industry’s focus

on increasing beef production with a never ending stream of

innovations. A better way of increasing productivity is not to

produce more of the same old thing but to produce new

products from the same asset base. Since much of the price

of natural resources is related to conservation and recreation, it is rational to base new products upon these values.

Raw values for natural resources are analogous to clouds.

They are real and can be seen but they are impossible to

grasp or to hold. They have no cash value in and of themselves but offer the possibility of creating wealth through

secondary products. Just as the rangeland grasses of the

nineteenth century were worthless to humans until livestock converted them into beef, conservation and recreation

values must be refined into products that can be marketed

and consumed. For a rancher to survive and even prosper in

the urbanizing west, the question is how to develop a range

of compatible products which tap into all three natural

resource values, commodity, recreation and conservation.

The answer to this question is two fold. The first requirement is for a rancher to evolve into a full resource manager

with an understanding of the structure and function of the

ecosystem. For decades range managers were taught what

was good for cows and grass with little emphasis placed on

other species or ecological processes. A resource manager

should now have a working understanding of the interactions among species since it is this interaction which gives

structure to an ecosystem. Also the manager needs to understand the multitude of processes which comprise the ecosystem function. These processes include recovery following

disturbance and the distribution of water and nutrients

throughout the landscape and the seasons. While the complexity of life on Earth insures that no individual can

understand everything, proper management of natural resources necessitates a manager who knows the land. A

resource manager who is able to keep the land healthy and

sustainably produce goods and services which society values, will have a long tenure on the land.

Once expertise in resource management is gained, the

next step is to develop the products and trade channels

necessary for delivery to the consumer. Since commodity

and recreation values have been around longer their markets are more well defined. A large infrastructure exists for

trading commodities and the market is readily accessible to

any producer. A broad and varied market exists for recreational products which usually take the form of an experience, a fishing trip, but may also include the tools which

make the experience more enjoyable, a new rod. Since

society has only recently begun to place significant value on

the conservation of natural resources, products and market

infrastructure are rare and unproven. Although this situation makes marketing somewhat more difficult, it rewards

creativity and gives small businesses equal footing with

larger concerns.

Conservation products will initially be marketed to governments and conservation organizations. This may take

the form of land sales, grants or conservation easements.

Often conservation may involve a service instead of a hard

product. Many people are interested in the land but few

understand how to manage resources. Opportunities abound

for individuals to provide broad based managerial service.

These managers need to be able to add real value to the

resource by improving wildlife populations as well as the

aesthetics such as riparian habitat. Other products and

services will undoubtedly be produced and refined over time.

In contrast with a rancher who is trying to maximize

production of beef from a finite set of resources, the resource

manager’s goal is to blend production from the three values

in a manner which maximizes profit. To do this one must

look for synergy between products which slash costs. An

example is a recreational enterprise which is based on

traditional ranch activities like branding and gathering

cattle.
USDA Forest Service Proceedings RMRS-P-7. 1999 31

Conclusions____________________

The greatest danger a rancher faces today is that the cow,

once only a tool, has become a way of life, and end in herself.

If ranching disappears as a viable use of natural resources it

will be because of resistance to change, not an ability to

evolve with the times.

Ranchers face three critical and permanent economic

realities, declining real beef prices, escalating resource

prices driven by conservation and recreation values, and the

internalization of costs once externalized by the industry. To

survive, individual ranchers must become economically relevant and use the strong forces of change in their favor.

It is when the rancher evolves into a resource manager

blending commodity, conservation and recreation values

into sustainable products that they will truly understand

needs and desires of other resource users. This common

ground will be the foundation for a new industry that

answers the critical question of how to gain economic benefits from natural resources without damaging biodiversity.
32 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Steve Harris works for Rio Grande Restoration, El Prado, NM 87529.

Abstract—The Rio Grande River’s biologically troubled status is

clearly linked to present and historic water management. To restore

the river to pre-settlement conditions will take a “tool kit” that

holds authorities, knowledge, and skills needed to correct historical

neglect and abuse. Tools include awareness, planning, partnerships, engineering solutions, and a cross-section of public and

private individuals.

In a presentation most of us heard earlier in the week,

Steve Hansen from the Bureau of Reclamation showed us

some data that leads, inescapably, to the conclusion that

there is simply not enough water available to the Middle Rio

Grande to continue to satisfy the kind of demands that are

being placed upon the river. A few moments ago, Paul

Tashjian from the Fish and Wildlife Service told us that the

Rio Grande is in the process of “dying” biologically, a conclusion borne out by the facts:

• The status of small fish species in the aquatic ecosystem—all gone except for the endangered Rio Grande

silvery minnow. Perhaps 23 aquatic species extirpated

from the middle river.

• The decline of the Rio Grande riparian forest, as documented in the Bosque Biological Management Plan.

• The status of neotropical migratory birds—107 species

in decline. In an accumulation of human induced impacts, some of this is no doubt attributable (at least in

part) to a fragmentation of habitat in the Rio Grande

Flyway.

• The fact that wintertime streamflows at El Paso contain

such concentrations of total dissolved solids that the

city doubts its ability to treat the water to drinking

water standards.

The fate of human occupation, the sustainability of our

communities, economies and cultures is directly linked to

the river, not just as a water resource but also as the big, wet

life support system that gave us birth.

Today, the river’s status can be clearly linked to present

and historic water management practices...the blunt fact

that over the past 86 years, 98 percent of the water produced

by Rio Grande watersheds gets consumed by the time the

river reaches Hudspeth County, Texas. Not only do we

How Great a Thirst? Assembling a River

Restoration Toolkit

Steve Harris

mercilessly use the river up, the future is likely to get worse.

Consider:

• That in the present scramble to secure municipal water

supplies, more than 100,000 acre feet of water that

presently escapes as streamflow (~55 kaf of SJ-C water

and ~60 kaf of wastewater from ABQ), may soon be

diverted and consumed.

• That without an expenditure of public monies, the

Middle Rio Grande Conservancy District will continue

to divert 5 or 6 times more water than its crops consume.

In talking about “restoring” the Rio Grande, I want to

make a couple of points as strongly as possible:

First, I do not propose that we can return the river to its

pre-settlement conditions. “Restoration”, as I am using the

term, means restoring a measure of lost biological integrity

and function. Nature had an irrigation and flood control plan

which we must try to rediscover, because unlike our own

plans, it let life exist. I’m embracing the term “restoration”

because the current notions of “preservation” or “protection”

will not ensure that we have a healthy Rio Grande in our

future. That unless we can begin to reverse it, the present

trend toward degradation will continue to its logical and

unfortunate conclusion.

Second, the river needs irrigating. More than any other

combination of factors, simply managing our water to mimic

the way nature does it, is the first order of business, if

restoration is the goal. We can’t zero out the flows (and with

100 kaf of new diversions on Albuquerque’s drawing board,

an utterly dry river bed would appear to become increasingly

likely), we must reconnect the river to its floodplain, providing periodic overbank flooding and we must shape our

managed hydrographs in conformance with the natural ebb

and flow conditions in which the river’s biota evolved. We

must understand and work in harmony with the river.

Third, the real issue in providing instream flow is not so

much a question of acquiring an additional quantity of water

(though some wet water will have to be dedicated from

existing and planned uses), but more a question of improvements in the timing of flows.

Fourth, there is reason for optimism: the minnow had a

good year in 1997, the whooping cranes have not left us

entirely and all the players seem to be willing to acknowledge a problem. Our history of water management has been

so haphazard that we can easily save 10 percent over present

uses (and maybe a great deal more) if we can implement an

integrated water conservation program.

Fifth, we cannot afford to fight about this very much. I do

not propose to dismantle agriculture to save the river.

Agriculture is under enough pressure without environmentalists sniping at it. Neither would I entertain a proposal to
USDA Forest Service Proceedings RMRS-P-7. 1999 33

desiccate the river to preserve the status quo; it isn’t working. We must learn to honor all aspects of our heritage:

healthy ecosystems and healthy economies.

The bad news is that the Rio Grande, like the planet’s

biological systems in general is, in the words of the immortal

Merle Haggard “rolling downhill like snowball headed for

hell.” The good news is that we can still avert the crisis. So

we must cling to our hope and not give up, just yet.

My assignment today is to convince you that we have a sort

of “tool kit”, comprised of all the authorities, knowledge and

skills which exist in this region to correct the neglect and

abuse we have heaped upon a once-functioning river. In

order to restore the Rio Grande, we will need them all.

In quenching our various and endless thirsts, we have

become accustomed to putting the river at the end of the line.

We have deluded ourselves into thinking that a river is

nothing more than a supply of water, that the vested needs

of downstream users guarantees that here will be ample

water in and for the river and that our water rights (mere

jottings on paper) equate to water itself. We will have to get

over these delusions.

It is quite useless to point fingers for the shortsightedness

of the past. Besides, there aren’t enough fingers to complete

the job. We believed what the engineers of 1890 told us about

rivers and, to a lingering extent, act as if we still believe

them, despite mounting evidence that nature had a terrific

plan for delivering water.

Just as we have all had our roles in trying to conquer the

river, so we can all be a part of its redemption. It is possible

that we will avert the crisis without ever pointing any more

fingers, but solutions will only come if we can deploy each of

the following tools:

Awareness—Since we are aware that we have a critical

problem that affects all of us, we must now make certain

that none of our actions and none of our inactions is serving

to perpetuate the problem. Each of us can and must employ

the tool which is our own awareness...and insist that any

who remain in denial come along with us.

I think we’re beginning to see the end game on water in the

Middle Rio Grande. If we wait to accept the great challenge

until the crisis is actually upon us, we will have already lostfirst the river, then the farm and then the house. There won’t

be any Animas River water or Lake Superior water or

iceberg towing projects to bail us out. Another aspect of

awareness is our understanding of how the Middle Rio

Grande water system works, including the effects of our

water manipulations on aquatic habitats. Despite some

heroic work by Steve Hansen, the Bureau and the City, we

still need to know more about the groundwater-surface

water interface, project return flows, evaporation and transpiration from all sources. The Corps, in partnership with a

number of agencies is developing URGWOM which promises to provide a look at the hydrologic effects of any number

of water management scenarios. This sort of information is

a valuable tool.

And the ability to do “adaptive management”, develop and

undertake practical experiments, monitor results and modify

such efforts is an essential tool, enabling us to avoid that

common pitfall, “paralysis by analysis”.

Planning—Planning is a particularly powerful tool to the

degree that it includes both economic and environmental

interests. The Fish and Wildlife Service put together an

unprecedentedly diverse team to write the silvery minnow

recovery plan: farmers, water users from upstream and

down, along with the biologists and bureaucrats who customarily write recovery plans. In fact this was an experiment. Letting affected economic interests into the species

recovery game had never been tried. A good theory, but I’m

not sure that it worked; I’m not sure that everyone was fully

engaged toward the main goal, which was to recover the

minnow.

Now, we have the Middle Rio Grande Regional Water

Planning effort, with 35 stakeholder representatives attending meetings. So far, it seems that the same sort of

dynamic prevails: the large water users are watching and

waiting and ready to bail out if the outcome doesn’t exactly

suit them. Right now, the regional plan is some distance

from acknowledging all of the complexities.

Additionally, these sorts of plans need to have their

implementation written right into them. Producing a document is only half the battle. As Bob Ohmart says: “when all

is said and done, a lot more gets said than gets done”. I sense,

though, that everyone in the Middle Rio Grande is getting

the idea that we really can’t go on like this and that critical

regional planning will eventually find its legs and begin to

walk.

Partnership—It goes by many names: sharing the load,

listening to the other person, fairness, reciprocity, cooperation, collaboration. Those of us who are, or have been,

married know that this can be a hard tool to get sharp.

Everyone has their own interests at heart and nobody can

defend my interests better than me and mine. So part of

partnership is being fierce in the defense of one’s own

interests; the other part is to respect the values of others.

This is where partnership gets tricky. To work together

requires that we have a common experience, interest or

goal, which in this case is the sustainability of our communities, farms and ecosystems. In varying degrees and proportions we all do value and respect these things.

To answer the river restoration challenge, we must all be

willing to consider viewpoints we are currently uncomfortable with. Today’s paradigm for governance is that I can

defeat my adversary’s initiatives as easily as he can defeat

mine. When gridlock ensues, everyone loses. The proper goal

of partnership in the Middle Rio Grande is that no one loses.

We may forego the “thrill of victory”, but we will eliminate

the “agony of defeat.”

Plumbing—I’m going to suggest that engineering projects,

the very tools that got the river into its present state may

also serve to get us out of this mess. For example, there’s

2-300 kaf of what appears to be federally-owned water,

undelivered San Juan-Chama water in storage in Heron

Reservoir. In 1996, it was proven that if the Bureau feels it

has the authority to do so, it can pass water through El Vado,

Abiquiu and Cochiti for environmental purposes. I must also

point out that, once that water is in the river, it’s going

downstream to ring the bell at Elephant Butte and satisfy

our obligation to Texas...unless, of course, it’s intercepted.

We’ve also got this maze of canals and drains and acequias

and subsurface seeps that is the MRGCD system. This is

75 year old plumbing, the inefficiencies of which are demonstrated by the fact that the District diverts 5 or 6 acre-feet
34 USDA Forest Service Proceedings RMRS-P-7. 1999

for each acre foot consumed by the crop. Chief Engineer

Shah tells me that much of this excess is necessary to get

enough head to push water through portions of the system,

particularly the highline canals. This raises the possibility

of reducing diversions by reengineering portions of the

District’s delivery system. Thus, the draglines and loaders

and dozers so loathed by environmentalists could be a very

powerful tool for restoring the hydrograph.

In putting forward our own Middle Rio Grande Plan,

yesterday, an Alliance of river protection advocates suggested that we would be willing to lead, or join, an appeal to

Congress for the vey significant funding these sorts of

projects will require.

People—Throughout the upper Rio Grande Basin, community members are demonstrating that they care very

much about the future of the river. I’m pleased to note that

Alamosa, Colorado and Socorro, New Mexico and El Paso,

Texas each have major projects underway, each aiming to

restore hundreds of acres of river banks and riparian wetlands to some semblance of a functioning condition. This

tells me that thousands within the basin are willing to

devote their energies to the river, against long odds. I

wonder how may more would express their loving concern

for the river if we could offer them strong hope of success?

I’m convinced that the majority of the 10 million folks with

whom we share the Rio Grande possess some sense of the

river’s importance to the long term survival of our region.

I hope I’ve left you with my own sense that we have a

lot of the tools we need: the incentive (survival), the engineering (water storage), the raw materials (remnant areas

of biodiversity), the knowledge (or the means to acquire

it)—to restore the Rio Grande. If the stakeholders, the City,

the District, their ratepayers, the Bureau, the pueblos, the

OSE/ISC, environmental groups and others, demonstrate

that we can bite the bullet, accept the responsibility, sit

down and tackle this together, then our legislative bodies

will not deny us the financial means.

References _____________________

Brookes, Channelized Rivers. Wiley, 1988

Collier, and others, Dams and Rivers: Primer on Downstream

Effects of Dams. USGS Circular # 1126, 1996

Clark, Water in New Mexico: A History of its Management and Use,

UNM Press, 1987

Crawford, and others, Middle Rio Grande Ecosystem: Bosque Biological Management Plan. USFWS, 1993

Daves, and others, City of Albuquerque Water Resources Management Strategy, 1997

DuMars and Nunn, eds., Middle Rio Grande Conservancy District

Water Policies Plan, 1993

DeGraaf and Rappole, Neotropical Migratory Birds. Cornell, 1995

Hansen, and others, Middle Rio Grande Water Assessment. USBR,

1997

Petts and Calow, River Restoration. Blackwell, 1996

Philippi, Floodplain Management-Ecologic and Economic Perspectives. Academic, 1996

Rosgen, Applied River Morphology. Wildland Hydrology, 1996

Whitney, and others, Rio Grande Silvery Minnow Recovery Plan.

USFWS, 1998
USDA Forest Service Proceedings RMRS-P-7. 1999 35

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Carol Raish is Research Social Scientist, Rocky Mountain Research Station, U.S. Department of Agriculture, Forest Service, Albuquerque, NM.

Abstract—Many of the livestock grazing permittees on the Carson

and Santa Fe National Forests in northern New Mexico are descendants of Hispanic settlers who have farmed and ranched in the

region for 400 years. Much of the permitted land was formerly

owned or used by local communities under Spanish and Mexican

land grants. Cultural differences and historical issues of landownership and use contribute to disagreements between permittees and

federal land managers. This study will examine current economic,

social, and cultural aspects of livestock ownership by these permittees to help agency managers administer the lands with increased

effectiveness by promoting greater cultural understanding.

Much of the current debate surrounding federal lands

occurs because land managing agencies have failed to emphasize and monitor sociocultural values and changing

attitudes toward land use and management. A comprehensive, nationally focused research project titled “Sustaining

Rural Communities: Measuring Social and Cultural Diversity in Land Use” addresses the need to emphasize and

monitor values and attitudes. A section of this project focuses on traditional livestock raising on public lands in

northern New Mexico. The Española/Canjilon pilot study

tests the northern New Mexico research design and implementation methods on the Española and Canjilon Ranger

Districts of the Santa Fe and Carson National Forests.

Historical Background ___________

To understand the complex issues surrounding livestock

grazing on federal lands in northern New Mexico, it is

necessary to understand the historical background of land

use and ownership in this area. Many of the small livestock

operations in northern New Mexico are owned by Hispano

families, regional residents since well before the U.S. conquest in 1848. (Small ranches are defined here as those with

less than 100 animal units yearlong—AUY. An AUY is the

forage required to support a cow and a calf for 1 year; Fowler

and others 1994: 2.) The Hispano ranching tradition began

with Spanish colonization in 1598 but did not become fully

Española/Canjilon Pilot Study: Economic,

Social, and Cultural Aspects of Public Land

Grazing on the Santa Fe and Carson

National Forests

Carol Raish

developed until after the reconquest of 1692 through 1696

(Earls 1985:179-181, Simmons 1979:182, Wozniak 1995).

During the Spanish Colonial (1598-1821) and Mexican (1821-

1848) periods, landownership and use were legalized or

confirmed by land grants from the Spanish Crown or Mexican government.

There were several types of land grants. Community

grants, used by a group of settlers in common (Eastman and

others 1971:4, Harper and others 1943:18-19), are of particular interest because they are a primary landownership

issue in the region. Within community grants, settlers

received individually owned building sites in the village and

plots of irrigated agricultural land. The irrigated plots, often

averaging only 5-10 acres (Van Ness 1987:172), grew smaller

when divided for inheritance. The villagers used the community grazing and timber lands and pastures in common

(Eastman and others 1971:4). Since groups of kinsmen often

tilled their fields cooperatively and herded their animals

together on large tracts of communally owned land, they

were able to survive on the small, scattered agricultural

plots.

Conquest of the region by the United States in the Mexican-American War of 1846 through 1848 changed landownership and patterns of range use. Under the Treaty of

Guadalupe Hidalgo, the United States was supposed to

recognize and respect the property rights of former Mexican

citizens. To obtain valid land titles according to U.S. law,

however, land grantees had to petition for title confirmation.

Although 128 land-grant claims and 19 Indian Pueblo grants

were confirmed in the state, many claims were rejected

(Eastman and others 1971:5, Eastman and Gray 1987:24).

Often, house lands and small irrigated plots were confirmed,

but the community pasture and woodlands, also part of the

grant and essential to the survival of small farmers and

herders, were not. Lands from unconfirmed claims reverted

to the public domain (Eastman and others 1971:5, Eastman

and Gray 1987:24). In addition, villagers lost significant

amounts of confirmed land because they were unable to pay

property taxes under the American system of monetary tax

payment, which differed substantially from prior systems of

payment based in animals and produce. Unscrupulous land

speculation also occurred, which took advantage of Hispanic

farmers who neither spoke English nor understood the

American legal system (de Buys 1985: 171, 178-179). After

passing through the hands of various owners, a large portion

of the lost grant lands ended up in federal control. Currently,

in north-central New Mexico, the Forest Service and the

Bureau of Land Management (BLM) manage much of this

land (de Buys 1985:171, 178-179, Eastman and others 1971:5).
36 USDA Forest Service Proceedings RMRS-P-7. 1999

Relevance of Research on North

New Mexican Grazing Issues ______

Many of the former grant lands came into federal control

in degraded condition, often resulting from large-scale timber harvesting and large, commercial ranching operations

that occurred after the land had been alienated from its

Hispanic owners (Rothman 1989). The methods used to

rehabilitate degraded land were sometimes thought harsh

and poorly explained by local ranchers who graze their

livestock on federal lands under permit (de Buys 1985:248-

249). Since many of the northern grazing permittees are the

descendants of grantees, many resent government restrictions and fees to use land they consider to be rightfully

theirs.

Discontent over federal grazing policies, protest over lost

grant lands, and general economic decline in the region led

to violence in the 1960s. Protests by the Alianza Federal de

Mercedes, led by Reies López Tijerina, culminated in the

now-famous raid on the Tierra Amarilla courthouse in 1967.

Two of the main goals of the group’s actions were to bring the

problem of massive land grant loss to world attention and to

address a series of grievances concerning management of

grazing on the national forests (deBuys 1985).

The violence of these protests led to reexamination of

Forest Service policies in northern New Mexico. The Forest

Service produced The People of Northern New Mexico and the

National Forests, commonly known as the Hassell Report

(Hassell 1968). The report recommended 99 measures, 26

related to grazing, to improve the situation of the Hispanic

villagers. Some measures were implemented, additional

money was brought into the region, and some progress was

made. In addition, the Forest Service developed a special

policy for managing the forests of northern New Mexico.

The Southwestern Policy on Managing National Forest

Lands in the Northern Part of New Mexico, or the Northern

New Mexico Policy, stressed the importance of valuing the

Hispanic and Indian cultures of the Southwest (Hurst 1972).

Policy implementation was based on the recommendations

of the Hassell Report (1968). The Forest Service periodically

reviewed implementation of the report recommendations.

After the last review in 1981, the agency decided that a

separate policy statement was no longer needed and that

further implementation would be through regional and

forest mission statements and plans (Hassell 1981).

Problems remain in the area and many of the conditions

highlighted in the Hassell Report (1968) have not improved.

Severe poverty, disappearance of traditional lifeways, and

environmental degradation are still major concerns. Unfortunately, many Forest Service employees are unaware of the

Hassell Report (1968) and the situations that led to its

development. They receive no special training in the cultural

traditions and social values of northern New Mexico. Significant misunderstandings persist, and the potential for conflict still exists. This likelihood is demonstrated by protest

responses to an injunction against logging and fuel-wood

harvesting to protect spotted owl habitat in 1995, hanging of

two Santa Fe environmentalists in effigy at a protest rally in

November of that year (McClellan 1995), and a bomb explosion at the Española Ranger District office in 1996. No one

was injured by the blast, which did minor external damage,

and no one has been arrested. This discussion does not imply

that Hispanic groups are responsible for the blast but indicates continued unrest in the area. Investigation of the

incident is focused on recent controversies involving the

Forest Service including environmental issues and disputes

over fuel-wood gathering and grazing rights (Korte 1996,

Ragan 1996).

Research Problem and Goals _____

This research project focuses on contemporary issues

among the forest users of northern New Mexico to provide

information and guidance to land managers. Understanding

the role of small livestock operations in northern New

Mexico communities is crucial to comprehending and resolving disputes over federal land and resource use. Thus, this

research will examine the economic, social, and cultural

contributions of livestock operations on the Carson and

Santa Fe National Forests to rural Hispanic communities of

the area. Local attitudes toward land management policy

and sustainable resource use will also be examined, as will

attitudes of Forest Service managers toward local issues.

The outcomes of this study will include an inventory of

contemporary community conditions that the Forest Service

should monitor into the future, and development of reliable

monitoring methods in a culturally diverse environment.

These methods can ultimately be used to monitor conditions

on other public lands with diverse user groups.

Elements to be inventoried and monitored include the

following:

a. Economic contribution of domestic stock to family and

community income.

b. Extent that public land use for grazing and other

purposes allows communities to maintain social cohesion

and traditional culture.

c. Local perceptions of public land use and land management policy.

d. Federal land managers’ perceptions of local issues.

e. Presence or absence of cultural differences in perceptions of sustainability and how to achieve it, and changes in

these perceptions in response to agency programs.

The Española/Canjilon pilot study will evaluate and refine the research design and the proposed implementation

methods on a portion of the study area.

Research Setting ________________

The Española Ranger District was selected first for the

pilot project because it is a good example of livestock operations on the Carson and Santa Fe forests. There are 9 active

grazing allotments on the district ranging from ca. 7000

acres to ca. 73,000 acres. Excluding 4 small allotments,

allotments range from ca. 4000 acres to ca. 100,000 acres on

the Santa Fe Forest. All the Española allotments have more

than 1 permittee per allotment, ranging from 2 through 16.

Seventy percent of the 77 active allotments on the Santa Fe

have more than 1 permittee, ranging from 2 through 20.

Forty percent of the 71 allotments on the Carson have more

than 1 permittee, ranging from 2 through 25. Multiplepermitte allotments, small herd sizes per permittee, and

grazing associations of permittees demonstrate the continuing communal range use in northern New Mexico. Of the 17
USDA Forest Service Proceedings RMRS-P-7. 1999 37

listed grazing associations on the Santa Fe, 6 occur on the

Española District. There are 24 associations on the Carson.

Herd sizes are generally small on the district and on the 2

forests. Of the approximately 55 people with Forest Service

permits on the district, 30 have permitted head numbers

from 1 to 25, 11 have 26 to 50, and 14 have 51 to 100 (of these,

only 5 have over 70 permitted head). There are no operations

with over 100 permitted head on the district. Española

demonstrates the allotment pattern common to the north

New Mexican forests, that of multiple permittees, grazing

associations, and small herd sizes. (Information on range

statistics from the Carson and Santa Fe National Forests

was obtained from range data tables provided by Jerry

Elson, Range and Wildlife Staff on the Santa Fe National

Forest; Sylvia Valdez, Resource Assistant on the Santa Fe

National Forest; Don Case, Range, Wildlife, Fish, Soil,

Air, and Water Staff on the Carson National Forest; and

Lorraine Montoya, Resource Assistant on the Carson National Forest.)

After discussions with range staff from both forests and

with representatives of local user groups, I decided to broaden

the pilot study by including a district from the Carson

National Forest along with Española. The Canjilon Ranger

District, with ca. 57 permittees, was recommended as a good

example of livestock operations on the Carson (Don Case,

pers. comm. 1997). Canjilon has 12 active grazing allotments ranging from ca. 300 acres to ca. 43,000 acres. Four of

the allotments have more than 1 permittee (ranging from 3

through 25), while 8 have 1 permittee. The district’s 4

grazing associations occur on the allotments with the largest

numbers of permittees. The majority of herd sizes are from

4 to 250, with 7 operations having 100+ head. The largest

herds per permittee occur on the single-permittee allotments. Canjilon provides some contrast with Española,

having more single-permittee allotments with larger herd

sizes, while still having many of the relatively small-sized

livestock operations typical of northern New Mexico.

Española/Canjilon Pilot Study _____

The Española/Canjilon pilot study will develop baseline

data describing economic, social, and cultural contributions

of livestock operations to rural Hispanos in the late 1990s.

This information will be useful for monitoring the role of

livestock operations in the future. Some comparisons to

previously collected information will also be made. Perceptions of public land use and land management policy, as well

as federal land managers’ perceptions of local issues, will be

examined in the larger study conducted on the 2 forests.

Future studies will also explore the possibility of cultural

differences in perceptions of sustainable resource use and

how to achieve it.

The pilot study assesses research questions that will guide

the larger study, and the methods and techniques that will

be used to collect information. Results of the pilot study will

be used to evaluate and refine the research questions by

developing new topics and questions, and by deleting inappropriate topics. Prior research indicates that livestock

operations contribute economically, socially, and culturally

to the owners’ lives. Pilot study results will be examined to

determine if new contributions should be added or if prior

contributions have shifted in emphasis.

Contributions of Livestock Operations

Research on small-scale cattle operations in the 1960s and

1970s demonstrated that, although domesticated animals

were important components of household economy, most of

the small operators did not depend on their crops and

animals for all their support. They generally had outside

jobs or were retired. The livestock made many contributions

to the household in addition to purely economic ones. The

animals added to family security by providing meat, and

sometimes milk, and were used as savings for retirement,

hard times, or special expenses (Eastman and Gray

1987:39-50).

The livestock also served important social and cultural

functions. Small-scale producers stressed the importance of

the quality of life that ranching provided them and their

families. They spoke of preserving a working relationship

with the land that could be passed with pride to their

children. Owning animals was a way for them to reaffirm

ancestral ties to lands and heritage. Often, owning animals

allowed the family to stay in the ancestral, rural community,

and to continue part of a traditional lifestyle (Eastman and

Gray 1987:39-50).

The Española/Canjilon study will gather information on

these economic, social, and cultural contributions at a time

of demographic change in the region. Following the format

of earlier research (Eastman and others 1971, Eastman and

others 1979, Gray 1974), the study will be organized around

a written questionnaire, supplemented by personal interviews. The questions will be grouped to elicit the following

information:

a. Background information on the permittee and his/her

family.

b. Background information on the livestock operation.

c. Contribution of the livestock operation to the household

economy.

d. Contribution of the livestock operation to the cultural,

lifestyle, and land-use values of the family.

e. Contribution of the livestock operation to the family’s

participation in the social network of the community.

f. Other contributions of the livestock operation considered important by the permittee.

Respondents will have an opportunity to discuss sustainable resource use, land loss issues, and operating under a

federal grazing permit in an interview after discussion of the

questionnaire. Information from this study will be compared

to information from earlier studies to assess possible changes

in the role of livestock operations between the time periods.

The working hypothesis is that there are no significant

differences between the current contributions of livestock

and those in the earlier studies.

Research Significance ___________

This research will contribute significantly toward understanding the role and dynamics of grazing operations on

public lands. The project will also have strong implications

for National Forest land management in northern New

Mexico and in other areas with culturally diverse user

groups. Questions of land use and grazing management are

critical political issues in the region, as is continued federal
38 USDA Forest Service Proceedings RMRS-P-7. 1999

ownership of public lands. Political leaders and land managers at the local, regional, and national levels require this

type of information to make informed resource-use decisions

and policies. Land managers from state and federal agencies

require knowledge of the results and difficulties inherent in

implementing grazing and resource-use policies. Other social scientists and ecologists will also find this work useful,

especially those examining the results of intercultural resource conflict and the overall role of human culture as a

critical factor in regional ecology. Most importantly, the

people of northern New Mexico should benefit because the

public and federal agencies will gain a better understanding

of their culture and the role that livestock operations play in

maintaining cultural traditions and livelihood.

References _____________________

Briggs, Charles L.; Van Ness, John R. 1987. Introduction. In: Briggs,

Charles L.; Van Ness, John R., eds. Land, water, and culture: new

perspectives on Hispanic land grants. Albuquerque, NM: University of New Mexico Press: 6-12.

de Buys, William. 1985. Enchantment and exploitation: the life and

hard times of a New Mexico mountain range. Albuquerque, NM:

University of New Mexico Press.

Earls, Amy Clair. 1985. The organization of Piro Pueblo subsistence: A.D. 1300 to 1680. Albuquerque, NM: University of

New Mexico. Ph.D. dissertation.

Eastman, Clyde; Carruthers, Garrey; Liefer, James A. 1971. Evaluation of attitudes toward land in north-central New Mexico.

Las Cruces, NM: New Mexico State University. Agricultural

Experiment Station Bulletin 577.

Eastman, Clyde; Gray, James R. 1987. Community grazing: practice and potential in New Mexico. Albuquerque, NM: University

of New Mexico Press.

Eastman, Clyde; Harper, Wilmer; Guerra, Juan Carlos; Gomez,

Bealquin. 1979. New Mexico small farms: a socioeconomic profile. Las Cruces, NM: New Mexico State University. Agricultural

Experiment Station Bulletin 407.

Fowler, J.M.; Rush, D.; Hawkes, J.M.; Darden, T.D. 1994. Economic

characteristics of the western livestock industry. Las Cruces,

NM: New Mexico State University. Range Improvement Task

Force, Agricultural Experiment Station, Cooperative Extension

Service, College of Agriculture and Home Economics Report 35.

Gray, James R. 1974. Economic benefits from small livestock

ranches in north-central New Mexico. Las Cruces, NM: New

Mexico State University. Agricultural Experiment Station Bulletin 280.

Harper, Allan G.; Cordova, Andrew R.; Oberg, Kalervo. 1943. Man

and resources in the middle Rio Grande valley. Albuquerque,

NM: University of New Mexico Press.

Hassell, M. J. 1968. The people of northern New Mexico and the

national forests. Albuquerque, NM: USDA Forest Service. Southwestern Region. Manuscript on file.

Hassell, M. J. 1981. Northern New Mexico policy review and action

plan. Albuquerque, NM: USDA Forest Service. Southwestern

Region. Memo on file.

Hurst, William D. 1972. Region 3 policy on managing national forest

land in northern New Mexico. Albuquerque, NM: USDA Forest

Service. Southwestern Region. Memo on file.

Korte, Tim. 1996. Tradition vs. environmentalists: fight flares over

wood gathering. The Press Democrat (Santa Rosa, California).

January 13.

McClellan, Doug. 1995. Protesters hang environmentalists in effigy: rival rally takes issue with message. Albuquerque Journal.

November 25.

Ragan, Tom. 1996. Forest feuds eyed in blast: FBI probes Española

bombing. Albuquerque Journal. January 9.

Rothman, Hal. 1989. Cultural and environmental change on the

Pajarito Plateau. New Mexico Historical Review 64(2): 185-211.

Simmons, Marc. 1979. History of Pueblo-Spanish relations to 1821.

In: Ortiz, Alfonso, ed. Handbook of North American Indians:

Southwest (9). Washington, DC: Smithsonian Institution: 178-193.

Van Ness, John R. 1987. Hispanic land grants: ecology and

subsistence in the uplands of northern New Mexico and southern Colorado. In: Briggs, Charles L.; Van Ness, John R., eds.

Land, water, and culture: new perspectives on Hispanic land

grants. Albuquerque, NM: University of New Mexico Press:

141-214.

Wozniak, Frank E. 1995. Human ecology and ethnology. In: Finch,

Deborah M.; Tainter, Joseph A., eds. Ecology, diversity, and

sustainability of the middle Rio Grande basin. Fort Collins, CO:

USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, General Technical Report RM-GTR-268:

29-51.
USDA Forest Service Proceedings RMRS-P-7. 1999 39

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Steve Kluge works for the Cibola National Forest, 2113 Osuna Rd.

Suite A, Albuquerque, NM 87113-1001.

Abstract—The Southwest Strategy is an effort by federal agencies to work with each other, the public, and tribal, state, and local

agencies to maintain and restore the cultural, economic, and environmental quality of life in Arizona and New Mexico. This update

explains the strategy and its progress to date.

On December 16, 1997, nine federal agencies in Arizona

and New Mexico committed to working with the public and

each other in a collaborative effort which is now known as

the “Southwest Strategy.” This is a bulletin to share information with employees about what has happened since that

date. If your questions are not answered, please see the last

section of this update for contacts.

What is the Southwest Strategy? __

The Southwest Strategy is a commitment by federal agencies involved in natural resources management to work in

collaboration with each other, the public, and tribal, state,

and local governments. The federal agencies participating

in the Southwest Strategy recognize and respect the jurisdictional authority of the Governors and sovereign nations

of Arizona and New Mexico. The goal of the strategy is to

maintain and restore the cultural, economic, and environmental quality of life in Arizona and New Mexico. The

strategy will address community development and natural

resources conservation and management within the jurisdictions of the involved federal agencies. It will proceed in a

manner that is scientifically based, legally defensible, and

implementable.

Which Federal Agencies are

Involved? ______________________

Many agencies within the Departments of Agriculture,

Defense and the Interior are currently participating in the

Southwest Strategy. Agencies included to date are the Bureau of Land Management, U.S. Geological Survey, Fish and

Wildlife Service, Bureau of Indian Affairs, National Park

“Southwest Strategy” Update

Steve Kluge

Service, Bureau of Reclamation, Natural Resources Conservation Service, Forest Service, Environmental Protection Agency and the Department of Defense. Other departments or agencies may join later.

Why Do This? __________________

Management of federal lands has become increasingly

complex in recent years. Arizona and New Mexico have large

expanses of public and tribal lands intermingled with private lands, fast growing metropolitan centers, scarce water

resources, unique cultural resources, diverse and fragile

ecosystems with numerous endangered species, and many

competing demands on public lands and water resources.

Agencies, tribes, and the public need to work better together

in a comprehensive, rather than piecemeal, effort.

How Will This Be Done? __________

A collaborative problem solving approach will be used to

address natural resources issues. Collaboration is a process

through which parties who see different aspects of a problem

can constructively explore their differences and search for

solutions. Through this approach concerns are heard and

addressed, information is shared, and technical knowledge

sought out.

Collaboration is not an end in and of itself, but is a means

to achieve more consistent and responsive service to the

public. It is also an agreement to continue talking despite

differences and changing circumstances.

Will This Strategy Affect Ongoing

Agency Business? ______________

No and yes. Agency work will continue as collaborative

processes are being developed. The legal and regulatory

responsibilities for each agency will remain the framework

for agency work, as always.

However, this is a new way of doing business. We want to

learn from and build upon existing successes as we deal with

increasingly complex issues in Arizona and New Mexico.

What is Happening? _____________

During the first stage of the strategy, federal agencies

have greatly improved interagency communication and collaboration. A number of internal interagency teams are

addressing issues of immediate concern to federal agencies

in the Southwest, such as community development, Endangered Species Act Section 7 streamlining, legal issues, and

communications.
40 USDA Forest Service Proceedings RMRS-P-7. 1999

In the second stage, the public and the federal agencies

will jointly design processes for future collaboration. State,

tribal and local governments, nongovernmental organizations, the private sector, and interested individuals will be

encouraged to participate. A few contacts have already been

made as interested groups have sought information about

the Southwest Strategy, such as Arizona’s and New Mexico’s

Soil and Water Conservation Districts and the Arizona

Resource Advisory Council.

In the third stage, the participants will use the new

processes to develop a comprehensive strategy to manage

natural resources in a manner that maintains and restores

the cultural, economic and environmental quality of life in

the Southwest.

Two small Southwest Strategy offices are being established in Albuquerque and Phoenix. There will be two

individuals working in Albuquerque and one in Phoenix.

These offices will coordinate activities, collect and disseminate work products, and act as points of contact for both the

public and agency personnel. The Albuquerque Southwest

Strategy Office will be up and running in mid-May and the

Phoenix office sometime later this summer.

How Will Non-Federal Partners

Participate? ____________________

In May 1997, initial meetings were held with representatives of organizations, state and local governments, and

individual citizens. Meetings will also be held with tribal

leaders. These meetings seek input on ways to launch future

collaborative efforts that will ultimately define the comprehensive strategy for resolving complex natural resource

issues while still recognizing and respecting federal

Governors’, tribal and local authority.

How Are the Federal Agencies

Organized Today to Proceed with

the Southwest Strategy? _________

The Regional Executive Committee is comprised of Southwest regional agency heads. The Regional Executive Committee is co-chaired by the U.S. Forest Service’s Regional

Forester and U.S. Fish and Wildlife Service’s Regional

Director. The Department of Defense Environmental Coordinator participates for the Department of Defense. The

Regional Executive Committee meets at least once a month.

The Regional Implementation Team serves as staff to the

Regional Executive Committee. Each participating agency

has a representative on the Regional Implementation Team.

The national executives and their staffs provide support,

guidance and oversight to the regional executives and their

staff. The national executive co-leads are the Director of the

Fish and Wildlife Service and the Chief of the USDA-Forest

Service. The national executives and their staff bring a

broad perspective to the issues in the Southwest. The national executives will also resolve issues elevated by the

Regional Executive Committee.

In the first stage of the Strategy, federal work groups were

established with representatives from the field, regional,

and national staffs. The roles of the work groups vary. Some

were designed to help get the strategy started. Others were

charged with developing ways to solve critical, immediate

issues. Immediate issues are those that involve species of

animals or plants or resources or the public at immediate

risk, or those issues that involve litigation.

Some of the groups will only have a short-term life span

while others may be ongoing. The Regional Implementation

Team provides guidance and direction to these groups.

What Work Groups Have Been

Organized to Date? ______________

The Communications/Collaboration Design Work Group

is comprised of two teams. The Communications Team

(COM) develops and releases information about the Southwest Strategy to both federal employees and the public. The

Collaboration Design Team (CDT) will assist agencies, tribes

and the public in developing processes for collaboration.

The Information Resource Management Work Group will

identify ways for participants to share information and

provide information in usable formats.

The Research and Data Collection Work Group will identify and respond to scientific data gaps and research needs.

The Section 7 Streamlining Work Group is developing

ways to make the Section 7 consultation process under the

Endangered Species Act more efficient.

The Legal Work Group provides technical and legal support, and coordination of litigation issues.

The Water Resources Work Group will collaborate with

federal, tribal, state and local authorities to design an

interagency process to address Clean Water Act compliance

and the Clean Water Action Plan.

The Community Development Work Group identifies ways

to address the economic and social effects on communities

resulting from grazing management changes and other

natural resource decisions.

The Endangered Species Act Work Group will coordinated

the implementation of requirements found in Biological

Opinions, as well as recovery activities among federal agencies.

How is This Funded? ____________

Funding to develop this strategy is coming from within

existing agency budgets.

How Long Will it Take to Develop

the Southwest Strategy? _________

Developing collaboration processes with the public is

starting. This will proceed at different paces in different

areas and will take at least several months to evolve. Some

contacts have already been made. The agencies are encouraged by the number of individuals and groups who have

asked to participate.
USDA Forest Service Proceedings RMRS-P-7. 1999 41

How do I Obtain Further

Information? ___________________

Questions regarding this interagency strategy may be

addressed to the Directors of Public Affairs for the Southwestern Region of the Forest Service in Albuquerque, Carolyn

Bye, 505/842-3290, or the U.S. Fish and Wildlife Service in

Albuquerque, Tom Bauer, 505/248-6911.

In addition to these interagency spokespersons, each

agency has designated a contact point within their offices

located within the Southwest. These contact persons will

handle internal and external requests for information:

Department of the Interior

Bureau of Land Management:

Kitty Mulkey (NM) 505/438-7514

Deborah Stevens (AZ) 602/417-9215

Bureau of Indian Affairs:

John Philbin (AZ) 602/379-6798

National Park Service:

Cecilia Matic 505/988-6014

Geological Survey:

Pat Jorgenson 650/329-4011

Bureau of Reclamation:

Vicki Fox (NM) 505/248-5371

Bob Walsh (AZ) 702/293-8421

Fish and Wildlife Service:

Tom Bauer 505/248-6911

Department of Agriculture

Forest Service:

Carolyn A Bye 505/842-3290

Natural Resources Conservation Service:

Gerry Gonzalez (AZ) 602/280-8777

Rebecca de la Torre (NM) 505/761-4404

Department of Defense

Region VI (NM):

Thomas Rennie 214/767-4678

Region IX (AZ)

Cindi Flemming 619/532-2297
42 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Sarah Kotchian is the Co-Chair, Rio Grande/Rio Bravo Basin Coalition.

In June 1994, one hundred people gathered for the first

Uniting the Basin Conference in El Paso to discuss the state

of their basin and to explore ways to improve its sustainability

for future generations. One of the recommendations of that

conference was the formation of an international non-governmental coalition of groups throughout the Basin to share

information and ideas and facilitate local efforts to improve

the river and the quality of life along it for all members of the

ecosystem. In 1995, a steering committee met to begin to

make that recommendation a reality. The non-profit Coalition now has a 15-member board of directors from throughout the basin, and partners and friends representing a wide

variety of grassroots environmental and business groups.

The response to Coalition initiatives has been tremendous, indicating the need and support for a Basin-wide

network. Within the first three years, the Coalition has

raised money for and donated computers and financial

resources to river groups throughout the Basin, providing

internet access and communication linkages between groups

and sub-Basin areas facing similar issues. The Coalition

also functions as an information clearinghouse, providing a

web page (www.utep.edu/rioweb/) and BasinNet listserve,

and publishing a newsletter called “La Corriente”. It has

founded the enormously successful Dia Del Rio, a celebration and restoration of the river on the third Saturday of

October each year by communities all up and down the river.

The Dia Del Rio celebration in turn inspired the Gathering of Waters project initiated by artist Basia Irland, an

initiative which collects river water in a vessel and has been

transferring it community to community, uniting upstream

and downstream partners. The Coalition has sponsored

Rio Grande/Rio Bravo Basin Coalition

Sarah Kotchian

fundraising trainings in both Mexico and the U.S., to

strengthen the capacity of local groups to be effective in river

protection. And it co-sponsored the first River Stewardship

conference with the New Mexico Conferences of Churches

and the U.S. Catholic Bishops this past spring to empower

local communities of faith to become more active on river

sustainability issues. In September, 1998, the Coalition is

hosting the Uniting the Basin Congress in El Paso, Texas.

The Coalition has two staff members, Bess Metcalf, the

Executive Director, and Gabriela Vale, the Mexican Outreach Coordinator for supporting Mexican grassroots river

groups.

The Coalition is dedicated to the sustainability of the

ecology, economy, and cultures of the Rio Grande/Rio Bravo

Basin through international cooperation and communication, education and public awareness, and positive action. It

has adopted principles that include strengthening grassroots

groups of citizen throughout the river basin, empowerment

of local communities to determine their own issues and find

their own solutions, a commitment to representing the

social, cultural, geographic, and ethnic diversity of the

Basin, and dedication to dialogue, consensus-building, and

the democratic process.

For more information on the Coalition, contact:

Bess Metcalf, Executive Director,

Rio Grande/Rio Bravo Basin Coalition

c/o C.E.R.M., P.O. Box 645, Burges Hall Room 315,

El Paso, TX 79908

(915) 747-5720

email: bmetcalf@utep.edu
River and

Riparian Issues

USDA Forest Service Proceedings RMRS-P-7. 1999 45

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Jeffrey C. Whitney is with the New Mexico Ecological Services Office, U.S.

Fish and Wildlife Service, 2105 Osuna Rd. NE, Albuquerque, NM 87113.

Abstract—There continues to be a great deal of interest and

discussion surrounding the demands of water management and

allocation and the relationship to ecological integrity of the Rio

Grande riparian ecosystem. Current river management too often

fails to consider the importance of natural variability of flows.

What is consistently overlooked is the relationship of a stream

course to its forming watershed. The standard practice of managing

for one or more of a few important or imperiled species by defining

how little water can be left in the river is not adequate based upon

new scientific understanding. Adaptive management approaches

can be used to mange for whole river ecosystems concurrent with

providing societal and cultural demands on these natural systems.

The Middle Rio Grande (MRG) riparian forest, or

“bosque”, represents the largest cottonwood gallery

riparian forest in the southwestern United States. This

reach of the Rio Grande extends from Cochiti dam downstream 260 km to San Marcial, New Mexico. It constitutes

8 percent of the river’s total length and 34 percent of its

length in New Mew Mexico. The current bosque is a relict of

past management activities and is notably different than

its historic character. The physical and biological characteristics of southwestern riparian systems are complex.

Natural processes in southwestern riparian systems and

the ecological adaptations of vegetation affected by flood induced disturbance are fundamental aspects to be considered.

What is consistently overlooked is the relationship of a

stream course to its forming watershed. Once understood,

this relationship facilitates the ability to recognize the

character and condition of the riparian reach under study

both from a temporal and spatial perspective. The annual

natural variability of flows from a watershed and infrequent

episodic high flows (floods) are important aspects in understanding the expected and necessary natural variability of

flows. Flood events reset the condition of these systems. Too

often the casual observer interprets the effects of reforming

floods as “destructive.” While understandable, this conclusion may be hasty and is often incorrect.

A complex set of factors are involved in the development

and maintenance of these landscapes. The variability in

Watershed/River Channel Linkages: the

Upper Rio Grande Basin and the Middle

Rio Grande Bosque

Jeffrey C. Whitney

hydrology and river morphology of these systems precludes

use of random sampling in order to accurately characterize

these dynamic habitats. As a result of man’s activity in most

southwestern watersheds today, the changes to the hydrology and the loss of active floodplain combined with changes

in sediment supply and availability in the river system have

all contributed to a loss of biological integrity.

The benefits of inter-annual flooding is a potential resource that was effectively used by the original floodplain

system. Development within the floodplain, accompanied

by diking, alterations of the natural hydrograph, and

channelizing, are the results of the perception that flooding

must be controlled.

Gregory and others (1991) describe riparian zones, the

interfaces between terrestrial and aquatic ecosystems, as

a mosaic of land forms, communities, and environments

within the larger landscape. These were perhaps the first

authors to present an ecosystem perspective of riparian

zones that focuses on the ecological linkages between terrestrial and aquatic ecosystems within the context of fluvial

land forms and the geomorphic processes that create them.

They observed “that geomorphic processes create a mosaic of

stream channels and floodplain within the valley floor.

Geomorphic characteristics and other processes including

stochastic disturbance both upland and fluvial in origin

affect riparian zones, determining the spatial pattern and

successional development of riparian vegetation.”

In general, the factors affecting the development of southwestern riparian habitat are as follows:

1. Creation of a favorable seedbed;

2. Progression of tree stands from nursery bars to

senescent individuals as they continually modify their

own habitat;

3. Light to moderate flooding favors the establishment

and development through deposition of nutrient-rich sediments and increased soil moisture; and

4. Successful seeding cannot be expected on an annual

basis since it depends upon a “proper sequence of flooding,”

that is, no flooding large enough to be catastrophic until

stands are well developed.

Stromberg (1993) found that flow volume and the related

attributes of water-table recharge and floodplain soil wetting are primary factors regulating riparian vegetation

abundance. For example, many riparian tree species in the

arid southwest are evolutionarily adapted to germinate

after high spring flows, which occur as a result of snowmelt

and run-off from winter rains, whereas others germinate

after high summer flows, which are driven by monsoonal

summer rains (Stromberg and others 1991). Many arid land

streams are water limited on an annual or seasonal basis
46 USDA Forest Service Proceedings RMRS-P-7. 1999

because discharge has such a high degree of temporal flux

(Graf 1982; Poff and Ward 1989). The combination of high

peak flows in conjunction with low mean annual flows may

serve to reduce the vegetation of small streams (Stromberg

and Patten 1990). Flooding plays an important role in

regulating accumulations of woody debris and nutrient

dynamics in southwestern riparian ecosystems. In arid

landscapes where precipitation is limited, moisture made

available through fluvial interactions may play an essential role in facilitating the release of nutrients contained

within wood and leaf litter on the forest floor (Ellis and

others 1995). Flood flows in some systems play a major part

in ‘shaping’ valley floors and in physically delimiting floodplain from adjacent uplands, by variously scouring or depositing alluvial sediment (Gregory and others 1991; Hill and

others 1991). Larger streams thus might be expected to have

a greater extent of sites suitable for establishing riparian

vegetation.

Flood flows of a given magnitude, frequency, and seasonal

timing are also important because of their roles in influencing species diversity patterns and in creating opportunities

for riparian vegetation recruitment.

Beyond the physical characteristics of watersheds and

their resultant channels, supplies of minerals and detritus

(nutrients) is consideration of the supply and availability of

elements to the stream biota is important. The impact of

short-term events like storms on the elemental dynamics in

streams should be assessed and compared with other controls. These factors are essential for rates of primary productivity and decomposition in streams. The major controls on

element supply to a stream include watershed geology and

hydrology, soil processes, land-use practices, landscape

vegetation, and atmospheric loading. These watershed- or

landscape-level process define the overall supply of elements to a stream. (J.L.Meyer and others 1988).

Landscape Scale Ecosystem

Management ___________________

The study of spatial and temporal patterns across landscapes is central to formulating ecosystem management

principles. The hierarchical structure of ecological systems

allow the characterization of ecosystems and the identification of patterns and processes at different scales. Ecosystem composition, structure, and function determine diversity patterns across a range of spatial-temporal scales.

There is no single correct scale at which to study and manage

ecological patterns, processes, and diversity. The ecological

hierarchy of interest is determined by the purpose of each

project. Hierarchical monitoring schemes must be formulated that consider all scales of ecological organization.

Patterns of natural variability across a range of scales must

be defined if ecosystems are to be sustained at all relevant

scales. Landscapes are heterogeneous mosaics of patches

(Forman and Godron 1986; Urban and others 1987).

Programmatic riparian restoration is further complicated since rainfall and streamflow do not annually coincide

with seed drop from many pioneer riparian tree species.

Many arid land streams are water-limited on an annual

or seasonal basis because discharge has such a high degree

of temporal flux (Graf 1982; Poff and Ward 1989). The

combination of re-organizing high peak flows in conjunction with low mean annual flows may serve to reduce the

vegetative cover of (small) streams (Stromberg 1993).

An alternative hypothesis is that geomorphological features rather than hydrological features regulate riparian

abundance within a watershed. As stream flow increases, so

too does the magnitude of the low frequency hydrological

events. Flood flows in some systems play a major part in

shaping valley floors and in physically delimiting floodplains from adjacent uplands, by variously scouring or

depositing alluvial sediment (Gregory and others 1991; Hill

and others 1991). Larger streams thus might be expected to

have a greater aerial extent of sites suitable for the establishment of riparian vegetation.

Flood flows of a given magnitude, frequency and seasonal

timing are also important because of their roles in influencing species diversity patterns and in creating opportunities

for riparian recruitment.

Linkages Between Watershed

Condition and Flows _____________

There is an obvious direct relationship between watersheds and the water courses which result. As conditions

within a watershed are altered either by natural biotic (for

example insect mortality to large stands of forested trees)

or abiotic events (such as fire, landslides) or by anthropogenic activities, development, road construction, timber

harvesting or livestock grazing as examples, the associated

watercourses adjust to the changes in discharge, seasonality, or landform. There is little argument that anthropogenic activities in riparian systems and their associated

watersheds have a marked negative impact upon these

natural systems. The magnitude and frequency of these

activities as well as the timing of the particular action have

a significant role in the exhibited resulting effects. To a large

extent mitigation and management can reduce these negative impacts to tolerable levels and riparian system functions may remain within the limits of acceptable natural

variation.

A properly functioning riparian stream system (including

the associated watershed) can be referred to as being in

dynamic equilibrium. This can also be thought of as being

within the acceptable limits of natural variation for that

stream system. In all discussions regarding river morphology, it is important to recognize the differences within

spatial and temporal scales. To describe a river system as

being in a state of dynamic equilibrium (or energy balance)

does not mean that it is static. To the contrary, this “equilibrium results from a collection of processes that are by

definition predicated on change” through time (Crawford

and others 1993). For example, even during periods when

the entire river system is considered to be in a state of

dynamic equilibrium, changes constantly occur in channel

segments or reaches as small as the outside bend of a

meander, or as large as many river kilometers upstream,

and downstream from a tributary inflow (Whitney 1996).

Likewise, this state of dynamic equilibrium, can accommodate climatic deviations from the norm distinguished between natural and human-caused perturbations. The geomorphic process triggered in response to a change in
USDA Forest Service Proceedings RMRS-P-7. 1999 47

magnitude or duration of a variable, regardless of the cause,

will be the same (Leopold and others 1964). The river constantly adjusts, always trying to establish a new equilibrium between its discharge and sediment load (Bullard and

Wells 1992).

Often times when specialists go to the river to assess what

needs to be done to restore the site, the focus remains on the

condition of the channel and aquatic habitat alone without

consideration of upstream factors responsible for the current condition of the reach being addressed.

Beyond that, many have difficulty imagining, let alone

measuring, highly variable conditions over complex large

watersheds. Because the effects of changes within watersheds are multifaceted and difficult to predict, planning and

implementation of successful active restoration projects

must include monitoring key watershed processes. Aspects

to be monitored include geomorphic conditions, relative

topographic relief, soils, climate, permeability, vegetative

ground cover, water chemistry, nutrient production, movement and cycling, flow characteristics, sediment delivery

and transport regimes, riparian conditions, and aquatic

organisms.

Natural Variability in River

Flows _________________________

Natural river systems can and should be allowed to repair

and maintain themselves (Poff and others 1997). Restoring

riparian ecosystems must involve restoring or at least mimicking their natural flow regime. Realistically this will

involve a mix of human-aided and natural recovery methods.

Management of a healthy river is more than creating an

artificial constant low flow or tolerating the occasional

“100-year flood” be it natural or orchestrated by man. There

are five often overlooked components of a river’s flow

regime: magnitude, frequency, duration, timing and rate of

change. Flow modification has cascading effects on the

ecological integrity of rivers. The importance of natural

variability to aquatic and riparian ecosystems demonstrate

that unfettered rivers have multiple benefits for nature and

for human society. Changes to the natural flow regime

constitute one particularly important and underappreciated cause of declining health of rivers. Natural variability

characterizes all ecosystems. Variability in river flow is a

prime example of such natural variability. Each river has a

natural flow regime, which can be altered by a variety of

human actions including dams, diversions and diverse ways

in which hydrologic pathways are altered. Natural variability in river flow creates a wide range of habitat types and

ecosystem processes that maintain the natural biological

diversity of aquatic and riparian (stream side) species. A

major consequence of this natural variability is that all

species experience favorable conditions at some time, preventing any one species from dominating.

Alterations of the natural flow regime result in numerous

physical, chemical and biological changes to river ecosystems and may traverse many political boundaries. (Tyus

1990) .

Changes in flow shape and duration can have direct and

indirect effects. Direct effects of flow alterations are certainly important if migrations are blocked, fish are trapped

in de-watered sections, or reproduction is disrupted. Insidious effects may be far more detrimental, and include

alterations and loss of stream habitat, introduction of competing non-native fishes, degradation of water quality, and

other effects. For example with a reduction in steam flooding

change nutrient cycles and disrupt food webs which have

serious ecosystem consequences.

Examples include not just fish migrations but also recruitment of riparian trees, maintenance of sandbars in river

channels, and sustenance of wetland habitat dependent

upon flood plain inundation. Our understanding of the

linkages between natural flow regime and the ecological

functioning of rivers provides a powerful scientific basis for

river management and restoration.

Water resource developments and operations may affect

stream resources both beneficially and adversely (Tyus

1990). Return flows from irrigation projects maybe warmer,

sediment laden, and contaminated with chemicals, including biocides and fertilizers. Conversely return flows into

river channels during droughts can provide some beneficial

effects. Planned flows can mitigate and potentially enhance

natural components of riverine systems.

Instream flows are a public trust, and stream ecosystems

must be protected as irreplaceable resources. Letting a river

do its own thing—come drought or high water—is more

complicated. Most western states have recognized in-stream

flow of some form. This may be by design or by default

depending upon the river system being examined. In fact, all

11 western states have some degree of in stream flow

mechanisms. Despite the lack of an existing instream flow

designation in New Mexico at this time, the State Attorney

General and The Office of the State Engineer in April of 1998

announced that in-stream flow does have value for fish,

wildlife, and ecological purposes. With the caveat that this

would only be possible if an existing water right was employed for such purposes, it still is a positive move toward a

fuller appreciation for free flowing water in riverine systems

in New Mexico.

Natural Flood Flow Disturbance ___

The variability of watershed condition, channel morphology, flow regimes, differences in flood generated disturbances, and the intensity of those perturbations are all

factors which have a direct role in the location, establishment, and relative maturity of a particular stand of riparian

broadleaf trees.

Hypotheses on the coexistence of plant species (Connell

1979), niche differentiation (Grubb 1977), and resource

partitioning (Denslow 1980) in plant communities have

relied heavily on the requirement for some form of disturbance during the life cycles of many plant species. In general,

disturbance reduces the dominance of a site by established

individuals and creates openings for colonization and growth

by new individuals. Establishment of woody plants species

associated with riverine systems in the arid southwest are

no exception to these general principles.

Large volume floods are the primary disturbance event

affecting southwestern riparian systems (Stromberg and

others 1991). Typically, these large flood events occur on

approximately a 10 year recurrence frequency (House 1993).
48 USDA Forest Service Proceedings RMRS-P-7. 1999

In uncontrolled systems, estimating flood frequency is complicated because climate affects the magnitude and frequency of storms that cause floods (Webb and Betancourt

1992). The magnitude of these recurring flood events is

dependent upon several features including storm event,

watershed condition (LaFayette and DeBano 1990), soil

saturation including snowmelt potential (House 1993), channel morphology, and condition and associated riparian vegetation cover (Stromberg and others 1991).

Desert streams draining large watersheds provide an

excellent opportunity to test successional concepts in running waters (Fisher 1986). The importance of hydrology to

arid land riparian vegetation has long been recognized.

Zimmerman (1969) stated that: “Drainage area, geology,

and flow regimen are probably the three most important

controls in the distribution of valley-floor vegetation” in the

arid southwest. Unfortunately, all too often researchers and

field personnel of various land management agencies have

focused too intently upon the FORM of a given riparian area

and not given substantive consideration to the FUNCTION

of the area evaluated (LaFayette and DeBano 1990).

In a generalized sense, little of what we know about lotic

systems has come from work done on southwestern “desert”

streams. Fisher and Minckley (1978) found that the generalized xero-riparian stream is “hydrologically flashy,” responding rapidly to summer storm events with “wall of

water” flash floods up to 50 cubic meters per second. The

product of this and other general features of desert streams

yields a stream where the main channel is wide, shaped

largely by rare flooding events.

A principle effect of natural disturbance is to alter the

availability of resources for plant growth. Pickett and White

(1985) suggested that there are at least two mechanisms by

which disturbances can temporarily increase the availability of light, water, and soil nutrients. The first is simply the

reduction in rates of uptake or use of resources due to the loss

of biomass. The second mechanism is the decomposition

and mineralization of nutrients held in organic matter

(Bormann and Likens 1979). Large scale disturbance as a

result of out-of-bank or scouring flood flows produces a

temporary increase in some of the resources necessary for

the establishment of new stands of canopy species and

understory plants in riparian systems in the arid southwest.

In addition, there is also a net gain of energy into these

systems through the movement of nutrients into the riparian zone from adjacent uplands (Meyer and others 1988).

There is a positive relationship between disturbance size

or intensity and the availability of resources for plant growth.

In addition to the expected benefits of reduced biomass per

unit area, the degree of reduction in rates of transpiration

and interception of water, and the uptake of nutrients, there

is typically a high degree of nutrient movement associated

with flows of all magnitudes in riparian zones.

An important feature of any increase in resource availability produced by a disturbance is its transient nature. As

biomass is re-established at a site, the relative availability

of resources for future colonists will, in general, decline.

Flood disturbance produces a distinct and marked transient

pulse of nutrients and organic matter into the riverine

system. This represents a distinctly different pattern to

which plant species can respond than that of an intact

community which has equilibrated with the rate of supply of

resources (Tilman 1982). In communities where there is

rapid regrowth of vegetation following a disturbance, the

availability of resources for colonization should reach a

peak soon after a disturbance. Consequently, the first plants

that become established after a disturbance should benefit

from greater availability of resources than plants that become established later. Seedlings of many species of woody

plants often establish rapidly. Rapid germination following

a disturbance flow should be particularly critical for species

of woody plants that are intolerant of shade.

Patterns of seed production and dispersal vary widely

among woody plants. One of the most conspicuous patterns

of seed production and dispersal is the copious production of

light, wind dispersed seed in the spring coinciding with

typical spring runoff peaks. This reproductive strategy is

generally correlated with the ability to respond to large

disturbances (Baker 1974). This is the case for many “pioneer” tree and shrub species which occupy recently disturbed, scoured, or deposited sediments in and along the

channels of southwestern riparian systems.

There is a high degree of variability among riparian tree

species to distinct geomorphological and hydrological

stream habitats (Asplund 1988). Brady and others (1985)

described the development of riparian gallery forest as

beginning with moist nursery bars located in overflow

channels or abandoned meanders that provide moist areas

for seepwillow (Baccaris glutinosa) to pioneer. As the stand

of seepwillow develops, sediment aggradation occurs providing a seed bed for cottonwood (Populus fremontii) seeds, or

the expansion of Gooding willow (Salix goodingii) roots.

The high degree of variation in stand structure and composition along a given reach in desert riparian systems is an

expression of a number of variables. These include but are

not limited to: flow regime, substrate, elevation, seed source,

timing of seed dispersal, anthropogenic activities. Therefore, it is important to take the long-term landscape (spatiotemporal) view of these systems if we are to truly understand

the complex interactions of the factors contributing to the

functioning of the channel and the degree to which vegetation is expressed. In addition, the associated riparian vegetation is found along the periphery of the flood channel. The

broad shallow base flows meander over the sandy alluvium

often is some distance away from the riparian vegetation.

Where sediments are deep, flows of low discharge may occur

only below the sediment surface. In these situations, surface

flow only emerges where associated with underlying shallow

bedrock and percolation occurs where bedrock recedes. This

intermittency is a function of channel morphology and

discharge. This leads to differential expression of the associated riparian communities found along the edge of the

channel at bankfull flow. When sufficiently large changes

between erosion and depositional processes occur, the riparian area may be unable to adjust to change, loses its equilibrium, and in extreme cases may be permanently altered and

possibly damaged (LaFayette and DeBano 1990).

These disturbance events remove most of the stream biota

excluding native fishes, and bank vegetation. The magnitude of the flow determines the degree of regeneration and

recruitment of the primary flora. Conversely, in the absence

of such flows, the existing stand can become either senescent

or can be overtaken by such species as salt cedar (Tamarix

pentandra). Thus, one view of succession is of a temporal
USDA Forest Service Proceedings RMRS-P-7. 1999 49

nature looking at conditions at intervals reset by flows of

varying magnitude and frequency. In contrast, many authors have attempted to explain these systems using a

Clementsian climax succession paradigm. This concept has

received considerable attention and many current classification systems strive to make these riparian habitats fit some

climax succession schedule. However, this has been difficult

to describe adequately and impossible to predict in these

disturbance driven systems. Fisher and Minckley (1978)

concluded that “an ecosystem in which the entire species

pool consists of ‘pioneer’ species is unlikely to exhibit

temporal succession.” The community and how the primary

species are classified thus may make application of a

Clementsian model awkward if not inappropriate. Sampling and extrapolating that data to fit the balance of the

study area is misleading and ineffective in describing a

riparian community overall due to variability of geology,

valley form and substrate. It may well be that the appropriate means to measure these sites is to evaluate the species

richness and the degree of maturity or size class diversity in

the particular stand over time between significant disturbance flows.

Biological Integrity ______________

The most influential definition of biological integrity

was proposed by Frey (1975) and further described by Karr

and Dudley 1981. The concept is defined as “the capability of

supporting and maintaining a balanced, integrated, adaptive community of organisms having a species composition,

diversity, and functional organization comparable to that

of natural habitat of the region” (Karr 1991).

Angermeier and Karr (1994) identified two important

distinctions between integrity and diversity from this definition. First, system integrity is reflected in both the biotic

elements and the processes that generate and maintain

those elements, whereas diversity describes only the elements. Integrity depends on processes occurring over many

spatiotemporal scales, including cellular processes giving

rise to genetic elements and ecosystem processes regulating

the flow of energy and materials. The second distinction

between integrity and diversity is that only integrity is

directly associated with evolutionary context.

When a river is dammed, integrity is reduced, resulting in

population declines which are adapted to the natural hydrological regime. Integrity goals also provide for natural fluctuation in element composition. Loss of a particular element,

a particular species for example, or replacement by a

regionally appropriate one need not indicate a loss of integrity unless the processes associated with the element’s

maintenance become impaired. Biological integrity is thus

generally defined as a system’s ability to generate and

maintain adaptive biotic elements through natural evolutionary processes. Current loss of biological integrity includes loss of diversity and breakdown in the processes

necessary to generate future diversity.

Ecological Restoration ___________

The goal of ecological restoration is to produce a selfsustaining system as similar as possible to the native biota.

Restoration goals must be based on social and political

constraints as well as biological potential. Restoration

methods usually mimic recovery from natural perturbations

and reflect important organizational processes. Common

approaches for aquatic systems include manipulating water

quality, habitat structure, hydrology, riparian/watershed

vegetation, and (less frequently) animal populations (Gore

1985; Osborne and others 1993). Restoration of terrestrial

systems typically focuses on establishing native vegetation

and manipulating succession. To maximize effectiveness,

restoration efforts should employ and encourage natural

ecological processes rather than technological fixes and

should incorporate spatiotemporal scales large enough to

maintain the full range of habitats necessary for the biota to

persist under the expected disturbance regime. Riparian

zones and floodplain are critical landscape components

linking aquatic and terrestrial systems; they regulate aquatic

habitat formation as well as movement of water, nutrients,

and organic material into aquatic habitats (Gregory and

others 1991).

“Restoration” may be reasonable in many cases. In other

instances, enhancement of the existing altered character of

our streams and rivers may be the best we can hope to

realize. Most riparian habitats are now a highly controlled

or altered system with much of their ecological integrity

hampered by our past or continuing activities. The thoughtful application of new understandings to the delicate and

intricate balance of nature, recognition of the inevitable

range of flood and drought, flexibility in management and

legal applications will be necessary for improvement of the

riverine habitats. The solution lies in the ability to explore

collaboratively means and methods to provide the societal

needs while simultaneously sustaining a healthy environment. At the present time there are a number of research,

monitoring, and planning activities underway designed to

contribute to the overall goal of improvement of southwestern riparian ecosystems. These activities are at all

levels of government and many are collaborative efforts.

Policy effectiveness also could be improved by shifting

focus from populations and species to landscapes. The organizational processes and ecological contexts that maintain

populations typically operate at larger spatiotemporal

scales than the populations themselves (Pickett and others

1992). Thus management approaches focusing on strictly

aquatic components (for example, designation of a stream

reach as wild and scenic or as critical habitat for an imperiled species) are unlikely to be effective over the long-term.

Dr. Hal Salwasser in 1991 made the observation that

traditional agricultural, fisheries, forestry, game management, and mining agencies must replace their narrow,

commodity and harvest-oriented philosophies with innovative perspectives founded on a broader range of social

concerns, longer time frames, and more interagency cooperation. Critical steps toward managing for biological

integrity include establishing scientifically defensible benchmarks and assessment criteria. (Angermeier and Karr 1994).

Although these steps are potentially contentious, current

uses of integrity goals indicate that success is attainable.

The morphic variables that interact to form the dimensions, profile and patterns of modern rivers are often the

same variables that have been adversely impacted by development and land use activities. To restore the disturbed
50 USDA Forest Service Proceedings RMRS-P-7. 1999

river, the natural stable tendencies must be understood to

predict the most probable form. If one works against the

natural tendencies of a river course in terms of watershed

yield, morphology, and channel and meander geometry. If

one works against these tendencies, restoration is generally

not successful (Rosgen 1994).

Restoration efforts in the uplands, river corridor, in the

floodplain, on public, private and tribal lands is ever increasing. We are instituting Adaptive Management in many

arenas to recreate habitat which has been lost or whose

quality has been severely affected by our past management

activities.

The solution at first blush appears to be either too simplistic or too overwhelming. Clear understanding of what

is needed, the operating space for change in administration,

and recognizing that we are all part of a basin wide community will provide opportunities to be better stewards of the

finite resources we utilize.

Societal Choices ________________

The causes of environmental degradation and loss of

biodiversity are rooted in society’s values and the ethical

foundation from which values are pursued. Solutions are

likely to emerge only from a deep-seeded will, not from

better technology. Adopting biological integrity as a primary

management goal provides a workable framework for sustainable resource use, but fostering integrity requires societal commitment well beyond government regulations and

piecemeal protection. Such a commitment includes selfimposed limits of growth and resource consumption, rethinking prevailing views of land stewardship and energy

use, and viewing biological conservation as essential rather

than as a luxury or nuisance. The decision to conserve or

exhaust biotic resources is before us. It can be informed by

science and influenced by government policy, but conservation primarily depends on a societal will grounded in recognition of its obligation to the future. (Angermeier and Karr

1994).

Quality of life does reside in a healthy environment. There

are numerous economic benefits associated with vibrant,

functioning ecosystems. Responsible management and administration at all levels of government and as individuals

will be necessary. But without attention to these aspects,

significant and perhaps irreversible consequences could

result. Ultimately, the habitat we save will be our own.

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52 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

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J. S. O’Brien and W. T. Fullerton are Hydraulic Engineers, FLO Engineering, Inc. Breckenridge, CO.

Abstract—Spring floodplain inundation is important to the natural functions of the Rio Grande bosque biological community including cottonwood tree germination and recruitment. To predict floodplain inundation, a two-dimensional flood routing model FLO-2D

will be applied to various reaches of the Rio Grande. FLO-2D will

assess overbank flooding in terms of the area of inundation, floodplain hydraulics and river discharge timing, frequency and duration. Floodwave attenuation is important in predicting floodplain

inundation. Initial FLO-2D applications will be made to the Isleta

reach (15 miles) south of Albuquerque and to a 20 mile reach near

the Bosque del Apache Wildlife Refuge.

The Rio Grande Bosque Hydrology Group has identified

several important projects designed to improve the natural

functions of the Rio Grande bosque biological community.

One of these projects is to investigate the potential for

overbank flooding to support cottonwood tree germination.

To predict overbank flooding discharge, the FLO-2D model

will be applied to various reaches of the Rio Grande downstream of Cochiti Reservoir. The initial test application of

the model was made to a 15 mile reach of the Rio Grande

downstream of the Isleta Diversion Dam south of Albuquerque. The second FLO-2D application will be made to a 20

mile river reach near the Bosque del Apache National

Wildlife Refuge. FLO-2D will assist in analyzing overbank

flooding in terms of timing, frequency and flood duration.

The prediction of overbank flooding and the application of

the FLO-2D model is a joint cooperative study involving the

support of the Albuquerque Projects Office of the Bureau of

Reclamation, the Fish and Wildlife Service and the Army

Corps of Engineers. All three agencies have been involved in

several aspects of this project including floodplain mapping,

river channel morphology and application of the model. The

Fish and Wildlife Service has supported the Bosque floodplain mapping and the initial test application of the FLO-2D

to the Isleta reach. The Isleta reach cross section survey was

conducted through a joint funding effort of the Fish and

Wildlife Service and the Corps of Engineers. The Corps of

Engineers have performed the digital floodplain mapping

used in the both the Isleta and Bosque reaches and supported the initial applications of the model. Primary funding

support for Bosque del Apache Wildlife Refuge project and

for the floodplain mapping was provided by the Bureau of

Reclamation. The Bureau was also responsible for getting

Simulation of Rio Grande Floodplain

Inundation Using FLO-2D

J. S. O’Brien

W. T. Fullerton

the cross section surveys completed. All three agencies have

purchased or obtained a copy of the FLO-2D model for future

applications.

FLO Engineering, Inc. is an engineering contractor for

the Bureau of Reclamation specializing in hydrographic

data collection, river channel morphology and hydraulic

engineering. Hundreds of cross sections throughout the

Middle Rio Grande valley have been surveyed by FLO

Engineering, Inc. The hydrographic data base compiled by

the Bureau on the Middle Rio Grande includes aerial photography, ortho-photographic mapping, discharge measurements, sediment transport and bed material data and

numerous cross section and floodplain surveys. These data

constitute one of the best hydrographic data bases on any

river in the country. From this data base, the FLO-2D model

input data files will be developed.

Description of the FLO-2D Model __

FLO-2D is a commercially available proprietary model

created by FLO Engineering. It has been applied to numerous flood hazard simulation projects throughout the west

including routing Green River seasonal flows from Flaming

Gorge to the Colorado River confluence and numerous alluvial fan flood hazard delineation projects. FLO-2D is a twodimensional, finite difference flood routing model using

either a kinematic wave, diffusive wave or the full dynamic

wave version of the momentum equation for unconfined,

overland flow or channel flow. It simulates the progression

of the flood hydrograph, conserving flow volume, over a

system of square grid elements representing topography

and flow roughness. FLO-2D is an ideal model for river

channel overbank flooding, alluvial fan flows, flow through

urban areas, or the hydraulic design of flood mitigation

measures. The model has a number of components which can

enhance the detail of a flood simulation including channelfloodplain discharge exchange, loss of storage due to buildings, flow obstruction, rill and gully flow, street flow, bridge

and culvert flow, levee and levee failure, mud and debris

flow, sediment transport, rainfall and infiltration (fig. 1).

FLO-2D has used by federal and state agencies and numerous consulting firms.

Creating a FLO-2D data base

A FLO-2D project data base requires a representation of

the potential flow surface topography in a square grid

format. A simple procedure has been devised with CADD

software for generating the grid system. Most CADD systems contain survey routines which enable a grid system to

be overlaid on a digitized map and the coordinates and

elevations exported to a file. Any size grid element can be

used by the model, but the timestep is governed by the wave
USDA Forest Service Proceedings RMRS-P-7. 1999 53

celerity and very small grid elements will require very small

timesteps. A typical grid element is 200 ft to 500 ft, but grid

elements ranging from 50 ft to 2,000 ft have been used in

simulations. The number of grid elements is essentially

unlimited.

Routing Algorithm Stability and Volume

Conservation

The timestep is incremented or decremented according to

strict flood routing numerical stability criteria. Numerical

stability has been linked to volume conservation which is the

basis for the model accuracy. When the model accurately

conserves volume, the model runs faster. If the model is

gaining or losing volume, the timesteps decrease. Volume

conservation is carefully tracked and is reported both during

the simulation and in output files. Typically timesteps range

from 1 to 60 seconds.

Overland and Channel Flow - Exchange of

Channel and Floodplain Discharge

Overland flow is simulated in eight directions (4 compass

and 4 diagonal directions). One-dimensional channel flow is

simulated with rectangular, trapezoidal or natural shaped

cross sections. A preprocessor program will convert HEC-2

cross sections into a data file formatted for FLO-2D. The

channel width can be larger than the grid element allowing

for more detailed floodplain simulations. When the flow in

the channel exceeds the bank height, FLO-2D will compute

the overbank discharge. This channel-floodplain flow interaction can occur with overland return flow to the channel

Figure 1—Physical Processes Simulated by FLO-2D.

(fig. 2). This is an important component for the application

of the model to the Rio Grande. The number of inflow

tributaries is unlimited.

Overland flow can be concentrated in small rills and

gullies as multiple channel flow. When specific grid elements are assigned multiple channels, discharge between

those elements occurs as concentrated flow in small, rectangular channels and not as overland sheet flow. Rainfall on

the overland portion of each grid element is routed into the

element rill or gully. More than one gully can be specified for

a grid element. When the rill or gully depth is exceeded, the

channel is expanded by a preassigned incremental width to

contain the gully flow. Variable rill and gully channel characteristics can be spatially delineated on the grid system.

Mud and Debris Flows

Hyperconcentrated sediment flow is simulated using viscosity and yield stress relationships as function of sediment

concentration. Several such relationships have been analyzed in the laboratory representing different soil types and

conditions. Very viscous mudflows may cease flowing on

very rough surfaces or very mild slopes. Conversely, mudflows can be diluted by rainfall inflow. Storage in small

debris basins and spillway discharge can be simulated.

Sediment Transport—Aggradation and

Degradation

Sediment transport is computed for arid region alluvial

systems using the Zeller-Fullerton equation. Almost any

sediment transport relationship can be programmed into

the model. For the Rio Grande bosque project, three new
54 USDA Forest Service Proceedings RMRS-P-7. 1999

sediment transport equations will added to the model. Aggradation and degradation is predicted if the sediment transport routine is invoked. Scour and deposition are distributed

uniformly on the grid element surface or channel bed.

Other FLO-2D Components

Rainfall and infiltration can be simulated on the potential

flow surface before or during the flood simulation. The

rainfall is then routed as overland sheet flow or as rill and

gully flow until it intercepts a main channel. Infiltration is

simulated with the Green-Ampt infiltration model and can

be spatially variable on the flow surface.

Street discharge is simulated as flow in a shallow rectangular channel. Streets may intersect and are delineated

with a width and curb height. Bridge and culvert flow on the

grid system can be simulated by user specified relationships

between the discharge and headwater depth.

Levees can be simulated by specifying flow directions and

crest elevations. Levee failure can occur by overtopping or at

a prescribed levee stage for a specified time period. Levee

failure is simulated on a grid element by grid element basis.

Flow around buildings and obstructions and floodplain

storage loss due to structures can be simulated on a grid

element basis. A portion or the entire grid element can be

removed from potential inundation. Similarly, the flow

transfer between grid elements can be partially or entirely

obstructed.

FLO-2D Results

Spatially and temporally varied output including flow depth,

velocity, discharge hydrograph, sediment concentration and

Figure 2—Channel-Floodplain Flow Interface.

bed elevation are written to output files. Discharge hydrographs

can be established for any channel or any overland grid element

in the system. Outflow grid elements can be reviewed separately. Grid elements can be grouped together as cross sections

to generate flow hydrographs. Maximum depth, velocity and

discharge files are automatically created. The flood progression

over the flow surface can be viewed graphically along with a

plot of the inflow hydrograph while the model is running. The

most common desired result is a map of the maximum flow

depths depicting the maximum area of inundation.

Application of FLO-2D to the Rio

Grande Isleta Reach _____________

In 1997, the Bosque Hydrology Group reviewed the potential application of the FLO-2D model to predict overbank

flooding along the Middle Rio Grande. Through funding

support from the Bosque Initiative and in cooperation with

the Corps of Engineers Albuquerque District, the FLO-2D

model was applied to a 15 mile reach of the Rio Grande

downstream of the Isleta Diversion located south of Albuquerque. This reach was identified by the Corps of Engineers

as a potential restoration area where overbank flooding may

enhance the bosque biology.

The Corps developed a digital terrain map (DTM) and

overlaid a grid system of 8,024 elements, 500 ft square

(fig. 3). The river reach included 234 channel elements

represented by 11 surveyed cross sections and 9 cross sections extracted from the 1995 DTM mapping. Infiltration

and the levee system were modeled. Three flood hydrographs

were simulated: The 250-year project flood event with a peak

discharge of 42,000 cfs; the 100-year flood with a peak
USDA Forest Service Proceedings RMRS-P-7. 1999 55

Figure 3—FLO-2D Grid System at the Isleta Diversion, Rio Grande
56 USDA Forest Service Proceedings RMRS-P-7. 1999

discharge of 15,326 cfs; and a high flow season hydrograph

with a peak discharge of 7,000 cfs. The project flood event

was simulated as both a levee and no-levee scenario. The

spatial flood inundation results are viewed graphically when

running FLO-2D or the post-processor programs.

Although this was a simple test application to determine

the utility of the model for predicting overbank flooding on

the Rio Grande, the results proved to be interesting. The

Corps of Engineers had originally modeled this reach with

HEC-2, a single discharge, one-dimensional step-backwater

hydraulic model. The project flood event results essentially

indicated bluff to bluff flood inundation across the Rio

Grande valley for the 40,000 cfs peak discharge. FLO-2D

routed the entire hydrograph and it was revealed that

because the hydrograph volume was so limited, floodwave

attenuation through the reach was pronounced and much of

the overbank flooding was abated by the end of the reach. In

the levee flood scenario, levees were overtopped in the

upstream 30 percent of the reach inundating about 40

percent of the floodplain outside the levees. In the downstream half of the reach, all the overbank flooding was

confined between the levees. No bluff to bluff flooding was

predicted with the FLO-2D model.

Without the levees, the flood inundated approximately 50

percent of the floodplain in the reach. Most of the floodplain

inundation occurred in the upstream half of the reach.

Again, the floodwave attenuation was so pronounced that

only a small portion of the reach was flooded. Higher floodplain depths were predicted along the eastern edge of the

floodplain against the valley bluff. The results from these

flood scenarios indicate that the flood hydrograph had a very

limited volume. The peak discharge decreased from 40,000

cfs at the start of the reach to a predicted 25,700 cfs at the end

of the reach for the levee simulation and to a predicted

15,700 cfs for the no-levee simulation. The importance of

overbank flooding in floodwave attenuation is clearly demonstrated in this test. The levees increase the potential

downstream flooding. If this Isleta reach is similar to the

upstream reach for several miles, it is unlikely that the

40,000 cfs peak discharge would arrive at the Isleta Diversion without experiencing some attenuation.

The 100-yr flood was only simulated for the case with the

levees. All of the overbank flooding was contained between

the levees. A portion of the channel in the lower third of the

reach conveyed all the flow. There was no predicted overbank

flooding for a reach of approximately two miles. The 100-yr

hydrograph peak discharge did not significantly attenuate.

The final flood simulation involved the high flow seasonal

discharge related to spring runoff of 7,000 cfs. In this flood

scenario, the areas of floodplain inundation were of primary

interest. Most of the upstream half of the reach was inundated, but only about one-third of the downstream half of the

reach was flooded. Channel conveyance capacity was greater

in the lower portion of the river reach. There was no significant floodwave attenuation.

The test application of FLO-2D to the Isleta reach proved

successful in several aspects. First, it was ascertained that

the model could successfully identify which reaches might be

preferable for overbank flooding. Secondly, the test demonstrated the importance of routing the flood hydrograph.

Timing and flow duration will be critical to assess overbank

flood potential in reaches further downstream of Isleta.

Given a prescribed volume as a flow augmentation release

from Cochiti Dam to enhance overbank flooding, the release

hydrograph can be adjusted to maximize either flood duration or area of inundation in various reaches. Finally, the

FLO-2D simulation highlighted several drawbacks in the

existing Isleta Reach data base.

Accurate prediction of floodplain inundation along the Rio

Grande is contingent on three important factors; adequate

DTM mapping (both in topographic accuracy and contour

resolution), appropriate cross section spacing and calibrated

roughness parameters. Through the FLO-2D Isleta application, it was determined that the eleven surveyed Cochiti

cross section lines provided by the Bureau and recently resurveyed by FLO Engineering did not match the extracted

DTM cross sections developed by the Corps of Engineers.

The two sets of cross sections were out of phase (they weren’t

surveyed in the same season) and Corps cross sections did

not represent a complete picture of the channel (thalwegs

were estimated). As a result, when the Isleta reach model

was developed, some grid elements had adverse bed slope

conditions and inappropriate roughness Manning’s n-values. Cross section and n-value adjustments were made to

permit the model testing to proceed, but it became apparent

that additional data collection was necessary to upgrade the

Isleta reach data base to obtain reliable results. Specifically,

the following hydrographic data collection will be required:

• Additional cross sections are needed in transitional

reaches where the channel changes from a narrow to a

wide cross section.

• All the cross sections should be surveyed in a relative

short period of time during a period of high flows to avoid

the effects of scour and fill in a reach.

• Water surface elevations should be surveyed at all the

cross sections during a relatively short period in conjunction with a discharge measurement to calibrate the

n-values during high flow.

It is anticipated that these data will be collected during

this spring runoff to enable the Isleta Reach to be accurately modeled with FLO-2D to predict potential overbank

flooding.

Prediction of Flow Hydrographs

Using FLO-2D __________________

The National Park Service and the Fish and Wildlife

Service Denver Office supported the development of a FLO2D discharge routing model for the Green River in Utah from

Flaming Gorge Dam to the confluence of the Colorado River,

a distance of 412 miles. The FLO-2D model was proposed as

hydrograph routing tool to support flow recommendations

for the Flaming Gorge biological opinion being written by the

Fish and Wildlife Service. To develop the routing model, a

digital topographic map was prepared, all available Green

River cross section surveys were compiled and inflow

hydrographs were assembled. This included seasonal high

flow hydrographs of Flaming Gorge Dam releases and the

tributary inflow of the Yampa, Duchesne, White, Price, and

San Rafael Rivers as well as Brush and Ashley Creeks.
USDA Forest Service Proceedings RMRS-P-7. 1999 57

The project goal was to use FLO-2D to predict the seasonal

flow hydrograph at any location in the Green River downstream of Flaming Gorge Dam on a daily basis. The project

objectives included:

• Calibration of the model for the 1996 high flow season.

• A review of the model accuracy by simulating the 1997

high flow data.

• An estimate of floodplain inundation area for these two

flow years.

• Simulation of the Flaming Gorge jet tube releases.

• Prediction of discharge timing and duration at any

location in the Green River.

Green River flows were simulated for 100 days of the 1996

high flow season beginning on April 1 and ending on July 9.

In 1996, five level loggers for monitoring river stage were

established throughout the Green River system. Combined

with the USGS gages at Jensen and Green River, they

constitute a system of seven known discharge points with

which to calibrate the FLO-2D predicted hydrograph.

A 2,000 foot square grid system was overlaid on the

digitized base map resulting in 2,482 grid elements of which

962 were designated as channel elements. A total of 268

surveyed cross sections were analyzed for channel geometry

relationships and assigned to the channel elements. Channel roughness and infiltration parameters were adjusted

within acceptable ranges to calibrate the predicted hydrograph at the seven points of known discharge in the Green

River. Generally, the final Manning’s n-value ranged from

0.024 to 0.050 with the higher n-values assigned to grid

elements in the steep canyon reaches. Some channel element cross sections and roughness values were adjusted to

reduce the abrupt transition between grid elements. The

assigned cross sections created adverse slope conditions for

some elements in the channel profile. For these elements,

the channel depth and bed elevations were adjusted to

achieve a uniform reach slope.

FLO-2D predicted a hydrograph for every channel grid

element (every 2,000 ft) throughout the Green River system

from Flaming Gorge to the Colorado River confluence. The

1996 measured hydrographs were used to calibrate the

model and then FLO-2D was applied to 1997 flows using the

same channel data base. Excellent correlation was achieved

between the FLO-2D predicted hydrograph and measured

discharge hydrograph at the USGS Jensen gage located at

one-third of modeled river system (fig. 4 and 5). Further

downstream at the USGS Green River gage (about twothirds through the system), there was some disparity between the predicted and measured discharge hydrographs

(fig. 6 and 7). The differences between the predicted and

measured hydrographs were attributed to:

• Small unmeasured tributary inflow between Jensen

and Green River.

• Storm inflow reflected in spikes in the measured discharge.

• Canal diversion at Green River, Utah.

• Estimated discharge reported for the Green River gage

(discharge record errors).

• Variable infiltration and evaporation losses in the reach

from Jensen to Green River.

Despite these correlative discrepancies, the USGS Green

River gage data compared very favorably with the FLO-2D

predictions.

The utility of the FLO-2D model was further demonstrated by simulating flows without the storage effects of

Flaming Gorge reservoir and by adjusting Flaming Gorge

Dam releases. These simulations indicated a substantial

increase in floodplain inundation when Flaming Gorge releases were timed to occur with the peak discharge in the

Yampa River. This application of FLO-2D to the Green River

illustrated the flexibility of the model as a management tool.

Figure 4—1996 Green River Hydrograph at Jensen, Utah
58 USDA Forest Service Proceedings RMRS-P-7. 1999

Application of the FLO-2D ________

Through the cooperation of the Albuquerque Projects

Office of the Bureau of Reclamation, Corps of Engineers, and

the Fish and Wildlife Service, the FLO-2D model will be

applied to a 20 mile reach of the Rio Grande near the Bosque

del Apache National Wildlife Refuge south of San Antonio,

New Mexico. The modeled reach will extend from the Highway 380 bridge to the south boundary of the refuge. This

project will encompass several aspects of the Rio Grande

Figure 5—1997 Green River Hydrograph at Jensen, Utah

Figure 6—1996 Green River Hydrograph at Green River, Utah

hydrology and channel morphology. The goal of the project

is to design a seasonal high flow hydrograph that will

inundate selected areas of the floodplain in this reach. The

high flow hydrograph will be analyzed in terms of it’s

frequency and flow duration. Initially, FLO-2D will be used

to simulate flow with a rigid boundary model. In subsequent

applications, FLO-2D will simulate channel flow with a

mobile bed. Several sediment transport models will be tested

and calibrated.

Preparation of the FLO-2D data base for Bosque reach

began last year when a series of 41 cross sections were
USDA Forest Service Proceedings RMRS-P-7. 1999 59

Figure 7—1997 Green River Hydrograph at Green River, Utah

surveyed in the study reach. The majority of these cross

sections have been surveyed several times over the last

decade. Twelve new cross sections were established in transition reaches from a narrow to a wide channel. A digital map

of the floodplain with 2 foot contours has been completed

from aerial photogrammetry by the Corps. On this base map,

a 500 ft square grid element system will be overlaid for the

FLO-2D model. The base map can be used by all researchers

participating in the Bosque Initiative. In addition, water

discharge, sediment load, bed material sizes, water surface

elevations, aerial photos of overbank flooding and other

hydrographic data have been collected over the past several

years which will be applied to calibrate the model. Three

flow hydrographs will be simulated:

• 10-year average hydrograph (peak discharge ~ 4,500 cfs)

• 2-year return period hydrograph (peak discharge ~

8,470 cfs)

• Low flow period hydrograph (peak discharge ~ 3,500 cfs)

An important part of this project will be the model calibration to existing data bases. In several locations along this

reach, bed scour reduces the propensity for overbank flooding during high flows. At 3,000 cfs, the water surface in

certain locations may be within a half foot of being bankfull.

Later in the hydrograph at a flow of 5,000 cfs, the water

surface elevation may be foot below the top-of-bank. This

channel bed response is difficult to predict because it depends on sediment supply as well as flow hydraulics. The

Bureau has developed a total load rating curve which will be

applied as the sediment supply to the study reach. One

project objective will be to determine the importance of

channel bed response to high flows in terms of the area of

inundation. Generally, the volume of the water stored in the

channel at a given time is relatively minor compared to the

total volume in the flood hydrograph, however, changes in

channel cross section and conveyance can significantly impact the location at which overbank flow occurs. For this

reason, both a rigid bed and mobile bed analysis will be

conducted with the FLO-2D model. At least three sediment

transport equations will be used in the model calibration.

It is anticipated that the model data base will be developed

during this summer and the project will be completed by the

end of 1998. The final product of this flood routing project

will be an area of floodplain inundation versus discharge

relationship that might be incorporated into reservoir operation and Rio Grande flow management to promote

overbank flooding near the Bosque del Apache National

Wildlife Refuge. The FLO-2D results and projected flood

inundation maps combined with projections of the Rio Grande

hydrology can be the basis for decisions regarding frequency,

duration and timing of high flows. This project objective is a

focal point of the proposed Rio Grande bosque restoration. If

the FLO-2D simulations are successful, there is interest in

developing the FLO-2D model for the entire Middle Rio

Grande from Cochiti Dam to Elephant Butte Reservoir.

Conclusions____________________

The FLO-2D model will be used to investigate the potential for limited overbank flooding along various reaches of

the Middle Rio Grande to enhance the natural functions of

the bosque biological community and to increase opportunities for cottonwood tree germination. Overbank flooding will

be evaluated in terms of river discharge, timing, frequency

and duration. The model has demonstrated its utility on the

Isleta reach illustrating the importance of simulating

floodwave attenuation. In an application for the Green River

in Utah, the FLO-2D model accurately replicated season

hydrographs measured in various locations throughout the
60 USDA Forest Service Proceedings RMRS-P-7. 1999

river system. In the coming year, the Isleta reach simulation

will be finalized and the model will be applied to a 20 mile

reach of the Rio Grande near the Bosque del Apache National Wildlife Refuge. The results of the model will include

area of inundation versus discharge/duration relationships

which can be used to investigate various combinations of

reservoir releases and operations.

Acknowledgments ______________

The application of the FLO-2D model to the Middle Rio

Grande is a cooperative effort of the Fish and Wildlife

Service, Bureau of Reclamation and Corps of Engineers. The

primary participants in this effort include Paul Tashjian

and Jeff Whitney of the Fish and Wildlife Service, Drew

Baird of the Bureau of Reclamation, and Doug Wolf and

William DeRagon of the Corps of Engineers. Support for this

project came from all three agencies with the Bureau of

Reclamation being the primary source of funding. The Bosque

Initiative provided the initial impetus to examine the potential for applying the FLO-2D model to the Isleta Reach. The

Bosque Hydrology Group of the Bosque Initiative is central

forum for discussion, direction and review of the FLO-2D

simulations.
USDA Forest Service Proceedings RMRS-P-7. 1999 61

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Gail Stockton is Hydraulic Engineer, U.S. Army Corps of Engineers, and

D. Michael Roark is Hydrologist, U.S. Geological Survey, Albuquerque, NM.

Abstract—The Upper Rio Grande Water Operations Model

(URGWOM) under development through a multi-agency effort has

demonstrated capability to represent the physical river/reservoir

system, to track and account for Rio Grande flows and imported San

Juan flows, and to forecast flows at various points in the system.

Testing of the Rio Chama portion of the water operations model was

completed in March 1998. Results indicate that RiverWare software

can be used to model the entire upper Rio Grande system. Model

development is in progress on the mainstem of the Rio Grande.

The process of moving water through the Rio Grande

basin has become increasingly complex. In 1996, six federal

agencies recognized the need for a tool that could help them

make timely decisions and improve storage and delivery

operations in the Upper Rio Grande Basin for more effective

and efficient system management. They needed a computer

model with accounting and forecasting capability that could

simulate near real-time reservoir operations. The agencies

agreed in a memorandum of understanding to cooperate to

develop a model for the upper Rio Grande basin from the

headwaters in Colorado to Fort Quitman, Texas and to

provide access to actual, forecasted, and planned reservoir

and river operational data through a unified data base for

data management and information sharing among basin

stakeholders.

As a result of 1997 model scoping and coordination activities with other basin interests, the cooperating agencies

finalized a plan for development of the Upper Rio Grande

Water Operations Model (URGWOM). The plan identified

computer software (RiverWare) and associated hardware

that could be used in developing the model and outlined the

tasks and schedule for model development.

Cooperative Effort _______________

Since 1996, the Bureau of Reclamation (Reclamation),

U.S. Fish and Wildlife Service, U.S. Geological Survey

(U.S.G.S.), Bureau of Indian Affairs, the International Boundary and Water Commission (U.S. Section), and the U.S.

Army Corps of Engineers (Corps) have partnered to develop the model. The cities of Albuquerque and Santa Fe,

Rio Grande Restoration, Sandia and Los Alamos National

Upper Rio Grande Water Operations Model:

a Tool for Enhanced System Management

Gail Stockton

D. Michael Roark

Laboratories also entered into this partnership in 1997.

Other entities, as well, have contributed to the effort through

technical review and outreach support.

The cooperative spirit of this effort is exemplified by the

co-located modeling team with members from Reclamation,

U.S.G.S., and the Corps working together and sharing a

melange of computer equipment and also by the technical

review team made up of stakeholders, interested individuals, and state, local, and federal agency staff who have

contributed many hours of technical review of the test case.

Rio Chama Test Case ____________

To test that RiverWare was capable of simulating the

entire Upper Rio Grande surface water system, the software

was first tested on the Rio Chama. This stream reach was

selected because of its operational complexity. It includes a

transmountain diversion, three reservoirs with complex

operational criteria and accounting procedures. Because it

has relatively simple river reach conditions and reasonable

availability of data, it was a good test of the capabilities of the

software.

RiverWare

RiverWare is a generic reservoir and river system modeling software that can be readily customized to fit a specific

river basin. It has been in development since 1993 and is the

result of a continuing collaborative effort by the Center for

Advanced Decision Support for Water and Environmental

Systems (CADSWES) at the University of Colorado, the

Bureau of Reclamation and the Tennessee Valley Authority.

RiverWare is object oriented, meaning that the software

has objects that represent features of the basin visually on

a computer screen such as reservoirs, confluence’s, gaging

stations, river reaches, diversions, data, etc. Objects contain

user selected physical process methods and numerical data.

For example, the modeler can specify different routing

method categories for a stream reach object: “no routing”,

time lag, Muskingham-Cunge, kinematic wave, etc. Variables called “slots” contain all the data that are required or

generated by the object. In the case of a stream reach, a reach

object may contain slots for inflow ,return flow, outflow, and

other data.

The software is referred to as data-centered because data

supplied to the model defines the specific river and reservoir

system. It is also rule-based; operating policies are incorporated into the model with a rules language. RiverWare uses

the operational rules to make decisions during a simulation.

None of these customizing features requires a change in the

hard code of the software so it is easily modified for changes
62 USDA Forest Service Proceedings RMRS-P-7. 1999

in policies or addition of new objects as the basin changes.

Since the data and rules defines the specific system, the Rio

Chama test case model was developed by entering Rio

Chama data and rules.

The software also has multiple calculation methods that

can be selected to customize the physical behavior of an

object. For example, there are about eight different calculations available to chose from for calculating spills from a

reservoir, everything from no spill to a complex combination

of regulated spill plus bypass plus unregulated spill calculation. In the specific case of Abiquiu Reservoir, the no spill

calculation was selected to represent the real situation.

After the objects are put into a workspace and the appropriate methods are selected they can be linked together to form

a river basin network.

The most recent improvement to RiverWare was the

addition of the water accounting function. Each object has

accounts slots for accounting data.

Conceptual Model Development

The Technical team began model development of the

Rio Chama by describing the existing physical and water

accounting systems, graphically and in text, to serve as a

basis for the construction of the model in RiverWare.

Public technical review and comments on the conceptual

model documents were provided by the Technical Review

Committee.

Physical Model

The physical model of the test case is a rule-based simulation of the physical system of the Rio Chama. The model

simulates the physical system from the top of the basin,

starting with the San Juan diversions and continuing downstream to the confluence of the Rio Chama with the Rio

Grande at Chamita. Figure 1 shows the topology or layout

for the Rio Chama in RiverWare. The Technical Team built

the computer version by constructing each object separately:

first, reservoirs; then, river reaches; followed by confluence’s

and diversions. Each object was verified by comparing to

historical data. After all objects were built, verified and

linked together, the over all model was checked against

records for a period from January 1985 to July 1996. Simulated results closely matched actual records. The resultant

physical model represents the Rio Chama physical system

and is the basis for the test case accounting and forecasting

models.

Accounting Model

The accounting model incorporates water ownership and

accounting functions into the physical model. It is essentially a data processing and reporting application of the

model structure. The layout for the accounting model is

displayed in figure 2. Since the water input data for San

Juan Chama Project accounting is measured at the outlet of

the Azotea tunnel, the San Juan diversions are not shown as

objects in the topology for the accounting model. However,

the rest of the physical model structure is used in the

accounting model.

The accounting model solves for inflow since the releases

from the reservoirs are measured and are direct inputs to the

model. It is designed to perform the same operations that

Reclamation’s daily water operations programs perform,

and to eliminate many of the hand calculations that are

presently needed to distinguish San Juan water from Rio

Grande. Additionally, it can simulate the two types of water

accounting in the river reaches between reservoirs. By mid

1999, the model will also be capable of simulating San Juan

Chama contractors accounts.

Forecast Model

The forecast model is used to simulate the operation of the

river and reservoir system by determining releases and

storage for a desired forecast period. Since it is based on the

physical model, includes the accounting functions of the

accounting model, and the rules based upon water operations regulations, constraints and preferences, it is a very

powerful tool to understand the system. The topology of the

forecast model is shown in figure 1.

Forecasted inflow hydrographs at all of the forecast points

and the initial conditions of the reservoirs are required

inputs to the model. The forecast model using the rules,

simulates how varying hydrologic conditions upstream may

affect water operations downstream. It simulates most routine water operations and clearly defined special operations,

including emergencies, thus giving water managers the

ability to make timely decisions.

Test Case Results

Figures 3, and 4 display few differences between the test

case model and Reclamation’s daily program calculations of

inflow and precipitation at Abiquiu Reservoir for 1985 to

1996. Comparisons of the two methods gave similar results

for outflow, and evaporation at Abiquiu and at the other

reservoirs.

Figure 5 shows the cumulative differences between the

two methods in storage at Abiquiu Reservoir. The total

cumulative difference between using the model to compute

storage versus using the daily programs is about 46 acre feet,

a small cumulative error for 10 years of record. Total storage

capacity for Abiquiu Reservoir at elevation 6220 feet is

189,307 acre feet.

The test case model forecast of total outflow at Abiquiu

Reservoir is compared with historical data for a 10-month

period of record in figure 6. The model simulations for San

Juan outflow and Rio Grande outflow also closely duplicate

the historical data. Historical time series data were used as

inputs at the upstream forecast points for these simulations.

Testing, therefore, indicated that the software RiverWare

successfully modeled the Rio Chama and could be used on

the mainstem of the Rio Grande. Since the test case contained most of the physical components such as diversions,

river reaches, confluences, and hydropower that will be

encountered in the remainder of the upper Rio Grande

Basin, a great number of operational rules and accounting

relationships have already been worked out to some degree

for the mainstem model development.
USDA Forest Service Proceedings RMRS-P-7. 1999 63

Figure 1
64 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 2
USDA Forest Service Proceedings RMRS-P-7. 1999 65

Figure 3

Figure 4
66 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 5

Figure 6
USDA Forest Service Proceedings RMRS-P-7. 1999 67

Mainstem Model Development_____

Following the completion of the test case in March 1998,

the Technical Team began the conceptual model of the

mainstem. Expected completion date of a functioning, but

not exhaustively calibrated and verified basic water operations (or “backbone”) model of the upper Rio Grande is Fall

1999. The fully refined model completion date is approximately 2002.

Data Base and Other Tools________

While URGWOM is under development, the Technical

Team is utilizing the Corps Data Storage System (DSS) to

format and store data. The team has written data management interface programs (DMI)s that interface the time

series data stored in DSS with the Rio Chama model for use

in testing and calibrating. The same will be done for the

mainstem since DSS is easy to use. Part of the Technical

Team is investigating needs and requirements for an

URGWOM Data Base. The Corps Hydrologic Engineering

Center provided a cursory screening of data base alternatives. Their preliminary report indicated that Reclamation’s

HDB has potential to serve URGWOM’s ultimate data

storage needs.

An URGWOM data base will store time series data,

spatial data, and accounting data. A unified data base will

provide a source of data for and from URGWOM that will be

accessible for use by anyone needing the data. It will be a

resource for other models such as planning models, as well

as a source of data for URGWOM model applications.

Water Operations Review

One of the applications of URGWOM is the Upper Rio

Grande Basin Water Operations Review (Water Operations

Review). This is a joint effort with Reclamation to take an

integrated look at the system. Part of this effort will be to

develop supplemental tools or models, that with input from

URGWOM, can determine what effects potential water

operations changes have on riparian vegetation, aquatic

communities, endangered species, cultural resources, and

other basin resources. The review will likely be a five-year

effort, starting in 1999.

References _____________________

Bureau Of Reclamation; U.S. Army Corps of Engineers; U.S. Geological Survey; in Cooperation with: U.S. Fish and Wildlife

Service; Bureau of Indian Affairs; International Boundary and

Water Commission (U.S. Section). 1997. Upper Rio Grande Water Operations Model Plan for Development. Albuquerque, NM.

96 p.

Bureau of Reclamation and others. 1997. Conceptualization of the

Test Case Reach of the Upper Rio Grande Water Operations

Model Part I - Physical Model (Draft). Albuquerque, NM. 58 p.

Bureau of Reclamation and others 1997. Conceptualization of the

Test Case Reach of the Upper Rio Grande Water Operations

Model Part II - Water Accounting and Ownership (Draft). Albuquerque, NM. 65 p.

The Center for Advanced Decision Support for Water and Environmental Systems; University of Colorado at Boulder; RiverWare

CADSWES-USBR Training: Simulation Modeling, June 3-5, 1997.

Boulder, CO.

Bureau of Reclamation; U.S. Army Corps of Engineers; Preliminary

Plan of Study Upper Rio Grande Basin Water Operations Review.

1998. Albuquerque, NM. 5 p.
68 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Jan M.H. Hendrickx, J. Bruce J. Harrison, Jelle Beekma, and Graciela

Rodriguez-Marin are with the Department of Earth and Environmental

Science New Mexico Tech, Socorro, NM 87801.

Abstract—This paper discusses management options for salinity

control in the Rio Grande Bosque. First, salt sources are identified

and quantified. Capillary rise of ground water is the most important

cause for soil salinization in the bosque. Next, a riparian salt

balance is presented to explain the different mechanisms for soil

salinization. Finally, the advantages and disadvantages of three

salinity control options are discussed: drainage systems, adaption

to natural conditions, and managed flooding.

The Rio Grande has two important functions. One is to

deliver water to aquatic and terrestrial habitats as well as to

urban and rural communities linked by the river; the other

is to transport salts and other wastes generated by those

habitats and communities to the Gulf of Mexico.

Until the beginning of this century an apparent salt

balance existed in the Rio Grande Valley. The accumulation

of salts in the soils adjacent to the river was counteracted by

frequent inundations that provided surplus water for salt

leaching. Infrequent major floods resulted in a reshaping of

the river landscape and reallocation of salt sinks. Construction of flood protection and irrigation works since the early

1900’s have resulted in a more regular river flow without

major flooding events. In addition, much river water has

been allocated for agriculture, wetlands, and domestic and

industrial water supplies. The combined effects of decreasing river water supplies and channelization of the river to a

permanent streambed have resulted in environmental conditions where soil salinity is no longer controlled by the

river (for example Crawford and others 1993; Conover 1954).

Since soil salinity determines to a large extent the success

of revegetation projects in the Rio Grande Bosque management measures are needed to control soil salinity levels. The

objective of this study is to discuss management options for

salinity control in the Rio Grande Bosque.

Salt Sources ___________________

A good understanding of salt sources in the Rio Grande

Bosque is needed for the development of effective salinity

Salinity Management in the Rio Grande

Bosque

Jan M.H. Hendrickx

J. Bruce J. Harrison

Jelle Beekma

Graciela Rodriguez-Marin

control options. Five salt sources contribute to the salinity of

riparian areas under natural vegetation: atmospheric deposition, mineral weathering, capillary rise, seepage from

higher areas West and East of the river, and flooding.

Atmospheric deposition in the interior of most continents

is about 40 kg/ha (Bresler and others 1984). Mineral weathering is an important process that affects the chemistry of

waters in rivers, soils, and shallow ground water. It involves

the dissolution, alteration, and precipitation of minerals and

for the most part takes place in the zone of aeration of soils.

Since the mineral weathering rate of a given soil is proportional to the amount of water that flows through the soil

(Langmuir 1997), it will increase with the leaching fraction.

Rhoades and others (1973, 1974) and Wierenga and others

(1972) studied in lysimeters the compositions of drainage

waters resulting from irrigation with eight synthesized

river waters of the Western USA under conditions of alfalfa

production on calcareous and noncalcareous sandy loams.

For Rio Grande water, leaching fractions above 25 percent

resulted in a net increase of salts in the drain water by

approximately 2-10 percent of the salts in the irrigation

water. When the leaching fraction is less than 25 percent,

salt precipitation will occur and will result in a decrease of

salt content in the drainage water. These percentages indicate that the contribution of mineral weathering to soil

salinity in the bosque is of the same order of magnitude as

atmospheric deposition.

The most important salt source at many locations is

capillary rise which results from upward water flow originating at the ground water table. The amount of capillary

rise depends on the depth of the ground water table and the

physical characteristics of the soil profile. Table 1 presents

capillary fluxes in a number of homogeneous soil profiles.

For example, a ground water table depth at 2 m will result

in capillary fluxes of 0.2 mm/day in a sand soil and 8 mm/day

in a loamy sand. Even if the ground water quality is good,

such rates can result in considerable salt depositions near

the soil surface or in the root zone. For example, ground

water with a total amount of dissolved solids of 500 mg/l will

accumulate 5 kg of salts per hectare for each millimeter of

capillary rise. This results in an annual salt load of, respectively, 365 and 14,600 kg/ha in the previously mentioned

sand and loamy sand soils.

Salt accumulation by capillary rise will rapidly decrease if

the ground water table is lowered. However, in many cases

the ground water table remains relatively shallow as a

result of ground water seepage. Such seepage may originate

from higher areas West and East of the river or from manmade sources. An example of man-made seepage is found at
USDA Forest Service Proceedings RMRS-P-7. 1999 69

Santa Ana Pueblo where surplus irrigation water from the

golf course on the mesa is seeping into the lower lying

riparian area. Another more important example are the

wetlands created to provide food and shelter for migratory

birds. The flooding of wetlands and the irrigation of adjacent

agricultural fields result in shallow water table depths

around the ponds and an increase in salinization as a result

of capillary rise. This can be observed in the Bosque del

Apache, La Joya, and San Bernardo reserves.

Another salt source is flooding since the water in the Rio

Grande contains approximately 300 to 500 mg/l total dissolved solids (Crawford and others 1993). This means that a

flood of 0.5 m water would deposit 150 to 250 kg salt per

hectare.

The most important salt source in riparian areas is capillary rise since its potential contribution exceeds by far the

salt amounts originating from atmospheric deposition, mineral weathering, and flooding. Areas with relatively shallow

ground water tables (1 to 3 m) that discharge ground water

seepage have the highest risk for salinization.

Riparian Salt Balance ____________

Salinization will occur when the amount of salt added to

the soil by rain water and flood water is greater than the

amount of salt removed by drainage waters. The salt balance

of the riparian root zone can be expressed as

 

R C F C G C P Cg S r f g ... . ++=+ Δ [1]

where R is rainfall entering the root zone (mm/year), Cr is

the salt concentration of the rain water (mg/l), F is the

amount of flood water entering the root zone (mm/year), Cf

is the salt concentration of the flood water (mg/l), G is the

amount of capillary rise into the root zone (mm/year), Cg is

the salt concentration of the ground water, P is the amount

of deep percolation or drainage water leaving the root zone

and entering the ground water, and DS is the amount of salt

stored in the profile. It is assumed that the salt concentration of the drainage water and capillary rise water is equal

to the salt concentration of the ground water which is quite

reasonable for annual periods but less so for shorter periods.

Equation [1] reveals several important aspects of riparian salinity balances. Firstly, soil salinization becomes

inevitable if no drainage takes place to evacuate the salts

from the root zone, i.e. if P=0 then ΔS will increase.

Without some form of drainage soil salinization cannot be

prevented even if the irrigation or flood water contains only

small amounts of salt. Of course, under the latter conditions

salinization would take a long time.

We have found evidence in the Bosque del Apache that

older soils contain more salts than younger ones. The age of

soils can be approximately determined from aerial photographs by observation of channel continuity and the degree

of organic matter and aeolian dust accumulation which are

reflected in soil color. The oldest river deposits show complicated patterns of channel breaches and different degrees of

organic matter and aeolian dust accumulation. The younger

deposits show more continuous channels and less diversity

in soil color.

Using these criteria we selected two locations with comparable point bar deposits and water table depths, but different estimated ages of isolation from the active river. At both

sites soil salinity was measured at several hundreds of

points using electromagnetic induction (for example

Hendrickx and others 1992; Sheets and others 1994). Average topsoil salinity in the younger deposits was 24 against

280 mS/m in the older deposits. Average subsoil salinity was

31 mS/m in the younger deposits and 225 mS/m in the older.

This shows a ten fold increase in soil salinity for comparable

deposits in terms of soil texture and depth to the groundwater as a result of age, i.e. the duration during which capillary

rise has contributed to salt accumulation in the soil profile.

Secondly, flooding only will lead to a decrease of soil

salinity if the flood water leaches out salts, i.e. if P>0 so that

the salts percolate into the ground water and can be transported towards a drain. Otherwise, the salts in the flood

waters actually will contribute to an increase in soil salinity.

Whether flooding will result in drainage depends on the

water retention and hydraulic conductivity of the soil profile. Before drainage occurs the root zone needs to be sufficiently wetted to allow downward flow. In most riparian

areas with shallow ground water tables this requirement

will not pose a problem. In addition, the hydraulic conductivity of all soil layers must be large enough to allow the

drainage water to pass through. This requirement poses

serious limitations on the use of flooding in soils that contain

clay layers with a low permeability. In such soils the flood

water will become perched on the clay layer. A large part of

the perched water will evaporate or transpire while leaving

the salts behind in the root zone and, thus, increase soil

salinity. This scenario is quite common in riparian areas.

Another important factor that determines the effect of flooding is the leaching efficiency. For an effective leaching it is

not sufficient to replace once all soil water by flood water. On

the contrary, the soil should be flushed several times to

make it salt free (Hoffman 1980).

For example, in the Bosque del Apache on soil unit 29

natural regeneration of cottonwood is being stimulated by

applying an annual flood of approximately 0.3 m. The flood

water carries cottonwood seeds that settle at the high

water lines. After several weeks seeds emerge and young

trees start growing. In unit 29, the soil profile consists of a

layer of 50 cm to 100 cm of sandy loam to loamy sand

overlying clay loam to clay. Before flooding the soil water

content in the top 40 cm and from 40 to 80 cm is, respectively,

3 and 9 volume percent. The soil water content in the

underlying clay loam is close to saturation. During flooding the soil water content increases to saturation which

is approximately 35 volume percent. This means that

Table 1—Maximum capillary rise (cm) for five fluxes (cm/day) in

homogeneous soil profiles (Hendrickx and others 1990).

Capillary Flux (cm/day)

Texture 2.0 1.0 .6 .1 .01

Sand 69 82 92 135 213

Loamy Sand 151 185 213 334 572

Sandy Loam 29 45 61 158 484

Loam 73 99 123 247 577

Silty Loam 59 90 121 321 1025

Clay Loam 126 165 197 342 639

Silty Clay Loam 7 12 18 65 219
70 USDA Forest Service Proceedings RMRS-P-7. 1999

(0.35-0.03)*40 + (0.35-0.09 )*40 = 23.2 cm water will be

stored in the top 80 cm of the soil profile during flooding.

Most of this water will evaporate during the gradual infiltration of the flood water into the soil and contribute little

to salt leaching. Instead it will add to the salt load. The

total amount of water stored in the soil profile at unit 29 is

about 30 cm. This means that an efficient leaching will

require at least 60 to 90 cm of water.

The relatively low permeability of the subsoil of unit 29

and the small amount of flood water applied have resulted

in an increased salinity after flooding. Salinity measurements before flooding in April 1997 and after flooding in

August 1997 revealed an increase of soil salinity from 150 to

262 mS/m in the subsoil and from 112 to 204 mS/m in the

topsoil. Standard deviations of the measurements were

high, indicating considerable variability from place to place.

A third aspect of equation [1] is the importance of capillary

rise. Since the salt concentration of the ground water is at

least one order of magnitude larger than that of rain water,

even a relatively small capillary flux, G, can cause a large

increase of soil salinity. Under the arid conditions of the Rio

Grande Valley it is a constant challenge in riparian nature

reserves to maintain a water balance in which the deep

percolation rate exceeds the capillary upward flux. Without

such condition no favorable salt balance can be maintained.

Salt Management Options ________

The physical principles for salt management in soils are

well understood (Bresler and others 1984, Smedema &

Rycroft 1983; Van Schilfgaarde 1974) and lead to three basic

strategies for salinity management in the Rio Grande bosque:

(1) Installation of drainage systems; (2) Adaptation to natural conditions; (3) Managed flooding.

Installation of drainage systems is the classical response

to salt problems in irrigated agriculture. The functions of a

drainage system are to lower the ground water table and to

discharge saline drainage waters percolating from the root

zone. The ground water table is lowered to a depth at which

the upward capillary flow becomes too small for any significant upward salt movement. This depth depends on the soil

type and can vary from 50 cm in a coarse sand to more than

400 cm in loamy soils (see also table 1). A drainage system

can consist of surface drains or of underground pipes

(Smedema and Rycroft 1983; Van Schilfgaarde 1974). The

outlet is the terminal point of a drainage system where it

discharges into the river.

In mountainous terrain with large elevation differences

drainage waters can be discharged by gravity but in many

arid river valleys the slope of the land surface is not sufficient

to drain by gravity. For example, the gravity system installed

near Las Nutrias (New Mexico) performs only marginally

since sufficient head is not available to discharge the drainage waters. Therefore, it is common practice to have the

drain waters accumulate in a sump and to discharge by

pumping. Such a system has been in use until a few years ago

in the Bosque del Apache. Although the system performed

well during a period of about fifteen years, it has been shut

down and will be not be replaced. The main reasons for this

decision are: (1) The initial installation costs are high (approximately $200,000 for 120 acres); (2) The life of the

system was shorter than expected due to clogging of the

tile drains; (3) The system was difficult to maintain

(John Taylor, personal communication 1998). These complaints are typical even in large irrigation projects with

trained personnel.

DralZage systems work well for moist soil management

and agricultural fields covering large areas. However, due to

high costs and problematic maintenance their use for restoration of native vegetation appears limited.

Adaption to natural conditions involves identifying optimal locations for revegetation of native species such as

cottonwoods. Hendrickx and others (1997) conducted a systematic study near El Paso and statistically confirmed the

dependence of cottonwood survival on soil salinity level

(table 2). They also observed a close relationship between

geomorphology and soil salinity. The lowest levels often

were found on small levees which naturally are the preferred

areas for cottonwoods. The highest levels occur in depressions such as old river channels with a fine soil texture that

enhances capillary rise.

At the Rio Bosque Park near El Paso it was found that 50

percent of the variability in salinity could be explained by

soil type and ground water table depth. This indicates that

in areas with soil and ground water table maps the location

of suitable restoration areas is relatively straightforward.

Otherwise an inexpensive salinity survey using electromagnetic induction can quickly indicate the areas with revegetation potential (Sheets and others 1994).

Managed flooding is often propagated as an efficient

and natural way to restore cottonwood and other native

vegetation. Flooding can only be successful for restoration if

it contributes to an effective salinity control. This requires

(1) a soil profile of sufficient permeability for salt leaching

and (2) sufficient quantities of flood water. If either of these

factors is not fulfilled, flooding will not lead to sustainable

restoration.

Managed flooding is a relatively inexpensive method to

control soil salinity and to promote bosque restoration.

However, the design of a flood management plan requires

detailed knowledge of the interaction between flood water,

ground water, soil, and vegetation.

References _____________________

Bresler, E., McNeal, B.L.& Carter, D.L. 1982. Saline and sodic soils.

Principles-dynamics-modeling. Springer Verlag, New York.

Conover, C.S. 1954. Ground water conditions in the Rincon and

Mesilla valleys and adjacent areas in New Mexico. U.S. Geological Survey Water-Supply Paper 1230.

Crawford, C., A.C. Cully, R. Leutheuser, M.S. Sifuentes, L.H.

White, J.P. Wilber, and R.E. Robino. 1993. Middle Rio Grande

ecosystem: bosque biological management plan. Biological Interagency Team. U.S. Fish and Wildlife Service, Albuquerque, New

Mexico.

Table 2—Relationship between cottonwood tree vigor class and soil

salinity (Hendrickx and others 1997).

Salinity (mS/m)

Tree vigor class N Meana Std Dev Minimum Maximum

Healthy Tree 30 60a 25 25 140

Marginal Growth 23 111b 64 24 225

Dying Tree 28 210c 112 85 534

aMeans with the same letter are not significantly different.
USDA Forest Service Proceedings RMRS-P-7. 1999 71

Hendrickx, J.M.H., M. Akram Chaudhry, J.W. Kijne, M. Sadiq, and

Iqbal Raza. 1990. Soil physical measurements for drainage design in arid regions. Symposium on Land Drainage for Salinity

Control in Arid and Semi-Arid Regions, Febr. 25-March 2, Cairo,

Egypt. Vol. 2:124-134.

Hendrickx, J.M.H., B. Baerends, Z.I. Raza, M. Sadiq, and M. Akram

Chaudhry. 1992. Soil salinity assessment by electromagnetic

induction on irrigated land. Soil Sci. Soc. Am. J. 56:1933-1941

Hendrickx, J.M.H., J. Beekma, R. Koch, G. Rodriguez-Marin. 1997.

Salinity survey for revegetation potential along the Rio Grande in

the Paso del Norte region. Report to the El Paso Field Division of

the U.S. Bureau of Reclamation.

Hoffman, G.J. 1980. Guidelines for the reclamation of salt affected

soil. In: O’Connor (ed) 2nd inter American conference on salinity

and water management technology, Juarez Mexico. pp 49-64.

Langmuir, D. 1997. Aqueous environmental geochemistry. Prentice

Hall, Inc.

Rhoades, J.D., R.D. Ingvalson, J.M. Tucker, and M. Clark. 1973.

Salts in irrigation drainage waters: I. Effects of irrigation water

composition, leaching fraction, and time of year on the salt

compositions of irrigation drainage waters. Soil Sci. Soc. Am .

Proc. 37:770-774.

Rhoades, J.D., J.D. Oster, R.D. Ingvalson, J.M. Tucker, and M.

Clark. 1974. Minimizing the salt burdens of irrigation drainage

waters. J. of Environm. Quality 3:311-316.

Sheets, K.R., J.P. Taylor, and J.M.H. Hendrickx. 1994. Rapid

salinity mapping by electromagnetic induction for determining

riparian restoration potential. Restoration Ecology 2:242-246.

Smedema, L.K. and D.W. Rycroft. 1983. Land drainage. BT Batsford

Ltd, London.

Van Schilfgaarde, J. 1974. Drainage for agriculture. Agronomy

Series #17, American Society of Agronomy, Madison, WI.

Wierenga, P.J., G.A. O’Connor, and H.E. Dregne. 1972. Soil and

water management for salinity control. New Mexico Water Resources Research Institute Report No. 018.
72 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Michael D. Marcus, Shannon M. House and Nathan A. Bowles are Project

Manager, Technician, and Onsite Supervisor, respectively, McCulley, Frick

& Gilman, Inc., Albuquerque, NM. Robert T. Sekiya and J. Steven Glass

are Project Engineering Technician and Project Coordinator, respectively,

Albuquerque Public Works Department, Albuquerque, NM.

Abstract—The City of Albuquerque has funded the Constructed

Wetland Pilot Project (CWPP) since 1995 at the City’s Southside

Water Reclamation Plant (SWRP). Results from CWPP and other

wetland treatment projects indicate that appropriately designed

surface-flow wetlands could increase the cost-efficiencies of wastewater treatment, as well as help the City meet present and future

discharge limits for nitrate, ammonia, organic nitrogen, various

metals, biological oxygen demand, and total suspended solids,

among other constituents. Results from CWPP also support the

option to construct a 5-acre or larger demonstration-scale treatment

wetland that would provide increased realism for evaluating the

effectiveness of wetland polishing and potential habitat benefits.

The City of Albuquerque City Council and the City’s

Public Works Department have funded the Constructed

Wetland Pilot Project (CWPP) located at the City’s Southside Water Reclamation Plant (SWRP). The CWPP started

July 1, 1995 to provide a pilot-scale evaluation of constructed treatment wetland effects and potentials to provide

cost-effective “polishing” (i.e., enhanced treatment) to improve the quality of the City’s wastewater discharges. Present

and future design-flow capacities for the SWRP are, respectively, 60- and 76-million gallons-per-day (mgd). This study

has been assessing alternative wetland treatment strategies that may help the City meet National Pollutant Discharge Elimination System (NPDES) discharge limits to

address increasingly stringent water quality standards for

the Rio Grande. These standards are established by the

New Mexico Water Quality Control Commission and by the

Pueblo of Isleta, located five miles downstream from

Albuquerque. The initial goal of the CWPP was to use the

information collected to help decide whether to conduct a

larger demonstration-scale study and/or begin construction

of a full-scale wetland treatment facility for the “polishing”

of SWRP’s effluent.

Albuquerque’s Constructed Wetland Pilot

Project for Wastewater Polishing

Michael D. Marcus

Shannon M. House

Nathan A. Bowles

Robert T. Sekiya

J. Steven Glass

Constructed wetlands have been found to provide viable

alternative treatment components to conventional “concrete-and-steel” wastewater treatment systems (U.S. EPA

1988). These wetlands include free-water surface (openwater) systems, with surface flows through shallow water

depths, and subsurface flow systems, with water flowing

laterally through sand and gravel. Constructed wetlands

provide cost-effective treatment to meet wastewater discharge requirements for many municipal discharges and

for other discharges across the U.S. and around the world

(Albuquerque-Bernalillo Constructed Wetlands Study

Group Report 1993, Hammer 1989, Kadlec and Knight 1996,

Moshiri 1993, and U.S. EPA 1988). Because of the construction and operation cost savings possible, the number of

municipalities benefitting from constructed wetland treatment technologies has increased. In the Southwest, for

example, only four constructed wetlands treating municipal

wastewater existed in Arizona during 1990 and 15 existed in

1994. By 1997 Arizona had 26 municipal and onsite constructed wetlands operating, with an additional 24 wetlands

either awaiting approval or under construction (Anonymous 1997, Gelt 1997).

Natural wetlands, which include swamps, bogs, sloughs

and marshes, are often described as “nature’s kidneys” to

characterize the water quality improvements produced in

waters flowing through these systems (Mitsch and Gosselink

1986). Constructed wetlands are similar to natural wetlands. Both involve communities of wetland plants, associated microorganisms, and chemical reactions in the water

and soil substrates to purify water. Also, constructed wetlands are similar to conventional wastewater treatment

facilities. Both are technologically-based designs that

strive to enhance natural processes to cleanup wastewater.

But, because constructed wetlands rely much less on concrete and steel (and more on land surface area), construction

and operation costs are often much lower for wetland facilities having comparable treatment capabilities. For example,

compared to the $360 to $625 million that officials estimated as needed to upgrade Phoenix’s 91st Avenue

Wastewater Treatment Plant, the projected cost of developing the existing $3.5-million Tres Rios Constructed Wetland

Pilot Project into a full-scale facility was an additional

$80 million (Gelt 1997, Greeley and Hansen 1996). That is,

upgrading the wetland treatment system was projected to

cost only 13 to 22 percent of the cost for a concrete and

steel upgrade to the plant to meet the same water quality

goals.
USDA Forest Service Proceedings RMRS-P-7. 1999 73

Beyond treatment benefits, constructed wetlands also

generally provide significant additional economic and societal benefits by enhancing a diversity of tourist, recreation,

education, and wildlife habitat attributes associated with

the wetland. Some benefits documented for the 150-acre

Arcata Marsh and Wildlife Sanctuary include use by water

birds, estimated at 1,492,253 use days per year, and waterfowl, 98,689 use days per year. Estimates for picnicking, relaxing, birdwatching, nature studies, jogging, walking, education, fishing, photography and art, vary from 5 to 80 people

per day, at 2 to 4 hours per visit. This open-surface constructed wetland system was developed between 1985 and

1989, and treats 2.6 mgd of municipal wastewater from

Arcata, CA (Gearheart and Higley 1993). Similarly, development

plans for the 800-acre Tres Rios constructed wetland project

in Phoenix include accommodations for more than a halfmillion visitors annually expected to access the recreational and educational features of the project (Tres Rios

Recreation Technical Committee 1997).

Design and Methods _____________

Albuquerque’s CWPP facility includes 12 individual

open-water (surface-flow) wetland treatment cells, each is

102-feet long and 40-feet wide (fig. 1). The constructed

wetland cells cover about 1.1 acres. Four wetland plant

species were planted in duplicated plantings across six pairs

of these cells to monitor effects by these communities on

Figure 1—Schematic diagram of the facility design for the City of Albuquerque’s

Constructed Wetland Pilot Project. (Note: Flow rates assume 72-hour retention

time in each cell; diagram shows locations for sample collections for wetland

influent (CWP00INF) and for wetland effluents (CWP01EFF-CWP12EFF) included on various subsequent figures in this report).
74 USDA Forest Service Proceedings RMRS-P-7. 1999

water quality, water loss through evapotranspiration, and

incidental habitat attributes. The water source for the wetland is treated, dechlorinated SWRP effluent, which is

diverted to the wetland shortly upstream from the conveyance structure carrying SWRP effluent to the Rio Grande.

The SWRP effluent is then distributed to the surface of the

wetland cells. For most of the study, wetland flows were

single-pass, through the length of the cells, before being

discharged at the ends opposite from the inflows through a

French-drain located along the bottom of the cells. Final

effluents from most wetland cells are recycled back into the

SWRP’s treatment waters.

Starting in March 1997, the effluents from Cells 9 and 11

were directed into Cell 7, and the effluents from Cells 10 and

12 were directed into Cell 8. This was done, not to address

specific treatment issues, but to allow greater latitude to

increase flow volumes to Cells 9 through 12. The effluent

flows from 7 and 8 are then recycled back into the SWRP.

Operation of the wetland facility has focused on maintaining

a 3-day target hydraulic retention time in each of the cells,

with water depths ranging from 6 to 36 inches, as appropriate for the plant species inhabiting each wetland cell. Under

the target hydraulic retention time, total target flow to the

wetland facility was approximately 115 gallons-per-minute

(gpm), 0.17 mgd, and 185 acre-feet per year.

Sampling was conducted from June 1996 through May

1998 to assess the removal efficiencies in each wetland cell

for parameters of potential concern for future NPDES discharge limits. Of particular concern, ammonia, nitrate plus

nitrite, total organic nitrogen, biological oxygen demand,

and total suspended solids samples were collected every two

weeks for analyses. Every four weeks, metals samples were

collected to assess silver, aluminum, and arsenic removals.

All analyses were conducted at the City of Albuquerque,

Public Works Department, Water Quality Laboratory.

Treatment wetlands generally include a series of wetland

cells, rather than the parallel, single-pass wetland flows

studied in the CWPP. Each cell in the series typically has

different vegetation types, water depths, and hydraulic

retention times to produce different environmental conditions that sequentially address different water quality restoration issues. Selection of vegetation types used in these

sequenced wetland cells often includes consideration of the

potential ecological benefits of the plant communities to

both aquatic and terrestrial animals.

In a simplified example, treatment wetlands constructed

to address nitrogen removal commonly hold a community of

larger emergent plants (for example, bulrush) in the first

treatment cell. These cells commonly contain very low to no

oxygen in the shallow waters surrounding the plants to aid

nitrate removal. Such conditions also aid the breakdown of

organic materials, converting organic nitrogen to ammonia.

The second community in the treatment series is often a

deeper, open-water, often pond like area, where ammonia

discharged from the previous wetland cells is converted into

nitrate. Next, a second emergent community often serves

largely as a filter to remove suspended algae and other

material, before the wetland water is discharged. The discharge structure for the wetland can produce additional

water quality effects. Figure 1 provides an expanded but still

simplified characterization of water quality effects possible

through a series of wetland cells having different vegetation

and treatment characteristics.

When reviewing and assessing the results from the CWPP,

it is very important to understand that the design and

operation of this facility have produced conditions that test

effects on water quality produced by alternative wetland

communities that might be used as the first wetland treatment component, as described in figure 2. In a full scale

wetland facility, effluents from wetland cells, which had

been designed and operated like the CWPP cells, would

commonly discharge into a series of subsequent wetland

cells for additional treatment, very commonly through sequenced oxic (oxygen containing) and anoxic (oxygen lacking) water conditions. Thus, the water quality effects reported in the following sections represent example results

from a range of water quality changes obtainable with

passage through only the first wetland cells from a possible

series of additional wetland communities. Because the CWPP

cells represent, in effect, only the first part of what could be

some potentially larger treatment wetland design, their

results are best characterized as likely representing the low

to average range of the treatment benefits possible for

SWRP effluents using wetland polishing. The water quality

conditions in effluents from the CWPP cells reported here

cannot be extrapolated to represent either the best or final

water quality results obtainable for SWRP effluents using

constructed wetland treatment.

Results and Discussion __________

Hydrology Characteristics in the Wetland

Cells

Hydraulic flow regimes in the wetland cells were relatively consistent during 1997, reasonably approaching target 3-day retention times. During 1996, hydraulic consistency and integrity of the wetland cells were compromised

due to problems with the wetland’s influent delivery system

and holes in the liners of the wetland cells caused by

muskrats that colonized the facility. The improved 1997

results occurred, first, because of improvements to the

influent plumbing that were installed and maintained by

the wetland staff. Second, removal and exclusion of muskrats from the facility allowed successful patching of holes in

the wetland liners.

Water Quality Changes in Routine SWRP

Discharges

Focusing on the period from March to November 1997,

the observations and results from this project show the

following:

Silver concentrations in SWRP effluents and CWPP

influents for 1997 both averaged 0.6 μg/l (fig. 3). During

this period, average effluent concentrations from wetland

Cell 5 (3-square bulrush) were less than the potential 30-d

average NPDES limit of 0.21 μg/l for a 76-mgd discharge.

Statistical analyses indicate that Cell 3 (spikerush), Cell 5,

and Cell 7 (open-water/ duckweed) produced effluent silver

concentrations that were significantly less than influent

concentrations. Greatest variability in silver effluent concentrations occurred in Cell 4 (spikerush), Cell 8 (openwater/duckweed), and Cell 1 (mixed species), respectively.

(Recall that effluents from Cells 9 - 12 provided the influents

to Cells 7 and 8.) Statistical analyses also indicate there was

no significant difference in net removal of silver among the

wetland cells, i.e., no cell was particularly better at removing
USDA Forest Service Proceedings RMRS-P-7. 1999 75

silver than another cell. The variability for silver in CWPP

effluents suggests that some recurring analytical interference or sample contamination problem (for example, entrained particles) may have produced high concentration

spikes.

Aluminum in SWRP effluents and CWPP influents averaged 82.6 and 98.6 μg/l, respectively (fig. 3). Average effluent

concentrations from all wetland cells, excluding Cell 3

(spikerush), produced effluent concentrations that averaged

less than the pending 30-d average low flow NPDES discharge limit of 60 μg/l for aluminum during 76-mgd discharges. Statistical analysis indicated that all cells during

this period, except Cell 3, produced effluent aluminum

concentrations that were significantly less than wetland

influent concentrations. Greatest variability in aluminum

effluent concentrations occurred in Cell 3. Statistical analyses also indicate that no cell was significantly better at

removing aluminum than another cell.

Arsenic concentrations in SWRP effluents and CWPP

influents averaged 7.0 and 7.1 μg/l, respectively (fig. 3). Both

values are less than the existing 30-d average limit for

arsenic of 13.7 μg/l. Cell 5 (3-square bulrush) produced the

minimum average effluent arsenic concentrations. This effluent averaged 5.1 μg/l, which is markedly greater than a

potential 30-d average NPDES discharge limit of 0.031 μg/

l for low-flow 76-mgd discharges. Statistical analysis of the

wetland effluent arsenic concentrations indicated that effluents only from Cells 5 and 6 (both 3-square bulrush cells)

were significantly less than concentrations in wetland influents. Statistical analysis also indicated that positive net

removal of arsenic by Cell 5 was significantly better than

Figure 2—Common design components (cells) and typical functions for a free-water surface constructed treatment wetland.

occurred in Cells 1 and 2 (mix species), Cell 3 (spike rush),

Cell 7 (open-water/duckweed), and Cells 9 and 10 (deepwater

plantings of softstem bulrush); no other significant differences in net removal of arsenic were indicated.

Ammonia concentrations in SWRP effluents and CWPP

influents, averaged 4.5 mg/l and 6.9 mg/l, respectively (fig.

3). Average concentrations in effluents from wetland cells

averaged 4.1 in Cell 5 (3-square bulrush) to 7.2 in Cell 12

(shallow plantings of softstem bulrush), reflecting the anoxic water quality conditions maintained in these cells, as

discussed above. Average concentrations in the SWRP effluent and all CWPP effluents exceeded the pending 30-d

average low-flow NPDES limit of 1.0 mg/l. Wetland discharge likely could meet permit limits through construction

of a direct injection of air or turbulent producing outlet

structure or to enhance nitrification and volatilization.

Nitrate plus nitrite concentrations in SWRP effluents and

CWPP influents averaged 10.6 and 8.9 mg/l, respectively

(fig. 3). Average concentrations in effluents from wetland

cells averaged 0.3 and 0.5 mg/l in Cell 3 and 4 (spikerush

cells) to 3.3 in Cell 10 (deep plantings of softstem bulrush).

Average concentrations in effluents from all wetland treatments cells were less than the pending 30-d average low-flow

NPDES limit of 9.0 mg/l.

Total Kjeldahl Nitrogen (TKN) or organic nitrogen in

SWRP effluents and CWPP influents in 1997, averaged 9.6

and 8.9 mg/l, respectively (fig. 3). Average concentrations in

wetland effluents ranged from 6.7 mg/l in Cell 5 (3-square

bulrush) to 9.1 mg/l in Cell 8 (open-water/ duckweed). The

NPDES permit contains no limit for TKN.
76 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 3—Average Concentrations, March-November 1997, in effluent from SWRP, influent to CWPP, and

effluents from CWPP Cells 1-12 (showing present and potential future NPDES discharge permit limits).
USDA Forest Service Proceedings RMRS-P-7. 1999 77

Biological Oxygen Demand (BOD) averaged 16.4 mg/l in

the SWRP effluent and 9.7 mg/l in the wetland influent (fig.

3). Average concentrations in effluents ranged from 3.3 to

5.1 mg/l for all wetland cells, with the exception of Cell 4,

which averaged 6.8 mg/l. The 30-d average BOD under the

existing NPDES limits is 30 mg/l; the pending 30-d low-flow

CBOD limit is 10 mg/l.

Total Suspended Solids (TSS) during 1997, averaged 17.0

mg/l in the SWRP effluent and 8.9 mg/l in wetland influent

(fig. 3). For wetland effluents, average TSS ranged from 1.3

to 3.4 mg/l in all but two wetland cells; average TSS from

Cells 3 and 4 (the two spikerush cells) averaged 6.3 and 8.3

mg/l. The present and pending low flow 30-d average NPDES

limit for TSS limit is 30 mg/l.

Fecal Coliform averaged 480 counts/100 ml in the SWRP

effluent and 460 counts/100 ml in the CWPP influent (fig. 3).

Across the CWPP effluents, fecal coliform ranged from 386

counts/100 ml in Cell 4 to 2896 counts/100 ml in Cell 3 (the

two spikerush cells). The 30-d average fecal coliform limit

under the present NPDES permit is 500 MPN/100 ml and

the pending limit is 100 counts/100 ml. For the wetland

effluents there were 79 cases where fecal coliform exceeded

100 counts/100 ml.

Fecal streptococci (FS) have been used with fecal coliform

(FC) to differentiate human fecal contaminations from that

of other warm blooded animals. In editions of Standard

Methods for the Examination of Water and Wastewater

previous to the 17th edition (American Public Health Association 1989), it was suggested that the ratio of fecal coliform

to fecal strep could provide information on the source of

contamination. A ratio greater than four was thought to

indicate human fecal contamination, whereas a ratio of less

than 0.7 suggested contamination from non-human sources.

In the 19th edition (American Public Health Association

1995), however, the reliability of these ratios is questioned

due to poor survival rates for certain fecal strep groups in the

environment (which would tend to increase FC/FS ratios)

and for other analytical-based reasons (which could decrease these ratios). Consequently, these ratios are no longer

considered dependable for use in differentiating between

bacterial contamination sources. Nevertheless, lacking another suitable alternative, it may be instructive to note that

of the 79 FC exceedances recorded in the wetland effluents,

only five effluents held FC/FS ratios greater than four,

which may indicate human source contamination. Four of

these events occurred during, and the fifth shortly after, the

July-August 1997 SWRP upset, which is described in the

next section. Of the remaining 74 exceedances, 45 cases (i.e.,

60 percent) held FC/FS ratios less than 0.7, potentially

indicating non-human bacterial sources.

Variability in analytical results for monitored water quality parameters produced marked differences between corresponding averages for some analyzed water quality parameters in the SWRP effluent and the CWPP influent

concentrations, as noted above. These differences may be

attributable to unquantified differences due to sampling

times, sampling frequency, sample collection or handling,

possible wetland piping effects, or other causes. For example, 24-hour composite samples are used to characterize

most constituents in the SWRP effluent. In contrast, analyses to characterize CWPP influents and effluents are based

on individual grab samples. Despite differences in the sampling approaches used, comparisons between overlapping

sampling intervals indicate that the results from the CWPP

influent samples for most analytes are reasonably representative of conditions in the SWRP effluent samples. In turn,

analyte results for grab sample collections of CWPP effluents are assumed to be generally representative of the range

of potential discharge conditions for the individual wetland

cells. Questions remain, however, as to the cause of occasionally high concentration spikes for individual constituents in

the CWPP effluents. Specifically, questions exist on whether

these concentration spikes would have appeared if composited

samples had been use to characterize the CWPP effluents.

Water Quality Benefits of the Wetland

During Treatment Failure

During late July and early August 1997, the construction

upgrade activities at the SWRP adversely affected the microbial flora in activated sludge treatment tanks, leading to

treatment failure. During this period, SWRP effluents were

ineffectively treated with multiple and recurring NPDES

permit violations for total suspended solids, biological oxygen demand, and fecal coliform. Water quality data collected

during this period clearly show the relatively high effectiveness of wetland treatment to buffer downstream receiving

waters from many adverse effects during periods of treatment facility failure.

TSS and BOD concentrations that violated NPDES permit limits for the SWRP effluent showed significant improvements after flowing through the CWPP. TSS concentrations detected during this upset in SWRP effluents ranged

over 180 mg/l, while effluent from all wetland cells were 19.0

mg/l or less, with most less than 4.0 mg/l; all TSS in all of the

CWPP effluents were less than the 30-d average NPDES

limit of 30 mg/l for a 76 mgd discharge. BOD concentrations

detected in SWRP effluents during this upset ranged over

160 mg/l. Concurrent effluent BODs from all wetland cells

ranged between 4 and 16 mg/l, all less than the present

30-d average NPDES limit of 30 mg/l.

Benefits of the CWPP were observed in metals removal

through the course of this upset. Silver concentrations detected in SWRP effluent and CWPP influent ranged to

0.51 μg/l, while concentrations of silver in effluents from

all wetland cells were at the minimum reporting limit for

silver, 0.05 μg/l. Aluminum concentrations detected in the

CWPP influent approached 110 μg/l; concentrations in effluents in wetland Cells 5, 6, 8, 9, 10, and 11 (including all

wetland vegetation species, except spikerush) were at or

near the minimum reporting value for aluminum, 0.40 μg/l.

Arsenic concentrations in the SWRP effluent approached 6

μg/l, while concentrations in effluents from the wetland cells

range from 3.1 to 4.5 μg/l.

Nitrogen components were generally removed over the

course of the treatment plant upset. Ammonia concentrations in SWRP effluents and CWPP influents ranged over

19 mg/l, compared to effluent from wetland Cells 5 and 6

(3-square bulrush cells), where ammonia concentrations

were less than 12 mg/l, despite the severely anoxic conditions existing in these cells. Nitrate plus nitrite nitrogen

concentrations in SWRP effluents ranged over 3.5 mg/l,

compared to average concentrations in all wetland cell

effluents of 0.2 mg/l, i.e., the minimum reporting value for

these analytes. TKN in SWRP effluents approached 32 mg/

l, compared to concentrations between 13 and 16 mg/l found

in effluents discharged from six (i.e., 50 percent) of the

wetland cells.
78 USDA Forest Service Proceedings RMRS-P-7. 1999

Additional Considerations

Assessments of relative evapotranspiration rates (ET),

sediment metals accumulations, bioaccumulation of metals,

and the economics of wetland development and treatment,

have been used to evaluate the effectiveness of wetland

operation. Additionally, these evaluations aid in assessing

whether to expand on the pilot project technology by constructing a 5-acre or larger demonstration scale, or full-scale

treatment wetland.

Relative ET rates were assessed using an independent

estimate produced for the City. Potential water loss through

wetland evapotranspiration was determined for a 450-acre

wetland facility. The assessment revealed that ET could

reduce discharge volumes from the SWRP by, perhaps, 1,800

to 2,250 acre-feet/year (i.e., four to five feet of water per year

over each acre of wetland).

Sediment metals accumulations were investigated by

research cooperators from the USGS BRD. Sediment samples

were collected from CWPP cells on February 19, 1997.

Concentrations were below or near the minimum reporting

values for total silver (<1 mg/kg), aluminum (<2 mg/kg),

arsenic (<5 mg/kg), and selenium (<5 mg/kg) in both the

inorganic and organic fractions assessed for all samples.

Typical environmental sediment concentrations were detected for iron, manganese, mercury, and zinc.

The uptake of metals by organisms is termed

bioaccumulation. USGS BRD researchers assessed concentrations of silver, aluminum, arsenic, mercury, and selenium in plant stems and roots, and benthic macroinvertebrate

tissues collected from CWPP cells and in bryophytes incubated in wetland cells during August 25-28, 1997. Silver was

not detectable in any of the tissues. Root concentrations for

aluminum, arsenic, and mercury ranged from nearly equal

to 10-times or greater than the stem concentrations. Root

concentrations for selenium were often less than stem concentrations for the CWPP plants sampled. Greatest root

concentration of aluminum, arsenic, and mercury occurred

in spikerush, with nearly equivalent concentrations found

in the roots of softstem bulrush. Concentrations of aluminum, arsenic, mercury and selenium were generally similar

for bryophytes incubated at CWPP cells and the Nature

Center (a natural wetland located upstream from the CWPP,

which acted as reference samples for this assessment).

With individual exceptions, concentrations of these four

metals in macroinvertebrates were variable, but generally

similar among samples collected from both CWPP and the

Nature Center.

An economic evaluation of wetland operation was considered in a 1997 draft benefit-cost analysis from the University of New Mexico (Holmes and Blackwell 1997). The

evaluation was conducted for a potential 500-acre treatment

wetland facility considered by the City. The analysis gave a

benefit-cost ratio of 1.17 for the conservatively short estimated project life of 15 years for a 500-acre constructed

wetland facility (typical operational durations projected for

constructed wetlands range 20 or more years). Similar

analysis and results from other locations reveal that constructed wetland treatment facilities often pay for themselves through cost saving and usage benefits after relatively short periods of operation.

Conclusions and

Recommendations ______________

Results from the pilot study offer support for constructing

a 5-acre or larger demonstration-scale treatment wetland,

which would enable increased realism to evaluate the effectiveness of wetland polishing. These results also support the

option to purchase available land and begin construction of

a full-scale treatment wetland facility to provide beneficial

polishing of Albuquerque wastewater, with concurrent wildlife and recreational benefits. The CWPP results indicate

that a wetland treatment system, if constructed using the

appropriate wetland plant communities in an appropriately sequenced flow configuration, can produce significant

benefits for polishing metals, nitrogen compounds, BOD,

and TSS in wastewater discharged by the SWRP. Potential

issues related to bacteria and ammonia can be remedied

relatively cost effectively.

References _____________________

American Public Health Association, American Water Works Association, Water Environment Federation. 1989. Standard Methods for the Examination of Water and Wastewater, 17th edition.

American Public Health Association, Washington, DC.

American Public Health Association, American Water Works Association, Water Environment Federation. 1995. Standard Methods for the Examination of Water and Wastewater, 19th edition.

American Public Health Association, Washington, DC.

Anonymous. 1997. Constructed Wetlands Treating More of Arizona’s

Wastewater. Arizona Water Resource 6(1): 1-2.

Bowen, H. J. M. 1979. Environmental Chemistry of the Elements.

Academic Press Inc., New York, NY.

Constructed Wetlands Study Group Report. 1993. Report to the

Bernalillo County Board of County Commissioners, Albuquerque

City Council, Mayor of Albuquerque and the Bernalillo County

Manager.

Gearheart, R. A. and M. Higley. 1993. Constructed Open Surface

Wetlands: The Water Quality Benefits and Wildlife Benefits–

City of Arcata, California. Pages 561-567 in Gerald A. Moshiri

(editor). Constructed Wetlands for Water Quality Improvement.

Lewis Publishers, Inc., Boca Raton, FL.

Gelt, Joe. 1997. Constructed Wetlands: Using Human Ingenuity,

Natural Processes to Treat Water, Build Habitat. Arroyo 9(4).

(http://phylogeny.arizona.edu/AZWATER/arroyo/094wet.html).

Greeley and Hansen. 1996. Economic Evaluation of Alternatives.

Section 9 in 91st Avenue Wastewater Treatment Plant Reclaimed Water Study, Phase V - Evaluation of Alternatives.

Hammer, Donald A. 1989. Constructed Wetlands for Wastewater

Treatment: Municipal, Industrial and Agricultural. Lewis Publishers, Inc., Chelsea, MI.

Holmes, Matthew and Blackwell, Calvin. 1997. A Cost-Benefit

Analysis of Albuquerque’s Engineered Wetlands.

Kadlec, Robert H. and Robert L. Knight. 1996. Treatment Wetlands. CRC Press, Inc., Boca Raton, FL.

Moshiri, Gerald A.(editor). 1993. Constructed Wetlands for Water Quality Improvement. CRC Press, Inc., Boca Raton, FL.

Mitsch, William J. and James G. Gosselink. 1986. Wetlands.

Van Nostrand Reinhold Company Inc., New York, NY.

Tres Rios Recreation Technical Committee and Phoenix Parks,

Recreation and Library Department. 1997. Tres Rios, Arizona:

Recreation Component.

U. S. EPA. 1988. Design Manual: Constructed Wetlands and

Aquatic Plant Systems for Municipal Wastewater Treatment.

EPA/625/1-88/022. Center for Environmental Research Information, Cincinnati, OH.
USDA Forest Service Proceedings RMRS-P-7. 1999 79

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Ross Coleman is Professional Wetland Scientist, HYDRA, Tijeras, NM

Abstract—Many wetland creation and restoration projects have

successfully restored or created appropriate hydrologic conditions

for the support of wetland ecosystems but have not been as successful in establishing a diverse biota of native wetland vegetation.

Recent work in the propagation and transplanting of native wetland

plant seedlings offers promise for increasing biodiversity while

reducing the potential for invasive species to create monotypic

stands of low habitat value.

In recent years the values of wetland ecosystems have

been recognized on a global scale. Programs have been

enacted which encourage or require the creation, enhancement, or restoration of wetland environments. While many

wetland projects have been very successful in establishing

fully functioning wetland ecosystems, others have met with

limited success for a variety of reasons, including low biodiversity of flora resulting from domination by one or more

“weedy” species.

Natural Colonization _____________

The traditional approach to wetland vegetation establishment has been something on the order of “build it and they

will come”. It has been assumed that by creating appropriate

hydrology, the wetland flora will respond. While this method

can be successful, especially in the instance where restoration is taking place at the former location of a wetland where

extant seed banks are still viable (Dahm and others 1995),

frequently the result is less than satisfactory. The natural

colonization method gives the practitioner or wetland manager little control over the species composition at the site.

One of the most common causes for low diversity of flora in

created and restored wetlands is due to the rapid colonization of invasive species, many of which are persistent (Levine

and Willard 1990). While some of these species may be

locally native, others are either introduced exotics or recent

arrivals from another region of the country. Some of the most

troublesome species include: the genus Typha (cattails - four

species occur in the southwest), Phragmites communis (common reed), Phalarus arundinacea (reed canary grass), Arundo

donax (giant reed), Lythrum salicariaL. (purple loosestrife),

and Sorghum halepense (Johnsongrass) (Whitson 1996, Corell

and Correll 1972). It is not unusual for some of these species

to create monotypic stands encompassing many hectares.

Methods for Increasing Biodiversity in

Wetland Creation and Restoration Efforts

Ross Coleman

The resulting wetland habitat is compromised with diminished wildlife, recreational, and aesthetic values.

Vegetation Establishment Via

Seedlings ______________________

Innovations in plant propagation technology and wetland

seed germination techniques have provided an alternative

method for the establishment of wetland vegetation. Most

common emergent macrophytes are now available commercially as container grown seedlings from a number of restoration and native plant nurseries. Some of these nurseries

offer custom growing for seed collected near the project site

or for rare plant materials. In recent years, wetland projects

that have utilized seedling transplants have noted success

in preventing or reducing domination by invasive species

while increasing the diversity of wetland flora (Ballek 1998).

Careful selection of plant materials for site climate, soil and

water chemistry, and hydrologic variability is essential. An

additional advantage to wetland vegetation establishment

from seedlings is the rapid colonization rates from rhizomatous spreading. This is particularly important where soil

erosion control is needed. Colonization from existing seed

banks (often not present at wetland creation sites) or from

intentional seeding can be very slow due to the notoriously

low rates of germination for many wetland species (Hammer

1992). The use of genetically adapted container grown seedlings for wetland creation, reclamation, and restoration

projects may enhance many of the functional values associated with wetlands. Some of these include: food chain support, sediment control, habitat for fish, shellfish, waterfowl

and other wildlife, habitat for rare and endangered species,

water quality improvement, education and research, and

recreation (National Research Council 1992). Recent regulatory requirements for monitoring of wetland mitigation

projects as well as independent research, may provide additional information useful in assessing the value of wetland

plantings via containerized seedlings.

References _____________________

Ballek, Len. 1998. Using Container Grown Seedlings, In: Native

Plant Highlight Corvalis, MT. 3 p.

Dahm, Cliff N.; Cummins K.; Valett M.; Coleman R. An Ecosystem

View of the Restoration of the Kissimmee River. In: Restoration

Ecology, 1995 September, 225-238 Vol. 3.

Hammer, Donald A. 1992. Creating Freshwater Wetlands. Lewis

Publishers Boca Raton. Fl 297 p.

Levine, Daniel A.; Willard D. 1990. Regional Analysis of Fringe

wetlands in the Midwest: Creation and Restoration. In: Wetland

Creation and Restoration. Kusler and Kentula Ed. Island Press

Washington D.C. 594 p.

National Research Council. 1992. Restoration of Aquatic Ecosystems. National Academy Press, Washington, D.C.

Watershed Issues

USDA Forest Service Proceedings RMRS-P-7. 1999 83

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Carleton S. White is Research Associate Professor, Department of Biology,

University of New Mexico, Albuquerque, NM 87131-1091. Samuel R. Loftin

is Plant Ecologist, Rocky Mountain Research Station, 2205 Columbia SE,

Albuquerque, NM 87106. Steven C. Hofstad is Graduate Student, Department of Biology, UNM. Current Address: Clay County Comprehensive Local

Water Plan Coordinator, Clay County Soil and Water Conservation District,

2223 E. HWY 10, Moorhead, MN, 56560.

Abstract—Shrubs and trees have invaded semiarid grasslands

throughout much of the Southwestern United States. This invasion not only has decreased grass cover, but also increased runoff

and erosion. In fact, sediment from rangelands constitutes the

single largest source of nonpoint stream pollutants within the

state of New Mexico. Fire, which was a natural factor that shaped

and maintained the grasslands, is a management tool that may aid

in restoring and maintaining grass cover. However, fire also poses

the risk of increasing erosion and further degradation because

protection afforded by vegetation is reduced immediately after the

fire. Using a randomized block study design, this study measured

vegetation cover, soil inorganic nitrogen (N) levels, and erosion

amounts associated with the first application of prescribed fire on

two semiarid grasslands. The potential for adverse effects from

these fires was great because they were performed at the beginning of a drought period. After the first growing season following

the fire, grass cover returned to pre-burn levels, and both soil N

and erosion amounts were similar to the unburned areas. Thus,

prescribed fire for reducing shrub and tree cover may pose minimal

adverse risk even under drought conditions.

Fire shaped vegetative communities and played a role in

ecosystem dynamics long before the influence of humans.

Indeed, it is difficult to find a terrestrial ecosystem that has

not been influenced by fire. In North America, lightningignited fires shaped prairies and forests (Biswell 1989; Cook

1995; Pyne 1982; Wright and Bailey 1982). Later, Native

Americans used fire for hunting, food gathering, and

maintaining open savanna-like landscapes, which provided

protection against enemy attack (Biswell 1989; Mitchell

1978, Pyne 1982; Wright and Bailey 1982). In the Southwestern United States, widespread fires at 5- to 10-year

intervals probably maintained semiarid grasslands

(Collins and Wallace 1990; Cook 1995; Gottfried and others

1995; Wright 1980; Wright and Bailey 1982). Past research

Response of Vegetation, Soil Nitrogen, and

Sediment Transport to a Prescribed Fire in

Semiarid Grasslands

Carleton S. White

Samuel R. Loftin

Steven C. Hofstad

has demonstrated that shrubs and trees rapidly invade

grasslands in the absence of fire (Briggs and Gibson 1992;

Wright 1980).

In semiarid grasslands of the Southwest, shrub and tree

invasions occurred following periods of extensive grazing

and droughts beginning in the late 1800’s and extending

to the middle 1900’s (Buffington and Herbel 1965). Even

without grazing impacts, fire suppression in the mid 1900’s

created optimum conditions for shrub invasion (Brown 1982),

which replaces soil-binding perennial grasses with shrubs

such as mesquite (Prosopis sp.), juniper (Juniperus sp.),

burroweed (Isocoma tenuisecta Greene), snakeweed

(Gutierrezia sarothrae (Pursh) Britt. & Rusby), and fourwing saltbush (Atriplex canescens (Pursh) Nutt.). Burroweed and snakeweed, in particular, have replaced grasslands on millions of acres in the Southwest (Brown 1982).

Concurrent with shrub invasion is an increase in runoff

and sediment production from grasslands. In New Mexico,

sediment contributions from rangelands (predominantly

grasslands) constitute the second leading cause of stream

impairment by nonpoint source pollutants (NMWQCC 1994).

Sediment represents a direct degradation of water resources, but it also represents the loss of productivity and

soil nutrients. Erosion in the Southwest is episodic in nature, with most soil movement occurring after large, intense

storms (Debano 1977). Erosion is initiated by raindrop

impaction, which breaks down soil aggregates and suspends

clays in surface waters (Brooks and others 1991). Vegetation

cover, especially grass cover, reduces raindrop impaction,

whereas bare soil promotes runoff and loss of sediment and

nutrients. The increase in bare area associated with shrub

invasion contributes to increased erosion and runoff from

shrub-invaded grasslands (Weltz and Wood 1986). Thus,

erosion rates may decline if the grass canopy can be increased and shrubs and bare soils decreased (Brooks and

others 1991; Morgan and Rickson 1995).

Drought also is a factor that leads to increased runoff

and erosion. Although counter-intuitive, Molles and others

(1992) reported increased summer runoff with decreasing

winter/spring precipitation in semiarid regions. Thus, periods of high runoff follow periods of winter/spring drought.

Mechanisms proposed by Molles and others (1992) to explain

this phenomenon include: (1) decreased vegetation and

herbaceous cover during drought increases the area subject

to raindrop impaction, which leads to increased runoff and

sediment transport; (2) an increase in soil hydrophobicity

(water-repellency) during drought increases runoff;

and (3) the increase in bare soil (and associated solar/

albedo relationships) may contribute to generation of
84 USDA Forest Service Proceedings RMRS-P-7. 1999

higher-intensity summer thunderstorms following drought.

Davenport and others (IN PRESS 1998) demonstrate how a

slight decrease in vegetative cover, which represent areas of

sediment removal, can connect areas of bare soil, which

greatly increases the “connectiveness” of open spaces and

greatly contributes to runoff. Increased runoff has greater

energy to carry sediment and erode soils. Periods of soil

erosion and arroyo-cutting follow periods of drought because of the strong effects that ground cover has on erosion

rates (Wood and others 1987). Cutting of arroyos favors

shrubs with deeper root systems that can reach deeper soil

moisture.

Perhaps the most cost-effective way of shrub control is

through the use of prescribed fire. Fire favors grass growth

by killing shrubs (which reduces competition for shallow

soil moisture by shrubs), increasing essential nutrients in

ash deposition (which is released from litter and burned

vegetation), and by increasing light at the soil surface and

reducing litter that acts as mulch (Wright 1980). However,

in shrub-invaded grasslands, the use of fire faces several

potential problems. The lack of fuel continuity may not

carry a fire across the landscape, except with high winds

that usually exceed those allowed under current burn prescriptions. Also, with very dispersed fuels, cost per unit

area increases and the area may require multiple applications of fire to significantly reduce shrub cover. The loss of

shrub and grass canopy immediately after a fire increases

the potential for soil erosion and nutrient loss. An area

treated with prescribed fire remains more susceptible to

runoff until the grass canopy can regain and exceed pre-burn

coverage. The combination of an increase in available nutrients and reduced vegetation cover creates the possibility for

loss of nutrient and soil resources (Baker 1990; Vitousek and

Howarth 1991).

The effects of fire can range along a gradient from minimal

to extreme, dependent upon the interaction of a variety of

conditions. To evaluate the effects of fire in semiarid grasslands, we constructed conceptual models that identified

potential patterns of response in a number of variables

based upon fire intensity or time since burning. A major

factor determining the magnitude of response is the fuel load

and its continuity, which are factors that contribute to fire

“intensity” (total energy released per unit area). If fuels

are sparse and/or widely separated, then fires will not carry

across the landscape and the effects would be minimal at the

landscape scale, but important to small areas (individual

plant scale). Sparse fuels with high fuel continuity may

carry a fire across the landscape, which will increase its

spatial coverage, but will still have low “intensity” (relatively low maximum temperature, short residence times,

and shorter flame lengths). If fuels are high and relatively

continuous, then both coverage and intensity will increase.

Fire consumes above-ground vegetation, so vegetation

cover will show an immediate decline following fire. However, nitrogen (N) mineralized during combustion of organic

matter is expected to promote grass growth. Grass cover

may return to or actually exceed undisturbed conditions due

to reduction of litter, increased sunlight, and increased

available nutrients. This would likely continue until the

buildup of litter slows nutrient cycling or allows fire to

progress through the system once more.

The immediate release of available N by fire is well

documented in nearly all vegetation types, but there is little

information on the effects of fire in semiarid grasslands on

potentially mineralizable N, upon which future productivity relies. The overall goal of management with prescribed

fire is to increase the rate of N turnover thereby favoring

vegetation that responds quickly to fire, particularly grasses

and forbs.

The objectives of this research were to determine the

effects of prescribed fire in two semiarid grasslands on

vegetation cover-type (bare, grass, or shrub), potentially

mineralizable N (as a measure of site fertility) and soil

erosion. Specific hypotheses included: (1) after an initial

decline in vegetation cover, grasses should respond more

rapidly than shrubs and achieve greater cover relative to

shrubs; (2) N in ash should increase the amount of mineralizable N following the fire, but mineralizable N should

return to that of control or unburned soils following regrowth of vegetation; and (3) high intensity precipitation

should increase erosion following burning until the vegetation cover recovers, which would then lead to a decline in

erosion. This article presents the 1-year results of the

first in what is expected to be many prescribed fires

directed at decreasing shrub invasion into semiarid grasslands in central New Mexico.

Methods _______________________

Site Description

The research is conducted at two study sites near

Albuquerque, New Mexico. The West Mesa site is west of

the City on Open Space property (fig. 1), and the Bernalillo

Watershed is north of the City on Cibola National Forest

property (fig. 1). The elevation of the West Mesa site is

about 1820 m and the Bernalillo Watershed is about 1660 m.

The West Mesa soil is a fine sandy loam and the Bernalillo

Watershed soil is a clayey loam (CS White, unpublished

data, 1996). The West Mesa grassland represents a Great

Basin Desert Scrub/Desert Grassland ecotone, and the

Bernalillo Watershed represents a Plains-Mesa Grassland/

Desert Grassland ecotone (Brown 1982). Dominant perennial grasses on the Bernalillo Watershed were: black, blue,

and sideoats grama (Bouteloua eriopoda (Torr.) Torr., B.

gracilis (Willd. ex Kunth) Lag. ex Griffiths, B. curtipendula

(Michx.) Torr.), respectively); purple threeawn (Aristida

purpurea Nutt.); galleta (Hilaria jamesii (Torr.) Benth);

and dropseed (Sporobolus sp.). Dominant perennial grasses

on the West Mesa were: Indian ricegrass (Oryzopsis

hymenoides (Roem & Schult.) Ricker): needle-and-thread

grass (Stipa comata (Trin. & Rupr.)); purple threeawn;

galleta; black grama; and dropseed. Annual precipitation

for both sites averages about 20 to 25 cm; however, precipitation measured at the Albuquerque station of the U.S.

Weather Bureau during the study period was considerably

less than the monthly mean of the previous 40 years

(fig. 2a). A precipitation deficit began during the beginning

of 1995 and lasted through the first 5 months of 1996, after

which slightly higher than normal precipitation occurred

through the rest of 1996 (fig. 2b).

Both sites were removed from livestock grazing; the animals were removed in 1947 from the Bernalillo Watershed

and in the early 1970’s from the West Mesa. Despite the

removal of grazing, each site had a substantial shrub

component, particularly broom snakeweed. The Bernalillo
USDA Forest Service Proceedings RMRS-P-7. 1999 85

Figure 1—Map showing the general locations of the Bernalillo Watershed and West Mesa

research sites located near Albuquerque, NM.

Figure 2—Monthly mean precipitation for the Abq weather station for the period since 1960 (open), and monthly

precipitation (solid) during 1995 and 1996 (a), and cumulative departure curve from the long-term mean

precipitation volumes beginning in 1995 through 1996 (b).
86 USDA Forest Service Proceedings RMRS-P-7. 1999

Watershed had extensive flood and erosion control features

constructed by the Soil Conservation Service and the Forest

Service in the 1950’s, including steep-slope terraces, furrow

plowing, pitting, check dams and grass seeding. These

efforts followed severe flooding and erosion that blocked the

main north-south highway with sediment in 1954, which

occurred during a period of record-setting region-wide

drought (Betancourt and others 1993).

Experimental Design

Each site includes eight plots; four control and four burned,

which were arranged in a randomized block design. At the

Bernalillo Watershed site, six plots (3 pairs of treatment

and control) are located on one mesa, while the other two

(1 treatment and 1 control) are located on a mesa to the

south (fig. 1). On the West Mesa, plots were arranged in a

near linear fashion below the ridge-line. At both sites, each

plot is 1 ha (100 m on a side) with at least 30 m separating

the plots on all sides. Soil and vegetation sampling took

place within a 60 m by 60 m area within the 1 ha plot to

protect against edge effects (fig. 3). Within each plot, three

permanently marked 60-m lines were used for vegetation

cover and density measurements. Soils were collected by

cover-type (shrub, grass, or bare soil) along three adjacent

60-m lines. In the Bernalillo Watershed, each plot had two

3 x 10 m runoff-erosion collectors, while the West Mesa had

only one collector per plot (to minimize potential disturbance

to archeological resources).

Prescribed Fire

The Bernalillo Watershed was treated with prescribed

fire November 15-16, 1995, with a total of about 168 ha

burned. The experimental plots were contained within the

burn area. The control plots were protected by fire retardant foam applied around their perimeters. Weather conditions were favorable for prescribed burning with warm

temperatures for the season (about 55 °F), moderate relative

humidity, and light winds. However, the fuels in the Bernalillo

Watershed were discontinuous, which resulted in patchy

coverage by the fire.

The West Mesa site was treated with prescribed fire

February 14, 1996. At this site, only the treatment plots

were burned. Again, weather conditions were favorable for

prescribed burning with warm temperatures for the season,

moderate relative humidity, and light but steady winds.

Fuels were more continuous at this site and the grasses

were of taller stature, which allowed for nearly complete

burn coverage with only small patches that did not burn.

The plots were blacklined on three sides, then lit across the

top and the fire moved with the wind across the entire plot,

leaving only a few patches unburned.

Measurements

Vegetation Community Structure—Aboveground

cover of individual plant species, as well as non-vegetation

ground cover by categories (bare soil, litter, gravel and rock),

were measured using the Community Structure Analysis

technique (Pase 1981, Wolters and others 1996). Each of

the three 60-m vegetation transects within each plot were

Figure 3—Design of experimental plots showing the

interior 60 m by 60 m area actually sampled, the soil

and vegetation transects (dashed lines) and the relative placement of the runoff collector (rectangular

shaded area in plot). Erosion bridges were installed

about 30 cm from the border of the runoff collector

centered along the top and one side of the collector

(darker shaded areas). Rain gutter with galvanized

sheet metal lip that drained into a 20 l bucket was

installed at the bottom of the collector.

measured. These transects were measured before the prescribed fire, soon after the prescribed fire, and after the first

growing season after the fire.

Soil Measurements and Analyses—Soil samples

were collected three times at both sites; before the prescribed fire, shortly after the prescribed fire, and after the

first growing season after the fire. Surface soil samples were

collected under three cover-types (shrub, grass, and bare

soil) by taking 4-cm wide cores to a depth of 20 cm at two

locations along three 60-m belt transects inside the sampling area. The six soil cores of each cover type from each plot

were composited into a single sample. This sample design

produced one composite sample from each plot for bare,

grass, and shrub cover-types (sample-size of four for treatment and control).

Samples were transported on ice to the University of

New Mexico, where they were sieved (2 mm), mixed, and

stored at 5 °C for further analyses. After determining waterholding capacity (WHC)(White and McDonnell 1988), a

portion of each sample was adjusted to 50 percent of determined WHC and up to 11 subsamples were apportioned into

plastic cups. Each cup contained approximately 30 g dryweight mineral soil. One subsample of each sample was

immediately extracted with 100 ml 2 N KCl for NH4

+-N and

NO3

–-N analyses. The remainder of the cups were covered

with plastic wrap, sealed with a rubber band, and incubated

in the dark at 20 °C. The plastic wrap minimized water loss
USDA Forest Service Proceedings RMRS-P-7. 1999 87

during incubation, yet exchange of CO2 and O2 was sufficient

to keep the subsamples aerobic during incubation. Moisture

content was monitored by mass loss and replenished as

needed. At weekly intervals, one subsample of each sample

was removed and extracted with KCl for 18-24 h. The

clarified KCl was filtered through a Kimwipe® and analyzed

for NH4

+-N and NO3–-N+NO2–-N on a Technicon AutoAnalyzer (Technicon, Tarrytown, NY) as described in

White (1986). Mineralizable N was equal to the maximal

amount of inorganic N (sum of ammonium and nitrate)

produced during incubation by each soil.

Water content of the composited sample was measured

gravimetrically after 24-h desiccation at 105 °C. Soil texture

was measured by the hydrometer method (Day 1965).

These sampling and analysis methods allowed for the determination of soil characteristics by cover-type.

Sediment Yield—Runoff-sediment collectors were designed after those used by the Water Erosion Prediction

Project (WEPP; USDA, 1196 Building SOIL, Purdue University, West Lafayette, Indiana 47907-1196). Size and

placement of the collectors at the West Mesa site were

negotiated with and approved by Albuquerque Open Space

archaeologists to minimize soil disturbance and damage to

articles of archeological value. Following site approval by

the State Historic Preservation Office, one collector per plot

was installed at the West Mesa site. Two collectors per site

were installed at the Bernalillo Watershed. All collectors

were constructed by installing galvanized flashing around

the perimeter of the 3 m by 10 m runoff collection area

after the fire treatment (fig. 3). Along the bottom 3-m side,

a plastic raingutter with galvanized flashing was installed

at ground level to collect runoff and sediment. At the end

of the gutter, a hole was dug and a 20-l bucket was placed in

the hole and attached to the end-cap on the gutter by a

section of garden hose. Both sediment in the gutter and

bucket were collected at periodic intervals. This experimental design resulted in four treatment and four control sediment samples for each collection at the West Mesa site, and

eight treatment and control sediment samples at the

Bernalillo Watershed (two collectors in four plots).

Soil Erosion Bridge—Change in soil microtopography

within each runoff collector was monitored using two soil

erosion bridges (one parallel to the top and one along the

side of each collector; fig. 3) established within the collectors

prior to the burn. A soil erosion bridge measures small-scale

changes in soil microtopography (Shakesby 1993; Wilcox

and others 1994). The purpose of the bridge is to accurately

determine net soil gain or loss. Following a burn, contraction

and expansion of vegetation could coincide with movement

of soil from bare areas to vegetated areas. Movement of soil

at this scale could result in a simple redistribution of soil

with no net gain or loss. Similar to the pattern described by

Watt (1947), the soil surface may rise as individual plants

become established and mature (termed a building phase),

and then degenerates upon plant mortality, but the area as

whole could remain in equilibrium with simple redistribution of materials within the area. Soil bridges were utilized

to measure changes in soil microtopography to provide an

accurate measure of net soil movement.

The actual bridge is constructed from an aluminum bar

(35 mm square), 1.5 m in length, with 31 holes machined and

fitted with brass bushings at 5 cm intervals (fig. 4). The

bridge is situated on two permanent rebar stakes, leveled

Figure 4—Schematic drawing of soil erosion bridge showing end rebar, center nail at soil surface, and 5 measuring pins.
88 USDA Forest Service Proceedings RMRS-P-7. 1999

with the help of a bubble level on the bridge, and secured

with wood shims to prevent movement of the bridge. To

increase the accuracy of this method, a spike with a dimple

in the head is driven into the ground below the center pin.

An aluminum pin is then inserted through the bridge and

into the dimple in the head of the nail. The end rebar stakes

and the center nail create a three point line, which increases

the accuracy over what would normally be a two point line

(Shakesby 1993; Wilcox and others 1994). Once the bridge is

secured, pins are inserted through holes in the bridge to the

soil surface and the portion of each pin extending above the

bar is measured. The 30-point profile reflects the soil surface

topography. When measured over time, these measurements document minor changes in soil surface dynamics

and net gain or loss in soil resources. The soil erosion bridges

were measured before the fire, immediately after the fire, in

July 1996 after the summer rains began, and after the first

growing season after the prescribed fire.

Statistical Analyses

Each site (Bernalillo and West Mesa) was analyzed separately. Effect of prescribed fire on soil potentially mineralizable N was analyzed using Analysis of Variance (ANOVA)

procedures in SAS (SAS Institute Inc., Cary, NC). Soil bridge

measurements and sediment transport were analyzed using

repeated measures ANOVA procedures in SAS, which generated an analysis for the treatment, collection, and their

interaction factors. Effect of the prescribed fire on vegetation

cover was determined using the GLM repeated measures

procedure on SPSS (v7.5, citation). Unless otherwise indicated, a significance level of P ≤ 0.05 was used.

Results ________________________

Bernalillo Watershed

Vegetation Cover—Vegetation cover both before and

after the prescribed fire was relatively sparse and patchy,

which lead to high within-treatment variances for all

collections. Cover of total vegetation, grass, and shrubs

was the highest in the collection before the fire treatment

(fig. 5), which was near the beginning of below-normal

precipitation in the region (fig. 2). All cover-types declined

on treatment and control plots in the second collection, after

the prescribed fire. Total vegetation and grass cover increased in the third collection to near that of the first

collection; however, shrub cover continued to decline in both

the control and treatment plots. For total vegetation cover,

grass cover, and shrub cover, treatment was not a significant

factor, nor was the time x treatment interaction. The time

factor was significant for the change in vegetation for both

time intervals (change from collection 1 to 2 (P = 0.001), and

from collection 2 to 3 (P = 0.038)).

Mineralizable N—Extractable inorganic N (sum of ammonium and nitrate) showed a general linear increase

throughout the 70-d incubation period for soils from all

cover-types (shrub, grass, and bare) from the Bernalillo

Watershed and the West Mesa sites. Thus, the sum of

ammonium and nitrate in the 70-d extraction equalled

mineralizable N in most soils. In soils from the Bernalillo

Watershed, mineralizable N is greatest in soils under shrub,

slightly lower in soils under grass, and lowest in bare soils

(fig. 6) for all collections. The fire treatment and the interaction of fire and collection were not significant factors

(P > 0.05) on mineralizable N levels, but time of collection

was highly significant (P = 0.003). The effect of collection is

shown by both the treatment and control samples increasing

after fire and then decreasing on the last collection (fig. 6).

Erosion—The amount of sediment transported from each

collector was highly variable following the fire in both

treatment and control plots (fig. 7). Although the means of

Figure 5—Changes in vegetation cover (circles, total

cover; squares, grass cover; triangles, shrub cover) on

the control (open symbols) and burned (filled symbols)

plots at the Bernalillo Watershed. Arrow indicates when

the prescribed burn occurred.

Figure 6—Changes in mineralizable N content of soils

beneath different vegetation cover-types (circles, shrub;

squares, grass; triangles, bare soil) on the control (open

symbols) and burned (filled symbols) plots at the

Bernalillo Watershed. Arrow indicates when the prescribed burn occurred.
USDA Forest Service Proceedings RMRS-P-7. 1999 89

the treatment plots were consistently higher than the means

of the controls, there was no significant effect of the treatment factor (P = 0.102) on sediment transport, which in part

was due to the high within-treatment variance. Collection

was a highly significant factor (P < 0.001), while the treatment x collection interaction factor was near significant

(P = 0.052). In general, the relative difference between the

treatment and controls diminished during the course of the

first year, which would be consistent with a relatively

greater increase in cover on burned plots in response to the

precipitation from June 1996 through the end of the year

with a corresponding increase in site stability following

plot establishment.

Soil Erosion Bridges—The repeated measures ANOVA

identified that treatment, collection, and their interaction

were all significant factors (P = 0.038, P = 0.001, and P =

0.045; respectively) for the change in soil microtopography

in the Bernalillo Watershed. Both treatment and control

soils show a decline in soil surface (representing net erosion)

during the course of the study, except for the control plots

which showed no change or a net gain for the last collection

(fig. 8). The rate of loss appears greater in the treatment

than in the control plots.

West Mesa

Vegetation Cover—Vegetation cover was relatively

uniform across the plots and the grasses were taller than at

the Bernalillo Watershed, which led to much more uniform

coverage by the prescribed fire treatment. Initially, total

cover, grass cover, and shrub cover were similar between

the treatment and control plots (fig. 9); however, all three

cover types were significantly reduced following the prescribed fire while cover by these types on the control plots

was unchanged. Following the first growing season after

the fire, grass cover on the burned plots increased 19.5

percent (from 0.7 percent cover to 20.2 percent), while grass

cover on the control plots increased by 4.7 percent (from

21.1 to 25.8 percent, which was not a significant increase).

Shrub cover was significantly reduced on the burned plots

after the fire and did not increase by the third collection.

Shrub cover in the control plots was not significantly different after the fire, but declined between the second and third

collection. For total vegetation cover, grass cover, and shrub

cover, treatment and the time x treatment interaction factors were significant (P < 0.05).

Mineralizable N—Mineralizable N was highest in soils

under shrub, intermediate under grass, and lowest in bare

Figure 7—Amount of soil trapped in the gutters at the

bottom of the runoff collectors in the control (open

circles) and burned (filled circles) plots for six different

collections during 1996 at the Bernalillo Watershed.

The first runoff events occurred in late June and early

July, 1996.

Figure 8—Net change in the soil surface measured

below the erosion bridges within the control (circles)

and burned (filled circles) plots at the Bernalillo Watershed. Arrow indicates when the prescribed burn

occurred.

Figure 9—Changes in vegetation cover (circles, total

cover; squares, grass cover; triangles, shrub cover) on

the control (open symbols) and burned (filled symbols)

plots at the West Mesa. Arrow indicates when the

prescribed burn occurred.
90 USDA Forest Service Proceedings RMRS-P-7. 1999

soils (fig. 10). The repeated measures ANOVA identified

collection to be the only significant factor (P < 0.001) for

mineralizable N in soils of the West Mesa. Mineralizable N

increased in all soil-types following the prescribed fire in

both treatment and control plots, except for the soils under

grass in the control plots. All soils showed a particularly

sharp decline in mineralizable N following the summer

growth in both the control and burned plots.

Erosion—Treatment, collection, and their interaction

were not significant factors for soil erosion at the West Mesa

site. Variance was very high in all collections in both the

treatment and control plots. The high variance and small

sample size (four plots per treatment) resulted in no significant differences between treatment and control plots

(fig. 11), but the means of the treatment plots were higher

than the mean of the control plots in all collections.

Soil Erosion Bridges—The treatment plots showed a

net rise in the soil surface immediately after the prescribed

burn, but the soil surface degraded to below the initial

level in both subsequent collections (fig. 12). The control

plots showed no significant change during the study period.

The only significant difference between the treatment and

control plots occurred in the immediate post-treatment

collection.

Discussion _____________________

To say that the weather conditions before and after the

prescribed fires were less than optimal would be an understatement. As with most management activities, an extensive planning and budget process preceded the actual

prescribed fires. The original study plan targeted a late

September-October prescribed fire at both sites, a period

when the days are still warm with breezes, but not high

winds, and maximum fine fuel in response to summer rains.

Figure 10—Changes in mineralizable N content of soils

beneath different vegetation cover-types (circles, shrub;

squares, grass; triangles, bare soil) on the control (open

symbols) and burned (filled symbols) plots at the West

Mesa. Arrow indicates when the prescribed burn occurred.

Figure 12—Net change in the soil surface measured

below the erosion bridges within the control (circles) and

burned (filled circles) plots at the West Mesa. Arrow

indicates when the prescribed burn occurred.

Figure 11—Amount of soil trapped in the gutters at the

bottom of the runoff collectors in the control (open circles)

and burned (filled circles) plots for six different collections

during 1996 at the West Mesa. The first runoff events

occurred in late June and early July, 1996.

Instead, the drought that started at the beginning of 1995

continued through the summer, providing little new growth.

In September the rains exceeded the long-term average

(fig. 2b), which forced a delay until November for the Bernalillo

Watershed and February for the West Mesa. Optimally, ash

produced by the fire would have leached into the soil with

the light rains expected at that time of year. However,

precipitation continued below normal through the winter

and winds blew ash off the burned plots, which was evident

from the ash trapped by vegetation in the unburned plots.

In the Bernalillo Watershed, this was particularly important because the control plots were “islands” within the
USDA Forest Service Proceedings RMRS-P-7. 1999 91

treated area and could receive ash from all sides. In contrast,

the treatment plots were “islands” within the sea of unburned grasslands at the West Mesa site, so potential ash

contribution was less than at the Bernalillo Watershed.

Rains finally came in June of 1996, but they were high

intensity thundershowers that generated runoff and soil

erosion, even on the control plots where vegetation was not

consumed by fire. Thus, the full benefit of nutrients in the

ash was not expressed at the treatment plots, and the control

plots benefitted from ash blown from the treatment plots.

For the collection after the fire, vegetation cover in the

control plots was less than before the fire, which in part

could have been caused by the persistent drought conditions

preceding the prescribed fire. However, trespass animals on

the site consumed an unknown amount of vegetation and

could be the cause of the observed decline. Perhaps the best

evidence of the drought was the persistent decline of shrub

cover throughout the first year of study. The decline may

indicate that shrubs are more susceptible to winter/spring

drought, which is the period when soil moisture at greater

depth is usually replenished. At both sites, grass cover in

both treatment and control plots increased in the final

collection while the shrubs showed no change or a decline.

Thus, the desired change in greater cover by grass relative

to shrubs occurred on both sites, but the change cannot be

attributed to fire alone because of the continued decline in

shrubs in the control plots at both sites.

Contribution of ash to the control plots may account for

the lack of an expected treatment effect in the soils of the

burned plots for mineralizable N. However, mineralizable N

also increased in the soils beneath shrubs and bare soils in

the control plots on the West Mesa after the prescribed fire.

This increase suggests that factors other than ash may

contribute to the mineralizable N pool in the soils over the

period between the pre- and post-burn soils. Possible explanations for the increase in mineralizable N could be the

contribution of readily mineralizable N following mortality

of microbial or root biomass during the drought period

between the initial and post-fire soil collections.

The decline in mineralizable N content of soils in all plots

at both sites between the second and third collection coincides with the increase in grass cover, which suggests that

the available N pool may be sequestered in current growth.

If precipitation remains above normal and available N is not

replenished before the next growing season, then the decline

in mineralizable N suggests that net primary production

may be limited by available N supply during the next

growing season.

The patterns of soil loss, although not statistically significant in most cases, were consistent with our expectations.

Reduction in vegetation cover was expected to temporarily

increase potential soil erosion, and the treatment plots at

both sites had consistently higher (but not significantly

different) soil loss than the control plots (fig. 7 and 11). As

vegetation cover increased following the summer rains,

erosion tended to decrease on both the treatment and control

plots at both sites. It is possible that storm intensity also

decreased over the summer, which could, in part, account for

the apparent decline in erosion. This pattern of declining

erosion as the summer runoff season advanced was also

shown by Wilcox (1994) at another location in New Mexico,

and Yair and others (1980) observed similar declines in

sediment concentrations with repeated runoff events in arid

regions of the northern Negev.

The soil bridges were installed on the sites before the

prescribed fires and before the flashing was installed

around the erosion collectors. The second bridge measurements reflect the combined effects of soil loss between the

two collections, disturbance from installation of the flashing, soil compaction from footsteps by personnel during the

prescribed fire, and trespass livestock at the Bernalillo

Watershed. Between the second and third sampling period,

both wind and water erosion could have contributed to the

soil loss seen at both sites. Rain splash and water erosion

probably were the major factors contributing to change

between the third and fourth collection, as evident from the

soil splashed onto the flashing between these collections

(personal observation). If the trend in increasing vegetation

cover continues, the soil surface is expected to stabilize, or

perhaps even show a net increase if the vegetation traps

enough particles and reduces compaction from rainsplash.

The soil bridges appear to over-estimate the rate of soil

erosion as seen in the runoff plot as a whole. When the

total mass lost during the study period from the erosion

plots is evenly distributed over the entire plot, the control

and treatment plots had an average loss of 0.09 mm and

0.14 mm, respectively, on the Bernalillo Watershed, and

0.12 mm and 0.2 mm, respectively, on the West Mesa. The

soil bridges indicate greater loss (1.0 mm and more) from all

plots, except the control plots on the West Mesa (fig. 8 and

12). Since the bridges were installed along the top and one

side of the erosion plots, it is possible that soil loss from

those positions is greater than from the plot as a whole.

Conclusions____________________

Hypothesis 1: after an initial decline in vegetation cover,

grasses should respond more rapidly than shrubs and achieve

greater cover relative to shrubs. This occurred on both

grasslands, but cannot be attributed to fire alone.

Hypothesis 2: N in ash should increase the amount of

mineralizable N following the fire, but mineralizable N

should return to that of control or unburned soils following

regrowth of vegetation. This pattern did not occur, in that

mineralizable N in both treatment and control soils rose

after the fire and declined following the summer growing

period.

Hypothesis 3: high intensity precipitation should increase

erosion following burning until the vegetation cover recovers, which would then lead to a decline in erosion. Although

not desired, this occurred at both grasslands with an apparent decline in erosion as the summer progressed. However,

we can only assume the decline in erosion was due to

increased vegetation cover because the contribution from

other factors is unknown.

The results of this study are noteworthy for two reasons.

First, the weather preceding and following the treatment

with prescribed fire was very dry. This drought period lasted

until early summer. The subsequent thunderstorms were

frequent and heavy. Thus, it was expected that runoff and

sediment yields and nutrient loss would be significantly

greater from burn plots as compared to control plots. Surprisingly, this did not occur with regularity. Second, shrub

cover was reduced and remained low relative to grass cover

after the fire at the West Mesa site, but not different from
92 USDA Forest Service Proceedings RMRS-P-7. 1999

the controls at the Bernalillo site. Research from other

semiarid grasslands suggest that stimulation of grass growth

occurs for up to four years following fires in these systems

(Bock and Bock 1990;Pase and Granfelt 1977). Grass cover

in the burn plots would have to continue to increase without

an increase in shrubs for the management objective to be

met following the first fire. It was anticipated that many

fires may be required to obtain the desired objective. Future

management will require continued treatment with fire to

maintain the grassland in proper functioning condition.

Acknowledgments ______________

This work was supported by grants from the National

Science Foundation (No. BSR-88-11906 and DEB-9411976)

and by the Rocky Mountain Research Station. Gratitude is

extended to all the people who helped in this research:

Richard Gatewood, Ruben Leal, Randi Paris, John Craig,

Chris Thomas, Bill Hauck, Robyn Phillips, Ray Romero,

Wendy Jones Brunnemann (City of ABQ Open Space), and

all the people who actually performed the prescribed burn

(Cibola National Forest - Sandia Ranger District, State

Forestry, Placitas Fire Brigade, Sandoval County Fire Department, New Mexico Forestry and Resources Conservation). This research is aided by a grant from the Cibola

National Forest. Further funding was obtained for the

support of Steve Hofstad from the University of New Mexico

through the Research Project and Travel Grant, the Student

Research Allocation Committee, and the Vice President’s

Research Fund provided by the Office of Research. This is

Sevilleta Long-term Ecological Research Program Pub. #116.

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USDA Forest Service Proceedings RMRS-P-7. 1999 93

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Bill Fleming is Associate Professor, School of Architecture and Planning,

University of New Mexico, Albuquerque NM 87131.

Abstract—Although watersheds are not equally healthy, there are

no generally accepted criteria for evaluating and comparing them.

This paper suggests several criteria which numerically evaluate

watersheds in four ways: (1) riparian health, (2) aquatic

macroinvertebrate biodiversity, (3) hillslope soil loss and (4) upland land use/flood peak potential. Each criterion is semiquantitatively evaluated on a scale of 1 to 10, with 1 the healthiest

and 10 the least healthy. The index is applied to two subalpine

watersheds near Santa Fe, New Mexico, comparing them using the

four numerical criteria. The Rio en Medio, site of the Santa Fe Ski

Basin, was rated “good” (with a score of 4.1), while an adjacent

undeveloped watershed, the Rio Tesuque was rated “excellent”

(with a score of 2.5).

Methodology ___________________

Four methodologies for evaluating watershed health are

described and then combined to form a watershed health

index. An example is presented comparing two adjacent

watersheds with different land uses near Santa Fe, New

Mexico.

Riparian Health

Several authors, such as Barbour and Stribling (1991),

have suggested criteria for evaluating the health of riparian habitats in the Western United States. Although their

criteria is heavily weighted toward stream habitats for

fish, the index has been adapted for a wider range of

species by others (Fleming and Schrader, 1998). Ten criteria

are described in table 1, beginning with stream discharge

necessary to support a healthy aquatic habitat for

macroinvertebrates and fish. For an optimum environment,

several authors, including Barbour and Stribling (1991)

consider that 0.05 m3/sec (2 cfs) are necessary to support a

high-quality, coldwater fishery. If less that 0.01 cfs are

flowing, the habitat is considered “poor.”

Streambed geology and embeddedness are critical for the

maintenance of necessary void spaces in the substrate for

macroinvertebrate habitat. If more than 50 percent of the

material is comprised of grain sizes in the gravel, cobble and

boulder categories, the habitat is considered “optimum.”

Watershed Health: an Evaluation Index for

New Mexico

Bill Fleming

Table 1—Riparian health indices.

 Parameter Excellent Good Fair Poor

Score 0-0.1 0.1-0.4 0.4-0.7 0.7-1.0

Flow (m3/sec) >0.05 0.03-0.05 0.01-0.03 <0.01

Streambed >50% boulders 25-50% 10-25% <10%

geology cobbles gravel

Embeddedness <25% 25-50% 50-75% >75%

Width/depth <78-15 15-25 >25

Bank stability >90% stable 70-90% 50-70% <50%

Buffer width >18m 12-18m 6-12m <6m

Vegetation >10 species 5-10 3-5 <3

diversity

Structural 3 height 21 1 sparse

diversity classes

Vegetation >90 % 70-90 % 50-70 % <50

percent

cover %

Canopy mixed sun/ sparse mostly sun no shade

shading shade canopy or shade

Streams reaches are evaluated with a “random walk” method,

in which the investigator crosses the stream in a zigzag

pattern, stopping every two steps to determine the size of

material in front of the instep of the wader (Sims and others

1995). At least 20 samples should be chosen in each reach

and a range of grain size percentages calculated. If more

than 50 percent of the substrate is sand size or smaller, the

habitat is considered “poor.”

Structural vegetation diversity is important for birds

and if grasses, shrubs and trees are present in the riparian

zone, this criterion receives an optimum rating. Vegetation

cover, expressed as a percent, is estimated by randomly

choosing a transect direction to walk, noting at every other

step whether or vegetation cover exists. Ninety percent

vegetation cover is optimum, while less than 50 percent is

considered poor. Vegetative diversity is evaluated by determining whether at least 10 different species occur in the

riparian zone, which is scored as optimum (less than 3

species is considered poor). The width of the vegetation

buffer is considered optimal is it exceeds 18 meters and poor

if it is less than 6 m. Canopy shading is considered optimal

if a mix of sun and shade, while full sun is considered poor.

The ratio of bankfull channel width to depth is optimal if

less than 7 (Rosgen, 1994) and poor if more than 25 (a very

wide and shallow stream). If the ratio of distance between

riffles to stream width is between 5 and 7, heterogeneity for

aquatic insects is optimal, while a ratio of more than 25 is

considered a poor habitat (Barbour and Stribling, 1991).

Upper bank stability is considered excellent if there are no

vertical and unvegetated banks, while more than 50 percent

of bank area in an unstable and eroding condition is rated

poor.
94 USDA Forest Service Proceedings RMRS-P-7. 1999

Table 2—Tolerance index for New Mexico macroinvertebrates.

Tolerance index

Order Family (10= most tolerant)

Ephemeroptera Tricorythedae 10.0

 (Mayflies) Baetidae 6.7

Siphlonuridae 6.7

Caenidae 6.7

Ephemerellidae 4.4

Heptageniidae 4.4

Leptophlebiidae 3.3

Plecoptera Perlodidae 4.4

 (Stoneflies) Taenipterygidae 4.4

Nemouridae 3.3

Capniidae 3.0

Pteronarcyidae 2.2

Chloroperlidae 2.2

Perlidae 2.2

Leuctridae 1.7

Trichoptera Hydropsychidae 10.0

 (Caddisflies) Limnephilidae 10.0

Psychomyidae 10.0

Leptoceridae 5.0

Brachycentridae 2.2

Lepidostromatidae 1.7

Rhyacophilidae 1.7

Coleoptera Elmidae 10.0

 (Beetles) Hydrophilidae 6.7

Dytiscidae 6.7

Haliplidae 5.0

Odonata most families 10.0

 (Dragonflies and Damselflies)

Diptera most families 10.0

 (Aquatic Flies)

Non-insects most families 10.0

 (snail, leeches, aquatic worms etc.)

Biodiversity of Aquatic Insects

An important indicator of the long term health of a

watershed are species of aquatic macroinvertebrates. Insects remain in streams during transitory periods of floods,

drought, periods of turbidity or heavy metal inflow. The

benthic insects are affected by chemical pollution and physical changes such as temperature pH, discharge and sediment resulting from upstream land use activities. Whether

or not sensitive families of insects remain in a stream over

the long term is a useful indicator of upstream watershed

health.

Stoneflies are generally the order of insects most sensitive to human impacts such as organic sewage pollution,

and if some of the more sensitive families are absent, it may

be indicative of nitrogen or phosphorus in higher than

natural concentrations. Usually stoneflies are a smaller

percentage of the insects (10-20 percent) and may be the

first to disappear with increased human impacts. Mayflies

are also sensitive to watershed disturbances, but may be

20-40 percent of the total number, and may be the next to

disappear in a stressed watershed. Caddisflies also include

species sensitive to sedimentation, in particular, but some

families are very tolerant and can live under highly disturbed conditions (for example Hydropsychidae). If an insect

collection is dominated by midges or worms, the watershed

and stream may be very degraded. The different families,

and percentages of each family, are indicators of the health

of the watershed.

The tolerance to watershed disturbance of the families of

aquatic insects occurring in New Mexico is shown in table 2

(based on Winget and Mangum, 1979 and interpreted by

Jacobi, personal communication, 1996). Higher numbers

mean the insect is more tolerant to watershed disturbance,

and those with an index of 10 may survive in stream

systems with high concentrations of sediment, nutrients

and metals. Low indices indicate that the family is sensitive

to watershed disturbances (such as the Pteronarcyidae family of giant stoneflies which dominates the upper Pecos

watershed).

To determine the biotic tolerance index for a watershed

above a sampling site, at least 100 insects are collected and

the numbers of each family determined. Numbers of each

family are multiplied by the tolerance index, and these

values added. The total number is then divided by the

number of insects collected to determine a biotic index for

the watershed or stream reach. If the index is less than 3.5,

the watershed condition may have little upstream disturbance, whereas values exceeding 7.5 may be highly impacted.

Hillslope Soil Loss

The Universal Soil Loss Equation has been used to predict

erosion rates in the Midwest for over 40 years, but only

recently has been adapted for Western forest and range

lands (Brooks and others 1997). In the West, the form of the

equation is usually the “modified” variety because the vegetation factor is better suited to forest and range lands than

the “agricultural practice” factor validated for hundreds of

erosion plots in the Midwest. The “modified universal soil

loss equation” (MUSLE) is used here as an indicator of

upland watershed health because it integrates four factors

critical in evaluating hillslopes: (1) precipitation intensity,

(2) slope steepness and length, (3) soil stability, and (4)

vegetation cover.

The power of high-intensity, short-duration rainstorms to

erode soil in New Mexico watersheds has been evaluated by

the Soil Conservation Service (now the National Resource

Conservation Service, USDA, 1977), and dimensionless values generally increase with elevation. In the Rio Grande

Valley near Albuquerque, rainfall intensity corresponds to a

contour with a value of “20”, whereas the crest of Sandia

Peak has a value of “60” with much more powerful summer

rainfall impact on soil.

With steeper and longer slopes, runoff will attain higher

velocities and erode more soil, if other factors remain the

same. Watershed management texts interpret “slope factors” to be used in the soil loss equation (Brooks and others

1997). Slope steepness is quickly measured in the field

with a clinometer and slope length determined with topographic maps.

Depending on the grain size composition, percent of organic matter and infiltration capacity of soil, erosion potential changes (Brooks and others 1997). Soil surveys evaluate

the “K factor”, or erodibility factor, for soils, or publish grain

size compositions which allow K factors to be calculated.
USDA Forest Service Proceedings RMRS-P-7. 1999 95

Table 3—Runoff curve numbers and watershed land use (Marsh,

1998 and Brooks and others 1997).

Land use Curve number

Commercial (roads, shopping centers) 7.0-9.5

Residential (single family) 3.5-5.0

(multifamily) 6.0-7.5

Industrial (light) 5.0-8.0

(heavy) 6.0-9.0

Parks 1.0-2.5

Playgrounds 2.0-7.5

Cultivated farmland (flat) 1.0-4.0

(rolling: 5-10 percent slope) 2.5-5.0

(hilly: 10-30 percent) 3.0-6.0

Rangeland (poor condition) 7.0-9.0

(fair condition) 5.0-8.5

(good condition) 4.0-8.0

Forest (poor condition) 4.5-8.5

(fair condition) 3.5-8.0

(good condition) 2.5-7.5

Table 4—Watershed health indices for Santa Fe watersheds.

Watershed health index Rio en Medio Rio Tesuque

Riparian health 2.6 0.7

Macroinvertebrate biodiversity 4.3 3.1

Hillslope erosion rates 2.2 0.7

Land use/flooding potential 7.3 5.5

Total (divided by 4 indices) 4.1 2.5

While the previous three factors in the soil loss equation

usually remain the same with watershed disturbance, the

vegetation cover may change significantly when development occurs. Activities such as logging, grazing, ski trail

construction, roads, and housing development reduce the

vegetation cover, sometimes eliminating the most important factor in protecting soil from intense rainfall. Watershed management texts list vegetation cover factors with

varying grass cover percentages and types of overstory

protection (Brooks and others 1997). Field surveys of cover

percent are made by randomly choosing several hillside

transects and pacing 10 steps per transect, noting whether

or not the front of the pace has vegetation cover or bare soil.

The four factors are then multiplied together, resulting in

soil loss in tons/acre/year. While forest and range landscapes

in the Western United States have not been validated with

same rigor as agricultural lands in the Midwest, values of

relative erosion rates are useful in rating watershed health.

The NRCS estimates that “tolerable” soil losses are those

exceeding 5 tons/acre/year, while Pimentel (1995) cites evidence that 0.5 tons/acre/year is an average worldwide value

for the rate of soil formation (lower in arid regions and higher

in humid landscapes).

A simplified health index for soil loss relates erosion

rates to a what could be considered a sustainable rate of

1 ton/acre/year, which receives an “excellent” rating of one.

As rates increase, the rating increases, with a soil loss of

10 tons/acre/year having a rating of 10 (poor watershed

condition). It is important to realize that many landscapes in

New Mexico have erosion rates exceeding 10 tons/acre/year,

resulting in a “poor” rating for these areas.

Upland Land Use and Flood Peak Impacts

Land use in upper watersheds clearly has impacts on

watershed health and downstream flood peaks. For watersheds of less than a square mile, the “rational equation” is

often used by planners to predict downstream flood peaks,

based on watershed area, hourly rainfall intensity and a

land use factor. For larger and more diverse watersheds, a

method developed by the former US Soil Conservation Service (now the NRCS), using runoff curve numbers, is a

generally accepted approach (Brooks and others 1997). The

SCS approach is similar to the rational method, but uses a

“runoff curve number” to evaluate land use and the

watershed’s hydrologic response in the form of flood peaks.

Since the objective here is not to predict changes in flood

peaks with land use alterations, but only to indicate the

critical factor involved in flood peak modifications, the curve

number will be used as an indicator for upland land use as

it relates to flood peak generation. As published by the

SCS in 1972, runoff curve numbers range from 6 to 94,

depending on the type of land use and how it impacts the

infiltration of surface runoff into the vegetation/soil cover.

Lower numbers indicate high infiltration rates and high

numbers low infiltration rates and consequent high flood

peaks (Brooks and others 1997). Table 3 shows one version

of curve numbers, and these are modified simply by division

by 10 so the index will correspond to the other three parameters in this analysis.

Application to Watersheds Near

Santa Fe _______________________

The methodology is applied to two adjacent watersheds in

the Santa Fe National Forest, 15 miles northeast of Santa

Fe, New Mexico in the Sangre de Cristo Mountains. Each

watershed is slightly over one square mile in area, ranging

in elevation from 9,800 feet to 11,100 feet. The Rio en Medio

watershed is the site of the Santa Fe Ski Basin, in which

approximately 35 percent of watershed area has been developed with parking lots, lodges, septic tank fields, ski runs

and lifts. The Tesuque watershed is in a relatively undeveloped condition, with one road used only for hiking, ski

touring and the maintenance of telecommunications antennae on Tesuque Peak. Table 4 summarizes the results.

Riparian health: Two riparian surveys were done in each

watershed, one at the base and a second approximately

0.3 miles upstream. Results of the two surveys were averaged for each watershed. The Rio en Medio had an average

rating of 2.6 and Tesuque Creek 0.7. Major differences were

less riparian vegetation and more sediment and

embeddedness in the Rio en Medio.

Biodiversity of aquatic insects: A total of 486 insects

were collected from the Rio en Medio and 518 from the
96 USDA Forest Service Proceedings RMRS-P-7. 1999

Rio Tesuque by the Santa Fe Preparatory School during

1993-94. Rio en Medio had an index of 4.3 and Tesuque

Creek 3.1, mainly resulting from a greater percentage of

stoneflies in the Tesuque (29 percent compared with 19

percent in the Rio en Medio).

Hillslope soil loss: Surveys on three slopes in both watersheds indicate an average erosion rate in the Rio en Medio

of 2.2 tons/acre/year, compared with 0.7 tons/acre/year in

the Tesuque. The difference results from hillslopes in the Rio

en Medio which have lower vegetation cover percentages

than the Tesuque.

Upper land use and flood peak impacts: Evaluations of

land use in the Rio en Medio resulted in a runoff curve

number of 7.3 because of the extensive ski area development.

The relatively undeveloped Tesuque watershed had a lower

curve number of 5.5. The flooding potential of both watersheds is relatively high for forested areas because of thin soil

covers which don’t store large amounts of soil moisture and

ground water for later baseflow.

References _____________________

Barbour, M.T. and J.B. Stribling. 1991. Use of habitat assessment

in evaluating the biological integrity of stream communities.

Biol. Criteria: Research and Regulation: 25-38.

Brooks, K., Ffolliet, P., Thames, J. and Gregerson, H. 1997. Hydrology and the management of watersheds, 2nd ed., Iowa State

Univ. Press, 547 p.

Fleming, W.M. and R.E. Schrader. 1998. New Mexico Watershed

Watch Handbook. NM Game and Fish Dept. Special Report, 56 p.

Pimentel, D. 1995. Soil erosion worldwide. Cornell Press, 468 p.

Rosgen, D. 1994. River restoration utilizing natural stability concepts. Land and Water, July/Aug: 36-40.

Sims, B., J. Piatt, L. Johnson, C. Purchase and J. Phillips. 1995.

Channel bed particle size distribution procedure used to evaluate

watershed cumulative effects for range permit re-issuance on the

Santa Fe National Forest. USDA Forest Service Technical Rpt.,

Santa Fe National Forest, Santa Fe NM, 12 p.

USDA, 1974. Rainfall intensities for New Mexico. Soil Conservation

Service Ag. Bull. 568.
USDA Forest Service Proceedings RMRS-P-7. 1999 97

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Dave Pawelek is Hydrologist, Cibola National Forest, Albuquerque, NM

87113. Roy Jemison is Hydrologist, Rocky Mountain Research Station,

Albuquerque, NM 87106. Daniel Neary is Supervisory Soil Scientist, Rocky

Mountain Research Station, Flagstaff, AZ 86001.

Abstract—Improving primary roads in the Zuni Mountains of New

Mexico must take into consideration the wet meadows and upland

areas. This study looks at spring flow rates, erosion, channels and

changes in plant cover and composition. The goal is to help planners

design environmentally sensitive roadways for wet meadow areas.

Wet meadows occur naturally in the high elevations of the

Zuni Mountains of New Mexico. These areas typically have

higher diversities of plant and animal species than adjoining

upland areas due to the availability of permanent or semipermanent water sources. The low-lying nature of these

areas has typically made them more suited for transportation routes and easier crossings than the immediate surroundings. Road and railway beds built in these areas often

constrict and cut off the natural flow of water through these

areas. Constriction and blockage of natural drainage ways

can lead to incised channels and lowered water table levels.

The vegetation in these areas typically changes from mesic

to xeric in response to the decreased water availability.

The roads staff on Cibola National Forest in New Mexico

are working to improve primary roads in the forest that have

deteriorated and do not provide safe, year round access. In

addition, they are obliterating abandoned roads and railroad grades originally built to remove timber from the forest.

The design and construction practices used for new roads

considers them as part of the ecosystem. In areas where the

roads intersect drainages, structures are installed to permit

water to pass beneath the road surface unobstructed. Structures used include multiple raised culverts spread across

meadow crossings and French drains. Both types of structures limit the concentration of surface flows. Eroded channels and dewatered meadows as a result of improper road

designs and construction practices can be observed along

unimproved forest roads in the Zuni Mountains. The damage created by these inappropriate designs and practices can

often be corrected and the areas rehabilitated.

Agua Fria meadow in the Zuni Mountains, 32-km southwest of Grants, New Mexico is a forest meadow that showed

evidence of having been a wet meadow. Observations by

A Constructed Wet Meadow Model for

Forested Lands in the Southwest

Dave Pawelek

Roy Jemison

Daniel Neary

forest personnel designing improvements for Forest Road 49

through the meadow, suggested that the area could have

been dewatered because of the location of old transportation

routes and drainage structures. A plan was developed and

implemented to rewet the meadow.

Before the road and meadow projects, Agua Fria was a

broad meadow with a relatively straight, 2-3 m deep, entrenched channel running down one side, that quickly funneled runoff through the area from the upper watershed.

Several abandoned railroad beds and Forest Road 49 crossed

the meadow, perpendicular to the direction of water flow.

The vegetation cover across the meadow was a mixture of

xeric grasses, shrubs and forbs with a few large Ponderosa

Pine and Juniper trees scattered throughout the area.

During the construction phase, the entrenched channel

was back-filled in sections to prevent water from flowing in

it. Beginning near the top of the meadow, a new highly

sinuous channel, .6 m deep, was constructed down the center

of the meadow. The channel was built to create a step-pool

sequence type flow pattern. Straight channel sections form

the steps and curved bank sections, reinforced with tree

stumps serve as the pools. The beginning and end of each

channel section is delimited by a rock weir structure that

concentrates water flowing in the channel. Concentration of

the flow in the channel keeps soils and other materials

suspended in the runoff from settling to the bottom. The

roadway across the meadow was built on top of an earthen

berm elevated almost 2 meters at the high point. Sixteen

culverts were installed through the berm, spaced across the

active runoff section of the meadow to permit water to flow

underneath the roadway with minimal obstruction. At the

down stream end of the meadow, the new channel was

merged with the old channel. Meadow areas disturbed

during construction were tilled and planted with a mixture

of native grass seed to encourage the quick establishment of

vegetative cover to prevent soil erosion. The construction

phase of the project was terminated in the fall of 1996.

The channel and roadway projects have been monitored

since completion by regular visits to the site. Runoff has only

been observed flowing in the channel during the spring

while snow was melting on the upper watershed. Runoff can

also be generated by large rainfall events. However, observations of the channel during the non-winter months have

not demonstrated that rainfall has generated adequate

runoff to promote continuous flow in the channel. Spring

runoff in 1996 and 1997 rarely produced flows that exceeded

the bank full stage of the new channel. Erosion and deposition in the channel was negligible in these years. Seed

planted in the areas disturbed during construction germinated, but did not grow well.
98 USDA Forest Service Proceedings RMRS-P-7. 1999

Spring runoff in 1998 began in March and flowed continuously until the end of May. Runoff exceeded the bank full

stage along most reaches of the channel until early April

after which regular flow measurements were continued. A

channel flow rate at slightly below bank full capacity was

measured and determined to be 34 cfs. We will attempt to

estimate what the maximum flow rates could have been

using high water marks noted upstream from the project

area. The high runoff rates observed during the spring of

1998 correspond with the 23 percent higher than the average annual precipitation observed for this area. Runoff

eroded and breached the channel in a number of locations,

which was expected. However, in one channel section towards the lower end of the project, water that breached the

channel was inadvertently diverted away from the new

channel into the former channel. It was estimated that more

than half of the above bank full flow was diverted at this

point towards the old channel. The runoff flowed along an old

road and then along the course of the old channel. Most of the

old channel had been back filled from upstream to the lower

end of the project, so the water actually flowed on top of the

backfill. These overland flows created several long and deep

head cuts and gullies from the lower junction of the old and

new channels moving up the meadow.

Vegetation in the seeded and undisturbed areas grew tall

and dense during the spring and summer of 1998. A vegetation survey will be conducted in October 1998 to compare

plant cover and composition with pre-project conditions

measured in the fall of 1994. The roadway was not affected

in any way by the runoff across the meadow.

Forty-five piezometers were installed across Agua Fria

meadow during September and October 1998 to monitor the

depth and distribution of the water table. The drilling

records will be used to determine the makeup of the subsurface soil layers. Forty 3-m deep wells were installed along 5

rows, uniformly spaced down the length of the meadow. The

remaining five wells were installed one per row, to a depth

of 10 m. During installation of the 10 m wells, freestanding

water was encountered at 9 m below the soil surface. Bedrock was encountered in one well at 10 m. The soil profile in

most wells consisted of thick clay layers divided by thin

layers of sand and gravel.

The hydrologic conditions required to support a wet meadow

currently do not exist in the Agua Fria meadow, based on our

observations to date. We anticipate that the recently elevated channel will direct sufficient spring runoff onto the

meadow surface and into the subsurface layers that a permanent to semi-permanent water supply is established that

will support wet meadow plant species. In the meantime, our

investigations are helping us understand how Agua Fria

meadow and Forest Road 49 function and change in response to our interventions.

The results of our investigations will provide information

to resource managers and roadway planners that can help

them design environmentally sensitive roadways for wet

meadow areas. In addition, our results will document the

effectiveness of stream channel redirection as a method to

rewet a dewatered forest meadow.
USDA Forest Service Proceedings RMRS-P-7. 1999 99

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Teresa L. Newberry is a Soil Scientist, University of Arizona, Tucson.

Abstract—This paper is the final report in a larger study of water

relations in pinyon pine ecosystems. This last study looks at wholetree response to climatic variability; water use efficiency was studied using 13C measurements of tree-rings.

The purpose of this study is to explore the physiological

response of pinyon pine to spatial and temporal variability

on a whole tree level using information on physiology and

growth recorded in tree-rings. The rationale of this approach

is that water relations of pinyon pine and any long-lived

species can only be truly understood in the context of the

spatiotemporal heterogeneity inherent to natural environments. In addition to providing a more complete characterization, exploring a wide range of spatial and temporal

scales can lead to deeper ecological insights (Betancourt

1993, Ehleringer & Field 1993, Gosz, J.R. 1993, Gosz and

Sharpe 1989, O’Neill 1986). In semiarid regions, annual

precipitation provides a dominant limitation of the ecosystem biomass, but is insufficient for predicting community

structure and composition. Rather, temporal variability in

precipitation has been hypothesized to more directly constrain community structure (Noy-Meir 1993, Crawford &

Gosz 1982, Neilson and others 1992, Sala and others 1992).

In addition to temporal variability, the high degree of spatial

variability inherent in natural environments also plays an

important role in community and ecosystem dynamics

(Bazzaz 1993).

This study is the final part of a larger study that explores

the water relations in pinyon pine on a variety of spatial

and temporal scales. The first stage of the study examined

physiological responses at a stomatal level measuring instantaneous and seasonal responses to changes in soil and

atmospheric moisture. The second stage of this study

measured physiological response at a needle level integrating stomatal responses at annual and interannual time

scales. This study measures whole-tree response to climatic

variability using tree-rings and represents an integrated

response of both stomata and different-aged needle cohorts

over a period of five years. These layers of complexity in

water relations of pinyon pine have been examined in order

to answer such questions as: Which climatic variables are

Effect of Spatial and Temporal Variability on

Water Relations and Growth in Pinyon Pine:

III. Whole Tree Response

Teresa L. Newberry

most important in affecting stomatal behavior and water

use efficiency and at what scale are they important: diurnal,

seasonal or annual? What is the diversity in physiological

response between individuals? Is there a physiological difference between ecotonal, xeric sites and mesic sites?

Since maximizing carbon gain and minimizing water loss

can be crucial in arid ecosystems where water is limiting,

the ability to adjust water use efficiency in response to

changing availability of water is an ecologically important

characteristic. In this study, water use efficiency is studied

using 13C measurements of tree-rings. The development

of isotopic models relating 13C to water use efficiency

(Farquhar and others 1982) has shown great promise in

providing physiologists with a powerful tool to investigate

physiological response at scales of growing seasons (Farquhar

and others 1988, Leavitt & Long, 1989, Leavitt 1994). Net

instantaneous water use efficiency (WUE), the ratio of

carbon assimilation to evapotranspiration, has been found

to correspond to high 13C—high 13C values corresponding to

high water use efficiency and vice versa (Farquhar and

others 1988). For long-lived species such as trees, combining this technique with tree-ring analysis provides a longterm record of physiological response to changing climatic

regimes.

Specifically, this part of the study will address the following questions:

1. Does water use efficiency change from year to year in

response to climatic patterns?

2. Does the whole tree response differ from the response

of different-aged needle cohorts?

3. Is winter or summer precipitation more important in

determining water use efficiency and growth in pinyon

pine?

4. Is the physiological response different at an ecotonal/

xeric site than at a more mesic site?

5. Is there a relationship between the plasticity of water

use efficiency and growth?

Methods _______________________

Site Description

The field sites are located in the Los Pinos Mountains on

the Sevilleta LTER in central New Mexico. There are two

field sites within about 3 to 4 kms of each other—one at

1700 m and the other at 2000 m elevation. Although the

two sites are in close proximity with only a small elevation

change, the site characteristics differ quite markedly. Goat
100 USDA Forest Service Proceedings RMRS-P-7. 1999

Draw, is an open woodland located at the pinyon-juniper

woodland/ juniper-grassland ecotone. The higher site, Cerro

Montoso, is a densely vegetated pinyon-juniper stand. The

lowest elevation site is representative of pinyon-juniper to

juniper-grassland ecotone. The density of pinyon pine is

much lower relative to the density of juniper. The higher

elevation site is representative of pinyon in the middle of its

range. Both sites are located on slopes of 10 to 20 degrees

with N-NW facing aspects. The soils of both sites are derived

from a granitic substrate and are coarse-grained in texture.

The physiological characteristics of both sites have been

studied extensively in previous studies. The Goat Draw site

is also an LTER site where population, growth and physiological characteristics have been studied.

Sample Collection

Cores were collected from four individual trees from each

site. The trees selected were those from which extensive

physiological measurements had been made in the previous

portion of this project. Two cores were collected from each

tree: one in the north cardinal direction and one in the south

cardinal direction. The cores were surfaced and dendrochronologically dated. The rings from individual years 1990 to

1986-1984 were separated under a binocular microscope

using a razor blade combining the material from the north

and south cores and analyzed for 13C. The samples chosen

for wood analysis were the same years on which leaf 13C

analysis had been conducted. Leaf 13C analysis was dependent on the retention time of the needles.

Isotope Analysis

Isotope analysis was conducted on the cellulose isolated in

a procedure after Green (1963) as modified by Leavitt and

Danzer (1994) for small samples. The samples were combusted to carbon dioxide in an oxygenated atmosphere at

800C in a recirculating microcombustion line. The carbon

dioxide was analyzed mass-spectrometrically and 13C was

computed relative to the PDB standard (Craig 1957). All

analysis was conducted at University of Arizona Laboratory

of Tree-ring Research.

Climate Data

Monthly PDSI and precipitation values were obtained

from Socorro Weather Station. Annual Palmer Drought

Severity Index (PDSI) and precipitation was represented

by taking the mean value from October of the previous year

until October of the current year. Winter PDSI and precipitation was presumed to represented by the mean values

from the months of November of the previous year until

March of the current year. Summer PDSI and precipitation

was estimated by taking the mean of the monthly values

from the period July to October.

Results ________________________

Variation in 13C Over Time

The results of 13C analysis of wood shows the year to year

variation in water use efficiency in pinyon pine (fig. 1). These

results show that although patterns for individuals

through time are very similar, the absolute values vary

between individuals. This would suggest that while individual trees have different water use efficiencies, their

response to year to year climate variability is similar. These

results are very similar to those of Leavitt (1994) which

showed that the absolute values varied among individuals of

same species at a site while the patterns through time were

similar in both coniferous and deciduous trees. The most

marked feature of these patterns is the dramatic increase in

13C for all trees at both sites in 1989. For the most part the

weather patterns during the years measured were close to

normal years of precipitation, 1989, however, was an extremely dry year. There does not appear to be much difference in the range and patterns of 13C between sites. The

mean value and standard deviation of 13C values at Goat

Draw is –20.66 ± .66 and at Cerro Montoso it is –20.71 ± .75.

The carbon isotope values of annual rings in pinyon pine

represent the integrated measure of water use efficiency of

Figure 1—Results of isotope analysis on wood at

Goat Draw and Cerro Montoso.
USDA Forest Service Proceedings RMRS-P-7. 1999 101

all leaf cohorts over whole tree over the course of a year with

some lag factors due to carbon translocation and storage.

Typically, needle retention in pinyon pines at these sites is

between five to seven years. A comparison of same year

needle and annual 13C values show that while the wood

values tend to be isotopically lighter the patterns of changes

from year to year are very similar (fig. 2, 3). The fact that the

patterns of 13C are similar to 13C in needles suggests that

the overall water use efficiency of the tree is most likely

under physiological control (i.e., the instantaneous response

of stomata to changes in water status) rather than anatomical control (i.e., wax layers, number of stomata, sunkenness

of stomata, photosynthetic efficiency, etc.). It also suggests

that decreased water use efficiency due to aging of needles

is not an important factor determining the overall water use

efficiency of the whole tree.

Figure 2—A comparison of leaf and wood isotope values for Goat Draw.

Figure 3—A comparison of leaf and wood isotope values for Cerro Montoso.
102 USDA Forest Service Proceedings RMRS-P-7. 1999

Relationship of Climate with 13C

This next section explores the relationship between 13C

and climate. Since the absolute values of 13C varied from

tree to tree separate regressions were done for each individual tree and 13C for the site was obtained by taking the

average of the correlation coefficients for individual trees.

Based on the typical rainfall cycles in New Mexico, three

periods were considered with respect to 13C values: annual

(October to October), winter (November to March) and

summer (July to October).

Goat Draw—Results of regression analyses show that

October to October PDSI has a strong influence on the

isotopic composition of the wood in pinyon pine (r2 = .57)

while October to October precipitation has only a moderate

influence (r2 = .34) (see table 1 and fig. 4). There is a large

spread of responsiveness to PDSI from individual to

Table 1—Results of regression analyses of climate vs. C13 values for Goat Draw—r2

values.

October to October July to October November to March

Tree # PDSI PPN PDSI PPN PDSI PPN

Tree#2 .87 .43 .76 .05 .92 .88

Tree#14 .39 .23 .31 .03 .38 .45

Tree#16 .93 .61 .83 .04 .92 .51

Tree#18 .09 .08 .04 .01 .07 .00

Site average .57 .34 .49 .03 .57 .46

individual. In the summer the difference in response to PDSI

vs. precipitation is most pronounced (r2 = .49 v. r2 = .03). This

reflects the importance of evaporative demand as well as

water availability. These results are consistent with studies

on stomatal response to vapor pressure deficit which showed

that stomatal conductance is sensitive to changes in vapor

pressure deficit and relative humidity as well as leaf water

potential (Newberry, in prep.). In the winter PDSI and

precipitation have roughly equal influence on carbon isotope

values (r2 = .57 v. r2 = .46) and, therefore, one may conclude

that evaporative demand does not play an important role in

winter due to cool temperatures. Both winter PDSI and

summer PDSI are equally important in determining 13C

values in pinyon pine (r2 = .57 v. r2 = .49) while winter

precipitation is much more important than summer precipitation (r2 = .46 v. r2 = .03). One interpretation of this is

that winter precipitation plays a greater role than summer

Figure 4—October to October PDSI and carbon isotope values at Goat Draw.
USDA Forest Service Proceedings RMRS-P-7. 1999 103

rainfall in determining water use efficiency in pinyon pine

for the subsequent growing season due to recharge of soil

water by snowfall while overall weather conditions (reflected in PDSI) of both seasons play the strongest role.

Cerro Montoso—Overall the response of PDSI and

precipitation was lower at Cerro Montoso than at Goat Draw

(table 2 and fig. 5). For example at Goat Draw r2 was .57 for

October to October PDSI while at Cerro Montoso it was .40.

This is consistent with previous results which showed that

the stomata of the trees at Goat Draw were more sensitive

to changes in environmental conditions than at Cerro Montoso

(Newberry, in prep.). Like Goat Draw, summer PDSI had a

greater effect on carbon isotope values and thus water use

efficiency than summer precipitation (r2 = .36 v. r2 = .12).

Like Goat Draw, 13C values were equally dependent on

Figure 5—October to October PDSI and carbon isotope values at Cerro Montoso.

Table 2—Results of regression analyses of climate vs. C13 values for Cerro Montoso—

r

2 values.

October to October July to October November to March

Tree # PDSI PPN PDSI PPN PDSI PPN

Tree#3 .30 .38 .33 0 .24 .98

Tree#6 .78 .54 .62 .07 .78 .14

Tree#11 .19 .18 .13 .05 .16 .06

Tree#15 .34 .41 .36 .37 .32 .19

Site average .40 .38 .36 .12 .38 .34

winter PDSI and winter precipitation. Also winter and

summer PDSI were equally important in determining the

annual water use efficiency of pinyon pine.

Growth and Climate

At Goat Draw growth is most strongly dependent on

October to October PDSI (r2 = .70) (table 3). This relationship

is curvilinear. October to October precipitation also plays

an important role in determining the annual growth rate

in pinyon pine (r2 = .55). Summer and winter PDSI and

precipitation appear to have equal importance in determining growth rates. There is some variability in growth

response of individuals, but not as great as the range of

water use efficiency response (r2 = .57 to .85 for Oct to Oct.
104 USDA Forest Service Proceedings RMRS-P-7. 1999

PDSI & growth). Some trees had a curvilinear growth

response while in others the relationship was linear.

At Cerro Montoso growth is most strongly dependent on

July to October PDSI (r2 = .62) although this is only just

slightly greater than the correlations with October to October PDSI (r2 = .54) and November to March PDSI (r2 = .48).

These relationships are curvilinear. October to October

precipitation has an r2 of .49. Similar to Goat Draw some

trees have a linear growth response while others have a

curvilinear growth response. There is also a range of growth

responses ranging from r2 = .49 to 87 for July to October

PDSI & growth.

Growth and Water Use Efficiency

A question of great ecological significance is do the trees

with the ability to increase their water use efficiency during

periods of drought have higher growth rates. Unfortunately,

it is impossible to answer this question directly because in

years of drought, growth rate is reduced. The relationship

between growth and physiological response to climate can be

examined indirectly however using several different approaches. The following questions could be asked: Does the

ability of individual trees to respond to drought by maximizing water use efficiency increase the total growth over the

time period studied? And, does a strong correlation of 13C

with climate mean a higher year to year variability in

growth? Regarding the correlation coefficients of 13C and

annual PDSI, total growth over the period studied, and the

standard deviation of annual growth over the period studied, there does not appear to be any relationship between

any of these variables. This does not mean that water use

efficiency does not maximize growth in pinyon pine, but

instead that other factors influencing growth such as photosynthetic rates, duration of photosynthesis and total leaf

area are very important in determining growth rates in

pinyon pine.

Conclusions____________________

Water use efficiency in pinyon is variable from year to year

in response to PDSI. Precipitation plays a secondary role

relative to PDSI in determining water use efficiency especially in the summer months when evaporative demand is

high. These results are consistent with previous studies

which have shown the stomata to be sensitive to both soil

moisture and vapor pressure deficits (Newberry, in prep.).

Both winter and summer PDSI are equally important in

determining water use efficiencies in pinyon pine. Winter

PDSI is most likely very important because of the winter

precipitation recharges soil water by snowfall prior to the

next year’s growing season.

At Goat Draw growth is most highly dependent on October

to October PDSI while at Cerro Montoso, Cerro Montoso is

most highly dependent on July to October PDSI although

this is just slightly greater than the dependence on October

to October PDSI. A comparison of the summer and winter

PDSI and precipitation shows that both seasons are important in determining growth rates for both Goat Draw and

Cerro Montoso.

The patterns of wood isotope values through time are

very similar to the leaf patterns although the wood tends to

be isotopically lighter than the leaf material. This result

suggests that the overall water use efficiency of the whole

tree is a function of physiological factors such as the instantaneous response of stomata to changes in water status

rather than anatomical factors such as wax layers, number

of stomata, sunkenness of stomata, photosynthetic efficiency, etc. It also suggests that decreased water use efficiency due to aging of needles is not an important factor in

determining the overall water use efficiency of the whole

tree and the 13C composition of the tree.

Although patterns of 13C through time are very similar

among individuals at both sites, there is a high range in

absolute 13C values and thus one would conclude that

there are differences in water use efficiencies between

individuals. The results of the regression analyses of 13C

with climatic factors show that there is also a range in the

responsiveness of water use efficiency to year to year changes

in weather conditions—although as mentioned above the

trees almost always move directionally in the same way. My

attempt to show that trees that were able to increase water

use efficiency would have higher growth rates was unsuccessful. This is most likely because other factors contributing to growth such as total leaf area, time spent photosynthesizing and photosynthetic rates also play an important role

in determining growth rates. In fact, results of a previous

study show that pinyon is a drought avoider and will completely shut its stomata in response to drought as opposed to

keeping stomata open while increasing water use efficiency

(Newberry, in prep.).

Although, the mean and standard deviation of 13C values

the two sites were identical, there were differences in the

correlations of 13C to year to year changes in climate. Goat

Draw trees more strongly tracked changes in annual precipitation and PDSI than Cerro Montoso trees and their

growth was more dependent on climate. This result is

consistent with previous results which showed that stomata of the trees are much more sensitive to changes in

Table 3—Results of regression analyses of climate vs. growth for goat draw and Cerro

Montoso-r2 values.

October to October July to October November to March

Tree # PDSI PPN PDSI PPN PDSI PPN

Goat Draw .70* .55 .54 .31 .62* .30

Cerro Montoso .54* .49 .62* .22 .48* .33

*curvilinear relationship
USDA Forest Service Proceedings RMRS-P-7. 1999 105

environmental conditions than at Cerro Montoso

(Newberry, in prep.) Since the standard deviation at both

sites is nearly identical while the correlation with climate is

different, one may conclude that Cerro Montoso is responding other sources of variation. These sources of variations

could be biotic in origin such as shading, herbivory and

competition for water since the higher elevation site is more

densely vegetated.

References _____________________

Betancourt, J.L., Pierson, E.A., Rylander K.A., Fairchild-Parks,

J.A. and J.S. Dean (1993) Influence of history and climate on

New Mexico Pinyon-Juniper Woodlands. Proceedings—Managing Pinyon-Juniper Ecosystems for Sustainability and Social

Needs.

Bazzaz (1993) Population and Community Perspectives. In Scaling

Physiological Process: Leaf to Globe. (Ehleringer, J.R. and

Field, C.B. eds.) pp. 223-251. Academic Press, San Diego.

Craig, H. (1957) Isotopic standards for carbon and oxygen and

correction factors for mass-spectrometric analysis of CO2.

Geochim. Cosmochim. Acta 12:133-149.

Crawford, S.C. and J.R. Gosz (1982) Desert ecosystems: their

resources in space and time. Environmental Conservation.

9:81-195.

Ehleringer, J.R. and C.B. Fields (1993) In Scaling Physiological

Process: Leaf to Globe. Academic Press, San Diego.

Farquhar, G.D., Hubick, K.T., Condon, A.G., and R.A. Richards.

(1988) Carbon isotope fractionation and plant water-use efficiency. In Stable isotopes in ecological research. (Rundel, P.W.,

Ehleringer, J.R. and K.A. Nagy, eds.) pp. 21-40. Springer-Verlag,

New York.

Farquhar, G.D., O’Leary, M.H., and J.A. Berry (1982) On the

relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves. Austr. J. Plant

Physiol.. 9:121-137.

Gosz, J.R. (1993) Ecotone Hierarchies. Ecol. Appl. 3(3):369-376.

Gosz, J.R. and P.J.H. Sharpe (1989) Broad-scale concepts for interactions of climate, topography and biota at biome transitions.

Landscape Ecology 3:229-243.

Green, J.W. (1963) Wood cellulose. In Methods of Carbohydrate

Chemistry. (Whistler, R.L., ed.) pp. 9-21. Academic Press,

New York.

Leavitt, S.W. (1993) Seasonal 13C/12C changes in tree rings: Species

and site coherence, and a possible drought influence. Can. J. For.

Res. 23:210-218.

Leavitt, S.W. and Danzer, S. 1993. Method for Batch Processing

Small Wood Samples to Holocellulose for Stable Carbon Isotope

Analysis. 65:87-89.

Leavitt, S.W. and Long A.(1989) Drought indicated in carbon-12/

carbon-12 ratios in southwestern tree rings. Water Res. Bull.

25:341-347.

Neilson R.P., King, G.A. and G. Koerper (1992) Toward a rule-based

biome model. Landscape Ecology 7:27-43.

Newberry, T.L. (1995) The Effect of Spatial & Temporal Variability

on Water Relations in Pinyon Pine: I. Stomatal Response

Newberry, T.L. (1995) The Effect of Spatial & Temporal Variability on Water Relations in Pinyon Pine: II. Whole Needle

Response

Noy-Meir, I. (1973) Desert Ecosystems: environment and producers. Annual Review of Ecology and Systematics 4:25-51.

Sala, O.E., Lauenroth, W.K., Parton, W.J. and M.J. Trlica (1981)

Water status of soil and vegetation in shortgrass steppe.

Oecologia 48: 327-331.
106 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Alan R. Johnson is Consulting Faculty, Department of Biological Sciences, St. Cloud State University, St. Cloud, MN. Bruce T. Milne is Professor

of Biology, and Peter Hraber is Doctoral Student, Department of Biology,

University of New Mexico, Albuquerque, NM.

Abstract—We conducted an analysis of land cover change in

selected piñon-juniper woodlands of New Mexico and Arizona,

using aerial photographs from the 1930’s through the 1980’s. Both

increases and decreases in woodland cover were observed. Fractal

dimensions of woodland patches and cover-type changes were analyzed following the method of Krummel and others (1987). The

analysis failed to identify the scale of anthropogenic disturbance,

although land cover change is clearly due in part to human activity.

The analytical method may be an insensitive indicator in these

woodland systems because the fractal properties of both natural

vegetative cover and human-induced changes are subject to topographic constraints.

Piñon-juniper woodlands are a common vegetation cover

type in semi-arid regions of North America. In the southwestern United States, the association is typically composed

of either Pinus edulis (Engelm.) Sarg. or Pinus monophylla

Torr. & Frem. in conjunction with various species of

Juniperus, most commonly J. monosperma (Englem.) Sarg.,

J. osteosperma (Torr.) Little, or J. scopulorum Sarg. In

Mexico, a variety of other piñon pine and juniper species can

be important woodland components.

Various processes, both natural and anthropogenic, lead

to changes in the spatial distribution of piñon-juniper woodlands over time. Important among these are (1) establishment of seedlings during periods of favorable climatic conditions, (2) mortality of seedlings or adult trees during drought

conditions, (3) invasion of junipers into grassland in response to overgrazing and/or fire suppression, (4) removal of

trees by humans as a result of fuelwood harvesting, chaining

for rangeland management, or clearing of land for urban or

agricultural uses.

One focus of landscape ecology is the development of

quantitative techniques for the analysis spatial patterns

and the changes in such patterns over time. Krummel and

others (1987) used a perimeter-area scaling method to

determine the fractal dimension of deciduous forest patches

Analysis of Change in Piñon-Juniper

Woodlands Based on Aerial Photography,

1930’s-1980’s

Alan R. Johnson

Bruce T. Milne

Peter Hraber

in the lower Mississippi River floodplain of the United

States. Their results showed a low fractal dimension (1.2) for

small patches (<55.7 ha) with an abrupt transition to a

higher fractal dimension (1.5) for larger patches (>100.4 ha).

This was interpreted as indicating that anthropogenic processes play a dominant role in shaping small forest fragments, while natural processes subject to topographic constraints determine the shape of larger forested areas. On the

basis of this result, Krummel and others (1987) suggested

that the fractal dimension of vegetated patches could be

monitored routinely as an indicator of landscape condition,

with abrupt shifts to lower values indicating anthropogenic

disturbance.

We have applied the method of Krummel and others

(1987) to quantify patterns and changes in selected piñonjuniper woodlands of Arizona and New Mexico, USA. Using

aerial photography, we calculated the fractal dimension of

woodland patches at each study site at various times within

a period extending from 1935 through 1988. Additionally, by

comparing consecutive photographs, patches representing

changes in land cover (i.e., loss or gain of woodland) could be

delineated. We extended the methodology of Krummel and

others by performing an analysis not only of the woodland

patches themselves, but also patches representing changes

in woodland cover over time. On the basis of our results, we

find only equivocal support for the notion that the method

can be used to routinely monitor anthropogenic disturbance

in these landscapes. Our analysis points out several methodological issues which require more intensive study before

the applicability of this technique to diverse landscape types

can be properly assessed.

Materials and Methods ___________

Four U.S. Geological Survey 1:24000 scale quadrangles

were selected as study areas for this research. This is a

subset of a set of approximately 30 study areas under

investigation in a study of woodland/grassland ecotones

(Milne and others 1996). The four quadrangles selected for

the current analysis were chosen to represent a variety of

climatic conditions, being arrayed along a longitudinal gradient of primarily winter precipitation in the west to a more

bimodal pattern of winter and summer precipitation in the

east. Panchromatic aerial photographs covering each quadrangle were obtained through the Earth Data Analysis

Center at the University of New Mexico. Information on the

locations of the quadrangles and the dates of the photography used is summarized in table 1.
USDA Forest Service Proceedings RMRS-P-7. 1999 107

Photographs were digitized using an 8-bit Hewlett Packard

Scanjet IIc flatbed scanner at a resolution such that each

individual pixel represented 2.5 x 2.5 m on the ground.

Images were transferred from the original TIFF format to

the VIFF format of the Khoros system (Konstantinos and

Rasure 1994, Rasure and Williams 1991) and then to ASCII

format for input to Grass 4.1 in which scanned images

were mosaicked together and geographically rectified to

the UTM coordinate system.

From imagery covering each 7.5 minute USGS quadrangle, a 1200 x 1200 pixel (3.0 x 3.0 km) subimage was

extracted for analysis. The approximate position of the

subimage within the quadrangle was determined randomly,

by partitioning the quadrangle into four quadrants, and

randomly determining the quadrant from which to extract

the subimage. Exact location of the subimage was chosen by

the analyst, with an effort made to minimize the inclusion of

heavily shadowed areas within the subimage, since dark

shadows can lead to errors in the subsequent classification.

The gray-scale subimages were classified into two classes

corresponding to wooded areas and grasslands by interactively setting a gray-scale threshold and comparing the

classified subimage to the original gray-scale subimage.

This interactive procedure appeared to produce results which

were as good or better than automatic classification schemes,

such as k-means cluster analysis (Tou and Gonzalez 1974,

p.94). A histogram equalization of the gray-scale was performed on some images to enhance their contrast prior to

classification (Jensen 1996, p.150).

Changes in land cover were detected by overlaying classified subimages from successive dates. However, since successive images cannot be expected to be rectified with exact

pixel-to-pixel accuracy, some allowance must be made to

avoid falsely classifying slight mis-rectifications as actual

changes in cover. This was done by defining a 4-pixel (10 m)

wide buffer zone at each woodland/grassland interface. The

buffer was created using a morphological edge detection

algorithm, which involved convolution with a kernel defined

to produce a two pixel thick external edge surrounding each

woodland or grassland patch (Giardina and Dougherty 1988).

Thus defined, the external edges of woodland and grassland

patches adjoin, yielding a buffer four pixels in thickness.

Table 1—Study areas and dates of aerial photography. Quadrangle names refer to

U.S. Geological Survey 1:24000 maps.

Quadrangle name Latitude Longitude Photograph dates

El Dado Mesa, NM 35° 22' 30"N 107° 22' 30"W 1935

1952

1988

Pine Canyon, NM 35° 15' 00"N 108° 07' 30"W 1935

1952

1987

Sandia Park, NM 35° 07' 30"N 106° 15' 00"W 1935

1951

1976

1987

Toothpick Ridge, AZ 36° 37' 30"N 112° 22' 30"W 1953

1981

Change in land cover was inferred only when a definitely

classified pixel (i.e., outside the buffer) of one type (woodland

or grassland) is definitely classified as the opposite type at

a succeeding date. Overlays of the classified subimages

(with buffer zone) produced maps of patches representing

land cover change, both woodland converted to grassland

and vice versa. Edge extraction and overlaying of subimages was done using the Khoros system (Konstantinos

and Rasure 1994, Rasure and Williams 1991).

Fractal dimensions were calculated using a C program

written by one of the authors (Johnson). Following the

methodology of Krummel and others (1987), patches were

ordered by size and regressions of log patch perimeter on log

patch area were performed in a sliding window containing

a constant number of patches, N. Separate regressions

were performed for each possible window, ranging from the

N smallest patches to the N largest patches. Krummel and

others (1987) employed a window size of N = 200 patches.

We performed regressions with window sizes of N = 50,

100, and 200 patches for each study area. The fractal

dimension, D, was computed as two times the slope of the

regression (Hastings and Sugihara 1993, pp.48-50, Lovejoy

1982).

Results ________________________

The amount of land surface showing a definite change in

cover type is summarized in table 2 for each subimage at

each time interval. The values in table 2 do not include any

changes which occurred in the buffer zone of the patches

defined in subimages, therefore, short distance (<10 m)

shifts in patch boundaries will be undetected. Thus, the

values in table 2 probably represent lower bounds on the

area of land cover which changed over each time interval.

Each subimage depicts an area of 900 ha. The areas exhibiting definite change in cover type over any given time

interval comprise only a few percent of the total area in the

subimage. The net effect of the changes can be either an

increase or a decrease in woodland, depending upon the

location and the time interval.

Patches of land surface which underwent a definite change

in land cover showed a strongly skewed distribution of sizes,
108 USDA Forest Service Proceedings RMRS-P-7. 1999

Table 2—Land surface areas exhibiting definite change in subimages from each study

site during each time interval. Positive values of net change represent in

increase in woodland cover, negative values represent a decrease.

Time Grassland Woodland Net change

Study site interval to woodland to grassland in woodland

El Dado Mesa 1935 - 52 15.0 ha 5.0 ha +10.0 ha

1952 - 87 15.2 ha 8.2 ha +7.0 ha

Pine Canyon 1935 - 52 1.5 ha 3.6 ha 2.1 ha

1952 - 86 7.3 ha 3.2 ha +4.1 ha

Sandia Park 1935 - 51 16.1 ha 29.4 ha 13.3 ha

1951 - 76 23.2 ha 5.0 ha +18.2 ha

1976 - 87 2.5 ha 20.3 ha 17.8 ha

Toothpick Ridge 1953 - 80 2.6 ha 16.4 ha +13.8 ha

with many more small patches than large ones. For instance,

in the Sandia Park subimage during the 1935-51 interval,

the size of the patches representing land cover change

ranged from 1 pixel (6.25 m2) up to 2631 pixels (16,400 m2),

but with the median patch size near the lower end at 4 pixels

(25 m2). Similar distributions were observed at other locations and at other intervals.

Sliding-window regressions were performed to evaluate

the scale-dependence of the fractal dimension of woodland

patches in all subimages. Only the 1935 Sandia Park

subimage displayed a clear scale dependence (fig. 1a). The

pattern was qualitatively similar to that observed by

Krummel and others in their study: a low fractal dimension

for small patches, with an abrupt shift to a higher dimension

for large patches. However, most subimages displayed no

clear shift in fractal dimension. The 1951 Sandia Park

subimage is typical: the variation in estimates of D for small

patches is accompanied by a substantial drop in the R2 of the

regression, and thus cannot be interpreted as clear evidence

for a scale-dependent shift in fractal geometry (fig. 1b).

Typical results of performing a sliding-window regression

to compute the fractal dimension of the patches representing definite changes in land cover are presented in figure 2.

As can be seen, the fractal dimension is relatively constant

at a value of approximately 1.5, independent of mean patch

size. This is true for both patches representing woodland

converting to grassland, and vice versa. The only suggestion

of a shift in the value of D is an increase for very small patch

sizes (<75 pixels, i.e., <0.045 ha). However, the increasing

values of D are accompanied by a decreasing R2 for the

regression model, indicating a poorer fit. The same pattern

illustrated in figure 2 (namely, a constant D 1.5 except for a

possible increase at small patch sizes) was evident at all

study sites at all time intervals.

Figure 1—Upper curve: Fractal dimension as a function of mean patch size, computed using a sliding window of 100

patches. Lower curve: R2 for each regression. Results are for the Sandia Park subimage. (a) woodland patches in 1935.

(b) woodland patches in 1951.

a b
USDA Forest Service Proceedings RMRS-P-7. 1999 109

Discussion _____________________

The changes in cover over time presented in table 2 are

consistent with a conceptual model of a slowly shifting

mosaic of vegetation in the landscape (Pickett and White

1985, Remmert 1991, Watt 1947, Wu and Loucks 1995). On

the time scale of decades, patches of former grassland are

converted to woodland as conditions appropriate for juniper

establishment are encountered, and conversely, patches of

former woodland are lost as trees die due to natural causes

or are removed by human activities. On a regional scale,

piñon-juniper woodlands may be in a dynamic steady-state

(sensu Bormann and Likens 1979) in which the proportion

of the landscape covered by woodland is constant over time,

except for stochastic fluctuations. Alternatively, there may

be an overall increasing or decreasing trend in the amount

of woodland cover, as the landscape adjusts to climatic

trends and changes in human land use patterns. The data

set used in this study is too small to distinguish between

these alternatives. However, the methods developed here

could be employed to address the issue. Resolution of this

question would settle a long-standing debate.

When the fractal dimension of woodland patches is examined, the usual pattern observed was a value in the range of

1.5-1.6, with larger fluctuations (and low R2) at small patch

sizes. Only in the case of the 1935 Sandia Park subimage

was there a pattern consistent with a systematic shift in

fractal dimension as a function of mean patch size. Visual

inspection of the original gray-scale images strongly suggests that anthropogenic disturbance occurs in other

subimages, but such disturbance is not detectable on the

basis of a routine application of the method of Krummel and

others (1987).

Figure 2—Upper curve: Fractal dimension as a function of mean patch size, computed using a sliding window of 100

patches. Lower curve: R2

 for each regression. Results are for the Sandia Park subimage during the interval from 1935

to 1951. (a) patches representing definite grassland converted to definite woodland. (b) patches representing definite

woodland converted to definite grassland.

Extension of the method to analyze patches representing

changes in woodlands between successive photographs did

not improve our ability to detect anthropogenic disturbance.

In all such analyses, the fractal dimension appeared relatively constant with a value near 1.5. The only observed

fluctuations occurred at very small patch sizes. However,

these fluctuations were always accompanied by substantial

reductions in the R2 of the regression, indicating a lack of

conformity to the power-law scaling, thereby making any

interpretation difficult.

One bias that might affect our estimation of fractal dimensions, particularly at small patch sizes, is an effect discussed

by Milne (1990). When fractal dimensions are calculated

from a perimeter to area ratio, the maximum value for any

possible arrangement of N pixels varies in a sawtooth

pattern as a function of N, and is often below the theoretical

maximum of 2.0. This effect is most pronounced when N is

small. In a test of the impact of this bias on our results, we

calculated a normalized fractal dimension as follows:

Dnorm = 2(D/Dmax)

where Dnorm is the normalized fractal dimension, D is the

fractal dimension from the usual perimeter-area relationship, and Dmax is the maximum fractal dimension for any

arrangement with the same number of pixels as the given

cluster. Note that the normalized fractal dimension will

always have maximum value of 2.

As expected, the greatest effect of this adjustment was at

small patch sizes. However, over the range of patch sizes

used in our analyses, the effect was not large, and did not

qualitatively change the nature of the graphs of fractal

dimension vs. mean patch size. Specifically, fluctuations in

a b
110 USDA Forest Service Proceedings RMRS-P-7. 1999

the graph at small patch sizes which were evident when the

usual fractal dimension was plotted were still evident when

the normalized fractal dimension was used (data not shown).

If anything, the amplitude of the fluctuations was somewhat

greater when the normalized fractal dimension was employed. Since the normalized fractal dimension did not

change the interpretation of our results, only data based on

the usual definition of fractal dimension were presented

here.

The fact that the fractal dimensions of both the woodland

patches and the patches representing change hover near a

value of 1.5 is suggestive. Topographic surfaces, particularly

mountainous areas such as our study sites, typically have a

fractal dimension Dsurface 2.5 (Mandelbrot 1983). If piñonjuniper woodlands were restricted to elevations above some

fixed threshold, one would expect the resulting pattern to

have a fractal dimension Dwoodland = Dsurface – 1 = 1.5. Of

course, in the real world, slope and aspect effects modify the

lower elevational ecotone of piñon-juniper woodlands, but

these effects may not change the fractal dimension much.

Thus, the fact that most patches have fractal dimensions

near 1.5 is consistent with the hypothesis that the distribution of woodlands, and changes in woodlands, are strongly

constrained by topography.

It may be reasonable to assume that even the patterns of

anthropogenic disturbance in these ecosystems may be largely

determined by topographic constraints. The Mississippi

floodplain forests analyzed by Krummel and others (1987)

were probably essentially continuous prior to human disturbance. Thus, any edges arising from human activity are

likely to be simple in shape, and to leave fragments with low

fractal dimension. Piñon-juniper woodlands in mountainous terrain, on the other hand, are fragmented in their

natural condition. Human activity may result in the removal

of patches, or parts of patches, of woodland. Yet even in a

highly disturbed piñon-juniper system, most of the edges

would still be topographically influenced. This effect is due

to a combination of (1) the large number of natural edges

controlled by topography, and (2) the tendency of human

removal of trees to follow elevational contours when there is

substantial topographic relief. Because both natural processes and human activities are influenced by topography, a

shift in fractal dimension may not occur.

Although topographic constraints could account for the

difference between our results and those of Krummel and

others (1987), there are several methodological problems

that might also have influenced our results or their interpretation. First, our results could be influenced by errors in the

initial classification of the gray-scale images into woodland

and grassland cover types. Most problematic are probably

shadows, since the true vegetation cover in heavily shadowed areas cannot be ascertained, and dark areas of shadowed grassland may be misclassified as woodland. Shadows

are most pronounced in areas of high topographic relief, and

the degree of shadowing and positions of the shadows may

change from photograph to photograph depending upon the

season and time of day. Thus, shifts in shadows could be misinterpreted as changes in woodland.

The second potential source of error is mis-rectification of

the images between dates. If there is mis-rectification, the

patches in one image will be shifted in position relative to

their location in the other image. A change map computed

from such mis-rectified data will show many falsely identified changes outlining the perimeters of all the patches.

Such an effect is visually apparent if change maps are

computed without first defining a buffer zone. However,

with the 10 m buffer zone, such outlining of all patches is no

longer apparent. Thus, we conclude that the buffer used in

this study is sufficient to eliminate most or all of the false

inferences of change due to mis-rectification.

Finally, our computation of the fractal dimension of

clusters could be affected by the use of the morphological

algorithm used to define the buffer. The morphological

algorithm essentially expands the width of the interface

between woodland and grassland patches. In so doing, the

perimeters of the remaining clusters may tend to smoothed,

and this effect might be most noticeable for small patches. If

so, the fractal dimension of patches after the buffer is defined

should be lower that their original fractal dimension, with

small patches being particularly affected.

The work of Krummel and others (1987) is frequently

cited as an example of human impact on landscape pattern,

but few other studies have applied the same methodology.

Perimeter-area relationships are frequently used to compute fractal dimensions in analyses of landscape pattern,

but the dependence on mean patch size is usually not

examined (for example, O’Neill and others 1988, Turner

1990). Some papers have employed modifications of the

Krummel and others (1987) methodology. For instance,

Turner and others (1991) describe a method they call the

“variance staircase” which is related to a fractal dimension.

Meltzer and Hastings (1992) employed “rolling regressions”

to calculate the size-related fractal properties of grass patches

in a rangeland in Zimbabwe, based on fit to a hyperbolic size

distribution. Vedyushkin (1994) reported scale-dependent

fractal dimensions for remotely-sensed data (normalized

difference vegetation index, NDVI, and thermal infrared

radiation, TIR) for a forest in central Russia, based on a boxcounting procedure. Although these studies can be viewed as

generally supportive of the hypothesis that landscape

patches display size-related shifts in their fractal dimension, they do not constitute independent support for the

specific methodology of Krummel and others (1987). Krummel

and others (1987) suggest that their “technique should be of

particular interest to the analysis of remotely sensed data,

as it provides a simple metric, D, that indicates the scale at

which processes are occurring on the ground.” However, the

published evidence for such utility is still appears to be based

on the analysis of a single map representing one portion of

the Mississippi floodplain.

Our results, based on applying the methodology of

Krummel and others (1987) to piñon-juniper woodlands in

the southwestern United States, raise questions about the

general utility of the method for detection of anthropogenic

disturbance. The possibility must be considered that scaledependent variations in the fractal dimension of patches

may only serve as good indicators of certain types of anthropogenic disturbance, or may only be useful in certain landscapes. Further investigation is needed to determine the

scope over which this methodology can be routinely used to

detect anthropogenic disturbance.
USDA Forest Service Proceedings RMRS-P-7. 1999 111

Acknowledgments ______________

We thank T.F.H. Allen for his insightful comments on a

poster presentation of our results. This research was supported by USDA Forest Service, Rocky Mountain Research

Station, Albuquerque, NM through Cooperative Agreement

No. 28-C4-880 to Drs. Johnson and Milne.

References _____________________

Bormann, F.H.; Likens, G.E. 1979. Catastrophic disturbance and

the steady state in northern hardwood forests. American Scientist 67:660-669.

Giardina, C.R.; Dougherty, E.R. 1988. Morphological Methods in

Image and Signal Processing. Prentice-Hall, Englewood Cliffs, NJ.

Hastings, H.M.; Sugihara, G. 1993. Fractals: A User’s Guide for the

Natural Sciences. Oxford Univ. Press, Oxford, England.

Jensen, J.R. 1996. Introductory Digital Image Processing: A

Remote Sensing Perspective. 2nd ed. Prentice Hall, Upper

Saddle River, NJ.

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Krummel, J.R.; Gardner, R.H.; Sugihara, G.; O’Neill, R.V.;

Coleman, P.R. 1987. Landscape patterns in a disturbed environment. Oikos 48:321-324.

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Science 216:186-187.

Mandelbrot, B.B. 1983. The Fractal Geometry of Nature. W.H.

Freeman, New York. Meltzer, M.I.; Hastings, H.M. 1992. The use

of fractals to assess the ecological impact of increased cattle

population: case study from the Runde Communal Land,

Zimbabwe. Journal of Applied Ecology 29:635-646.

Milne, B.T. 1990. Lessons from applying fractal models to landscape patterns. In: M.G. Turner and R.H. Gardner (eds.) Quantitative Methods in Landscape Ecology, Springer-Verlag, Berlin.

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P. Hraber, P. Detection of critical densities associated with piñonjuniper woodland ecotones. Ecology 77:805-821.

O’Neill, R.V.; Krummel, J.R.; Gardner, R.H.; Sugihara, G.; Jackson,

B.; DeAngelis, D.L.; Milne, B.T.; Turner, M.G.; Zygmunt, B.;

Christensen; S.W., Dale; V.H.; Graham, R.L. 1988. Indices of

landscape pattern. Landscape Ecology 1:153-162.

O’Neill, R.V.; Gardner, R.H.; Milne, B.T.; Turner, M.G.; Jackson, B.

1991. Heterogeneity and spatial hierarchies. In: Ecological Heterogeneity, J. Kolasa and S.T.A. Pickett (eds.) Springer-Verlag,

Berlin. pp.85-96.

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Disturbance and Patch Dynamics. Academic Press. San Diego,

CA. Rasure, J.R.; Williams, C.S. 1991. An integrated data flow

visual language and software development environment. J. Visual

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Remmert, H. (ed.). 1991. The Mosaic-Cycle Concept of Ecosystems. Springer-Verlag. Berlin, Germany.

Tou, J.T.; Gonzalez, R.C. 1974. Pattern Recognition Principles.

Addison-Wesley. Reading, MA.

Turner, M.G. 1990. Spatial and temporal analysis of landscape

patterns. Landscape Ecology 4:21-30.

Turner, S.J.; O’Neill, R.V.; Conley, W.; Conley, M.R.; Humphries,

H.C. 1991. Pattern and scale: statistics for landscape ecology. In:

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Vedyushkin, M.A. 1994. Fractal properties of forest spatial structure. Vegetatio 113:65-70.

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112 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Deborah Ulinski Potter is Physical Scientist, U.S. Department of Agriculture, Forest Service, Watershed and Air Management, 517 Gold Ave., S.W.,

Albuquerque, NM 87102.

Abstract—Previous publications discussed the results of my

dissertation research on relationships between seasonality in precipitation and vegetation patterns at landscape scale. Summer

precipitation at a study site in the Zuni Mountains, NM, was

predicted from lightning strike and relative humidity data using

multiple regression. Summer precipitation patterns were mapped

using a Geographic Information System (GIS). Winter precipitation

and vegetative cover were obtained from the Terrestrial Ecosystem

Survey (TES). Finally, winter and summer precipitation amounts

and their percent of annual precipitation were compared to grass

and tree cover. Results indicated that winter precipitation influenced tree cover. Grass cover dominated by Bouteloua gracilis was

most closely related to summer precipitation. Grass cover dominated by Festuca arizonica was most closely related to winter

precipitation. This manuscript presents a synthesis of the dissertation research. It discusses how land managers can use lightning

strike data and TES information. Ecosystem management applications for predicting precipitation and vegetation patterns at landscape scale are explored. For example, vegetation regeneration may

be more successful if precipitation patterns are known. Understanding relationships between vegetation and precipitation patterns can also be used to assess the behavior of fire and for restoring

disturbed areas. Additional research at landscape scale could improve our understanding of potential changes in vegetation patterns due to climatic warming.

Study Site and Methods __________

In New Mexico, 50-70 percent of the annual precipitation

comes from convective thunderstorms in the months of June

through September. This precipitation has high spatial

variability that may not be detected by conventional precipitation monitoring stations. It can be accurately estimated

using lightning strike data with a spatial resolution of about

2 km, and the method is appropriate for landscape scale

(Gosz and others 1995).

Lightning direction finders detect cloud-to-ground lightning that is in progress. The instruments sense low-frequency

radio pulses associated with lightning discharges. Lightning

Applications for Predicting Precipitation and

Vegetation Patterns at Landscape Scale

Using Lightning Strike Data

Deborah Ulinski Potter

sensors are operated throughout the United States by Global Atmospherics, Inc. as part of a National Lightning

Detection Network. Gosz and others (1995) developed algorithms between lightning and summer precipitation quantity to determine rainfall depth and distribution at the

Sevilleta National Wildlife Refuge, NM. These methods

were later applied to a 140 km2 site (Pole Canyon) in the west

Rio San Jose watershed near Grants, New Mexico (Potter

1996; Potter and Gorman 1996; Potter and others, in press).

This study site was a prototype for ecosystem management

located within the Mt. Taylor Ranger District of the Cibola

National Forest.

First, summer precipitation was predicted from lightning

strike and relative humidity data using multiple regression. Then summer precipitation patterns were mapped

using a geographic information system (GIS). Winter precipitation and vegetative cover were obtained from the

Terrestrial Ecosystem Survey (TES) of the Forest Service

Southwestern Region (USDA Forest Service 1986). Finally,

winter and summer precipitation amounts and their corresponding percent of annual precipitation were compared to

grass and tree cover using modeling capabilities within the

ARCINFO Geographic Information System.

Both precipitation and vegetation data were ranked and

divided into three classes. Map overlay and cross-tabulation

techniques were used to compute percent composition of

vegetation classes within each precipitation class. Relationships between precipitation and vegetation by growth form

(for example, trees and grass) were tested using Cramer’s V

statistic, a measure of association. Results indicated that

winter precipitation influenced tree cover. Grass cover dominated by Bouteloua gracilis, a warm-season species, was

most closely related to summer precipitation. Grass cover

dominated by Festuca arizonica, a cool-season species, was

most closely related to winter precipitation.

These results were consistent with findings by Phillips

and Ehleringer (1995) that winter precipitation reaches

deep soil layers and is subsequently utilized by tree roots

while summer rains have minimal uptake by trees. Other

factors that can affect vegetation patterns were also discussed in the dissertation. The following discussion focuses

on applications of these research results and related studies.

Discussion _____________________

Gosz and others (1995) noted that contour plots of precipitation generated from lightning data could be combined with

satellite data for vegetation, i.e., a greenness index, to

identify areas that will have short-term increases in primary production of terrestrial vegetation. Knowledge of

precipitation patterns could be used to maximize the
USDA Forest Service Proceedings RMRS-P-7. 1999 113

effectiveness of restoration projects such as reseeding or

sludge application. For example, degraded areas that recently received a high intensity of lightning strikes could be

targeted for immediate restoration. Improved timing of the

project could lead to greater success in the germination,

growth and survival of seeded plants. Hogg and Schwarz

(1997) investigated conifer regeneration across a moisture

gradient from semi-arid to moderately moist climates. They

found that regeneration capacity was related to a climatic

moisture index.

Patterns in precipitation and vegetation could also be

used to help determine desired livestock stocking rates and

timing or to evaluate existing livestock management practices. Oesterheld and others (1998) determined relationships at regional scale between stocking rates and the

normalized-difference vegetation index-integrated value

(NDVI-I) obtained from advanced very high resolution radiometer (AVHRR) data. AVHRR data are used to estimate

aboveground net primary productivity. Although the remote-sensing method was applied at regional scale, it could

be adapted to predict stocking rates at regional scale,

landscape scale, and for areas within a landscape. Variations in soil moisture, soil quality and other factors are also

important in selecting or evaluating livestock management

alternatives.

Lightning strikes are the primary cause of natural fire

ignitions. Latham and others (1997) combined lightning

location data and fire risk data (ignition potential based on

fuel maps) to estimate probable fire occurrence. Predictions

were compared to the sole use of lightning data and the

National Fire Danger Rating System to assess wildfire

potential. Results were better than using lightning strikes

alone since some fires are short duration or fail to spread

after ignition. Combining Latham’s techniques with those of

Gosz and others (1995) could improve wildfire predictions by

accounting for the spatial variability in precipitation. Results could enhance the benefits of savings in fire suppression time and cost, and reduced risk to firefighter safety.

Climate effects on the growth of individual trees and

species can be derived at fine spatial scales from statistical

relationships between ring widths and monthly total precipitation and monthly mean temperature. Relationships

between trees and precipitation will vary among species,

and results of this investigation were similar to ring-width

studies of confers. Meko and others (1994) reconstructed

amounts of cool-season precipitation from ring-width indices of conifers in the Sonoran Desert that are droughtsensitive. They also analyzed the relationship between summer precipitation and ring-width components formed before

and after the summer rainy season began. Results showed

no relationship between summer rainfall and total ring

width. Growth was strongly related to winter precipitation.

However, a relationship with summer precipitation was

detected in the late-growth component of separated ring

widths.

Any application of the research for ecosystem management needs to be framed in an ecological context. According

to the Ecological Society of America’s Committee on the

Scientific Basis for Ecosystem Management (Christensen

and others 1996) “ecosystem management is management

driven by explicit goals, executed by policies, protocols, and

practices, and made adaptable by monitoring and research

based on our best understanding of the ecological interactions and processes necessary to sustain ecosystem structure and function.” The following seven components are

essential:

“1. long-term sustainability as fundamental value; 2.

clear, operational goals; 3. sound ecological models and understanding; 4. understanding complexity and interconnectedness; 5. recognition of the dynamic character of ecosystems; 6. attention to context and scale; 7. acknowledgment

of humans as ecosystem components; and 8. commitment to

adaptability and accountability.” Products from the dissertation study contribute to ecological modeling at landscape

scale and our understanding of ecological complexity and

the dynamic character of ecosystems.

TES Applications

The Southwestern Region’s Terrestrial Ecosystem Survey

for classifying and mapping terrestrial ecosystems is a

valuable source of soil, climate and vegetation data. A

secondary benefit of the lightning research was to explore a

new application for TES data. More recently, the practicality

of using TES data as input variables to predict fire behavior

was investigated by Mark Grupe.

In Grupe’s study (1998) the FARSITE model for predicting

fire growth (Finney 1993) was applied to a prescribed fire

planned at Barranco Canyon within the Cibola National

Forest, Mountainair District. Data for tree height and canopy

cover were direct inputs for FARSITE while crown base

height and crown bulk density were interpreted from the

TES. A Geographic Information System was used to handle

data and for spatial modeling. Management applications of

TES data and GIS will likely increase with time due to their

ability to help address complex ecosystem issues.

Applications for Lightning Data

Lightning direction finders are one of several remote

sensing methods to locate lightning and understand thunderstorm activity. A Lightning Detection and Ranging

(LDAR) system has been developed to detect and locate VHF

radiation emitted by lightning strikes (Forbes 1993). In

addition to other types of ground-based systems, there are

space-based precipitation radar systems and lightning detectors in geostationary orbit.

NASA plans to measure tropical rainfall using a spacebased precipitation radar system. It’s designed to provide

high resolution, 3-D images of rainfall distributions and

intensity over land and ocean. This Tropical Rainfall Measuring Mission (TRMM) will also provide information on

cloud cover, type, and temperatures and radiative energy

that is emitted and reflected from the Earth. A Lightning

Imaging Sensor (LIS) associated with the TRMM Observatory will be used to study the global occurrence of lightning and its relationship to precipitation (Christian and

McCook 1997). Resolution is 5-10 km with coverage over a

large portion of the Earth’s surface. These data can help

quantify associations between tropical rainfall and global

circulation of the atmosphere.

A Lightning Mapper Sensor from geostationary orbit will

continuously map lightning discharged during day and
114 USDA Forest Service Proceedings RMRS-P-7. 1999

night at a storm-scale spatial resolution. It will detect and

locate discharges from both cloud-to-ground and intra-cloud

lightning over large portions of the Earth. The data will be

available in real-time for severe storm detection and warning, convective rainfall estimates and storm tracking.

Another potential use is to improve long-term weather

forecasting.

Applications for predicting relationships between climate

and lightning vary by spatial scale. For example, Williams

(1992, 1994) developed a method to analyze global temperatures from lightning flashes and subsequent changes in the

amplitude of Schumann resonances associated with the

earth’s electromagnetic field. Methods developed by Gosz

and others (1995) and refined by Potter and others (in press)

are appropriate at the landscape scale. The National Weather

Service (NEXRAD) radar system detects precipitation intensities within thunderstorms. Using surface observations,

estimates of precipitation volume could be calibrated from

the radar data. Thus, in the future Doppler radar could be

used to quantify precipitation amounts at fine spatial scales.

Conclusions____________________

In the dissertation study, canopy cover for grasses and

trees was a function of seasonal precipitation. Vegetation

measures vary and can be related to several factors. For

example, Walker and Langrige (1997) found that the best

indicator for grass biomass rates in Australian savannas

was an index that incorporated subsoil and topsoil moisture.

Similarly, Iverson and others (1997) used an integrated

moisture index to predict forest productivity and species

composition at dry versus mesic sites. Although average

climate conditions were used in this study, climatic extremes can also be essential factors for vegetation patterns.

Various factors affecting vegetation pattern were presented

as alternate hypotheses in the dissertation.

Knowing how vegetation patterns are related to precipitation patterns at landscape scale can be useful in fire management, ecosystem restoration projects, and ecosystem management. Such information could be used to improve wildfire

predictions and staffing plans. Degraded areas that recently

just received a high intensity of lightning strikes could be

targeted for immediate restoration projects such as reseeding or sludge application. Patterns in precipitation and

vegetation could also help determine livestock stocking

rates and timing, or be used to evaluate existing management practices. Understanding how the distribution of

grasses and trees changes in response to precipitation and

other climate variables might help managers determine

whether desired plant distributions can be achieved and

sustained.

In addition to management applications, there are potential research applications from the study. The modeling

capabilities of ARCINFO could be used to help predict

migration patterns of trees and grasses at landscape scale in

response to various climate change scenarios. Anticipated

improvements in wildland fire assessment by combining

Latham’s techniques with those of Gosz and others (1995)

would require additional investigation or collaboration.

Acknowledgments ______________

The initial research was funded by Cooperative Agreement No. 28-C4-810 between the University of New Mexico

Department of Biology and the USDA Forest Service Rocky

Mountain Research Station. I am grateful for that research

opportunity through the Rio Grande Basin grant administered by Dr. Deborah Finch and in cooperation with the

Sevilleta Long Term Ecological Research site (LTER). Access to UNM facilities and assistance from LTER staff are

appreciated.

References _____________________

Christensen, N.L., A.M. Bartuska, J.H. Brown, S. Carpenter,

C. D’Antonio, R. Franics, J. F. Franklin, J.A. MacMahon, R.F.

Noss, D.J. Parsons, C.H. Peterson, M.G. Turner and R.G.

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Restoration and

Monitoring Issues

USDA Forest Service Proceedings RMRS-P-7. 1999 119

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Samuel R. Loftin is Ecologist, USDA Forest Service, Rocky Mountain

Research Station, Albuquerque, NM.

Abstract—The majority of upland ecosystems (desert scrub, grassland, pinyon-juniper, ponderosa pine and higher elevation conifer

forests) in the Middle Rio Grande Basin were historically dependent on periodic fire to maintain their composition, productivity,

and distribution. The cultural practices of European man have

altered the function, structure, and composition of virtually all

Middle Rio Grande Basin ecosystems. Centuries of widespread

livestock grazing has altered natural fire frequencies and intensities in upland habitat types. Fire suppression has lead to an

increase in woody plant abundance on many upland sites, from

grassland to ponderosa pine forests. The negative consequences

range from increased surface runoff and soil erosion in grasslands,

shrublands and pinyon-juniper woodlands to increased potential

for severe wildfire in ponderosa pine forests. The goal of restoration

in these systems is to reintroduce fire. Unfortunately, due to

varying levels of degradation, it may not be possible, or reasonable,

to simply burn areas and expect them to recover their former

attributes. Successful restoration requires some knowledge of the

extent of degradation and the potential for recovery. I will discuss

the process of identifying problems, determining land status, and

defining realistic objectives. I will present three case studies as

examples of ecosystems in different stages of degradation that

required different restoration procedures for reintroduction of fire.

Ecological restoration is defined as the process of assisting the recovery and management of ecological integrity.

Ecological integrity includes a critical range of variability in

biodiversity, ecological processes and structures, regional

and historical context, and sustainable cultural practices

(The Society for Ecological Restoration). Restoration of Middle

Rio Grande upland ecosystems generally involves reintroduction of fire. Restoration of some systems may begin with

a prescribed fire, however, other systems have changed to

the point that additional treatments are necessary before

fire can be used. An understanding of ecosystem disturbance

dynamics and their potential to create problems, as well as

the health and status of the system in question, can help to

determine appropriate procedures for ecosystem restoration

or to prioritize multiple restoration projects given limitations of time and resources. Monitoring programs must be

implemented to provide the data necessary to make objective evaluations of the consequences of disturbance and

ecosystem status.

Trial by Fire: Restoration of Middle Rio

Grande Upland Ecosystems

Samuel R. Loftin

Problem Identification ___________

It is important to understand the difference between

disturbances and problems. A disturbance can change any

combination of the functional, structural, or compositional

components of an ecosystem. The change may be temporary

or permanent. The change is not necessarily detrimental to

the health of the ecosystem. Certain disturbances, such as

fire or flooding, are critical to the long-term maintenance of

grassland and riparian ecosystems, respectively.

The changes brought about by disturbance may result in

a problem or they may not. From a purely ecological standpoint, this is dependent upon the response (the resistance

and resilience) of the ecosystem in question and the magnitude and intensity of the disturbance. But in large part the

perception of a problem is dependent upon the values and

judgment of the person or persons managing the land.

Although the perception of a problem will always be somewhat subjective, it should be possible to identify ecosystem

indicators that can be objectively quantified and monitored.

Problems could be more objectively defined as one or more

indicator values occurring outside of some range of acceptable variation. Possible ecological indicators might include

components of ecosystem function (surface runoff, soil erosion, fire/flood occurrence and frequency) and ecosystem

composition and structure (invasive native and exotic plants,

threatened and endangered species). Social and economic

indicators could also be developed and incorporated into the

analysis.

Ecosystem Status _______________

Ecosystem status can be conceptualized using a state

and transition model (fig. 1) such as the Rangeland Health

Model proposed by the National Research Council Committee on Rangeland Classification (Busby and others 1995,

CRC 1994). In this model, ecosystems are classified as

healthy, at risk, and unhealthy. A healthy ecosystem can

sustain the stability of soils, watersheds and ecological

processes and the capacity to produce commodities and

satisfy values. An ecosystem at-risk shows signs of degradation and has an increased vulnerability to further

degradation but ecological processes can still be used to

restore the system within a time frame meaningful to humans. An unhealthy ecosystem has been degraded to the

point that improvement cannot occur without external inputs such as seeding, soil amendments, thinning, etc. The

circles with letters represent a range of ecosystem states

within these health classifications. The vertical axis represents biological potential or the capacity to produce commodities and satisfy values (CRC 1994). The vertical dashed

lines represent thresholds between ecosystem states. Using
120 USDA Forest Service Proceedings RMRS-P-7. 1999

a typical grassland degradation scenario, the state represented by circle A would be a healthy, productive grassland

or grassland savanna ecosystem. Disturbances such as

grazing and fire suppression can lead to problems like woody

plant encroachment and a reduction in herbaceous plant

abundance which may indicate that the first threshold

(early warning line) has been crossed and the original

grassland is at risk (circle B). Removal of grazing pressure

and reintroduction of fire could halt the degradation process

and initiate restoration. Continued disturbance could lead

to further reductions in herbaceous ground cover with significant increases in surface runoff and soil erosion which

would indicate that the second threshold (threshold of rangeland health) has been crossed. At this point (circle C) a

positive feedback cycle of increasing degradation has been

initiated and the system is no longer under biological control. Consequently, ecological processes alone cannot be

used to restore the system within a time frame meaningful

to humans. If no action is taken the system will continue to

degrade (?) and/or eventually stabilize as a new vegetation

assemblage at a much reduced biological potential (circle D).

Realistic Objectives _____________

The ability to distinguish between disturbances and the

problems they create, and determine ecosystem status will

provide insight into what types of restoration procedures

will be most effective and where limited resources will best

be used. Burning an unhealthy degraded woodland is not

likely to restore a grassland. Either additional measures

must be taken or resources should be used on at-risk sites

that have a greater potential for recovery. Conversely, fertilizing and reseeding an at-risk site may be unnecessary if

equally beneficial results can be obtained at a much lower

cost by burning.

Role of Monitoring ______________

Monitoring is critical to the success of this process. Data

from indicators are necessary to quantify the effects of

disturbance, objectively identify problems, and determine

ecosystem status. All too often, this research included, few

to no data are available to make these pretreatment evaluations and we must rely on a subjective evaluation of the

site. Once a course of action has been determined, data are

critical to objectively evaluate treatment effects and progress

toward management objectives.

There are two basic types of monitoring programs. The

first, a general or baseline monitoring program, can be used

to identify changes in ecosystem indicators but cannot be

used to determine the cause of these changes. In order to

attempt to determine cause and effect a specialized or

research monitoring design must be used which involves

monitoring on treated sites as well as untreated control

sites.

There are pros and cons to both forms of monitoring.

Although cause and effect cannot be determined with a

baseline monitoring program, it is a much more cost effective

method for monitoring at broad scales. In this age of adaptive management, we should be using an adaptive monitoring approach with baseline monitoring applied at broad

scales to detect changes in ecosystem indicators. If a change

in an indicator is determined to be a problem, or a potential

problem, a specialized monitoring design could be implemented at a finer scale to determine the cause of the problem

and help determine the appropriate management response.

Case Studies ___________________

The following case studies of restoration of former grassland ecosystems in various stages of degradation are used as

examples of the process described above. In each case the

treatments and objectives change depending upon the problems and ecosystem status.

The Albuquerque Open Space (AOS) site is a healthy

bunchgrass grassland located west of Albuquerque near the

Double Eagle Airport. The site is dominated by Indian

ricegrass, Oryzopsis hymenoides (Roem. & Schult.) Ricker,

and needle and thread grass, Stipa comata Trin. & Rupr.

The potential problem with this site is not that it is being

disturbed but that there is a lack of disturbance. The site has

not been grazed or burned for over 20 years and there is a

large standing dead component in the aboveground biomass

pool. The standing dead biomass contains nutrients that are

unavailable for plant growth and reproduction and that

would normally be recycled through the soil by grazing or

fire. Our objectives for this site were to use fire as a nutrient

cycling process to stimulate new growth and reproduction.

The Bernalillo Watershed (BW) site is located south of

Placitas, NM and is dominated by a mixture of blue grama,

Bouteloua gracilis (H.B.K.) Lag. ex Steud., and galleta,

Hilaria jamesii (Torr.) Benth., grasses and broom snakeweed,

Guttierezia sarothrae (Pursh) Britt. & Rusby, an invasive

native shrub. This site was an overgrazed juniper woodland

prior to the 1950s when the juniper was removed with heavy

equipment and the soils were contoured to hold the runoff.

Although there has been no significant livestock grazing on

this site for 50 years, the native grasses have not recovered,

the shrub component is high, and there is evidence of runoff

and soil erosion. This site was classified as at risk because of

its degraded state and we believe that it is still possible to

restore a grassland using ecological processes with limited

Figure 1—Rangeland health model adapted from a report

by the National Research Council Committee on Rangeland Classification (1994) and Busby and others (1995).
USDA Forest Service Proceedings RMRS-P-7. 1999 121

outside input. Our objectives for this site are to use prescribed fire to increase the herbaceous plant abundance and

subsequently stabilize the soils. We plan to use sequential

applications of prescribed fire separated by recovery periods. Our hypothesis is that with each fire the shrub component will decline and the herbaceous vegetation will increase. After three to four restoration fires the herbaceous

vegetation should have recovered enough to stabilize the

soils and fire can then be used once every 10 years or so for

ecosystem maintenance.

The Guaje site is located north of Los Alamos, NM, on the

Santa Fe National Forest, Espanola Ranger District. This

site is a pinyon, Pinus edulis Engelm., - oneseed juniper,

Juniperus monosperma (Engelm.) Sarg., woodland with a

degraded blue grama understory. As with the BW site, the

primary disturbance (in this case livestock grazing) has been

removed for many years but the grassland community has

not recovered on its own. The site was classified as unhealthy because there has been significant runoff and soil

erosion with headcutting and arroyo formation evident

throughout the study site. Significant outside inputs will be

necessary to restore the herbaceous understory and stabilize the soils. We have thinned the trees in an attempt to

directly reduce competition for water between the trees and

herbaceous vegetation. We used the slash as a surface mulch

to indirectly increase water availability to the herbaceous

vegetation by reducing evaporative soil water loss and by

increasing surface roughness, thereby reducing runoff and

increasing infiltration. We plan to reintroduce fire once the

herbaceous plant community has recovered to a point that

there are sufficient fuels to support a surface fire.

Methods _______________________

Vegetation on all study sites was sampled using the

Community Structure Analysis (CSA) technique of Pase

(1981). The AOS and BW sites both have four, 1 hectare

control (unburned) and four, 1 hectare burned plots. Within

each plot are three 60 meter CSA transects. The Guaje site

has no treatment replication. The thinned and control areas

are approximately 20 hectares each and each contains five

100 meter CSA transects.

The AOS site has been burned once in February 1996.

Because of adequate fuel quantity and distribution, this site

burned well and most of the vegetation was consumed. The

BW site was first burned in November 1995 and then again

in January 1998. Because of the patchy distribution of the

fuels and vegetation and less than optimum conditions,

neither fire spread well and both fires left behind substantial patches of unburned vegetation. Fire success might have

been greater if we had burned in the late spring, however,

due to management concerns and the availability of fire

crews, we decided to burn in the fall or winter. The Guaje site

was thinned in April 1995. All pinyon less than 20 cm (8

inches) diameter and all juniper were cut by chain saw and

the slash was redistributed by hand. Some jackpot burning

of large slash accumulations was conducted in the fall of

1996 to reduce the fire hazard. Otherwise no burning has

been conducted on the site.

The effect of prescribed fire or thinning treatments was

tested by comparing post-treatment conditions on the treated

plots to any change on the control plots for comparable time

periods. A repeated measures analysis was utilized with

treated vs. control included as a treatment factor, posttreatment years as repeated measures, and the pre-treatment sampling period as a covariate. In some instances, the

effect of the treatment was not the same for both posttreatment years (i.e., significant interaction between treatment and time). In these instances, significance of the

treatment for individual years was assessed by applying a ttest to the change from pre-treatment conditions for each

treatment for a particular year. Type I error for these sets of

t-tests was maintained by applying a Bonferroni adjustment

to significance levels of individual tests (Miller 1981). All

analyses were conducted using SPSS 4.0 (SPSS Inc. 1990).

Results ________________________

There was a significant decrease in total herbaceous plant

cover on the AOS site immediately after the November 1995

fire and all subsequent sampling periods showed no significant treatment effect (fig. 2A). There was no significant

treatment effect on total herbaceous cover on the BW site

until after the second fire in January 1998 (fig. 2B). All posttreatment sampling periods showed a significant herbaceous plant cover response to tree thinning on the Guaje site

(fig. 2C).

Figure 2—Total herbaceous cover on study sites. Bars

with the same letter, within a site and sampling period,

are not significantly different (P>0.05). Pretreatment

means are displayed for comparison but were used as

covariates in the repeated measures analysis and are

not included in the multiple t-test evaluation of means.
122 USDA Forest Service Proceedings RMRS-P-7. 1999

Discussion _____________________

The Rangeland Health Model would predict that natural

processes could be used to maintain the functional, compositional, and structural properties of a healthy site, that atrisk sites can be restored using natural processes, and that

restoration of unhealthy sites requires outside inputs. Herbaceous plant cover on the healthy AOS site showed a

significant response to the first reintroduction of fire. The

quantity and homogeneous distribution of herbaceous biomass on the site was sufficient to carry the fire and lead to the

desired reduction of herbaceous cover. One growing season

following the fire, herbaceous plant cover was not significantly different on the two treatments, indicating a rapid

recovery on the burned plots. On this site, fire is easily

reintroduced and could be used to increase landscape-scale

habitat diversity by creating a mosaic of different successional patches.

The at-risk BW site has not responded as rapidly to

prescribed fire treatments. The first fire resulted in a nonsignificant decline in herbaceous plant cover on the burned

plots probably because of the patchy nature of the vegetation/fuels matrix. A substantial portion of the decline in

herbaceous plant cover on this site was due to a drought in

the winter of 1995/96. Compounding drought stress with fire

could have had disastrous results, however, herbaceous

cover on both treatments recovered within one growing

season which would indicate that this system is very resilient to both drought stress and fire. The second fire, despite

the less than optimal burn conditions, resulted in a significant reduction in herbaceous plant cover. We plan to use this

2-3 year cycle of fire and recovery as a test of the restoration

potential of the site. However, because this site is not

functioning as a healthy grassland, it will take some time for

natural processes to affect restoration, if at all.

A good test of the Rangeland Health Model would have

been a prescribed burn in untreated pinyon-juniper. Unfortunately, these projects were not originally designed as a

test of the Rangeland Health Model, consequently we did not

consider using fire as a restoration technique in the unhealthy pinyon-juniper site. Subsequent interpretation of

the model indicates that we would have been wasting our

time and resources. Although the thinning treatment is

more expensive and time consuming the results have been

very encouraging. We believe that the herbaceous plant

community has recovered to the point where we can now

reintroduce fire. The timing for reintroduction of fire can be

critical in this system. A window of opportunity exists

between burning too soon and burning too late. Burning too

soon can result in hot fires that kill herbaceous plants

because the slash has not had time to decompose. Burning

too late can result in fires that are not hot enough to kill the

cohort of seedling and resprouting trees that are released

following the thinning treatment. We believe that the appropriate time to burn this site is in the next 1-3 years. Of course

this window will be different for different sites and/or environmental conditions.

Conclusions____________________

Middle Rio Grande upland ecosystems evolved with fire.

Restoration and maintenance of their function, composition,

and structure will require the use of fire. The potential for

successful reintroduction of fire back into upland ecosystems depends upon the status of the system and the disturbances acting on it. The process of objectively identifying and

distinguishing between disturbances and problems and determining ecosystem status can lead to insights on appropriate management actions. These objective determinations

are best made through the use of data derived from monitoring appropriate abiotic, ecological, and social indicators.

Appropriate monitoring procedures and programs would

provide data for these pretreatment determinations as well

as for evaluation of management treatments and progress

toward goals.

References _____________________

Busby, F.E., Ruyle, G.B., and Joyce, L.A. 1995. Minimum ecosystem

function: a strategy to integrate methods to classify, inventory,

and monitor rangelands. In: N.E. West (ed.) Rangelands in a

Sustainable Biosphere. Proceedings of the Fifth International

Rangeland Congress, Vol. II. Society for Range Management,

Denver, CO. 202 p.

Committee on Rangeland Classification. 1994. Rangeland Health:

New Methods to Classify, Inventory, and Monitor Rangelands.

Board on Agriculture, National Research Council. Washington,

DC. 180 p.

Miller, R.G., Jr. 1981. Simultaneous Statistical Inference, 2nd ed.

New York: Springer-Verlag. 299 p.

SPSS Inc. 1990. SPSS/PC+ 4.0. Chicago, IL.
USDA Forest Service Proceedings RMRS-P-7. 1999 123

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

James R. Thibault, Douglas L. Moyer, Clifford N. Dahm, Michael C.

Marshall, are with the Department of Biology, University of New Mexico,

Albuquerque, NM. H. Maurice Valett is with the Department of Biology,

Virginia Polytechnic Institute and State University, Blacksburg, VA.

Abstract—Land-use practices such as livestock grazing influence

the structure and function of riparian/stream ecosystems. In New

Mexico, four streams were selected to determine the impact of

moderate livestock grazing on morphology, solute transport, and

nutrient retention. Each stream contained a reach currently exposed to grazing and an exclosed, ungrazed reach. Channel width/

depth ratios and in-stream standing stock of plant biomass were

greater in the grazed reaches. Solute transport was determined by

injecting a conservative tracer (NaBr) and applying a one-dimensional transport with inflow and storage (OTIS) model. Grazed

reaches exhibited enhanced transient storage, represented by a

larger cross-sectional area of storage zone relative to wetted channel area (As/A). The extent of nutrient retention was determined by

co-injecting a reactive tracer (NaNO3) with the conservative tracer.

Nitrate uptake lengths were shorter in grazed reaches, an indication of more effective nutrient retention. Our results suggest that

moderate livestock grazing alters channel structure and vegetation,

influencing ecosystem-level processes.

Riparian/stream ecosystems are three-dimensional interfaces that connect terrestrial and aquatic ecosystems. The

riparian component extends laterally to the limits of flooding and vertically to the canopy of streamside vegetation; the

aquatic system includes stream surface water and shallow

groundwater (Gregory and others 1991, Malanson 1995).

Riparian vegetation provides numerous ecosystem functions, including habitat, nutritional resources, and bank

stabilization (Crawford and others 1993). Riparian vegetation also has a role as a dispersal site and corridor for biota

(Gregory and others 1991). As a whole, riparian/stream

ecosystems are valuable resources that contribute to water

quality and supply terrestrial and aquatic wildlife habitat

and recreational uses.

Effects of Livestock Grazing on Morphology,

Hydrology and Nutrient Retention in Four

Riparian/Stream Ecosystems, New Mexico,

USA

James R. Thibault

Douglas L. Moyer

Clifford N. Dahm

H. Maurice Valett

Michael C. Marshall

Anthropogenic disturbances have greatly altered the structure and functioning of these ecosystems, affecting native

communities and influencing biodiversity and successional

processes. A disturbance is an episode that disrupts an

ecosystem, altering resources, substrate availability, or the

physical environment (White 1979). While disturbances can

promote diversity, it may be at the expense of existing native

communities (Hobbs and Huenneke 1992). Alternatively,

many ecosystems rely on disturbances to maintain indigenous communities. Disturbances can thus be viewed as

potentially destructive or beneficial. Human-induced disturbances often impart protracted adverse effects to natural

ecosystems, such as eutrophication. Processes such as productivity and nutrient cycling respond directly to human

modification (Vitousek 1994). For example, Likens and

Bormann (1995) found that clearcutting a forest was followed by increased nitrate leaching in its catchment. The

loss of nitrogen from the upland system and subsequent

loading to the stream could be viewed as a destructive

ecological disturbance.

In western North America, riparian/stream ecosystems

have been subjected to various anthropogenic disturbances

such as livestock grazing, agriculture, mining, industrial

and urban intrusion, and river regulation (Crawford and

others 1993, Malanson 1995). Livestock grazing is the most

extensive land management practice in this region

(Fleischner 1994). Previous research has addressed the

impacts of grazing on particular components of riparian/

stream ecosystems, including vegetation, erosion, geomorphology, water quality, and fish habitat (Moyer 1998 and

references therein). However, effects of grazing are less

understood from the perspective of the ecosystem as a

whole, where nutrients can be regarded as an organizing

focus (Krebs 1994). Nutrients regulate rates of important

ecological processes, including primary productivity and

decomposition (Meyer and others 1988). Stream productivity is dependent on both allochthonous inputs of nutrients

and nutrient cycling within the ecosystem (Mulholland and

others 1995).

In lotic systems, dissolved nutrients are not cycled in

place, but are transported downstream with other solutes.

The uptake and release of nutrients by biota in streams is

described as nutrient spiraling (Newbold and others 1981).

Thus, stream nutrients undergo both hydrologic export and
124 USDA Forest Service Proceedings RMRS-P-7. 1999

biological retention (Valett and others 1996). Solutes are

also retained hydrologically in flowpaths moving at slower

velocities than those predicted by advective transport in the

thalweg of a stream (Morrice and others 1997). Hydrologic

retention can be determined by the injection of a conservative tracer into the stream. Injection data are incorporated

into a transport model that calculates hydrologic parameters such as advection, dispersion, and transient storage

(Bencala 1984, Stream Solute Workshop 1990, Runkel and

Broshears 1991). Nutrient retention in streams has been

measured as nutrient uptake length, the average downstream distance a dissolved nutrient molecule travels before

it is utilized by biota (Elwood and others 1983). Nutrient

uptake length is inversely related to uptake rate. In a given

system, shorter uptake lengths indicate more efficient

nutrient cycling.

To maintain ecological functioning and thus support multiple-use status in riparian/stream ecosystems, it is essential to comprehend the movement and retention of solutes, particularly nutrients (Newbold and others 1981,

Stream Solutes Workshop 1990). Our research studies the

effects of livestock grazing on riparian/stream ecosystem

structure and function by examining solute dynamics. In

particular, we investigate the influence of moderate livestock grazing on channel morphology, solute transport, and

nutrient retention.

Study Sites_____________________

Four streams in the Rio Grande catchment of New Mexico

were used as research sites (fig.1, table 1). The Rio Peñasco

(RP) is located in the Lincoln National Forest in the Sacramento Mountains of southern New Mexico. Chihuahueños

Figure 1—Study site locations, New Mexico, USA.

Table 1—Description of the four riparian/stream research sites in New Mexico.

Stream Reach Base flow Exclosure

Site order length (m) discharge (L/s) age (yrs)

Rio Peñasco 1 120 5 6

Chihauhueños Creek 1 200 18 5

Rio las Vacas 3 400 70 12

Rio de Don Fernando 1 120 5 9

Creek (CC) and the Rio las Vacas (RLV) are situated in the

Santa Fe National Forest in the Jemez Mountains of northern New Mexico. The Rio de Don Fernando (RDF) is located

in the Carson National Forest in the Sangre de Cristo

Mountains of northern New Mexico. Study sites are described in more detail (catchment size, elevation, lithology,

stream sediments, and riparian and upland vegetation) in

Moyer (1998).

Each site is comprised of a riparian/stream section subjected to moderate grazing (grazed) and a nearby section

exclosed from grazing (ungrazed) by the U.S. Forest Service.

The management history of many grazing sites is unknown,

and grazing intensities have been qualitatively defined in

several ways (Fleischner 1994). Although our sites are

defined as moderately grazed by the USFS, grazing intensities are not well known. At RP, approximately 250 head of

cattle are moved through a 111 ha allotment (~2.3/ha) each

November, while 40 to 50 cows pass through an 81 ha CC

allotment (~0.5/ha) during July to October. At RLV, roughly

40 head of cattle graze on a 60 ha allotment (~0.7/ha) from

June to October. At RDF, about 15 cows graze on a 20 ha

allotment (~0.8/ha) from July to October (Moyer 1998).
USDA Forest Service Proceedings RMRS-P-7. 1999 125

Methods

Field work was carried out from June to August 1997. At

each site, paired reaches (grazed, ungrazed) were established. Reach lengths were based on stream discharge (table

1, Moyer 1998). Along each reach, five sampling transects

were situated at equal intervals, oriented perpendicular to

the longitudinal axis of the stream (Moyer and others 1998).

Morphologic, hydrologic and nutrient transport features

were examined at each site.

Morphology

Wetted width and average depth of the stream were

measured at each transect (Rosgen 1994). Values were used

to determine the mean width to depth ratio (w/d) for each

study reach. We also measured wetted perimeters and

calculated ratios of wetted perimeter to wetted width. Stream

beds consisted of patch types dominated by bare (unvegetated)

sediments, macrophytes, sedges, and filamentous algae

(Moyer 1998). The percent of stream area occupied by each

patch type was assessed. Total standing stock of aboveground

vegetative biomass was calculated using ash-free dry mass

concentrations (Benfield 1996) from stream samples and the

area of the channel covered by the respective patch types.

The percent of riparian area covered by herbaceous and

woody vegetation was measured using 1 m2 quadrats. Several additional measurements were made, including channel gradient and sinuosity, dominant sediment type, porosity, total suspended sediments, and subsurface biomass.

These are described in Moyer (1998).

Hydrology

In lotic ecosystems, the transport and retention of solutes

are determined by hydrologic factors, i.e., solutes flow with

the water. Retention occurs when water moves into slower

moving zones relative to the main body of water, where it can

be considered temporarily stored (Bencala and Walters

1983, Webster and Ehrman 1996). Transient storage zones

include shallow groundwater and surface water environments such as pools and backwaters (Moyer and others

1998, Webster and Ehrman 1996). When a solute pulse is

transported downstream, some of the solute mass passes

into transient storage zones, temporarily decreasing the

concentration in the active channel (Runkel and Broshears

1991). Hydrologic parameters were investigated by employing a conservative (nonreactive) solute to act as a tracer with

which to formulate data and construct a solute response

curve. A concentrated solution of sodium bromide (NaBr)

was injected upstream at a constant rate, elevating the

stream Br– concentration slightly above background levels.

At the downstream end of the reach, Br– concentration was

monitored using an Orion 290A ion selective electrode.

Surface water samples were collected (1) as the pulse

arrived (the rising limb of the solute response curve), (2) once

it reached and maintained a plateau concentration, and

(3) after the injection was terminated and stream Br– concentrations approached background levels (during the falling limb of the curve). Samples were analyzed in the lab for

Br– using a Dionex DX-100 Ion Chromatograph. Solute

injections are described in more detail in Moyer (1998).

Data from the injections (Br– concentration vs. time) were

plotted as a solute response curve and fit to a hydrologic

model of one-dimensional transport with inflow and storage

(OTIS; Runkel and Broshears 1991). This model computes

values for five hydrologic variables: advective velocity (bulk

fluid motion), dispersion (solute spreading), lateral inflow

(inputs of unlabeled water), transient storage (temporary

storage of solutes in slow-moving compartments), and the

storage zone exchange coefficient (rate of exchange between

the storage zone and the channel flow) (Runkel and Broshears

1991). Stream discharge, determined by separate injections

at the top and bottom of each reach, is entered into the model.

Assuming a steady state discharge for the entire reach, a

best-fit line through the Br– response curve is iteratively

adjusted by manipulating the following parameters: stream

cross-sectional area (A, m2), dispersion coefficient (m2/s),

storage zone cross-sectional area (As, m2), and the storage

zone exchange coefficient (s–1) (Bencala and Walters 1983,

Stream Solute Workshop 1990, Moyer 1998). Several hydrologic characteristics were derived based on these parameters, including the area of the storage zone relative to the

cross-sectional area of the stream channel (As/A, for example

Bencala and others 1993). We also determined the hydraulic

retention factor (Rh), which describes the amount of time a

parcel of water spends in the storage zone per meter of

stream (Rh = As/stream discharge, Morrice and others 1997).

Nutrient Retention

Nutrient retention was measured by the nutrient uptake

length. A reactive tracer, nitrate (as NaNO3), was co-injected with the NaBr solution. A reactive solute reacts

biotically and/or abiotically in the ecosystem, whereby its

concentration is subject to change as it is transported downstream (Stream Solute Workshop 1990, Webster and Ehrman

1996). Once the injected Br– reached plateau concentration,

samples were collected at each transect and analyzed for

NO3-N concentrations via colorimetric methods (Wood and

others 1967) on a Technicon AutoAnalyzer II. NO3-N values

were corrected for dilution and background concentration,

natural log transformed, and regressed against distance

downstream. Nutrient uptake length was calculated as the

negative inverse of the relationship between these two

parameters (Newbold and others 1981, Webster and Ehrman

1996, Moyer 1998). Nitrate retention methods are discussed

in greater detail in Moyer (1998).

In addition to the injections, surface waters were sampled

for background levels of biogeochemically active solutes,

including NO3-N, ammonium (NH4-N), and soluble reactive

phosphorus. These data, along with N:P ratios, are presented in Moyer (1998) and Moyer and others (1998).

Statistical Analyses

Statistical analyses were performed to uncover significant

differences for a given variable between grazed and

ungrazed reaches, both within and across study sites. Nonparametric t-tests were used to identify differences between

each reach for each variable. Pearson Correlation Analyses were used to reveal relationships between the different variables. Step-wise multiple linear regressions were

used to create predictive models for key morphological,

hydrological, and nutrient retention parameters. Additional

information pertaining to the statistical analysis of this

research is presented in Moyer (1998).
126 USDA Forest Service Proceedings RMRS-P-7. 1999

Results ________________________

Morphology

Mean w/d ratios were lower in ungrazed reaches at all 4

sites, with significant differences at CC and RLV (P = 0.012

and 0.022, respectively, fig. 2). Wetted perimeter to wetted

width (wp/ww) ratios were 1.5, 1.8, and 1.1 times lower in

grazed reaches at RP, CC and RLV, respectively. At RDF,

the wp/ww ratio was greater in the grazed reach. Aboveground

organic matter was greater in the grazed reaches at RP,

RLV, and RDF (fig. 3). Significant differences occurred

between grazed and ungrazed reaches at RP and RLV (n =

3, P = 0.0018 and n = 3, P = 0.039, respectively). A step-wise

multiple linear regression indicated that within each reach,

aboveground organic matter was best predicted by w/d ratio

(R2 = 0.95, P = 0.0001). Riparian vegetation was generally

more extensive along ungrazed reaches. Ungrazed reaches

contained greater areas of either herbaceous or woody riparian vegetation at all sites (table 2).

Hydrology

The average area of the storage zone relative to the crosssectional area of the channel (As/A) was 45 percent smaller

in ungrazed reaches across all sites (fig. 4). A step-wise

multiple linear regression indicated that within each reach,

total aboveground organic matter was an important predictor of transient storage (as As/A, R2 = 0.94, P = 0.0001).

Hydrologic retention varied between grazed and ungrazed

reaches. Hydraulic retention factors (Rh, s/m) were 5.6, 1.3,

and 1.4 times greater in grazed reaches at RP, CC, and RLV,

respectively. At RDF, Rh in the ungrazed reach was twice

the value found in the grazed reach. Based on cross-site

comparisons of Rh, grazed reaches demonstrated on average 303 percent more hydraulic retention than ungrazed

reaches.

Nutrient Retention

Grazed reaches generally exhibited more efficient nutrient retention compared to ungrazed reaches. Nitrate uptake

lengths were shorter in all 4 grazed sites, with significant

differences at RP and RDF (P = 0.0001 and 0.0068, respectively, fig. 5, Moyer 1998). A step-wise multiple linear

regression indicated that the area of stream channel devoid

Figure 2—Comparison of wetted width to wetted depth

ratios for ungrazed and grazed reaches of Rio Peñasco

(RP), Chihuahueños Creek (CC), Rio las Vacas (RLV),

and Rio de Don Fernando (RDF). Error bars are standard errors of the mean. Asterisk denotes significance

at p < 0.05.

Table 2—Percent cover by riparian patch-types from grazed (G) and ungrazed

(U) reaches at the four research sites. Data are means ± standard

errors.

Percent Percent Percent

Site bare soil herbaceous cover woody cover

Rio Peñasco-G 28.8 ± 5.5 71.2 ± 5.5 0.0

Rio Peñasco-U 5.9 ± 4.0 94.1 ± 4.0 0.0

Chihauhueños Creek-G 49.2 ± 6.6 50.8 ± 6.5 0.0

Chihauhueños Creek-U 13.4 ± 4.3 86.6 ± 4.3 0.0

Rio las Vacas-G 46.8 ± 11.2 53.2 ± 11.2 0.0

Rio las Vacas-U 49.1 ± 8.3 47.1 ± 9.8 2.5 ± 1.5

Rio de Don Fernando-G 27.5 ± 9.1 70.6 ± 9.3 1.9 ± 1.9

Rio de Don Fernando-U 43.9 ± 9.7 49.4 ± 10.0 6.7 ± 2.3

Figure 3—Comparison of total aboveground ash-free

dry mass (plotted on logarithmic scale) within ungrazed

and grazed reaches of Rio Peñasco (RP), Chihuahueños

Creek (CC), Rio las Vacas (RLV), and Rio de Don

Fernando (RDF). Error bars are standard errors of the

mean. Asterisk denotes significance at p < 0.05.

Figure 4—Comparison of area of the storage zone normalized to stream area (As

/A) for ungrazed and grazed reaches

of Rio Peñasco (RP), Chihuahueños Creek (CC), Rio las

Vacas (RLV), and Rio de Don Fernando (RDF).
USDA Forest Service Proceedings RMRS-P-7. 1999 127

of aboveground vegetation (bare patch-type) was the single

most important variable for predicting NO3-N uptake length

(R2 = 0.97, P = 0.0001, fig. 6). Complete, extensive morphological, hydrological and nutrient transport experimental

data and analyses resulting from this research are presented in Moyer (1998) and Moyer and others (1998).

Discussion _____________________

Grazed stream channels exhibited mean w/d ratios 150 to

500 percent greater than those in ungrazed reaches (fig. 2).

Wider, shallower channels are typical of streams exposed to

livestock grazing (Duff 1979, Fleischner 1994). Ratios of

wetted perimeter to wetted width indicate less channel

complexity in grazed reaches, likely diminishing aquatic

habitat variability. Herbaceous and woody riparian vegetation covered a less extensive area along grazed reaches.

However, in-stream vegetation (sedges, filamentous algae)

was more abundant in grazed compared to ungrazed channels, which were characterized by extensive bare patchtypes (Moyer 1998). Channel width exerts a positive influence on the amount of in-stream organic matter. Trampling

and loss of riparian vegetation increase w/d ratios and create

less stable stream banks (Moyer and others 1998). As a

result, in-stream vegetation becomes more abundant, composed mostly of vascular hydrophytes (for example sedges,

Moyer 1998). Plants of this type are known to colonize

disturbed streams, and are typically succeeded by riparian

vegetation such as willows and cottonwoods, which help

fortify channel structure (Hendrickson and Minkley 1984,

Moyer 1998). Our grazed study reaches appear to be maintained in a state of early secondary succession (Moyer 1998)

due to the seasonal disturbance imposed by grazing.

Stream hydrologic retention was also influenced by grazing. Conservative tracer injections demonstrated a greater

capacity for transient storage in grazed reaches (fig. 4).

Transient storage (as As/A) was best predicted by the amount

of in-stream vegetation. Mulholland and others (1994) also

report a positive relationship between As/A and in-stream

organic matter (as periphyton biomass). Wetted channel

width was also an important influence on solute retention

(data presented in Moyer 1998). These findings suggest that

channel structure and in-stream vegetation exert strong,

retentive influences on the movement of water through the

ecosystem.

Nutrients are taken up more rapidly by the biotic community in grazed reaches, indicated by shorter uptake lengths

(fig. 5). Uptake lengths are well correlated with the area of

stream bed represented by bare patch types (fig. 6). The

results suggest that nutrient uptake length is influenced by

the amount of in-stream vegetation. Taken together, instream vegetation and the hydraulic retention factor (Rh)

account for 99 percent of the variability associated with

nutrient uptake (Moyer 1998). Hydrologically, it appears

the two factors combine to slow the movement of water,

allowing the stream community a greater opportunity to

utilize the passing nutrients (Moyer and others 1998). Uptake length is inversely related to stream width, and should

decrease as a channel widens (Stream Solute Workshop

1990). A significant, positive correlation exists between

aboveground organic matter and w/d. The higher w/d values

in grazed reaches may contribute to enhanced nutrient

retention by promoting the growth of in-stream vegetation

and by the increased sediment area with which solutes can

come in contact. The successional state of in-stream biota

also affects the potential for solute uptake (Grimm 1987).

Nutrients were retained more efficiently in the early secondary successional stage typical of grazed reaches. Efficient

nutrient retention also is typical during rapid regrowth of

disturbed forest ecosystems (Vitousek and Reiners 1975). As

succession proceeds, retention efficiency generally declines

(Vitousek and Reiners 1975).

Long-term monitoring of riparian/stream ecosystems following the attenuation or elimination of livestock grazing

would enable researchers to consider the effects on succession with more accuracy. Studies could occur on a seasonal

basis to include active and dormant grazing intervals, as

well as the effect of higher stream discharges (for example

during spring runoff). Additionally, a more quantitative,

precise definition of grazing intensity would be useful. The

effects of moderate grazing versus overgrazing could be

compared, enabling researchers to provide land managers

with more accurate information (for example the expected

effects of a particular grazing regime on a riparian/stream

ecosystem).

Figure 5—Comparison of nitrate uptake length for ungrazed

and grazed reaches of Rio Peñ asco (RP), Chihuahueñ os

Creek (CC), Rio las Vacas (RLV), and Rio de Don Fernando

(RDF). Asterisk denotes significance at p < 0.05.

Figure 6—Relationship between nitrate uptake length

(plotted on a logarithmic scale) and percent bare sediment. Data are from ungrazed (n = 4) and grazed (n = 4)

reaches.
128 USDA Forest Service Proceedings RMRS-P-7. 1999

Conclusions____________________

With respect to ungrazed riparian/stream ecosystems,

stream channels are wider and less complex in moderately

grazed systems. In addition, in-stream vegetation is more

abundant in grazed streams. As a result, nutrients are

retained to a greater degree compared to ungrazed sites

characterized by less in-stream vegetation and more established riparian vegetation. The effects of grazing on ecosystem-level processes in streams have not been well studied.

At the present time we know of no analogous study with

which to compare our research. It is uncertain how alterations to hydrology and nutrient retention affect the ecosystem within and downstream of grazed areas. A knowledge of

nutrient cycling is an important component in the management of ecosystems, particularly in lands mandated for

multiple-use. Land-use decisions such as livestock grazing

have the potential to modify nutrient dynamics. The impacts

of these changes in nutrient dynamics on riparian/stream

ecosystems remain to be determined.

Acknowledgments ______________

Research was funded by Cooperative Agreements 28-JV7-

950 and 28-C4-833 to H.M. Valett and C.N. Dahm by the

USDA Forest Service Rocky Mountain Research Station

and the University of New Mexico. The authors thank

Livia Crowley (Lincoln National Forest), Ben Kuykendall

(Carson National Forest), Robert Martinez (Santa Fe National Forest), and Richard Montoya (Santa Fe National

Forest) for assistance in identifying and accessing research

sites. Special thanks to Chelsea Crenshaw, Christine Fellows, Lisa Metz-Roberts, Michelle Baker, John Craig,

Jacqueline Walters, and Kathy Smith for field and laboratory assistance.

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Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Mark D. Ankeny is Senior Scientist, L. Bradford Sumrall is Staff Engineer and Kuo-Chin Hsu is Hydrologist, Daniel B. Stephens & Associates,

Albuquerque, New Mexico.

Abstract—Storm water or overland flow can be captured and

injected into a soil trench or infiltration gallery attached to a siphon

and emplaced adjacent to a stream or arroyo bank. This injected

soil water can be used by stream side vegetation for wildlife habitat,

bank stabilization or other purposes. The siphon system has three

hydrologically-distinct flow regimes: (1) infiltrating flow, (2) cycling

outflow, and (3) constant outflow. These flow regimes are dependent

upon infiltration gallery design, soil hydraulic conductivity, and

rainfall intensity. The design is low-cost and is predicted to be selfcleaning and low maintenance.

Soil functions as a plant growth medium, a regulator and

partitioner of water flow, and as a buffer of environmental

change. A National Research Council report (1993) reviews

soil’s role in the hydrologic cycle. Rainfall in terrestrial

ecosystems falls on the soil surface where it either infiltrates

the soil or moves across the soil surface into streams or lakes.

The condition of the soil surface determines whether rainfall

infiltrates or runs off. If it infiltrates the soil, it may be stored

and later taken up by plants, move into ground waters, or

move laterally through the earth, appearing later in springs

or seeps. This partitioning of rainfall between infiltration

and run-off determines whether a storm results in a replenishing rain or a damaging flood. The movement of water

through soils to streams, lakes, and ground water is an

essential component of recharge and base flow in the hydrological cycle (Stephens, 1995).

Current engineering practices in the Southwest often

reduce infiltration and increase runoff by collecting and

conveying storm water quickly and efficiently for ultimate

discharge to an existing surface water course. The goals of

this management strategy are to reduce hazards to the

public and minimize property damage. Although this strategy maximizes the objectives in terms of safety and risk

reduction, it prevents the beneficial use of storm waters

through recharge. Conveyance times are minimized while

flow rates are maximized to remove it from highways,

streets and public areas. With concern growing over the

availability of water supplies for public and industrial use,

alternative uses of storm water must be considered, and if

practical, implemented. One such strategy is to recharge

Establishing Riparian Vegetation Through

Use of a Self-Cleaning Siphon System

Mark D. Ankeny

L. Bradford Sumrall

Kuo-Chin Hsu

vadose zone aquifers through the use of a sub-surface siphon

system to increase recharge and storage (Ankeny and

Sumrall, 1998).

The operational objective is to maximize long term water

recharge in an infiltration gallery while minimizing long

term maintenance requirements. The objectives of the

analysis for this structure is multi-fold and includes: (1) determination of hydraulic parameters governing system operation, (2) quantification of water velocities within the system

needed to entrain sediment carried into the system, and

(3) quantification of the recharge potential of the system

through various storm events.

Physical Design_________________

The siphon system is schematically illustrated in figure 1.

The siphon behaves as a standard siphon and cycles (drains)

as the water level exceeds the critical head in the siphon.

After the drainage cycle, the siphon breaks and the siphon

reservoir refills. The siphon reservoir consists of the drainage pipe, the large air-filled pores in the gravel backfill, and

the air-filled pore space in the surrounding soil (fig. 2). As the

siphon refills, water infiltrates into and is redistributed by

the soil.

The siphon system consists of a perforated pipe buried in

a gravel-filled trench (fig. 2). The perforated pipe is bedded

at a nominal slope toward the discharge with an ascending

limb angled upward at the terminal end. This upward

angled non-perforated portion is formed into a radius of

approximately 180 degrees forming an inverted P-trap. This

radius is directed downward for discharge. The system

operates passively by capturing a point source flow such as

a storm drain inlet or other concentrated flow source.

When the siphon cycles, water velocity in the drainage

pipe increases, silt in the overlying gravel is back flushed,

and water in the drainage pipe reaches entrainment velocity

for silt and clay deposited during the infiltration phase of

the cycle. Thus, a siphon can take a linear input of water,

sediment, and potential energy and turn it into a nonlinear

system that retains a large fraction of the water and potential energy while discharging the sediment and part of the

water.

Water Flow _____________________

TOUGH-2, a multiphase, multidimensional flow and

transport code (Pruess 1991) was used to model trench

infiltration across a range of soil types and hydraulic heads.

Output from this model was used as input for a spreadsheet

application to model the infiltration gallery/siphon system.
130 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 1—Siphon/infiltration gallery schematic.

Figure 2—Siphon/infiltration gallery cross section.
USDA Forest Service Proceedings RMRS-P-7. 1999 131

The equation governing siphon operation is the energy

equation developed by Bernoulli.

 

P V

g

Z P V

g

Z h i i

i

o o

o f γ γ + += + ++

2 2

2 2

where Z = elevation of the pipe (m) subscripts: P is pressure

(N/m2), g is fluid density (kg/m3), V is fluid velocity (m/sec),

g is the gravitational constant (m/sec2), and hf is the head

loss within the system (m). Head loss is system dependent

and includes friction losses and pipe bends. The subscripts

“i” and “o” refer to inlet and outlet values, respectively. This

governing equation is used to calculate flow within the

spreadsheet model.

In addition to standard hydrologic modeling, the siphon is

governed by logical statements embedded within the spreadsheet code to start and stop the siphon based upon water

level in the system and upon the previous status of the

siphon.

Three flow regimes exist for an infiltrating siphon system:

(1) infiltrating inflow, (2) cycling outflow, and (3) continuous

outflow, figure 3 shows siphon behavior under the three flow

regimes.

The results shown in figure 3 are for a 50 meter long by

0.2 meter wide by 1.75 meter deep soil trench backfilled with

coarse gravel placed over a 0.10 meter diameter perforated

pipe. Porosity of the gravel is 35 percent. The siphon empties

into an arroyo 1.5 meters below the bottom of the trench. The

soil used for calculations is a loamy sand with a permeability of 4.1*10-5 m/s. The rational method is used to estimate

runoff and a runoff coefficient of 0.90 is used. Rainfall

intensity is varied from a drizzle (1 mm/hr) in figure 3a to a

light rain (5 mm/hr) in figure 3b and to a downpour (50 mm/

hr) in figure 3c. Each rainfall intensity results in a different

flow regime.

In infiltrating inflow (fig. 3a), infiltration into the trench

bottom and walls exceeds inflow. All water infiltrates, and

trench water level is less than the water level needed to

activate the siphon (critical head).

In cycling outflow (fig. 3b), when inflow exceeds trench

infiltration capacity, the water head in the trench exceeds

the critical head, and the siphon is activated. For flow to

stop, the rate of outflow must exceed the sum of inflow and

infiltration up until the point at which the trench is emptied

of water. At this point, air entering the pipe through the

inlet or through the perforations is able to break the water

column and stop the siphon.

In continuous outflow, an equilibrium is reached between

inflow and outflow (fig. 3c). Water level in the trench and

infiltration from the trench are constant.

Figure 3—Flow regimes: infiltrating inflow is shown in 3a; cycling outflow is shown in 3b (next page), and continuous

outflow is shown in 3c (next page).
132 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 3— Continued from previous page.
USDA Forest Service Proceedings RMRS-P-7. 1999 133

All of these flow regimes potentially can be seen in a single

rainfall event. Figure 4 schematically shows rainfall intensity over the course of a typical southwestern thunderstorm.

Rainfall starts, quickly builds to maximum intensity, and

then slowly tails off. Runoff and erosion intensity follow a

similar qualitative pattern. At low rainfall intensities with

low sediment inputs, all water infiltrates. As the rainfall

intensity increases, sediment input increases, the cycling

threshold is reached, and the system starts to cycle. If

rainfall intensity increases sufficiently, sediment concentrations may increase, and a continuous outflow flow regime

can be established. As rainfall decreases, the system will

then revert to cycling outflow, and finally, to infiltrating

inflow regimes.

Sediment

Sediment accumulation varies with flow regime. Under

infiltrating flow, all water infiltrates and sediment accumulates in the system. However, because infiltrating flow

generally occurs during low rainfall intensity events, little

sediment enters the system.

During cycling flow, sediment accumulates during the

infiltration phase of the cycle and is flushed during the

siphon phase. Design parameters must be set to ensure an

adequate velocity to entrain sediment in the perforated pipe

and to back flush the overlying gravel backfill. The water

Figure 4—Changes in siphon system behavior over the course of a rainstorm.

velocity obtainable in the system defines the particle size

that can be entrained and removed. This velocity sets the

upper limit on particle size that can be accommodated by the

system.

During constant outflow, little sediment is likely to accumulate in the pipe. However, sustained unidirectional flow

into soil is likely to result in some soil plugging and permeability decline. The time frame is likely to be empirically

dependent upon soil properties, sediment flux, and particle

size distribution.

Vegetation/Siphon System

Interactions ____________________

Root systems can increase soil saturated hydraulic conductivity over an order of magnitude (Prieksat and others

1994). Increased root biomass results in more root channels

as well as an associated increase in faunal activity creating

wormholes and other channels. These preferential flow

paths increase saturated hydraulic conductivity. In arid

and semi-arid systems, plant growth is usually limited by

water availability. Because plants maintain fairly constant

root:shoot ratios, root mass and soil hydraulic conductivity

are often directly correlated with water availability. Thus, a

potential positive feedback loop exists where increased water availability from the siphon system increases plant and

root mass which increases soil hydraulic conductivity which,

in turn, increases water recharge and water availability.
134 USDA Forest Service Proceedings RMRS-P-7. 1999

These soil-plant-water relationships can be exploited in a

siphon system. By increasing water availability, both root

growth and hydraulic conductivity of the infiltration system can improve over time. This is particularly true of

finer-textured semi-arid and arid soils where little

macroporosity exists. Addition of plant roots and water leads

to new macropore channels. The reduced carbon released by

these roots ultimately results in soil aggregation. These soil

aggregation processes are driven by reduced carbon from

plants and can be used to combat the natural tendency of

pressurized particulate-containing water to plug infiltration systems.

Siphon/Riparian Zone

Interactions ____________________

Most previous buffer zone and riparian zone research

(primarily from the Northeast and the Midwest) has operated on the premise that vegetation is necessary to establish

control of run-off. In the western U.S., establishment of

vegetation is often problematic due to intermittent water

supply. Thus, contrary to what is typically found in the

eastern U.S., runoff must be controlled to (re)establish

vegetation in arid and semi-arid areas. Runoff control can

provide water for establishment of vegetation. One problem

is obvious: to obtain the benefits of vegetated buffer zones in

arid and semi-arid areas, we need effective methods to

convert transient runoff into a steady water source for

establishment of vegetation.

Healthy riparian areas provide numerous benefits when

viewed as a component of the basic hydrologic unit, i.e., the

watershed. Woody riparian species provide channel and

bank stability and thus prevent incisement of the channel.

Local ground-water levels are maintained due to slow release of bank storage. Natural fluvial processes create channels which efficiently transport water. Water quality is

improved where sources of sediment from destabilized banks

are eliminated. Shading reduces extreme fluctuations in

temperature and evaporative losses from perennial streams.

Additionally, riparian zones can attenuate high flood flows

while promoting sediment deposition and ground water

recharge. These attributes optimize the hydrologic response

of a watershed with regards to the storage and discharge of

water.

From a soil science perspective, grazing and cropping

practices have often reduced soil water storage capacity and

increased run-off. A common result has been lowering of

local water tables with permanent stream reaches becoming intermittent. From a hydrological perspective (Munzel

1983), these same agricultural practices lead to an exaggerated seasonal flow regime and increase the frequency,

severity, and unpredictability of high-volume flows.

Subsurface flow, including that from recharge galleries,

generally provides a more constant source of water than

surface flow. Obligate phreatophytes, such as cottonwoods,

require a constant source of water for survival. Facultative

phreatophytes, such as salt cedar (Tamarix sp.), tolerate

drier periods. In southwestern riparian zone forests

(bosques), replacement of native vegetation (such as willow

and cottonwood) by exotics (such as salt cedar and Russian

olive) has occurred with watershed degradation over time.

The recharge component of the water balance considered

critical for maintaining base flow in streams is therefore

important in maintaining desired vegetation.

Surface waters have been diverted and infiltrated for

thousands of years in various parts of the world (Bruins and

others 1986). Wills (1988) summarizes much of the literature on prehistoric southwestern U.S. agriculture and water

harvesting. The primary objective of water harvesting is

short-term water storage in the soil profile for crop growth.

In the southwest, Native American farmers place fields to

optimize water and sediment trapping (Nabhan 1984).

These relationships among soil, vegetation, and erosion/

deposition are eloquently discussed by Jenny (1980). Soils

derived from aeolian deposits, alluvium and colluvium are

generally considered unsuitable for agriculture because of

their high infiltration rates (Tabor, 1995). This characteristic of rapid infiltration, however, appears to improve the

suitability of these soils in siphon systems and in arroyo

bank stabilization.

While water erosion processes are complex, as evidenced

by an abundant and growing amount of technical literature,

the principals of erosion control are often stated as these

relatively simple principles: Plant, plant residue, or mulch

cover should be increased in intensity or in time to decrease

energy and volume of run-off water. In the west, local

increase of recharge also may facilitate erosion control. The

rationale is this: Increased recharge results in increased

bank vegetation, and increased bank vegetation reduces

bank erosion. Bank erosion is a major contributor to the

sediment load in many western streams. Thus, increased

recharge from siphon systems is likely to reduce bank

erosion on appropriately selected stream banks.

References _____________________

Ankeny, M.D. and L.B. Sumrall. 1998. A siphon/infiltration gallery

design for increased recharge. Patent in Progress. U.S. Patent

and Trademark Office.

Bruins, J.J., M. Evenari, and U. Nessler. 1986. Rainwater-harvesting agriculture for food production in arid zones: the challenge of

the African famine. Appl. Geography. 6:13-32.

Jenny, H. 1980. The Soil Resource. Springer-Verlag, New York.

Menzel, B.W. 1983. Agricultural management practices and the

integrity of instream biological habitat. pp. 305-329, in Agricultural Management and Water Quality, F.W. Schaller and G.W.

Bailey, eds. Iowa State University Press. Ames, IA.

National Research Council. 1993. Soil and Water Quality: An

Agenda for Agriculture. National Academy Press. Washington,

D.C.

Prieksat, M.A., T.C. Kaspar, and M.D. Ankeny. 1994. Positional

and temporal changes in ponded infiltration in a corn field. Soil

Sci. Soc. Am. J. 58:181-184.

Pruess, 1991. TOUGH-2: A general purpose numerical simulator

for multiphase fluid and heat flow. LBL-29400, Lawrence

Berkeley Laboratory, Berkeley, CA.

Stephens, D.B. 1995. Vadose Zone Hydrology . Lewis Publications,

Boca Raton, FL. 347 pp.

Tabor, J.A. 1995. Improving crop yields in the Sahel by means of

water-harvesting. J. of Arid Environments. 30:83-106.

Wills, W.H. 1988. Early prehistoric agriculture in the American

southwest. 188 pp. School of American Research Press,

Santa Fe, NM.
USDA Forest Service Proceedings RMRS-P-7. 1999 135

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Joanne Mount is a Biologist with the Rocky Mountain Research Station,

Albuquerque, NM.

Abstract—This on-going study will provide data on changes in

vegetation in the Middle Rio Grande since 1984.

One of the first activities of the Bosque Initiative was a

pilot project initiated in June of 1995 by the Army Corps of

Engineers to determine if there had been a change in stand

structure and species composition of the Bosque since 1984.

It was decided from this project that significant change had

occurred to warrant further investigation of the entire Middle

Rio Grande.

This project includes vegetation between the levees from

Cochiti Dam to Elephant Butte Reservoir and the entire

flood plain from the south boundary of Bosque Del Apache

National Wildlife Refuge to }dry land road.~ The riparian

forest consists of approximately 42,020 acres and is 232 river

miles in length.

There are two main objectives. The first is to record change

in stand structure and species composition since the 1984

Hink and Ohmart Middle Rio Grande Biological Survey. The

Hink and Ohmart Biological Survey was done to identify the

major types of riparian habitat and to characterize the

vegetation and terrestrial vertebrate communities of each

type.

The second objective of the this project is to update

information on stand structure and species composition of

the riparian vegetation and to produce a map that will be

available to cooperating agencies. These include:

Bosque Improvement Group

U.S. Fish and Wildlife Service

Rocky Mountain Research Station

U.S. Forest Service, Region 3

Bureau of Reclamation

Army Corps of Engineers

Isleta Pueblo

Santa Ana Pueblo

Middle Rio Grande Conservation District

Vegetation Classification on the Middle Rio

Grande

Joanne Mount

Aerial photography was flown May 1995, October 1996

and May 1998 at a scale of 1:400. Stand structure and

vegetation composition are evaluated using the same methodology Hink and Ohmart used in the 1984 Middle Rio

Grande Biological Survey. Six categories are identified based

on height of overstory and understory vegetation volume.

Polygons are field verified for accuracy using a standard

50x25 meter rectangular plot with a 25-meter line transect.

The species composition is evaluated from a threshold of 25

percent or more.

Vegetation polygons are delineated and transferred to

Orthophoto base maps. These base maps are projected in

UTM (zone 13), datum:NAD 27, spheroid:Clark 1866, at a

scale of 1:400. The base maps are edited using Unix LT4X

and are then imported into ARC/INFO. The finished product

will be available in an ARC/INFO data base. The river will

be represented by three reaches: Albuquerque, Isleta and

Socorro.

Results will provide participating river management agencies a valuable diagnostic tool that describes the existing

vegetation composition and stand characteristics of the

Middle Rio Grande from Cochiti Lake to Elephant Butte

Reservoir.

Acknowledgments ______________

The author thanks the U.S. Fish and Wildlife Service,

and the Bureau of Land Management, and the Albuquerque

Corps of Engineers for funding this project. In particular, I

thank Jeff Whitney and Debbie Finch for their support.
136 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Ondrea C. Linderoth is Natural Resource Planner, City of Albuquerque,

Open Space Division, Albuquerque, NM.

Abstract—Restoration techniques for riparian habitats in the

Southwest are being widely studied. Efforts for natural regrowth of

native species are a high priority. Techniques for native cottonwood

(Populus fremontii) regeneration are being investigated in the

Rio Grande Valley State Park. Experimentation with flooding of

riparian zones using different techniques is beginning to show

promising results.

The Rio Grande Valley State Park (RGVSP) is a 5000 acre

park in the greater Albuquerque area of New Mexico (fig. 1).

The Park is managed by the City of Albuquerque, Open

Space Division (OSD) in coordination with the Middle Rio

Grande Conservancy District. Other agencies with jurisdiction of the river area include the Bureau of Reclamation

and the Army Corp of Engineers. These agencies, as well as

others, have collaborated on many projects to restore and

enhance the bosque in this stretch of the middle Rio Grande.

Different techniques for restoration in the Park are being

coordinated and/or implemented by OSD.

Cottonwood Pole Planting ________

The cottonwood pole planting program which is implemented by the OSD, Operations & Maintenance Section, has

been successfully running for the last ten years. This program continues to grow in size and success every year.

Monitoring of these poles has shown an approximate 90

percent success rate. Almost 1000 poles are planted in the

State Park every year. An estimated 10,000 poles have been

installed to date.

Methods for installation include the “use of young trees

(2-4 years) found growing in riparian areas which can be

transplanted or utilizing young trees grown by nurseries for

installation” (Barron, 1995). This young stock is utilized

when dormant and placed in pre-drilled holes in the riparian

area. The holes must be drilled to the groundwater table. A

single pole is placed into the hole and pushed through until

it is touching the water. Poles are then protected using

woven wire wrapping. This material protects the young

tree from potential predators such as beaver.

Restoration Efforts in the Rio Grande Valley

State Park

Ondrea C. Linderoth

Experimental Microirrigation

Project ________________________

Open Space is working in coordination with the USDA,

Natural Resource Conservation Service (NRCS), Plant Material Center on an experimental plot in the RGVSP. NRCS

established an experimental microirrigation site on the

west side of the river near the Calabacillas Arroyo and has

been monitoring the site since 1997. This is a one-acre study

site with approximately three fourths of the site being

enclosed by a fence. The site is irrigated through a well

system utilizing three types of microirrigation. Weed control

was performed by hand and “cottonwood seedlings were

sprayed monthly from August to October 1997 to control

cottonwood leaf beetle” (USDA, NRCS, 1997).

The site has proven to be successful in generating native

cottonwood seedlings by keeping the soil moist during seed

dispersion. “Over 12,500 seedlings were established at this

one-acre site by October 1997" (USDA, NRCS, 1997). Due to

this success, an additional site is being created on the east

side of the river.

Ground Level Manipulation _______

A new concept that was implemented during the restoration of a burned site was to include sculpting of the ground

level to partially inundate the area with ground water when

the river is running high. This area, called the Zoo Burn site,

is located on Tingley Drive on the east side of the river behind

the Zoo. This treatment allowed the cottonwoods, willows,

seepwillows, and other species that were planted at the

Zoo Burn site to be closer to the water source and establish

more successfully. The area is partially flooded during high

water and native wetland species have been planted and

established in this ‘moist soil’ area. The site is now in its

second season and all species that were planted as well as

volunteer native species are thriving. Because of the ‘wetness’ of the site, migratory bird species are also attracted to

the area and sandhill cranes have been viewed in the area.

Though no statistical or definitive information has been

collected at this time, observation of the progress of the sight

seems to show that his type of restoration is very successful.

Exotic Species Removal __________

Removal of exotic species is another management tool that

is being implemented in the RGVSP. In coordination with

the U.S. Army Corps of Engineers and the USDA Natural

Resource Conservation Service, a salt cedar removal project

was implemented in 1997 as mitigation for the Middle Rio

Grande Flood Protection: Bernalillo to Belen, New Mexico

levee rehabilitation project. Within the RGVSP, the project
USDA Forest Service Proceedings RMRS-P-7. 1999 137

took place on the west side of the river between Alameda

Blvd. and La Orilla channel. Three areas were treated for

removal of salt cedar and follow up spraying of Tamarisk

(Tamarix pentandra) seedlings as mitigation for the rehabilitation project; one at the La Orilla channel outfall, and

two on the east side of the river south of Paseo del Norte.

These areas have recently been replanted in 1998 with

native species.

The plan for this mitigation is spelled out in the Fish and

Wildlife Mitigation Plan of the Final Environmental Assess

non-native species within the project area. The techniques

followed for removal are as follows: Sites were chosen where

large patches of the exotic species, Tamarisk, existed. The

site was then cleared and grubbed “to remove the roots and

discourage re-sprouting” (ACOE, 1996). Follow up included

herbicide treatment of sprouts and removal of dead and

down material prior to replanting. The material that was

removed was burned on site. Replanting using cottonwood

poles occurred during the dormant season (January-April)

following the removal of Tamarisk. The mitigation will

Figure 1—Location map: Rio Grande Valley State Park, Albuquerque, NM.

occur over a three year period with 10 sites identified

throughout the RGVSP and the Corrales Bosque Preserve

just north of and adjacent to the RGVSP.

Created Wetlands _______________

The Alameda Wetland project is currently under construction at the Alameda/Rio Grande Open Space property at

the north end of the RGVSP. This property was jointly

purchased by the City of Albuquerque, Open Space and

Bernalillo County. Construction of a parking lot was completed in 1997 by Bernalillo County. The second phase of

activities for the site is the implementation of a created

wetland. The project is being constructed by the Bureau of

Reclamation, with additional funding from the U.S. Fish

and Wildlife Service for the liner, and Intel providing funding for wetland and upland plant species. Open Space is

planning and overseeing project implementation while providing additional funding. Open Space will manage and
138 USDA Forest Service Proceedings RMRS-P-7. 1999

maintain the wetland once it is completed. This will be a

five acre wetland created for increased habitat near the

RGVSP riparian zone.

Over the last 60 years, the Middle Rio Grande bosque has

lost approximately 85 percent of its wetland areas. This as

well as the increased population in the Albuquerque area,

has created pressures on habitat and the wildlife that dwell

within. Opportunities for projects of this kind will continue

to be investigated in the RGVSP to meet Open Space goals

to increase wildlife habitat.

Albuquerque Overbank Project ____

Open Space is one of the participants involved in a multiagency project to manipulate the riverbank to encourage

overbank flooding and, in turn, potentially foster natural

cottonwood generation. The Albuquerque Overbank Project

has been implemented in coordination with the Bureau of

Reclamation (lead agency), Middle Rio Grande Conservancy

District, University of New Mexico, New Mexico Natural

Heritage Program, and Open Space. The site is approximately 3 acres in size and is located on the west side of the

river north of Rio Bravo Blvd. The area has been successfully

prepared for natural overbank flooding by removing existing

non-native vegetation including Russian Olive (Elaeagnus

angustifolia) and Tamarisk (Tamarix pentandra). It was

felt that there was a need for action due to the decline of the

“ecological health of the bosque as reflected by exotic species’

invasions and reduced native stand vigor” (BOR, 1998).

From this, the need is to then understand how to reestablish

a healthy native riparian habitat. This is one of the few

geographical areas in the RGVSP that allowed an opportunity for overbank flooding without threat to private home

sites.

The project is currently being monitored for vegetation

populations and species diversity, groundwater level and

nutrient analysis, soil analysis, and surface water fluctuations. A draft outline has been compiled to date which will

be developed into a final report for distribution. The site is

currently receiving minimal flooding and the group is exploring options for release of additional waters.

Discussion _____________________

All of the projects discussed have had positive effects on

riparian restoration in the RGVSP. Techniques for providing moist soil or natural inundation by water in the riparian

zone are most successful in fostering native cottonwood

generation. Ongoing study of these projects and implementation of follow up or varying studies will help elaborate

which techniques or techniques are the most successful in

restoring native riparian habitat.

Acknowledgments ______________

The author wishes to thank the Middle Rio Grande

Conservancy District, Army Corp of Engineers, Bureau of

Reclamation, University of New Mexico, New Mexico Natural Heritage Program, Natural Resource Conservation

Service, Intel Corp. and the U.S. Fish and Wildlife Service

for their participation and support of these project studies.

References _____________________

Barron, Tony. 1995. Restoration guidelines for riparian areas

using dormant stock “pole” cuttings. City of Albuquerque, Open

Space Division, Albuquerque, NM. 4 p.

United States Army Corp of Engineers, Albuquerque District. 1996.

Revised Fish and Wildlife Mitigation Plan for Middle Rio Grande

Flood Protection: Bernalillo to Belen, New Mexico, Corrales Unit.

6 p.

United States Department of the Army, Natural Resources Conservation Service, Los Lunas Plant Materials Center. 1997.

Annual Interagency Riparian Report (1997) Eleventh Edition.

31 p.

United States Department of the Interior, Bureau of Reclamation.

1998. Draft Albuquerque Overbank Project. 2 p.
USDA Forest Service Proceedings RMRS-P-7. 1999 139

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Esteban Muldavin is Senior Research Scientist and Elizabeth Milford and

Yvonne Chauvin are Assistant Ecologists, New Mexico Natural Heritage

Program, Department of Biology, University of New Mexico, Albuquerque, NM.

Abstract—The Bureau of Reclamation routinely mows vegetation

on side bars along the Rio Grande to assist with river flow management. To address the question of how such mowing affects vegetation composition and structure, three bars in the middle Rio Grande

near Albuquerque, New Mexico were selected in 1994 for an experimental mowing program. Three 50-foot-wide strips on each bar

were left unmowed, with the area between the strips mowed as

usual. This mowing pattern was repeated in 1995 and 1996. In

August 1996, vegetation composition, abundance and structure

were measured under the two conditions of the treated bars and

at one additional bar with no history of mowing. Species composition and abundance were compared among sites and treatments

using ANOVAs and canonical discriminant analysis. The greatest

negative effect was on the native cottonwood where there were

significant declines of 70-90 percent on some sites with respect to

cover, stems and individuals. Mowing also reduces the exotic

Russian olive cover by 50-70 percent on sites where it is dominant.

Although cover may decline, Russian olive often responds by

resprouting and creating vigorous multiple-stemmed individuals.

Coyote willow was affected less by mowing; at the site with the most

willow cover (Belen), declines in both cover and the number of

individuals were only about 32 percent. This relatively higher

mowing tolerance may reflective coyote willow’s greater

adaptativeness to natural disturbances such as flooding. What is

clear however, is that regardless of what shrubs are dominant,

cottonwood is always the most negatively affected by mowing.

The Bureau of Reclamation (BOR) conducts mowing of

the vegetation on side bars along the Rio Grande to assist

with management of the river flow. Questions have arisen

about the effect of this mowing on vegetation composition

and structure. Are exotic species or natives affected by

mowing? Is there an effect on overall biodiversity? How is the

structure of shrub vegetation (stem number and size) affected? An experimental mowing and not-mowing program

was begun by the BOR in 1994 on three river bars in the

middle Rio Grande near Albuquerque, New Mexico. The

bars were treated in the winters of 1994, 1995, and 1996.

To evaluate the effects of mowing and not-mowing, the New

River Bar Vegetation Mowing Response in

the Middle Rio Grande

Esteban Muldavin

Elizabeth Milford

Yvonne Chauvin

Mexico Natural Heritage Program (NMNHP) measured

vegetation composition, abundance and structure at these

sites in the summer of 1996. Permanent monitoring sites

were established and the results from the first year’s sampling with respect to exotics and overall plant species

diversity and stand structure are reported here.

Methods and Materials ___________

Study Sites

In 1994, three river bar sites along the middle reach of

the Rio Grande near Albuquerque, New Mexico were selected for experimental mowing and not-mowing of vegetation. These sites had been subjected to ongoing mowing

by the BOR for a number of years. They are located from

north to south along the Rio Grande at the I-40, I-25 and

NM 6 (Belen) bridges, respectively (fig. 1 and 2). On February 21, 1994 each bar was mowed in such a way as to leave

three, 50-foot-wide strips unmowed with intervening mowed

vegetation. Each strip was marked with either rebar or

wooden stakes. The intervening areas were, on a continuing

basis, mowed the following winters of 1995 and 1996. The

style of mowing was not documented, but there are indications that mowers may have differentially treated cottonwoods by mowing around them in the treatment areas.

As a comparison, a site with no known history of mowing,

south of the Central Avenue bridge and parallel to Tingley

Beach, was included in the study. This site consists of a side

bar and an island bar. Thus, there are three sites with a

history of mowing that now contain strips of vegetation that

have not been mowed for three years, plus one site that has

never been mowed.

The I-40 site is located on the west bank of the river

between the Central and I-40 bridges. It is dominated by

Russian olive (Elaeagnus angustifolia) in the shrub layer,

with some younger cottonwoods (Populus deltoides var

wizlezenii) and seepwillow (Baccharis salicifolia). The understory is dominated by alkali sacaton (Sporobolus airoides)

with fair amounts of Baltic rush (Juncus balticus) and

saltgrass (Distichlis spicata) (fig. 3 and 4).

The unmowed side bar and island bar south of Central,

hereafter referred to as the Tingley Beach site, is located

on the east side of the river approximately a mile south of

the Central bridge. The side bar has one major and a few

smaller high-flow channels cutting through it. The nearby

island bar lies 20 meters to the northwest across a shallow

channel. It has a raised central portion, which is dominated

by shrubs, with lower areas at the edges and north and south

points dominated by grasses and alfalfa (Medicago sativa).
140 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 1—Map showing locations of I-40, Tingley Beach and I-25 study sites.
USDA Forest Service Proceedings RMRS-P-7. 1999 141

Figure 2—Map showing location of Belen study site.
142 USDA Forest Service Proceedings RMRS-P-7. 1999

Transects were only established on the higher portion of the

island bar, as this is area is more representative of the other

bars being examined. Both the bar and the island are

dominated by coyote willow (Salix exigua) in the shrub layer,

with the understory dominated by meadow fescue (Festuca

pratensis) (fig. 5 and 6).

The I-25 site is located on the west bank of the river

immediately south of the I-25 bridge across the Rio Grande,

and just north of Isleta Pueblo. In the spring of 1994 this site

was burned when the neighboring bosque caught fire. The

shrub layer is dominated by Russian olive with a fair amount

of coyote willow. The major understory plants are alkali

muhly (Muhlenbergia asperifolia), heath aster (Aster

ericoides), vine-mesquite (Panicum obtusum) and saltgrass

(fig. 7 and 8).

The Belen site at the NM 6 bridge is on the west bank of

the river just south of the bridge within Senator Willie M.

Chavez State Park. The dominant shrub is coyote willow

with more cottonwood and Russian olive than the Tingley

site. The understory is dominated by alkali muhly with

strong components of Nebraska sedge (Carex nebrascensis),

seepwillow, and Indianhemp (Apocynum cannabinum)

(fig. 9 and 10).

Figure 3—Photo of I-40 site, looking down the Line 2

control (unmowed) transect. Many Russian olives and

cottonwoods are now over three meters in height after

three years.

Figure 4—Photo of I-40 site, looking south across

Line 3 from the treatment (mowed) transect to the

control (unmowed) transect in the background. Russian olive is abundant and cottonwoods are scattered on this site.

Figure 5—Photo of Tingley side bar site, looking north at line

2. Heavy coyote willow cover is typical of this site with some

scattered cottonwood regeneration.

Figure 6—Photo of Tingley island bar site, looking northwest at the island from the side bar. The central raised

portion of the island is dominated by coyote willow.
USDA Forest Service Proceedings RMRS-P-7. 1999 143

Figure 7—Photo of I-25 site, looking down Line 2 treatment

(mowed) transect showing heavy Russian olive shrub cover

typical of this site.

Figure 8—Photo of I-25 site, looking south across Line 2 from

the treatment (mowed) transect to the control (unmowed)

transect in the background. The mix of coyote willow and

Russian olive is typical of mowed transects at this site. This

area was burned in the spring of 1994.

Figure 9—Photo of Belen site, looking down Line 1

control (unmowed) transect showing heavy coyote

willow cover.

Figure 10—Photo of Belen site, looking south across

Line 1 from the treatment (mowed) to control (unmowed)

transect in the background. Heavy coyote willow cover

with scattered cottonwoods is typical of this site.
144 USDA Forest Service Proceedings RMRS-P-7. 1999

Sampling Methods

To measure vegetation composition and structure, permanent vegetation monitoring transects were established on

all four sites. The mowed and unmowed strips were relocated from maps, field marks, and with the aid of BOR

personnel. On the three experimentally mowed sites, a

transect line was established down the center of each of the

three unmowed strips, with three comparison transects

established in the mowed adjacent areas, for a total of six

transects per site. The mowed transects were always placed

to the north of their unmowed mate. Also, three transect

lines each were established at the unmowed side bar and

island sites. Transect pairs were numbered one to three,

working north to south, and labeled C or T for control

(unmowed) or treatment (mowed). From this point forward

mowed transects are referred to as “treatment” and unmowed

transects as “control”.

All transects were permanently marked at each end with

a meter length of rebar driven into the ground with about a

third of the length showing, then covered with white PVC

pipe. Metal identification tags where attached to the start

rebar of each transect. The rebar locations were recorded

with a Global Positioning System (GPS) unit and differentially corrected to +/- 5 meters (UTM). Photos were taken

along the transects from each end along with representative

photos taken of each site and are provided in a supplementary folder.

Beginning at a randomly placed start-point on the transect

lines, one meter square quadrat frames were placed on the

upstream side of the transect lines at regular intervals,

ensuring 10 quadrats per transect line for a total of 30 per

treatment and 30 for control at each site.

In each quadrat, for each shrub species, the number of

stems in 5 cm diameter root crown (DRC) classes were

counted and the average height by DRC class estimated.

Stem numbers were counted from the root-crown, and individuals were estimated on proximity of emergent stems.

Additionally, the aerial cover of all vascular plant species

was estimated using a modified Krajina cover scale (table 1).

Sampling was performed August 13-23, 1996, at the end

of the peak of the growing season.

Analysis

Data were entered into the NMNHP data system following NMNHP quality control protocols, then analyzed using

the SAS statistical package versions 6.11 for aix (SAS 1990).

Species identifications were confirmed from the voucher

specimens, and the specimens were deposited at the University of New Mexico herbarium.

Species composition and abundance were compared among

sites and treatments, particularly with respect to exotic

versus native species. Analysis of variance (ANOVA) was

used to compare the average cover, number of stems and

number of individuals per quadrat for the most common

shrub species across site, treatments type and site/treatment type combined. ANOVA was also used to compare the

most common understory species across site, treatment type

and site/treatment types combined. Pair-wise comparisons

were made using Fisher’s Least Significant Difference (LSD)

means test (Sokal and Rohlf 1981).

Species diversity was assessed with three different indices. Species richness was evaluated from the direct counts of

species number per transect, a method considered valid

when samples are of equal size (Ludwig and Reynolds,

1988). The modified Hill’s ratio evenness index (E5) was

used to assess species evenness. Hill’s N1 diversity index,

which estimates the number of abundant species present,

was used to assess species diversity (Ludwig and Reynolds,

1988).

To evaluate overall relationship among sites and species,

multivariate canonical discriminant analysis was performed

on both the shrubs and understory species for site/treatment

type combined. Canonical discriminant functions optimize a

linear combination of the original variables to maximize

discrimination among groups. The correlation between the

canonical functions and the original variables can be determined and is reported as an among-group canonical structure. This structure can then be used in a way similar to

correlation coefficients to evaluate the importance of each

original variable in discriminating among groups.

Results ________________________

There were 67 species encountered in the study. The top

three shrubs (Russian olive, Rio Grande cottonwood and

coyote willow) and the top seven grasses and forbs were

selected for univariate Analysis of Variance (ANOVA) and

multivariate canonical discriminant analysis. ANOVA results indicated that there were significant differences among

sites and treatments with respect to species cover, stems and

individuals. Pair-wise comparisons between treatment and

control are treated below followed by a summary analysis

using canonical discriminant analysis.

Shrubs: Russian Olive, Cottonwood, and

Coyote Willow

The sites show a range of variation with respect to overall

shrub species composition and cover, irrespective of treatment (tables 2-4) The I-40 site is strongly dominated by

Russian olive with only minor amounts of willow (table 2).

Table 1—Modified Krajina scale used to estimate aerial

cover of all vascular plant species.

Percentage

Symbol cover Scaler

Percent

+0 N/A Outside quadrat

+ N/A Solitary or very few

1 <0.1 Seldom cover

2 <1 Very scattered

3 1-4

4 5-10

5 10-25

6 25-33

7 33-50

8 50-75

9 >75

10 100
USDA Forest Service Proceedings RMRS-P-7. 1999 145

Table 2—Russian olive means and standard deviations by site and treatment for percent cover, average number of individuals and average number

of stems per quadrat. The significant difference row indicates if the LSD showed a significant difference between the treatment and the

control of the given site for species means. * = significantly different; NS = not significantly different.

I-40 I-40 I-25 I-25 Belen Belen Tingley Tingley

Russian olive control treatment control treatment control treatment side bar island bar

Cover

Mean 64.1 25.9 53.7 21.6 13.7 6.77 0.002 3.97

Standard deviation 41.1 29.2 35 23.5 27.9 15.2 0.009 16.6

Significant pair difference * * NS NS

Number of individuals

Mean 0.8 0.667 0.717 0.183 0.15 0.2 0.033 0.033

Standard deviation 1.13 1.0 0.838 0.359 0.494 0.596 0.183 0.183

Significant pair difference NS * NS NS

Number of stems

Mean 2.83 4.87 7.9 2.53 0.867 1.2 0.033 0.033

Standard deviation 4.19 8.79 9.14 6.42 2.37 3.69 0.183 0.183

Significant pair difference NS * NS NS

Table 3—Coyote willow means and standard deviations by site and treatment for percent cover, average number of individuals and average number

of stems per quadrat. The significant difference row indicates if the LSD showed a significant difference between the treatment and the

control for the given site for species means. * = significantly different; NS = not significantly different.

I-40 I-40 I-25 I-25 Belen Belen Tingley Tingley

Coyote willow control treatment control treatment control treatment side bar island bar

Cover

Mean 0.585 0.5 19.7 25.4 58.8 38.6 68.4 50.2

Standard deviation 3.2 1.9 31 27.9 23.3 26.7 27.6 29.9

Significant pair difference NS NS * *

Number of individuals

Mean 0.017 0.033 1.1 1.15 5.3 3.43 4.22 5.78

Standard deviation 0.091 0.183 1.32 1.5 2.14 1.92 2.87 3.18

Significant pair difference NS NS * *

Number of stems

Mean 0.133 0.133 9.2 10.8 15.6 13.4 19.1 19.3

Standard deviation 0.73 0.73 14.9 13.7 9.91 10.4 14.5 13.5

Significant pair difference NS NS NS NS

Table 4—Cottonwood means and standard deviations by site and treatment for percent cover, average number of individuals and average number

of stems per quadrat. The significant difference row indicates if the LSD showed a significant difference between the treatment and the

control for the given site for species means. * = significantly different; NS = not significantly different.

I-40 I-40 I-25 I-25 Belen Belen Tingley Tingley

Cottonwood control treatment control treatment control treatment side bar island bar

Cover

Mean 9.33 1.47 0 0 12.8 3.55 2.52 0.752

Standard deviation 24.4 7.58 0 0 18.1 12.4 9.07 1.63

Significant pair difference * NS * NS

Number of individuals

Mean 0.067 0.033 0 0 0.5 0.133 0.083 0.4

Standard deviation 0.286 0.183 0 0 0.965 0.49 0.265 0.77

Significant pair difference NS NS * NS

Number of stems

Mean 0.167 0.067 0 0 1.13 0.3 0.133 0.4

Standard deviation 0.747 0.365 0 0 2.45 1.29 0.434 0.77

Significant pair difference NS NS * NS
146 USDA Forest Service Proceedings RMRS-P-7. 1999

In contrast, the unmowed Tingley Beach site is dominated

by coyote willow and lacks significant Russian olive (table 3).

The I-25 site is also dominated by Russian olive, but has a

significant component of willow intermixed in the canopy.

Similarly, the Belen site is dominated by willow, but has a

significant amount of Russian olive. There was an overall

differential distribution of cottonwoods as well. They were

well represented at the I-40 site, common at the Belen site,

scattered at the Tingley Beach site, and absent at I-25 site.

Similar site trends were also evident in terms of number of

stems and individuals (tables 2-4).

Regardless of these site differences, there are still several

within-site treatment effects that are apparent on a pairwise basis. It appears that the mowing affected cottonwood

more than the exotic Russian olive, and that coyote willow

was least affected. Generally, the controls (unmowed) had

higher shrub cover, particularly for Russian olive and cottonwood, and less so for willow.

For Russian olive, cover significance declined between

50-60 percent relative to the unmowed transects on the I-40

site and I-25 sites where it was most abundant to begin with,

and the same trend is indicated at the Belen site (table 2).

But there was a differential response with respect to stems

and individuals; on the I-40 site despite the reduction in

cover, the number of individuals did not significantly decline

and there is a suggestion that the number of stems may have

increased with mowing. On the I-25 site Russian olive

individuals and stems did decline, but this confounded by

the intense burn that occurred on the site in 1994. The

combination of mowing and burning may negatively impact

Russian Olive.

Coyote willow cover was not as strongly affected by mowing. Treatment effects were only significant at the Belen

site, with a decline 35 percent in willow cover, and a commensurate decline in the number of individuals on mowed

transects, but the number stems actually increased. The I25 site had a fair amount of willow, but no treatment effect

was detectable. There was also a minor difference at the

untreated Tingley Beach sites with the island showing

slightly less cover for willow, but more stems. More than

likely this reflects the younger age class of willows on the

island with a greater number of stems, but less canopy for

their size.

Cottonwood showed significant declines (70-90 percent)

with mowing at both the Belen and I-40 sites. The same

trend was evident for stems and individuals, but was only

significant at the Belen site. No cottonwoods were present on

the I-25 site, most likely due to the high mortality following the 1994 fire. The Tingley site cottonwoods showed a

similar pattern to the willows, with a significant increase in

stems on the island site and a corresponding trend of lower

cover, which was probably related to stand age.

Herbaceous Cover and Diversity

On a site basis, there were several differences with respect

to understory species dominance. Meadow fescue was abundant and dominated the Tingley Beach site, and was uncommon or absent at the other sites. There was also significantly

higher cover of fescue on the island bar than on the side bar.

Alkali muhly was a common associate, but never dominant.

In contrast, alkali muhly dominated the Belen site along

with Nebraska sedge. Alkali muhly was also a dominant on

the I-25 site, but this time co-occurring with inland saltgrass,

with a significant component of heath aster. Alkali sacaton

was the primary dominant on the I-40 site with both inland

saltgrass and alkali muhly as common co-dominants, and on

the controls, Baltic rush and Nebraska sedge.

On a pair-wise analysis of treatment affects, there was a

trend towards increasing grass cover with mowing (table 5).

On the I-40 site, Alkali sacaton showed a strong, significant

increase in cover and dominance with mowing; on the control

sites it was a co-dominant with cover comparable to other

graminoid species. Baltic rush tended to decrease on mowed

transects, significantly so at the I-40 site. Nebraska sedge,

although it showed a decrease on mowed transects at I-40,

increased on mowed transects at Belen, and there was no

overall significant difference between treatment and control. Inland saltgrass response was also equivocal; it dramatically increased with mowing on the I-25 site, but declined somewhat at the I-40 site. The common forb, heath

aster, was most abundant at the I-25 site and showed a

significant decrease on mowed transects. On other sites it

was not abundant enough to detect a treatment effect.

With respect to diversity measures, there was only a

slight indication of direct treatment effect with decreasing

species richness (total number of species) with mowing

(table 6). This was mostly evident at the Belen site, and in

the comparison of all sites to the Tingley Beach site. The

never-mowed Tingley Beach site had the highest species

richness over all sites. Only the Belen controls had a similar

number of species. With respect to the number of very

abundant species (N1) and abundant species (N2), no strong

patterns emerge. There is an indication that the I-40 site

was not only lower in diversity, but tended to have fewer codominants as indicated by the lower N1 and N2 values in

comparison to other sites. But overall, the ratio N2 to N1 as

represented by E5 indicates that abundance was relatively

evenly distributed among all sites except Tingley Beach

Site. This may reflect the strong dominance at this site by

willows with a diverse but lower cover understory.

An Overview with Canonical Discriminant

Analysis

The canonical discriminant analysis of shrub cover of

Russian olive, cottonwood, coyote willow and salt cedar

demonstrated the overall differences between sites and

treatments. Only the first two canonical functions were

significant, with eigenvalues greater than 1.0, and accounted

for 92.3 percent of the variation (table 7). Figure 11 is a

graphical representation of the distribution of centroids

(collective means) of the site/treatment combinations with

respect to these first two functions. Function 1 accounts for

77.2 percent of the variation and is primarily responsible for

separating sites. The canonical structure indicates that

Russian olive and coyote willow cover are the primary

discriminators along this axis, with salt cedar as a minor

element (table 7). There is some overlap between I-25 Control and I-40 treatment (they have similar covers for Russian

olive), and between Belen Control and Tingley Beach Island

(they have similar willow cover). Function 2 serves to

separate treatment and controls, but only accounts for
USDA Forest Service Proceedings RMRS-P-7. 1999 147

Table 5—Average herbaceous and graminoid percent cover per quadrat by site and treatment. The significant difference row indicates if the

LSD showed a significant difference between the treatment and the control for the given site for species means. * = significantly different;

NS = not significantly different.

I-40 I-40 I-25 I-25 Belen Belen Tingley Tingley

Grasses and forbs control treatment control treatment control treatment side bar island bar

Heath aster

Mean 0 0 27.4 15.6 0.333 0.002 0.25 0.417

Standard deviation 0 0 31.4 17.6 1.43 0.009 0.763 1.48

Significant pair difference NS * NS NS

Inland saltgrass

Mean 10.9 2.22 5.52 20.7 0 0 0 0

Standard deviation 26.5 8.17 10.6 20.4 0 0 0 0

Significant pair difference * * NS NS

Meadow fescue

Mean 0000 0.967 0 5.05 26.6

Standard deviation 0000 5.29 0 17.5 33.3

Significant pair difference NS NS NS *

Alkali muhly

Mean 3.5 6.68 21.1 22.4 25.8 30.5 2.89 2.42

Standard deviation 16.2 17.4 20.4 17.2 18.7 27.9 8.53 4.71

Significant pair difference NS NS NS NS

Alkali sacaton

Mean 7.6 34.6 1.25 0 0 0.167 0.337 0

Standard deviation 18.1 32.7 4.44 0 0 0.634 1.43 0

Significant pair difference * NS NS NS

Baltic rush

Mean 13.1 0 0 0 3.02 0.002 0.417 0

Standard deviation 25.1 0 0 0 10.5 0.009 1.48 0

Significant pair difference * NS NS NS

Nebraska sedge

Mean 3.5 0 0 0 16.2 20.1 0 0

Standard deviation 15.9 0 0 0 22.4 34.7 0 0

Significant pair difference NS NS NS NS

Table 6—Average number of species, Hill’s evenness and diversity index per transect by site/treatments.

Hills diversity I-40 I-40 I-25 I-25 Belen Belen Tingley Tingley

 indices control treatment control treatment control treatment side bar island bar

N0 (Number 11.0 9.67 13.7 13.3 18.0 13.7 19.7 18.3

of Species)

N1(very abundant 5.15 5.78 8.27 8.29 9.55 6.39 5.13 7.50

species)

N2 (abundant 4.30 5.09 6.92 7.34 8.19 5.26 3.38 5.45

species)

E5 0.799 0.856 0.811 0.875 0.843 0.784 0.533 0.686

(evenness)

Table 7—Shrub cover canonical between group

correlation structure for the two significant

canonical discriminant analysis (CDA)

functions.

CDA CDA

 Species function 1 function 2

Russian Olive –0.91 0.39

Cottonwood 0.03 0.71

Coyote Willow 0.97 0.22

Salt Cedar 0.58 -0.25

Eigenvalue 1.39 0.27

% of variation 77.2 15.1

Cumulative % 77.2 97.3
148 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 11—Shrub canonical discriminant analysis

(CDA) site/treatment centroid position on functions 1

and 2. I40C = I-40 control transects; I40T = I-40

treatment; TBAR = Tingley side bar; TISL = Tingley

island bar; I25C = I-25 control; I25T = I-25 treatment;

BELC = Belen control; BELT = Belen treatment.

Figure 12—Forb and graminoid canonical discriminant

analysis (CDA) site/treatment centroid position on functions 1 and 2. I40C = I-40 control transects; I40T = I-40

treatment; TBAR = Tingley side bar; TISL = Tingley island

bar; I25C = I-25 control; I25T = I-25 treatment; BELC =

Belen control; BELT = Belen treatment.

Table 8—Herbaceous and graminoid cover canonical

between group correlation structure for the three

significant canonical discriminant analysis (CDA)

functions.

 Species CDA 1 CDA 2 CDA 3

Cuman ragweed 0.58 –0.21 0.27

Indianhemp –0.16 –0.37 0.72

Heath aster 0.94 0.25 –0.09

Seepwillow –0.43 0.02 0.62

Nebraska sedge –0.2 –0.42 0.86

Thymeleaf sandmat –0.46 0.16 –0.35

Canadian horseweed 0.73 –0.18 –0.34

Inland saltgrass 0.57 0.31 –0.03

Smooth horsetail –0.09 –0.47 –0.69

Meadow fescue –0.23 –0.5 –0.68

Baltic rush –0.18 0.04 0.03

Alkali muhly 0.48 –0.14 0.81

Vine mesquite 0.93 0.23 –0.04

Russian thistle –0.49 0.81 –0.01

Indian grass 0.56 0.27 0.18

Alkali sacaton –0.51 0.85 –0.02

Eigenvalue 1.88 1.43 1.16

% of Variation 33.6 25.5 20.8

Cumulative % 33.6 59.1 80

15.1 percent of the variation. The strong difference between

treatment and control at the I-40 and Belen sites is evident

and driven primarily by the difference in cottonwood cover

and secondarily by Russian olive. Neither willow nor salt

cedar appear to be very important discriminators.

The discriminant analysis based on understory herbaceous cover is less clear. There were three significant functions derived from the basis of 16 species’ cover values. The

I-25 site is clearly isolated along the positive end of the

function 1 axis (fig. 12). This is primarily a result of positive

correlations for heath aster and vine mesquite (Panicum

obtusum), and to a lesser degree for Canadian horseweed

(Conyza canadensis), Indian grass (Sorgastrum nutans) and

alkali muhly. Conversely, the I-40 treatment is found on the

far negative end of the axis primarily as a result of high

alkali muhly and alkali sacaton cover. The I-40 treatment is

further separated along the second axis by alkali sacaton,

and to a lesser degree Russian thistle (Salsola kali) (table 8).

Axis 2 also isolates the Belen and Tingley Beach sites on

the negative side as a function of negative loading on meadow

fescue, smooth horsetail (Equisetum arvense) and Nebraska

sedge. The only noticeable treatment effect in functions 1

and 2 is for the I-40 site, and it is primarily driven by high

grass cover on the treatments. There are a few limited

treatment effects apparent along canonical axis 3 for the

Belen site and I-25 site (fig. 13). These differences are driven
USDA Forest Service Proceedings RMRS-P-7. 1999 149

Figure 13—Forb and graminoid canonical discriminant

analysis (CDA) site/treatment centroid position on functions 1 and 3. I40C = I-40 control transects; I40T = I-40

treatment; TBAR = Tingley side bar; TISL = Tingley island

bar; I25C = I-25 control; I25T = I-25 treatment; BELC =

Belen control; BELT = Belen treatment.

primarily by differential cover of Nebraska sedge and alkali

muhly. For the Tingley Beach site, there was a slight difference between the island and the sidebar, primarily driven

by relative meadow fescue and smooth horsetail cover.

Discussion _____________________

Mowing has a differential impact on various species,

which is highly apparent on some cases regardless of specific

site conditions. The greatest negative effect was on the

native cottonwood, where there were significant declines on

some sites with respect to cover, stems and individuals.

Mowing also reduces the exotic Russian olive cover, but not

as effectively as it reduces the cottonwood. In contrast to

cottonwood, Russian olive seems to respond well in some

cases by resprouting and creating vigorous multi-stemmed

individuals. The native coyote willow does not seem to be

very affected by mowing or not mowing. However at Belen,

the one mowed site strongly dominated by willow, willow

cover and number of individuals was reduced by about a

third. Since coyote willow is a disturbance-adapted species

it is not surprising that it shows less effect from the mowing

then the other two later successional stage species, and

that it may even respond positively to mowing. What is clear

is that regardless of which other shrubs were dominant,

cottonwood was always the shrub most negatively affected

by mowing.

The general trend for the grass cover to increase on mowed

transects is not surprising, since mowing, by reducing the

shrub cover, increases the amount of light available to the

understory. However, in many cases the increase in understory cover on mowed transects was not very great, and is

rarely statistically significant. For the one common forb and

the common rush and sedge, cover actually decreased on

mowed transects, in two cases significantly so. The rush and

the sedge are both native wetland obligate species, and their

decrease could indicate a negative impact on wetland quality as a result of the mowing.

Mowing may be having a negative effect on overall species

richness as indicated by the high species richness at the

unmowed Tingley sites and by the tendency for unmowed

transects to have higher average species richness than

mowed transects at the same site. The dominant shrub

species at a site also appears to be a factor in species

richness, as species richness was lower on those sites with

higher Russian olive cover (I-25 and I-40).

Evenness appears to increase on mowed transects, at least

at the two sites dominated by Russian olive (I-25 and I-40).

However, at the Belen site the unmowed transects had

higher species evenness. The never-mowed Tingley Beach

site had the highest species richness but the lowest species

evenness; this indicates that mowing is increasing species

evenness by reducing less-common species and favoring an

even distribution of common ones.

Hill’s N1 diversity index measures species diversity by

combining species richness and evenness to produce an

estimate of the number of abundant species. Since it combines richness and evenness and since these showed opposite trends, it is not surprising that the sites intermediate on

both were the ones that showed the highest diversity. In fact,

the sites highest in average Hill’s N1 diversity index, I-25

and Belen, were also the ones intermediate not only in

species richness and evenness, but also in dominant shrub

species.

The greatest difference in exotic versus native species is

more related to the differences between sites, rather than to

direct treatment effects. The difference between sites is

especially marked when comparing the I-40 and I-25 sites to

the Belen and Tingley sites; the first two being strongly

dominated by Russian olive and the second two by coyote

willow. The differences between these sites may be due to

differences in soil moisture and possible flooding disturbance. The two willow sites may be lower in elevation and

thus flooded more frequently and have wetter soils at depth.

Furthermore, the I-25 site was burned in the spring of 1994,

providing an additional variable that may be affecting species composition and abundance.

The conclusions drawn here are based on a very limited

sample of sites and replications within sites, and on the basis

of only one reading after three years of treatment. Continued, effective and uniform treatment may enhance differences in the future. Adding additional sites with treatments

will also help further isolate environmental characteristics

from treatment effects. At the same time, there should be

more detailed comparative studies on soils, landforms, hydrology and fire history done in order to make effective and

definitive statements about the causes of differences in

species composition, dominance and the overall structure in

relation to mowing.
150 USDA Forest Service Proceedings RMRS-P-7. 1999

Acknowledgments ______________

Support for this work was provided through Cooperative

Agreement No. 6-FC-40-19890 between the Bureau of Reclamation, Albuquerque Office and the New Mexico Natural

Heritage Program, Biology Department, University of New

Mexico, Albuquerque, NM.

References _____________________

Ludwig, J.A., and J.F. Reynolds. 1988. Statistical Ecology: A Primer

on Methods and Computing. John Wiley and Sons, New York.

SAS/STAT User’s Guide. Version 6, Fourth edition. 1990. SAS

Institute Inc. Cary, North Carolina, U.S.A.

SCS. 1995. Plants Database. USDA Soil Conservation Service,

Washington D.C.

Sokal, R.R., and F.J. Rohlf. 1981. Biometry: The Principles and

Practice of Statistics in Biological Research. W.H. Freeman and

Co., San Francisco.
USDA Forest Service Proceedings RMRS-P-7. 1999 151

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

David R. Dreesen is Agronomist, and Gregory A. Fenchel is Plant Materials Center Manager, USDA-Natural Resources Conservation Service, Los

Lunas Plant Materials Center, 1036 Miller St. SW, Los Lunas, NM 87031.

Joseph G. Fraser is Senior Research Specialist, New Mexico State University,

Agricultural Science Center, 1036 Miller St. SW, Los Lunas, NM 87031.

Abstract—Flood control, irrigation structures, and flow control

practices on the Middle Rio Grande have prevented the deposition

of sediments and hydrologic conditions conducive to the germination and establishment of Rio Grande cottonwood (Populus fremontii

S. Wats.). The Los Lunas Plant Materials Center has been investigating the use of micro-irrigation systems on xeric flood plain sites

to promote regeneration from natural cottonwood seed dispersal.

The initial study showed no establishment benefits resulting from

organic–rich substrates versus indigenous mineral surface soil. In

the second study, three emitter types (53 L/hr spitter, 14 L/hr

spitter, 24 L/hr bubbler) produced mean wetted soil surface areas of

2.7, 0.58, and 0.33 m2, respectively, and median seedling counts per

plot of 70, 29, and 16, respectively. In the initial study, the plots with

the greatest cottonwood seedling density after one growing season

contained 22 seedlings/m2 (15 cm height) without weed control

(infested with Kochia scoparia (L.) Roth) and 86 seedlings/m2 (69 cm

height) with weed control. Primary weed pests in the second study

were Tamarix, Cenchrus, and Artemisia species; weed infested plots

had 35 to 45 percent fewer seedlings than plots with weed control

after one growing season. Technology development will concentrate

on reducing labor costs for irrigation operation and weed control, the

major costs in applying this technology. Micro-irrigation technology

offers an alternative method of managed cottonwood regeneration for sites where flood irrigation or pole plantings are not

practical because of economic, engineering, water use, or jurisdictional constraints.

Flood control and irrigation structures as well as flow

control practices on the Middle Rio Grande have drastically

altered sediment deposition and soil moisture conditions on

the flood plain. These changes have prevented the necessary

soil conditions and water regimes required for the regeneration of Rio Grande cottonwood (Populus fremontii S. Wats.)

and other riparian trees and shrubs on flood plain sites

remote from the river channel (Whitney 1996). The lack of

regeneration of the dominant native trees, the spread of

Establishment of Rio Grande Cottonwood

Seedlings Using Micro-irrigation of Xeric

Flood Plain Sites

David R. Dreesen

Gregory A. Fenchel

Joseph G. Fraser

exotic woody species (Tamarix spp. and Elaeagnus

angustifolia L.), and the perturbation in ecosystem function attributable to the lack of flooding has resulted in a

rapid decline in the health of the riparian cottonwood forest

(Dick-Peddie 1993, Crawford and others 1996).

The Los Lunas Plant Materials Center (USDA-NRCS) has

been investigating techniques to reestablish the dominant

native trees and shrubs in these degraded riparian cottonwood forests for the past 15 years. These efforts have been

made in cooperation with federal (Army Corps of Engineers,

Bureau of Reclamation, Bureau of Land Management,

Fish and Wildlife Service, Bureau of Indian Affairs), state

(Park and Recreation Division, Game and Fish Department)

and local agencies (Albuquerque Open Space Division).

Throughout the 1980’s and early 1990’s, these efforts focused on enhancing the success of pole plantings of Rio

Grande cottonwood, Goodding’s willow (Salix gooddingii

Ball), and coyote willow (Salix exigua Nutt.). Recent studies

have investigated the use of pole plantings to establish

important shrub species of the cottonwood riparian forest

including false indigo (Amorpha fruticosa L.), New Mexico

olive (Forestiera neomexicana Gray), and seepwillow

(Baccharis spp.). In the past several years, we have redirected much of our research into investigating methods to

establish Rio Grande cottonwood seedlings by supplementing surface soil moisture using micro-irrigation techniques.

The existing riparian cottonwood forest disseminates

massive quantities of viable seed within the flood plain of

the Rio Grande. Soil moisture conditions conducive to the

germination and early survival of these seedlings are

generally only found on banks and sandbars. Most of these

seedlings are washed away by high water flows the following

spring (Whitney 1996). We investigated the concept of providing a precise application of water to xeric flood plain sites

remote from the river channel to create an optimum seedbed

for seed adherence, germination, and seedling survival until

the sapling roots reach the capillary fringe above the water

table. If this technique proves feasible, it may substantially

reduce the costs of forest regeneration in relation to pole

planting, which typically costs from 25 to 40 dollars per pole

(Los Lunas Plant Materials Center 1997). Costs of pole

plantings include not only the immediate expense of dormant pole cuttings and installation, but also the costs

involved with pest damage control (for example, tree guard

installation and cottonwood leaf beetle suppression). However, seedlings established using micro-irrigation will also

require cottonwood leaf beetle control. In addition to the

potential economic incentives, the use of micro-irrigation to
152 USDA Forest Service Proceedings RMRS-P-7. 1999

establish a cottonwood riparian forest from natural seed

dispersal will impart much greater genetic diversity than is

achieved by planting poles derived from clones in production

nurseries.

This paper addresses our initial proof of concept studies

which sought to determine: 1) the effect of organic-rich

substrates on seedling survival and growth; 2) the influence

of different types of micro-irrigation emitters on the area of

wetted soil surface and the number of seedlings established;

3) the effect of weed competition on seedling density and

height growth; 4) the amount of irrigation water applied

during the germination and early establishment phase; and,

5) irrigation system design and costs of a hypothetical large

scale cottonwood regeneration project. Discussion of future

investigations concentrate on 1) reducing costs for irrigation

operation and weed control, 2) simplifying the micro-irrigation system, and 3) minimizing water use.

1996 Study—Soil Surface

Treatments _____________________

Observations of volunteer cottonwood seedlings in the

bare-root nursery at the Plant Materials Center indicated

seedling establishment occurred on organic-rich soil-less

mixes with micro-sprinkler irrigation every 6 hours. These

observations prompted trials of surface materials that might

promote seedling establishment by increasing cottonwood

seed adherence and providing optimum moisture during

germination and early growth. The cost of soil-less mix

compelled the testing of less expensive organic substrates

and 2 different thickness’ of these surface treatments.

Methodology

The study was conducted at the Rio Grande Nature Center

on disturbed sandy loam soils having a severe infestation of

summer cypress (Kochia scoparia (L.) Roth). Plots (each

2.4 m x 3.0 m) were dug to a depth of 0.15 m with the bucket

of a front end loader tractor. The plots were ripped an

additional 0.5 m in depth to break a caliche layer. The plots

were then back-filled with indigenous mineral soil, mulch, or

soil-less mix to provide 2 depths of organic substrates.

The surface treatments were as follows: 1) indigenous soil,

2) shredded residential green waste 5 cm thick, 3) shredded

residential green waste 15 cm thick, 4) soil-less mix (component volume ratio 6:3:1 pumice:peat:composted bark) 5 cm

thick, and 5) soil-less mix 15 cm thick. The plots were

replicated in 3 blocks with the treatments in random order.

Regardless of the thickness of the soil treatment, the surface

of plots was level with the surrounding terrain so surface

runoff would not flow onto the plots.

Each of the 15 plots was irrigated with one variable flow

micro-sprinkler having a maximum flow rate of 87 L/hr, a 90

degree spray pattern, and a wetted plot area of 5m2. The 15

micro-sprinklers were connected to lateral surface pipelines

of 0.75 inch polyethylene tubing with 0.25 inch microtubing. Irrigation frequency and duration were controlled

using a battery operated irrigation controller. The water

source was an existing shallow well with a photo-voltaic

powered submersible pump.

Irrigation of the plots was started on May 3, 1996 to

allow germination of weed seed. A 2 percent solution of

glyphosate (‘Roundup’) was applied twice to reduce weed

populations prior to cottonwood seed dissemination. At this

location, seed dispersal began May 31, 1996 and continued

until July 20, 1996. For 5 weeks, 23 L of water were applied

4 times daily at 3 hr intervals to each plot (i.e., 92 L/day per

plot or 3.1 gal/week per square foot). On July 9, 1996, the

irrigation schedule was changed to a weekly application of

870 L per plot in a single ten hour period (i.e., 4.3 gal/week

per square foot) until November 1, 1996 when irrigation

was stopped. In April 1997, irrigation resumed with 1500 L

per plot applied once a month in a single 3 day period (i.e.,

1.7 gal/week per square foot).

On July 2, 1996, hand weeding of one experimental block

of 5 treatments was stopped to examine the effect of weed

competition on cottonwood establishment; these plots are

denoted as NWC (no weed control). The other plots, WS

(weed suppression), were hand weeded weekly for the remainder of the 1996 growing season. A pre-emergent herbicide (0.17 percent pendimethalin, ‘Stomp’) was applied to

the WS plots in March 1997 after spot spraying volunteer

grass seedlings with a 2 percent glyphosate solution. In

addition, the WS plots were hand weeded in July and August

1997. In 1997, the seedlings were sprayed with a 0.001

percent solution of cyfluthrin (‘Tempo II’) monthly from

June to October to control cottonwood leaf beetle. Cottonwood seedling density was measured in November 1996 and

1997 using a meter square frame placed in the center of each

plot; seedling height of 5 to 10 seedlings per plot was also

recorded.

Results and Discussion

By July 1, 1996, the larger seedlings in the indigenous soil

treatment were in the four to five leaf stage (5 to 8 cm in

height) and had root lengths of up to 10 cm. In contrast, the

seedlings in the shredded green waste and soil-less mix

treatments were stunted with heights of 2 to 3 cm, root

lengths less than 8 cm, and red to yellow discoloration. On

July 2, each WS plot was fertilized by applying 50 L of

100 mg/L nitrogen (10 kg/ha) as a soluble fertilizer solution

(‘Peters 20-10-20 Peat Lite Special’ with minor- and micronutrients). The NWC plots were not fertilized.

After the first growing season, the WS treatments having

the greatest seedling density and tallest seedlings were the

indigenous soil (77 seedlings/m2 and 0.75 m) and the shredded green waste 5 cm thick (86 seedlings/m2 and 0.69 m) as

shown in table 1. After the second growing season, these

same treatments had the tallest seedlings; the seedling

density of the indigenous soil treatment (25 seedlings/m2)

was not significantly different than the other treatments

except for the 15 cm thick soil-less mix (11 seedlings/m2).

These data show no benefit in seedling growth or establishment as a result of the organic-rich surface treatments. The

micro-irrigation schedule apparently provided equivalent

seed adherence and surface moisture for the establishment

of cottonwood seedlings on indigenous mineral soil negating

any perceived benefits of the organic-rich substrates.

The seedling density after the second growing season

ranged from 24 to 33 percent of the density after the first
USDA Forest Service Proceedings RMRS-P-7. 1999 153

growing season for treatments with high initial densities.

The competition for light, nutrients, and water resulted in a

substantial natural thinning process.

Those plots with no weed control or fertilizer additions

showed very little if any survival after the first growing

season. Only the shredded green waste plots showed negligible survival and growth after the first growing season.

The coarse texture of the shredded material might have

reduced weed establishment allowing some cottonwood

seedlings to survive.

This initial experiment clearly showed that indigenous

mineral soils could provide a satisfactory substrate for

cottonwood seedling establishment if surface soil moisture

is precisely controlled. At this site, weed competition and low

fertility favored weeds over cottonwoods even with nonlimiting soil moisture.

1997 Study—Evaluation of

Micro-irrigation Devices __________

The 1996 study showed that micro-sprinklers could provide

sufficient control of surface moisture to allow cottonwood

seedling establishment. The large wetted area produced by

these sprinklers resulted in a large dense thicket of seedlings. Smaller wetted areas would require less natural

thinning by competition, reduce weed control efforts, and

reduce the amount of water to establish cottonwoods on one

spot (with the eventual thinning to one tree). Therefore, the

goal of the 1997 study was to determine the number of

seedlings established in wetted areas created by 3 microirrigation emitter types. In addition, the 1997 study site was

more representative of typical restoration locales which lack

existing wells and pumping equipment and comprise large

disturbed areas.

Methodology

The 0.4 ha site is located just downstream of the confluence

of the Calabacillas Arroyo on the west bank of the Rio

Grande within the Rio Grande State Park (administered by

the Albuquerque Open Space Division). Approximately

three-fourths of site was enclosed with snow fence to limit

disturbance by public activity. The remaining 0.1 ha was not

fenced and was adjacent to a horse and walking path. The

site characteristics include loamy sand soil and limited

vegetative cover primarily of Artemisia spp. and Cenchrus

longispinus (Hack) Fern. (sandbur) with little woody vegetation except a few widely separated coyote willow thickets

outside the study site.

A 5 m deep well was developed using a 2 inch well-point.

A gasoline-powered centrifugal pump capable of providing

245 L/min at 40 psi and with a suction lift of 4.6 m supplied

water to the irrigation system. The discharge was filtered

(spin-clean filter) and supplied a 1.5 inch PVC header that

spanned the length of the enclosure and extended into the

unfenced area. The lateral lines (16 within the enclosure and

2 outside) consisted of 30 psi fixed pressure regulators

connected to 0.75 inch polyethylene tubing with capped ends

Table 1—Rio Grande cottonwood seedling height and seedling density on micro-irrigated plots at the Rio

Grande Nature Center. Means and standard errors reported for plots with weed suppression and

fertilizer application; plots with no weed control or fertilizer application were not replicated.

Surface treatments

Soil-less Soil-less Green Green

Indigenous mix mix waste waste

soil 5 cm 15 cm 5 cm 15 cm

Plots with weed suppression

and fertilizer application

Mean seedling height (m)

After first growing season 0.75 0.39 c 0.23 c 0.69 0.47 b

(Standard error) (0.01) (0.02) (0.03) (0.08) (0.04)

After second growing season 1.75 1.28 0.77 b 1.61 1.35 b

(Standard error) (0.10) (0.24) (0.14) (0.22) (0.05)

Mean seedling density (no./m2)

After first growing season 77 63 c 15 c 86 a 57 b

(Standard error) (2) (1) (5) (4) (4)

After second growing season 25 21 11 b 21 19

(Standard error) (2) (2) (2) (3) (8)

Plots with no weed control

and no fertilizer application

Seedling height (m)

After first growing season 0 0 0 0.15 0.15

After second growing season 0 0 0 0.51 0

Seedling density (no./m2)

After first growing season 0 0 0 22 4

After second growing season 0 0 0 7 0

a Mean significantly different from indigenous soil treatment at P≤0.10 and P>0.05.

b Mean significantly different from indigenous soil treatment at P≤0.05 and P>0.01.

c Mean significantly different from indigenous soil treatment at P≤0.01.
154 USDA Forest Service Proceedings RMRS-P-7. 1999

to allow flushing. The emitters were attached to the laterals

with 0.125 inch micro-tubing. The 3 emitter types were miniflow spitters [Roberts Spot-Spitters‚ ] (14 L/hr at 15 psi with

a 90 degree spray pattern), medium-flow spitters (53 L/hr at

15 psi with a 160 degree pattern), and a lead-weighted

bubbler (24 L/hr at 15 psi with a point source). Each lateral

line had between 7 and 10 mini-flow spitters, 4 to 8 mediumflow spitters, and 2 to 3 bubblers for a total of 313 emitters

(167 mini-flow, 95 medium-flow, and 51 bubblers). The

percentage of water applied by each emitter type was calculated by multiplying the number of emitters by the flow

rate; these percentages are 27 percent for mini-flow spitters,

59 percent for medium-flow spitters, and 14 percent for

bubblers.

Before initiating the cottonwood establishment study,

the study area was irrigated and sprayed biweekly with a

4 percent solution of glyphosate herbicide. Daily irrigation

for cottonwood seed germination began June 16, 1997; for

the next six weeks the irrigation system was operated

during daylight hours at three hour intervals for a period of

one half hour. After six weeks, the seedlings were irrigated

for three hours once or twice a week depending on precipitation. During seed adherence and germination phase (i.e.,

first six weeks), from 115 to 190 m3 of water were applied

each week (see fig. 1). In the establishment phase (next 12

weeks), from 10 to 45 m3 of water were applied each week.

For the entire growing season, 1234 m3 (326,000 gal or 1 acre

foot) of water were used in the study during a total application period of 145 hr.

All plots inside the fenced area were hand weeded by the

irrigation system operator. On three occasions during the

growing season, 8 days of labor were spent weeding the plots

inside the enclosure. The plots outside the fence were not

weeded during the first growing season. Seedlings were

sprayed monthly from August to October 1997 with 0.001

percent cyfluthrin (“Tempo II”) to control cottonwood leaf

beetle. The numbers of seedlings established in the 313 plots

were counted in October 1997. For the medium-flow spitter

plots, counts of greater than 100 per plot were recorded and

analyzed as a count of 100.

Results and Discussion

At this location, cottonwood seed dispersal began the third

week of June 1997. Initial seedling emergence was observed

during the fourth week of June. After the first growing

season, the mean seedling numbers per plot (± standard

error) for each emitter type were as follows: mini-flow

spitters 32 (±19) seedlings per plot, medium-flow spitters

67 (± 27) seedlings per plot, and bubblers 20 (±14) seedlings

per plot (see table 2). The distribution of seedling numbers

for the 3 emitters is presented in figure 2. The most common

seedling count classes were 11 to 40 for the mini-flow

spitters, 61 to 80 and >100 for the medium flow spitters, and

1 to 30 for the bubblers. Only two out of 313 plots lacked

established seedlings in October 1997. The total seedling

establishment within the study site after the first growing

season exceeded 12,700.

The percentage reduction in seedling density resulting

from no weed control was derived from mean seedling counts

per plot (and median seedling counts per plot): 37 percent (44

percent), 38 percent (35 percent), and 42 percent (45 percent)

for mini-flow spitters, medium-flow spitters, and bubblers,

Figure 1—Irrigation water applied during the first growing season to the cottonwood seedling plots at the study site located

on the west side of the Rio Grande below Calabacillas Arroyo. Water applied for the week preceding the date given.
USDA Forest Service Proceedings RMRS-P-7. 1999 155

Table 2—Number of Rio Grande cottonwood seedlings established per plot during the first growing season using 3 types

of micro-irrigation emitters. Study site located on the west side of the Rio Grande below Calabacillas Arroyo.

Emitter Plot Number Standard Most Seedling

type type a of plots Median Mean error common b density c

(no.) (no./plot) (no./plot) (no./plot) (no./plot) (no./m2 )

Mini- All 167 29 31.7 19.1 11 to 40 50

flow WS 148 32 33.1 19.4 nd 55

spitter NWC 19 18 20.8 12.2 nd 39

Medium- All 95 70 67.2 d 27.1 d 61 to 80, >100 26

flow WS 86 72 69.7 d 26.4 d nd 27

spitter NWC 9 47 43.2 20.4 nd 17

Bubbler All 51 16 19.9 14.0 1 to 30 48

WS 46 18 20.8 14.4 nd 55

NWC 5 10 12.0 5.5 nd 30

a WS = weed suppression, NWC = no weed control, All = WS plus NWC plots.

b Three most common classes of seedling counts based on class intervals of 10.

c Median number per plot divided by estimated wetted area.

d Counts greater than 100 treated as 100 in mean and standard error analysis.

nd Not determined.

Figure 2—Rio Grande cottonwood seedling count distribution per plot for the 3 types of micro-irrigation emitters used at

the study site located on the west side of the Rio Grande below Calabacillas Arroyo.
156 USDA Forest Service Proceedings RMRS-P-7. 1999

respectively. At the end of the first growing season many

seedlings in the enclosure exceeded 0.3 m in height while

some seedlings exceeded 0.6 m in height. With no weed

control (outside the enclosure), the average seedling height

was between 0.1 and 0.2 m. The plots with larger wetted

areas appeared to have greater weed populations. These

weeds in descending order of predominance were Tamarix

spp., Cenchrus longispinus, and Artemisia spp. The reductions in survival and growth can not be related entirely to

weed competition because the plots outside the enclosure

suffered some disturbance by foot traffic and horses; this

activity probably destroyed some seedlings and dislodged

micro-tubing and emitters. The fencing prevented any obvious disturbance by people or pets to the plots receiving weed

control.

The estimated wetted areas produced by the 3 emitter

types are 2.71, 0.58, and 0.33 m2 for medium-flow spitters,

mini-flow spitters, and bubblers, respectively. The seedling

density derived from these wetted areas are presented in

table 2 using median seedling counts; the derived seedling

densities are 55, 27, and 55 seedlings/m2 for mini-flow

spitter, medium-flow spitter, and bubbler plots with weed

control. The corresponding water delivery rates are 24, 20,

and 73 L/hr per m2. This data might indicate that soil

moisture could be limiting establishment on the mediumflow spitter plots. However, the calculated water delivery

rate in the 1996 study at the Rio Grande Nature Center was

17 L/hr per m2; therefore, sub-optimum irrigation interval

and duration are probably more responsible for reduced

density than water delivery rate.

The findings of this study after the first growing season

include: 1) the small wetted area provided by bubblers was

sufficient to establish seedlings in almost all plots; 2) the

bubblers seemed to support less weed invasion than the

other emitters and had appreciably lower flow rates than the

medium-flow spitter; 3) weed control is critical for effective

establishment because it provides higher seedling densities

and more vigorous seedlings; and, 4) fencing might be

required near areas with foot or horse traffic.

The intent of this study was not to determine minimum

irrigation requirements for seedling establishment. However, high estimates of water use can be projected from the

irrigation application rates of these emitters. The mini-flow

spitters with the smallest flow rates used 345 m3 of water to

establish 5,300 seedlings; these data yield a water use of

65 L per seedling during the first growing season.

Economic Analysis of a Hypothetical

Irrigation System ________________

The high costs of most riparian restoration constrain the

amount of disturbed areas that can undergo cottonwood

regeneration. Pole planting costs of $2500 to $4000 per acre

($6200 to $9900 per ha) for cottonwood regeneration result

from a recommended density of 100 trees per acre (250 trees

per ha) assuming no mortality. The costs of irrigation and

weed control used in the 1997 study can be extrapolated to

an extended use of these methods for cottonwood regeneration of a large disturbed riparian area. The following analysis relies on many assumptions and can not account for many

site characteristics, which could affect the engineering or

the economics of the system. The intent is to provide a basis

for evaluating the potential utility of the technology.

System Analysis of a Hypothetical

Restoration Situation

The 6 hp pump used in the 1997 study is capable of

providing 65 gpm (3900 gph) at 40 psi with a suction lift of

15’. A system composed solely of bubblers which deliver

3.6 gph at 10 psi could use up to 1080 bubblers (3900 gph/

3.6 gph). The main line would have to consist of 2 inch ID

pipe to accommodate 65 gpm. The mainline could be downsized to 1.5 inch ID toward the ends of the main line where

flow rates would be less than 30 gpm. Spin clean filters

would have to be installed in the pump discharge line to

remove fine sand and silt from the irrigation water and

minimize bubbler clogging. By assuming an acceptable density of cottonwood establishment of 100 trees per acre and

assuming modest losses of young trees, 120 bubblers per

acre could achieve the desired regeneration density. A total

of 9 acres could be irrigated using these assumptions (1080

bubblers/120 bubblers per acre). By assuming a roughly

rectangular disturbed area of 400 by 980 feet, a 2 inch main

line 600 feet long would be required. Each lateral line could

be 250 feet in length to provide a somewhat sinuous bubbler

layout. If 30 bubblers were installed on each lateral (recommended maximum for uniform delivery with 0.5 inch ID

tubing is 1.8 gpm), 36 lateral lines would be used for the 1080

bubbler allotment. If the bubblers are located within 10 feet

of the lateral lines, the total lateral length (9000 feet) and

bubbler corridor (20 feet) yield a potential irrigated area of

180,000 ft2 or 46 percent of the total area. The micro-tubing

that supplies each bubbler could be spaced about 8 feet apart

on alternating sides of the lateral. If the length of microtubing varied between 5 and 10 feet with an average length

of 7.5 feet, then 8100 feet of micro-tubing (0.125 inch ID)

would be used.

The fixed costs of the irrigation system which are independent of the exact area or distribution system configuration

include the 6 hp gasoline pump ($900), materials and installation of the 2” well point with a galvanized steel pipe length

of 20 feet ($400), and miscellaneous parts including spin

clean filters, suction and discharge hoses, and pressure

gauge ($300). The variable costs dependent on system configuration include the main line 2 inch ID (600 feet - $180),

main line fittings and fixed pressure regulators (36 lateral

connections - $400), lateral line 0.5 inch ID polyethylene

tubing (9000 feet - $675), lateral line fittings (36 laterals -

$100), micro-tubing 0.125 inch ID (9000 feet - $160), and

1080 bubblers ($450).

The labor, travel, and supply costs required by the 1997

study which would be applicable to a typical restoration

project are presented as well as an estimated multiplying

factor based on the total area of the hypothetical site being

9 acres:

1) Application of herbicide $850 x 3 = $2550

2) Plot mowing and raking $725 x 5 = $3625

3) Install irrigation system $1075 x 2 = $2150

4) Irrigate at 3 hour intervals for 6 weeks $6400 x 1 =

$6400

5) Irrigate every 4 to 5 days for 12 weeks $3600 x 1 = $3600

6) Supplemental hand weeding excluding routine weeding by irrigation system operator $1575 x 1 = $1575
USDA Forest Service Proceedings RMRS-P-7. 1999 157

Conclusions

These cost estimates yield the following summary results

for a 9 acre cottonwood regeneration project for the first

growing season:

1) Fixed equipment costs $1600

2) Variable irrigation supplies cost $1965 or $220/acre

3) Labor, travel, and weed control supplies cost $19900 or

$2200/acre

4) Total $23465 or $2600/acre

The decisive factor in this analysis is the substantial costs

resulting from weed control activities (33 percent of total)

and irrigation operation (43 percent of total). The estimate

of $2600/acre falls in the low range of estimated pole planting costs. Costs in future years should be small because only

repair of pumping equipment and irrigation system components will be required, much less intensive weed control will

be needed, and irrigation frequency will be greatly decreased (for example, every 2 weeks in second year). Pole

planting also requires future costs for pest control and

possible tree guard removal. Any appreciable reduction in

the cost of weed control and irrigation would imply that

micro-irrigation could be a cost effective method of cottonwood forest regeneration.

Planned Studies ________________

Minimizing Water Use and Irrigation Labor

The micro-irrigation approach to be investigated in 1998

focuses on the use of micro-porous tubing (Tyvek‚) as the

water emission device. This tubing operates at very low

pressures (2 to 6 psi) and at very low delivery rates (for

example one liter per day per foot of micro-porous tubing).

These factors should allow continuous operation of the

irrigation system during the germination phase and the use

of a water storage tank, which would only require periodic

refilling. The storage tank could be sized with a 3 day

capacity to prevent the need for irrigation labor over weekends. After the germination phase, the system could be

manually turned on for a day, once or twice a week, to

minimize the number of days the system needs attention.

Potential Weed Control Alternatives

Use of pre-emergence herbicides could be tested including: 1) particular chemicals with less adverse effects on

cottonwood seedlings; 2) timing of application in relation to

cottonwood germination and establishment; and, 3) rates of

application. More effective nutrient additions by application

of controlled release fertilizer might allow the cottonwood

seedlings to better compete with weeds. The use of solarization could destroy the existing weed seed bank in the surface

soil before cottonwood seed disseminates.

Conclusions____________________

Micro-irrigation applied to xeric flood plain sites offers

a method to establish cottonwood seedlings from natural

seed dispersal. Micro-irrigation emitters providing small

wetted areas (i.e., less than 1 m2) allow the establishment of

sufficient seedlings for probable long term survival of at

least one sapling per irrigated spot. Areas with pedestrian or

horse traffic may require temporary fencing to prevent

disturbance of the seedlings or the irrigation system. Weed

control has been a significant factor in providing high survival and growth rates for cottonwood seedlings. Labor for

weed control and irrigation operation are the highest cost

activities for a cottonwood regeneration project based on the

present micro-irrigation technology. Potential improvements in micro-irrigation emitters and system design could

significantly reduce irrigation labor costs and minimize

water used for seedling establishment. Better weed control

strategies and application of controlled-release nutrients

could reduce long-term weed control costs.

Micro-irrigation technology is an additional tool for land

managers confronted with riparian restoration projects. The

use of a particular restoration technique (for example, natural flooding, flooding resulting from human intervention,

pole planting, or micro-irrigation) will depend on the hydrologic, edaphic, economic, engineering, and jurisdictional

constraints of the restoration site.

References _____________________

Crawford, Clifford S.; Ellis, Lisa M.; Molles, Manuel C.; Valett,

H. Maurice. 1996. The potential for implementing partial restoration of the Middle Rio Grande ecosystem. In: Shaw, Douglas W.

and Deborah M. Finch, tech coords. Desired future conditions for

Southwestern riparian ecosystems: Bringing interests and concerns together. 1995 Sept. 18-22, 1995; Albuquerque, NM. General Technical Report RM-GTR-272. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest

and Range Experiment Station. 93-99.

Dick-Peddie, William A. 1993. New Mexico vegetation, past, present,

and future. University of New Mexico Press. 244 p.

Los Lunas Plant Materials Center. 1997. Annual interagency

riparian report, 1997, 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service, Los Lunas, NM.

31 p.

Whitney, Jeffrey C. 1996. The Middle Rio Grande: Its ecology and

management. In: Shaw, Douglas W. and Deborah M. Finch,

tech coords. Desired future conditions for Southwestern riparian ecosystems: Bringing interests and concerns together. 1995

Sept. 18-22, 1995; Albuquerque, NM. General Technical Report

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Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Clifford S. Crawford is Emeritus/Research Professor and Lisa M. Ellis is

Graduate Research Assistant, University of New Mexico, Albuquerque, NM.

Daniel Shaw is Science Teacher, Bosque Prep School, Albuquerque, NM.

Nancy E. Umbreit is Biologist, U.S. Bureau of Reclamation, Albuquerque,

NM.

Abstract—Extensive regulation of the Middle Rio Grande’s natural flow regime, together with the effects of introduced tree species,

landscape fragmentation, and increasing wildfires, are obstacles for

any level of restoration of its native riparian forest (bosque). However, carefully monitored partial restoration is possible and greatly

needed to prevent the bosque’s serious decline. Monitoring can

reveal temporal and spatial changes in the bosque’s ecological

dynamics. The Bosque Ecosystem Monitoring Program, which currently uses volunteers to synchronously record changes in biological

populations and ecological processes at four sites in the middle

valley, shows how this can be done. Partial restoration depends on

well timed releases following heavy spring runoff. When these

exceed bankfull stage, overbank flooding will (1) establish new

cottonwood-willow stands at suitable locations and (2) enhance

ecological maintenance of mature stands. Partial restoration can

potentially involve alternative, non mutually exclusive manipulations of the river’s hydrology within a given reach. A different

approach, currently exemplified by the Albuquerque Overbank

Project, involves lowering a bank so that natural flooding can

establish new native vegetation. These conceptual and empirical

efforts can build a foundation for bosque managers to assess where

modified native bosque can persist, and can be the beginning of a

comprehensive program to manage the riparian forest on a sustainable basis.

Regulation of the Rio Grande’s flow regime in the 20th

century has drastically altered the ecological dynamics of its

riparian zone (Crawford and others 1993, 1996a). Historically, the river’s channel shifted laterally across a generally

wide floodplain (Biella and Chapman 1977, Gile and others

1981). Following wet winters, snowmelt in mountain watersheds would have produced overbank flooding downstream,

which would have enabled seeds of native cottonwood,

Populus deltoides ssp. wislizenii, and willow, Salix spp., to

Restoration and Monitoring in the Middle

Rio Grande Bosque: Current Status of

Flood Pulse Related Efforts

Clifford S. Crawford

Lisa M. Ellis

Daniel Shaw

Nancy E. Umbreit

germinate on newly deposited point bars and freshly scoured

banks. Flooding, as inferred from Ellis and others (1998,

Molles and others 1998) would also have enhanced decomposition and mineralization of wood and leaf litter on the forest

floor, making nutrients available for uptake by already

established bosque vegetation (Ellis and others 1998). Thus

the basin’s hydrology, conditioned by climate (Molles and

others 1992), would have brought about a changing mosaic

of bosque stands in varying states of development throughout the Holocene (Crawford and others 1996a).

The present landscape of the basin is very different, even

along the so-called Middle Rio Grande between Cochiti Dam

and Elephant Butte Reservoir, where one of the most extensive native riparian forests in the southwestern United

States still exists (Howe and Knopf 1991). There, as elsewhere along the Rio Grande, the flow regime no longer

exhibits flood pulses of historic proportions. The last great

pulse resulted in the devastating spring flood of 1941, which

may have been responsible for most of the bosque’s remaining cottonwoods.

Currently, controlled releases, especially in the downcut

reach between Cochiti and Bernalillo, seldom exceed bankfull

stage and therefore seldom produce conditions conducive to

bosque establishment or maintenance. Meanwhile, the nearly

continuous strip of native and introduced trees along the

entire middle reach reflects the fact that the river is now

stabilized in space by reservoirs, levees, jetty jacks, diversion dams, irrigation systems, roads, and bridges. Thus in

historical terms the Middle Rio Grande is a new river with

a new bosque. Its flows are about half of what they were six

decades ago (Crawford and others 1993) and much of its

bosque is hydrologically “disconnected” from the river (Molles

and others 1998). As a result, the native bosque is in a state

of decline (Howe and Knopf 1991) and has been called an

endangered ecosystem (Crawford and others 1996a). How to

halt that decline and bring about some degree of partial

(functional) restoration is the problem we now address.

Monitoring _____________________

There is now widespread recognition of the importance of

environmental monitoring (Bricker and Ruggiero 1998).

Riparian monitoring is receiving increasing attention (National Research Council 1992) and is emphasized in recommendations of the Middle Rio Grande Ecosystem: Bosque

Biological Management Plan (Crawford and others 1993).
USDA Forest Service Proceedings RMRS-P-7. 1999 159

Several agencies, for example the Bureau of Reclamation,

have for years monitored shallow groundwater, streamflow

rates, and other factors relevant to bosque functioning in the

Middle Rio Grande valley.

In contrast, monitoring of a suite of ecosystem variables

that both impact and reflect bosque functioning has begun

only recently, but has already demonstrated the value of

long-term data to support restoration efforts. Monitoring

the local bosque’s ecology began a decade ago with “Bosque

Biology,” a University of New Mexico course in which students periodically sample certain elements such as litterfall

or arthropod activity. Data collected over the years have

proven to be effective indicators of the deteriorating condition of the riparian forest in central Albuquerque (Molles

and others 1998). In 1991, lessons learned and ideas developed in the course were applied to a 6-year study (supported

through the Fish and Wildlife Service by the Bosque Initiative, in addition to National Science Foundation funds, and

performed mainly at the Bosque del Apache National Wildlife Refuge) of the effects of flooding on the bosque’s ecology.

During that project, the results of year-round monitoring of

key biological populations and ecological processes revealed

much about the expected magnitude and timing of ecosystem reorganization accompanying experimental flooding

(Molles and others 1998). Such insight would not have been

possible without adherence to a rigid monitoring protocol.

The Bosque Ecosystem Monitoring

Program

Since 1996, the Bosque Ecosystem Monitoring Program,

in which biologists at The University of New Mexico and

educators from Bosque Prep School work together closely,

has incorporated procedures from both of the above studies.

Supported initially by the National Science Foundation and

now by the Bosque Initiative and Bosque Prep School, the

program presently focuses on synchronous monitoring of

four identically designed but structurally different sites

between northern Albuquerque and Belen. Two of the sites

undergo partial flooding in years of high spring flows while

the other two, both in Albuquerque, have not been flooded for

decades. Data are collected by volunteers (these include

students and their teachers at Bosque Prep and in other

Albuquerque, Los Lunas and Belen secondary schools, as

well as older citizens). Following analysis in The University

of New Mexico’s Biology Department, the data will become

available to bosque managers. Meanwhile, all participants

are encouraged to inform their communities of their bosque

activities.

Restoration ____________________

Preventing the irreversible decline of the Middle Rio

Grande bosque is central to the goal of the Middle Rio

Grande Ecosystem: Bosque Biological Management Plan. It

is also an avowed objective of a variety of federal and state

agencies, and of environmental organizations concerned

with the condition of the basin’s environment. Yet while a

number of the plan’s management recommendations are

being implemented and certain habits are being protected,

little is being done to return degraded parts of the bosque to

a state approximating past structure and function. To some

extent this is because agencies charged with managing the

riverine/riparian ecosystem do not have mandates that

contend with ecosystem-level problems. Also, there appears

to be no stated consensus among managing agencies as to

what “bosque restoration” actually means. Finally, the

bosque’s relationship with the river brings up the issue of

interfering with flow regulation and perhaps water rights,

complex matters that are troubling to many.

Still, these difficulties are not insurmountable. Having

studied the bosque for many years, we feel that “restoration”

is feasible if applied in the context of its limitations. In our

view, returning the bosque to some designated historical

state makes little sense. Too much change has occurred to

the system for that to be a realistic option. We prefer the

more flexible concept of “partial restoration” (Crawford and

others 1996b), which advocates seasonal soil wetting at

carefully selected riparian locations in order to bring about

establishment and/or maintenance of native woody vegetation. Such a practice would promote decomposition, mineralization, and nutrient cycling (Ellis and others 1998, Molles

and others 1998), thereby reducing the fuel load of accumulated litter (Stuever and others 1997). We contend that a

combination of methods, such as simulated flooding, manipulation of flow regime, and alteration of bank structure

can be used to this end.

Partial Restoration: Potential

Obstacles and Solutions _________

Flood Pulse Disruption

Because the Middle Rio Grande’s late spring flood pulse is

more predictable but less extreme than it was before regulation, the opportunity for water to flood overbank is consistently low to the north and high to the south, except during

drought years when it is low all over. Assuming continued

growth in the basin and concomitant increases in human

consumption of Rio Grande water, it is likely that overbank

inundation will decline progressively south of Albuquerque.

In that case we anticipate two broad solutions to the problem

of native bosque establishment and maintenance. One is to

mechanically lower the river bank in select places, while the

other is to create more sites (mainly point bars) for seedling

establishment by increasing the frequency of river meanders and/or braids. Both would effectively return the flood

pulse to limited stretches along the river. Examples of both

approaches are discussed below.

Exotic Trees

Saltcedar, Tamarix ramosissima, is rampant to the south

and Russian olive, Eleagnus angustifolia, tends to dominate

in the north of the Middle Rio Grande riparian forest. In

Corrales and other places, Siberian elm, Ulmus pumila, is

strongly represented in the understory and will likely become the main overstory tree as the old cottonwoods die off

in the next century. While these and other exotic trees are

difficult to control and have become, for practical purposes,

fixtures in the bosque landscape, a degree of containment of

these trees is possible, as pointed out in Recommendation
160 USDA Forest Service Proceedings RMRS-P-7. 1999

No. 17 of the Bosque Biological Management Plan. Mechanical means (for example bulldozing followed by root plowing)

are suggested, and herbicides may be needed as well. As the

recommendation points out, if cleared areas are near the

river and subject to flooding, they can be converted to new

stands of native trees. Recent research by Sher (1998)

provides evidence that seedlings of the native cottonwood

are competitively superior to those of saltcedar whenever

abiotic conditions allow establishment.

Landscape Fragmentation

Recommendation No. 7 of the Bosque Biological Management Plan addresses the problem of bosque fragmentation

by multiple forces. Partial restoration of highly fragmented

areas some distance from the river but still between the

levees may be possible, depending on the kind of disturbance. Further clearing and mechanical lowering of the

disturbed site, when combined with soil wetting (using

runoff water or other sources) in late spring could be used to

recruit native tree seedlings. Pole planting has been successful for small scale restoration and could be useful in many

fragmented sites as a supplement to, rather than a replacement for natural cottonwood regeneration.

Bosque Wildfires

Unmanaged bosque wildfires, caused mainly by humans,

are on the increase (Stuever and others 1997). Depending on

their intensity, they can seriously restrict or inhibit cottonwood regrowth while promoting stump sprouting of exotic

trees. For a short time following a fire in late spring, it may

be possible to thoroughly wet the soil column by various

means (for example flooding from the river or pumped

groundwater) to allow pole planting and/or natural cottonwood-willow seedling startup to restore native bosque. Shade

provided by mature cottonwoods can greatly reduce saltcedar

development (Everitt 1995 and many personal observations), but shade tolerant Russian olive is not so easily

constrained.

Beavers and Defoliating Insects

Beavers, Castor canadensis, were largely eliminated from

the valley in the 19th century, were restocked in the mid1900s (Crawford and others 1993) and are now common

along the Middle Rio Grande, where they live in holes in the

bank. Beavers depredate all age classes of cottonwoods

(Campbell 1990), but young trees seem especially vulnerable when present. New cottonwoods established by overbank

flooding may have to be screened with chicken wire where

beavers are active. Alternately, local populations may have

to be trapped out and re-located.

Several species of insects account for substantial defoliation of cottonwoods in the bosque (Yong and Crawford 1997,

also ongoing research by K. Eichhorst). In particular, the

cottonwood leaf beetle, Chrysomela stricta, can affect over 60

percent of the leaves produced in the vicinity of Albuquerque, but far less at sites studied to the south. Reasons for this

are under current study. Leaf consumption occurs mainly in

late spring and early summer, which means that new leaves

form the beetle’s diet. Defoliation of seedlings and young

trees could be a setback for partial restoration in areas

where beetle populations are high.

Partial Restoration: Current

Approaches ____________________

Hydrologic Manipulation: Alternatives

Based on Geomorphology

While there may be fairly broad support for improving the

bosque’s riverine and terrestrial habitats by “mimicking

typical natural hydrographs,” and for allowing “fluvial processes to occur within the river channel and the adjacent

bosque to the extent possible” (Recommendations 1 and 2,

respectively, in the Bosque Biological Management Plan), a

consensus has still not been reached on how to achieve these

goals.

A consensus based on principles of fluvial geomorphology

could be reached, however, because river regulation has

resulted in a series of discharge gradients generated by

impoundments and/or other diversions that trap sediment

moving downstream. The gradients begin with downcutting

below such structures, causing what can be termed F or G

type channels (Rosgen 1996). As the balance between

aggradation and degradation shifts downstream with the

addition of sediment from banks and tributaries, the channel tends to take on more of a sinuous or C type configuration. Below that, the increasingly aggraded river becomes

wider and more braided, in effect a D type system.

This repeated pattern of flows offers opportunities to

apply a variety of hydrologic manipulations to achieve partial bosque restoration. The confined river with its reduced

flows provides a hydrologic template that is substantially

different from those of the past. Decisions based on cross

sectional stream morphology at any location can lead to

relatively confident estimates of the discharge required for

seasonal overbank flooding at specific sites along a given

gradient. The next step, how to manipulate the flow regime

in order to make that happen, is more problematic.

Several approaches presently are being considered. One is

to move the levees back from the river. Where possible, that

would increase the width of the active floodplain. The river

then would be able to form new channels, which would create

new establishment sites for native woody vegetation. Locations for such a project between Bosque del Apache and the

upper end of Elephant Butte Reservoir have been seriously

considered by the Corps of Engineers and the Bureau of

Reclamation, with some input by environmentalists and

non-agency experts, but the matter remains unresolved.

Another option is to increase the degree of braiding of the

river bed. As a rule, the river’s historic pattern was braided

and slightly sinuous (Biella and Chapman 1997). Riparian

vegetation would have become established on periodically

inundated river bars associated with this pattern, as currently happens in locations characterized by aggraded beds.

Mechanically induced braiding could open up additional

establishment sites, if desired. The reach below the mouths

of the Rio Puerco and the Rio Salado would be a candidate for

this approach; it tends to be shallow and wide, and is already

braided to some extent.
USDA Forest Service Proceedings RMRS-P-7. 1999 161

A third approach is to spatially change the river’s flow

regime by increasing the number of meanders in given

lengths of river. The argument for this is based on the fact

that while present meanders were created by heavy flows

before the levees were built, regulation has negated future

flows of such magnitude. Moreover, since on average the

channel contains only about half the water it held in the days

before flood control was strongly implemented (Crawford

and others 1993), and since river width is a function of river

wavelength (Leopold 1994), a given reach can sustain additional sinuosity. That in turn means more point bars for

cottonwood-willow establishment.

How these approaches would affect the survival of the

endangered silvery minnow, Hybognathus amarus, has not

been sufficiently examined. If they were to promote overbank

flooding during the breeding season, young fish might benefit from nutrient rich water moving slowly through the

riparian forest. Other unresolved questions addressing restoration related river manipulation include how and where

to do it, who would pay for it, and what political obstacles

might impede it. Nevertheless, combinations of manipulation based approaches to partial bosque restoration, when

carefully planned and executed, seem reasonable. Flexibility in implementing them would be critical, as would motivation within key agencies. Doing nothing, however, will

lead to a collapse of the native bosque.

Albuquerque Overbank Project: an

Experiment in Restoration

At this writing the Albuquerque Overbank Project (AOP)

is an ongoing experiment to mechanically create a cottonwood-willow establishment site along the Rio Grande within

the city limits. The AOP was initiated by a team from the

Bureau of Reclamation, The University of New Mexico

Biology Department, the City of Albuquerque Open Space,

the New Mexico Natural Heritage Program, the State of

New Mexico Environment Department, the Middle Rio

Grande Conservancy District, the Fish and Wildlife Service,

and the Corps of Engineers. It is funded largely by the

Bureau of Reclamation, although each of the other entities

as well as several volunteers have contributed various forms

of support. Rather than dealing directly with the river’s

hydrology, the AOP is manipulating the river’s west bank

approximately 5 kilometers south of the Bridge Street Bridge

to allow overbank flooding.

The project, diagrammed in figure 1, first involved clearing about 1.6 hectares of dense Russian olive from the

downstream half of an alternate river bar. The trees were

stockpiled and later removed and chipped. Next, 0.96 hectares of the cleared area by the river were lowered by about

0.6 meters. Roughly 6117 cubic meters of the exposed soil

were root plowed and root ripped, then used to cover part of

a large sand bar extending downstream from the alternate

bar. Undulations throughout the cleared area were created

to enhance the chances of cottonwood and willow seedling

establishment during the initial phase of post-flood drawdown in late June.

Meanwhile, 18 equally spaced shallow groundwater wells

(piezometers) were installed in five equidistant lines leading

from the levee to the west, through the existing old bosque,

and out to the river. Five wells were placed north of the

undisturbed zone as controls and seven more are in the old

bosque by the western levee. All wells were surveyed for

elevations above sea level; this will enable the team to

determine whether site treatment has any influence of

groundwater changes. Well monitoring for water depth and

chemistry is performed at monthly intervals, or more frequently during peak flooding. Vegetation transects were set

up adjacent to the well lines and plant surveys were conducted prior to tree removal. Quadrat sampling along the

transects took place prior to tree removal and commenced

again following floodwater subsidence. Site patterns of soil

salinity were measured twice before overbank flooding began in April.

The AOP’s underlying hypothesis is that the treatment

will produce a natural plantation of native tree seedlings.

Success in the first year of operation will depend on the

timing of post-flood drawdown relative to seed arrival.

Runoffs in subsequent years will vary and may or may not

contribute to what could be the uneven beginning of a new

patch of native bosque. The approach is admittedly something of a gamble, but it follows the paradigm of “something

is better than nothing.”

Conclusions____________________

Partial restoration and monitoring of the Middle Rio

Grande bosque should be integral to its management. Enough

is now known about the ecosystem and its relationship to the

river’s flow regime and hydrology to efficiently manage for a

sustainable riparian forest containing a substantial number

of native trees. A flexible program of establishment and

maintenance by manipulated overbank flooding will make

such management possible, provided resource agencies and

environmentally concerned citizen groups work together,

acquire funding, and argue successfully for keeping sufficient water in the river for this purpose.

Working together on relatively small restoration projects

like the AOP is one way to create a climate of trust and

cooperation that can extend to larger, reach length restoration projects. We recommend that such a “bottom up” approach be given increased recognition among agencies responsible for sustainable management of the Middle Rio

Grande bosque ecosystem.

Acknowledgments ______________

The authors appreciate the support provided them over

the years by the institutions they represent, the Bosque

Initiative, and the National Science Foundation. We also

thank Bill Zeedyk and Mark Harberg for useful comments

on the contents of this paper.
162 USDA Forest Service Proceedings RMRS-P-7. 1999
USDA Forest Service Proceedings RMRS-P-7. 1999 163

References _____________________

Biella, J.V.; Chapman, R.C. (eds.). 1977. Archaeological investigations in Cochiti Reservoir, New Mexico. Volume 1: a survey of

regional variability. Report submitted to National Park Survey,

Santa Fe, for U.S. Army Corps of Engineers. Albuquerque, NM.

Bricker, O.P., Ruggiero, M.A. 1998. Toward a national program for

monitoring environmental resources. Ecological Applications 8:

326-329.

Campbell, M.L. 1990. A survey of mammal populations in the Rio

Grande Valley State Park. Final report submitted to City of

Albuquerque, Open Space Division. Albuquerque, NM.

Crawford, C.S.; Cully, A.C.; Leutheuser, R.; Sifuentes, M.S.; White,

L.H.; Wilber, J.P. 1993. Middle Rio Grande ecosystem: bosque

biological management plan. Report submitted to U.S. Fish and

Wildlife Service, Albuquerque, NM.

Crawford, C.S.; Ellis, L.M.; Molles, M.C.,Jr. 1996a. The Middle Rio

Grande bosque: an endangered ecosystem. New Mexico Journal

of Science 36: 276-299.

Crawford, C.S.; Ellis, L.M.; Molles, M.C.,Jr.; Valett. 1996b. The

potential for implementing partial restoration of the Middle Rio

Grande ecosystem. pp. 93-99. In: Desired future conditions for

Southwestern riparian ecosystems: Bringing interests and concerns together. USDA Forest Service General Technical Report

RM-GTR-272, Fort Collins, CO.

Ellis, L.M.; Crawford, C.S.; Molles, M.C.,Jr. 1998. Comparison of

litter dynamics in native and exotic vegetation along the Middle

Rio Grande of central New Mexico. Journal of Arid Environments

38: 283-296.

Everitt, B.J. 1995. Hydrologic factors in regeneration of Fremont

cottonwood along the Fremont River, Utah. Natural and Anthropogenic Influences in Fluvial Geomorphology, Geophysical Monograph 89: 197-208.

Gile, L.H.; Hawley, J.W.; Grossman, R.B. 1981. Soils and geomorphology in the Basin and Range area of southern New Mexico—

Guidebook to the Desert Project: New Mexico Bureau of Mines

and Mineral Resources, Memoir 39, 222 p.

Howe, W.H.; Knopf, F.L. 1991. On the imminent decline of the Rio

Grande cottonwoods in central New Mexico. Southwestern Naturalist 36: 218-224.

Leopold, L.B. 1994. A view of the river. Harvard University Press,

Cambridge, MA. 298 p.

Molles, M.C.,Jr.; Dahm, C.N.; Crocker, M.T. 1992. Climatic variability and streams and rivers in semi-arid regions. pp. 197-202.

In: Roberts, R.D.; Bothwell, M.L.,eds. Aquatic ecosystems in

semi-arid regions: implications for resource management. N.H.R.I.

Symposium Series 7, Environment Canada, Saskatoon.

Molles, M.L., Crawford, C.S.; Ellis, L.M.; Valett, H.M.; Dahm, C.N.

Managed flooding for riparian ecosystem restoration. BioScience

(in press).

National Research Council, Committee on Restoration of Aquatic

Environments. 1992. Restoration of aquatic ecosystems: science,

technology and public policy. National Academy Press, Washington, DC. 552 p.

Rosgen, D. 1996. Applied river morphology. Wildland Hydrology,

Pagosa Springs, CO. 343 + xxvi p.

Sher, A.A. 1998. Seedling ecology of competing riparian tree species:

native cottonwood (Populus deltoides ssp. wizlisenii) and introduced saltcedar (Tamarix ramosissima). Ph.D. dissertation, The

University of New Mexico, Albuquerque, NM.

Stuever, M.C.; Crawford, C.S.; Molles, M.C., Jr.; White, C.S.;

Muldavin, E. 1997. Initial assessment of the role of fire in the

Middle Rio Grande bosque. pp. 275-283. In: Greenlee, J.M., ed.

Proceedings of the First Conference on Fire Effects on Rare and

Endangered Species and Habitats. The International Association

of Wildland Fire, Coeur d’Alene, ID.

Yong, T.-Z.; Crawford, C.S. 1997. Ecology of two micro-lepidopteran

leaf-rollers in an arid-land riparian forest. The Southwestern

Naturalist 42: 155-161.

Figure 1—Diagram based on an aerial photograph of the Albuquerque

Overbank Project site on the west bank of the Rio Grande approximately 5 kilometers south of the Avenida Caesar Chavez Bridge in

Albuquerque, NM. All vegetation was stripped from the barred elliptical

zone, and the area between the river and the zone’s dividing line was

lowered by about two-thirds of a meter in February 1998. Soil removed

in the process was deposited on the lower river bar to the right of center.

Triangles represent locations of shallow groundwater piezometers

along transects also used to study vegetation cover.
164 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Robert R. Parmenter is with the Department of Biology, 167 Castetter

Hall, University of New Mexico, Albuquerque, NM 87131. Telephone: 505-

277-7619. FAX: 505-277-5355. EMAIL: parmentr@sevilleta.unm.edu

Abstract—The purpose of this paper is to describe the research

program of the Sevilleta Long-Term Ecological Research Program

(LTER) at the University of New Mexico. Details and data for each

of the research topics described can be found in the Sevilleta LTER

Internet Homepage (http://sevilleta.unm.edu).

The Sevilleta LTER Program is conducted by the University of New Mexico’s Department of Biology in close collaboration with the U.S. Fish and Wildlife Service, and is funded

by a major grant from the National Science Foundation. The

Sevilleta LTER is part of a coordinated network of 21

LTER sites that span North America (including two sites in

Antarctica). The Sevilleta LTER Program concentrates its

research efforts on the Rio Grande Basin in central New

Mexico.

The Sevilleta Long-Term Ecological Research Program

(LTER) was initiated in October, 1988, and has focused on a

suite of ecological hypotheses concerning climate dynamics

and the responses of organisms in a biome transition zone in

central New Mexico. The Sevilleta LTER research region

straddles several major biomes of the Southwest, and the

large geographic scale of the Sevilleta region is important for

studies that range from genetics and physiology at the

organismal level, to the dynamics of biome transition zones.

The region is strongly influenced by the El Niño Southern

Oscillation (ENSO), with major fluctuations in precipitation

on semi-decadal time scales.

Under the Sevilleta LTER program, mathematical water

balance models are providing a unifying synthesis of the

LTER core topics and the various levels of organization

studied by the participating investigators. The water balance approach takes advantage of continued studies from

1988-1994 (for example, vegetation, climate data, precipitation estimation from lightning, other GIS data, and remotely

sensed imagery) and provides a conceptual and quantitative

context for a number of new studies that provide a richer and

more complete characterization of the Sevilleta region. In

addition, LTER scientists will implement a systems model of

the CENTURY class in a geographical context, in which the

water balance will be driven by the nonequilibrium water

model. Thus, the models will provide a synthesis of existing

Sevilleta Long-Term Ecological Research

Program: Measuring Ecosystem Responses

to Environmental Change

Robert R. Parmenter

and future data concerning the core areas of organic matter

processing, primary production, and inorganic inputs. The

synthesis will be of immediate use in relation to the disturbance and population core topics, including vegetationenvironment relations, nutrient dynamics, species distributions and abundances, animal population studies, and

population genetics. These field and laboratory studies will

provide the necessary biological components that represent

the contingencies and feedbacks that are both the responses

to, and the constraints on, the dynamics of water.

Site Description _________________

The University of New Mexico’s Sevilleta Long-Term

Ecological Research Program (LTER) in the central Rio

Grande Basin is part of a National Science Foundation

network of research sites that examines the responses of

ecosystems to environmental changes. The Sevilleta LTER

Program is located primarily at the Sevilleta National Wildlife Refuge (Socorro County, NM), but researchers also

utilize areas in Cibola National Forest, Bosque del Apache

National Wildlife Refuge, El Malpais National Monument,

Bandelier National Monument, Los Alamos National Laboratory, Pecos National Historical Park, Petroglyphs National Monument, Kirtland Air Force Base, and the USAF

Melrose Range. These varied study sites include a wide

range of ecosystem types, including Chihuahuan Desert,

Great Plains Grassland, Colorado Plateau Shrub-Steppe,

Pinon-Juniper Woodland, Bosque Riparian Forests and

Wetlands, Ponderosa Pine Forests, Mixed-Conifer Montane

Forests, and Subalpine Forests and Meadows. The dominant theme of the Sevilleta LTER Program is to examine

long-term changes in ecosystem attributes (for example,

population dynamics of plants and animals, nutrient cycling, hydrology, productivity, species diversity) as a result

of both natural and man-made disturbances (for example,

global warming, acid rain, grazing, wildfires, droughts, and

the “El Nino—Southern Oscillation’’ (ENSO)). Through these

long-term studies, scientists will improve their understanding of the natural dynamics of ecosystems in the heterogeneous landscape of central New Mexico.

Sevilleta LTER: A Regional

Research Program ______________

The Sevilleta research region spans the Rio Grande Basin.

In the Socorro County area, study site elevations range from

1,350 m at the Rio Grande to 2,195 m in the Los Pinos

Mountains in the east, to 2,797 m at Ladone Peak in the

northwest, and to 3,450 m in the Magdalena Mountains to
USDA Forest Service Proceedings RMRS-P-7. 1999 165

the southwest. Other important regional features include

the San Agustin Plains to the west, and the Jornada del

Muerto (“Journey of Death”) valley to the south. The San

Agustin Plains is an ancient lakebed, which has had a

number of paleoecological studies that have characterized

the long-term vegetation changes in the region; it is also the

site of the Very Large Array Radiotelescope funded by NSF.

The Jornada del Muerto extends southward some 125 km,

and is largely uninhabited except for military personnel at

the White Sands Missile Range, site of the first atomic

bomb test. The Jornada del Muerto area is the northward

extension of habitats characteristic of the Jornada LTER.

Variations in elevation, parent material and geomorphic

setting have combined to produce a variety of soils and

habitats ranging from thin and rocky residual soils to deep

alluvium. For example, in the Sevilleta NWR outside of the

floodplain, there are 3 orders, 6 suborders, 10 great groups,

17 subgroups, and 38 named series of soils represented. In

the floodplain are additional Entisols and Vertisols. The

variability attributed to topography, geology, and soils over

a number of scales contributes directly to the variety of

gradients in the region. There are wide ranges of variation

in soil properties such as texture, depth, presence of argillic

and calcic horizons, A-horizon organic matter content, temperature and moisture regimes, and salinity.

The imposition of climatic dynamics in combination with

diverse microsite characteristics presents numerous, excellent opportunities for research on species and ecosystem

dynamics. Climatic dynamics occur over a range of time and

space scales and the research region offers an opportunity to

examine many of them. There is a rich set of “behaviors” in

response to the dynamics of climate. At one end of the

spectrum, areas as large as the Sevilleta or Magdalena

Mountains can be viewed as a single pixel and will show

variations in spectral reflectance from seasonal to annual

time-scales and longer. At another point in the spectrum,

species are subject to genetic change and demonstrate an

evolutionary response to climate dynamics, at both fine and

broad scales. In between these examples is a rich diversity

of biological and ecological features that can be studied. The

current research ranges from studies of genes to landscapes.

Although the dedicated research areas form the core of

the site research, there are excellent opportunities to evaluate management influences on species or landscapes. Intensive grazing occurs outside the boundaries of the research

areas and fence-line contrasts have been studied frequently.

The Rio Grande provides irrigation water, and floodplain

agriculture also has been studied. The juxtaposition of

reserved and managed areas also allows studies of, for

example, species’ refuges, dispersal factors, the influence of

exotics, and disturbed-land restoration.

LTER in a Biome Transition

Zone __________________________

Topography, geology, soils, and hydrology, interacting

with major air mass dynamics, provide a spatial and temporal template that has resulted in the region being a transition zone for a number of biomes. The region contains

communities representative of, and at the intersection of,

Great Plains Grassland, Colorado Plateau Shrub-steppe,

Chihuahuan Desert, Interior Chaparral, and Montane

Coniferous Forest. The elevational gradient of the

Magdalena Mountains provides further transitions for Interior Chaparral, Pinon-Juniper Woodland, Montane Conifer

Forest, Subalpine Conifer Forest, and Subalpine Grassland.

The Magdalena Mountains represent the northeastern

limit of Interior Chaparral and are unique in having both

Subalpine Conifer Forest and Interior Chaparral on the

same mountain range.

The regional location at the junction of a number of biomes

is critical for quantifying (1) gradient relationships with

distance, (2) the scale-dependent or independent nature of

spatial variability, (3) how steep gradients influence system

properties, (4) integrated responses across the region, and

(5) biome responses to climate change.

Biodiversity ____________________

The size of the area, the heterogeneous topographic and

geological features, and the characteristics of a biome transition zone have resulted in a rich diversity of species. At

least 104 families, 1,201 species and 208 varieties of plants

occur within the study region, and many species are at their

distributional limits. For example, 54 plant species terminate their geographic distributions within the Sevilleta

NWR. Some of these species represent major life forms and

physiologies, such as the C3 perennial grasses (Oryzopsis).

The terrestrial vertebrate fauna includes 89 species of mammals, 353 birds, 58 reptiles, and 15 amphibians. A substantial proportion of these species have a geographic distribution boundary within the region. Reptiles provide the most

dramatic example, as 47 of the 58 species end their distributions in the vicinity of the Sevilleta (33 of these are northern

limits of desert species). In addition, a high diversity of

ground-dwelling arthropods, with distinctive habitat-specific

assemblages, has been documented in recent and ongoing

studies.

An important feature of the biodiversity of this region is

the number of examples of sympatric swarms of closely

related species. This sympatry affords opportunities for

studying the evolutionary differentiation of species. For

example, six species of mice in the genus Peromyscus occur

on the Sevilleta (a seventh may also occur), of which five

have been found coexisting on a one hectare plot. Four

species of Bouteloua grasses can be found in the same

habitat, and seven species of lizards in the genus

Cnemidophorus are present. Six of these seven lizard species are found in Sevilleta shrubland habitats, and all seven

are present in the shrubland/pinon-juniper transition.

LTER Program as an “Ecological

VLA” __________________________

At a regional scale, the central New Mexico landscape is

composed of a mosaic of biome types, many of which are

represented by study sites in the Sevilleta LTER. The study

region also straddles the boundary between major seasonal

air masses (for example, the “Arctic express’’ on the Great

Plains influences Sevilleta’s eastern edge; Great Basin

polar air masses extend to Sevilleta’s northern edge; the

Bermuda High generates summer convective storms over
166 USDA Forest Service Proceedings RMRS-P-7. 1999

the mountains, which track northeast across Sevilleta’s

lowlands). Superimposed on these spatial patterns are the

temporal dynamics of the ENSO phenomenon. These climate phenomena are a function of orographic effects of the

southern Rocky Mountains and the New Mexico basin-andrange topography.

Given the reasonably large latitudinal, longitudinal and

elevational gradients found in the Sevilleta study region,

Sevilleta LTER researchers have access to many representative biome “patches” that lie close to the edges of their

continental distributions. The LTER capitalizes on this

“biome diversity” to scale-up the population, community and

ecosystem studies, and address biotic responses to climate

change on a regional basis. To accomplish this, we have

developed an ecological analog to NSF’s Very Large Array

Radiotelescope (VLA). The VLA is composed of a series of

scattered, individual dish-antennae, that, when monitored

simultaneously, reveal high-resolution data on obscure astronomical objects. As a rule, signal resolution increases

with greater antennae numbers and spread-diameters.

In line with this approach, the LTER Program established

a number of research sites (VLA antennae analogs) in

various habitats ranging from Rio Grande riparian forest

through grassland, shrub-steppe, desert shrubland, pinonjuniper woodland, mixed-conifer subalpine forest, and subalpine meadow. In combination with the Sevilleta LTER

Program, the studies at Bosque del Apache NWR, Cibola

National Forest, Kirtland Air Force Base, and four National

Monuments are becoming important components of the New

Mexico “Ecological VLA.” With this network of sites, that

spans a two-fold gradient in precipitation amount (VLA

spread-diameter analog), we can address problems that

require simultaneously-measured, multi-biome data. Such

topics include the role of drought or wet cycles on (1) primary

production, decomposition and nutrient cycling budgets at a

regional scale, (2) species diversities and trophic structures

of biotic assemblages across landscapes, and (3) population

dynamics and demographics of plants and animals with

multi-biome distributions. The benefit of this approach is

enhanced greatly by the fact that all these regional research

sites are subjected to the same regional climate dynamics;

for example, a drought year for one site is a drought year for

all. With the ecological VLA approach, the LTER Program

can conduct a “natural experiment,’’ examining proportionate or disproportionate responses of biome types under a

similar climatic “treatment.”

Hypotheses Addressed by the LTER

Program _______________________

The LTER Program addresses a number of ecological

questions, including: 1) How do the El Niño/La Niña climate

dynamics influence ecological processes, such as nutrient

cycling and energy flows, as well as the population abundances and spatial/temporal distributions of plants and

animals; 2) What effects do climate dynamics have on the

species compositions and trophic structures of the various

biome types; 3) Across the central New Mexico landscape

mosaic, are there similar or disproportionate responses

among communities in various biome types when subjected

to a common, regional climate change (for example, drought);

4) Are patterns of plant and animal demographics, density/

abundance, survivorship, and reproduction associated with

habitat-specific variables (for example, primary production,

precipitation, soil moisture, temperature); 5) How does the

heterogeneity of habitat mosaics, in concert with their ecotones, influence floral and faunal distributions, and which

species might be poised for habitat invasion/retreat following abrupt or long-term climate changes?

Project Description ______________

The following provides a conceptual description of the

Sevilleta research program’s present status and future direction, based largely on current trends and national funding priorities in ecological research. Following this section is

a more detailed projection of the long-term future of the

Sevilleta LTER Program.

The primary values of the research region include: (1) the

dedicated research areas occupying a large area (150,000

ha), (2) the location at transitions spanning a number of

biomes, and (3) the high biological and environmental diversity. The transitions can express themselves in a number of

ways, as various gradients of soils, geology, and topography

change through space and time. Climate change will also

express itself over a range of time and space scales and the

ecological transitions of the Sevilleta region represent an

opportunity to examine many of them. We anticipate that

the area will demonstrate a wide range of “behaviors” in

response to the dynamics of climate. For example, the 1950’s

drought caused marked vegetation boundary movement in

much of the region. The 1988-89 La Niña event produced a

strong winter drought that prevented spring production of

C3 grasses. Other wet years in the early 1990’s caused

increased production and expansion of C3 perennial grasses

(Oryzopsis). The area is expected to provide a rich set of

ecological “tools” capable of quantifying the range of responses to environmental dynamics.

The high biodiversity is related to the large area, heterogeneous habitats and the transitional area for so many

biomes. This offers excellent possibilities to understand the

factors that contribute to the high diversity, including the

high degree of sympatry for closely related species. Population studies are focusing on the interaction between climate

change and evolutionary change. Climate change may both

stretch the limits of response and change the process of

evolution through climate-induced changes in population

structure. The effects of a dynamic and heterogeneous environment are expected to be magnified for species at the

margins of their ranges. Such species, near the limits of

physiological tolerance, are most likely to be affected by

short time scale changes, and their population dynamics

may reflect the rapid environmental changes typical of this

region.

Disturbance patterns and frequencies are important forcing functions for the ecology of the area. “Disturbance” is

viewed and studied across many scales that range from

antelope hoof-marks in the soil crust between plants, to

individual plant mortality (gap dynamics), to mammal mound

activity, to frequency and intensity of flooding/scouring in

ephemeral streams, to the grassland and forest fires that are

increasing in frequency in the protected areas, and to decadal

patterns of climate dynamics.
USDA Forest Service Proceedings RMRS-P-7. 1999 167

Landscape dynamics also receive significant attention.

The hundreds of square kilometers surrounding the Sevilleta

Field Station provide a natural laboratory for studying the

interplay between temporal environmental variation and

the spatial patterning of habitat. Viewed from afar, the

extensive landscape exhibits repeating patterns of lowelevation grassy plains punctuated by ascending topography that may be viewed as a superstructure upon which

environmental gradients are arrayed. As precipitation and

temperature vary temporally, we expect to see spatially

correlated shifts in the distributions of habitats, and consequently species distributions may be envisioned as ever

expanding and contracting mosaics constrained by the shifting habitats. An interesting analogy between the landscape

dynamics and the annealing of alloys provides a theoretical

framework for the envisioned fluctuations. Annealing is the

process of repeated heating and cooling of mixtures. Heating

excites the component molecular species to seek new configurations that result in minimized free energy levels upon

cooling. Variation in annual precipitation constitutes an

“excitation” of the system, thereby allowing the entire collection of species to seek new “free energy levels” which may be

characterized by such measures as genetic similarity, species richness (per area), primary production, or by multivariate vectors of community composition. The free energy

achieved depends on the organismal, demographic, community, and ecosystem level interactions of the populations

involved.

Restoration biology also is an area of intense interest in

the region. The grassland and desert shrub areas of most of

New Mexico were heavily grazed for centuries. The research

areas allow experiments and studies of natural succession

and recovery. Species reintroductions also are being planned,

such as the native Desert Bighorn Sheep in the Sierra

Ladrones and pronghorn antelope on the Sevilleta NWR

west of the Rio Grande. The riparian cottonwood forest along

the Rio Grande also has been greatly altered by harvesting,

river control from impoundments, and invasion by exotics.

UNM and FWS ecologists have initiated a new research

program at Bosque del Apache NWR that examines aspects

of cottonwood forest restoration, focusing particularly on

flood manipulations of the Rio Grande and the effects on

riparian forest ecosystem processes.

Summary of “Core” Program

Studies ________________________

The Sevilleta LTER Program is an integral part of the

regional research effort, and has already proven to be a

tremendous asset to both resident and visiting research

scientists. The “long-term” nature of the LTER funding

schedule (6-yr intervals) contributes a large degree of continuity and stability to the region’s research program, ensuring consistent collections of important “core” data sets. The

following sections summarize the various ecological research programs that continually accumulate these “core”

data sets, all of which are accessible to any interested

scientist. The existence of these ongoing projects greatly

enhances the data bases available to scientists during all

phases of project implementation, from hypothesis development and experimental design through data analysis and

interpretation. The LTER “core” projects take advantage of

the region’s large size and valuable characteristics as a

biome transition zone. The approaches are designed to

emphasize a variety of scales and levels, including landscapes, phenotypic plasticity, and evolution. Numerous

other ongoing studies in geology, anthropology, hydrology

and geomorphology will not be discussed because of space

limitations.

Meteorological Studies

The Sevilleta NWR has been instrumented with 7 fullyequipped meteorological stations and data-loggers, over 50

rain gauges, and an additional 20 collectors for precipitation

chemical analysis. The Langmuir Laboratory is also equipped

with meteorological stations. Historical weather records

(100+ yr) for the region are available from the Socorro, NM,

weather station. The LTER also acquires lightning strike

data (frequencies and locations) for the entire central New

Mexico region. All weather data are archived in the Sevilleta

Information Management System (SIMS), and are available

on request.

Vegetation Assemblage Studies

The principal, large-scale environmental gradients are

related to the north-south and east-west characteristics of

meteorologic dynamics and topography. Major transects 3

km wide, 30 to 50 km long are designed to traverse the

transitions between biome types as well as maximize or

minimize environmental gradients (for example, temperature and precipitation) and elevation. Transects of this scale

allow remote sensing analyses from aircraft and satellite to

be coordinated with balloon photography and ground truthing

to identify gradients in spectral reflectance, species distributions, and substrates. Within the transects, 1 km2 plots

concentrate traditional plant (as well as animal) measurements and permanent photography quadrats.

Watershed Studies

The justifications for including a watershed approach

within the region are: (1) water courses amplify variation in

precipitation, especially in arid and semiarid regions where

there is a nonlinear relationship between variation in precipitation and variation in runoff. Hence, biological responses (demographic, functional, etc.) to changes in mean

climate will be magnified along ephemeral watercourses;

(2) drainage networks have a natural, hierarchical organization and scale by both size and dynamical behavior, with

the smallest watersheds flowing at high frequency and low

magnitude and large watersheds at low frequency and high

magnitude (Yair 1983, Yair and Shachak 1982); (3) watershed studies have, as a central focus, movement of water

across the landscape (the focal constraint in the region’s

ecology), and represent especially steep, spatially predictable, gradients in water availability; and (4) watershedbased analyses allow comparative studies with other research environments. The watershed studies are based on a

conceptual view of watershed processes developed in the

Negev Desert. The focus is on biotic responses to the hydrologic redistribution of water as a consequence of interaction

between scale, climate, local geology, and microtopography.
168 USDA Forest Service Proceedings RMRS-P-7. 1999

These interactions result in spatially predictable patterns of

average runoff intensity and frequency. During the last ten

years, eight ephemeral stream sites nested within the Rio

Salado drainage have been studied with watershed areas

spanning several orders of magnitude (4 at about 22 ha, 2 at

240 ha, 1 at 3,000 ha, 1 at 300,000 ha). The hydrologic data

of U.S.G.S. for the Rio Puerco (1 million ha) and the Rio

Grande (5.5 million ha) provide long-term, broad scale results. Recent studies of El Niño/La Niña effects in the

region also identify temporal predictability at certain scales.

The watershed studies (1) form a model for studies of other

constraints which change across scales in other landscapes,

and (2) form an empirical basis in attempts to link ecological

studies to regional and global biogeospheric studies.

Plant and Animal Population Studies

For plant population studies, the ideas focus on the interaction between climatic change and evolutionary change.

Climate change may both stretch the limits of response and

change the process of evolution through climate-induced

changes in population structure. For long-lived species, it is

crucial to understand the limits of phenotypic response. For

shorter lived species, genetic change is possible. The effects

of short term climatic change on the evolutionary process

is being studied by investigating the effects of La Niña

and El Niño conditions on gene flow and reproduction in

current populations.

Plant productivity responses to environmental dynamics

may change beyond simple responses to climate due to

enhanced susceptibility to herbivores. Monitoring specific

interactions between a plant species and its herbivores show

at what levels plants react initially to climate change.

Genetic variation of spatially separated populations and

changes in response to changing environment as well as

altered herbivore interactions are hypothesized to control

landscape patterns of species.

For animal populations, movement of individuals is being

quantified, as well as dynamics of populations, abundance

and distribution of species, and trophic and taxonomic composition of assemblages of mammals (rodents, rabbits, coyotes), birds, and surface-active arthropods. Patterns and

rates of genetic change (in isozymes and mitochondrial DNA

clones) are monitored in rodents. These measurements are

made over a sufficient range of spatial and temporal scales:

(1) to document the response to heterogeneity across the

entire region; and (2) to assess the detailed response of

individuals and local populations to both natural environmental change and any experimental manipulations. Specimens are sorted and recorded using the Museum of Southwestern Biology (MSB) computerized information retrieval

system.

Fertilization Studies

The abundance of plants from many different biomes

suggests intriguing questions of nutrient limitation. Ecosystem nutrient limitation has been noted in many studies

while others clearly indicate that each species responds

individually to resource availability in relation to its requirements. The ability to predict strong El Niño or La Niña

events offers additional capabilities to study nutrient

limitation. During wet springs associated with El Niños,

cool season plants are expected to be limited by nutrients

rather than moisture. The warm season grasses also would

be nutrient limited during an El Niño year because of

nutrient immobilization by spring growth of cool season

grasses. In La Niña years both cool and warm season

grasses should be more water limited than nutrient limited.

Fertilization experiments on Sevilleta grasslands have been

initiated to evaluate these hypotheses.

Wildfire Studies

Natural fires have become more common on the grassland areas of the protected research areas (no cattle grazing). The studies of these natural fires shows that the

influence of fire is very species specific because perennial

grasses with large, belowground root systems (for example,

Blue Grama of the Great Plains flora) survive while

Chihuahuan Desert species (for example, Black Grama,

desert shrubs) are depleted. Thus, in the tension zone

between Chihuahuan and other biomes, fire may be a primary agent in controlling species movement due to climate

dynamics. In areas where the desert species have been

established for a longer period (i.e., more like desert habitat

than transition habitat), the grass component has been

greatly reduced and fires are rare or nonexistent. The

natural fires allow studies of species and the effects on

subsequent ecosystem processes. Factorial experiments have

been conducted that relate burning and herbivore (large

ungulates) activity to plant and animal community composition and ecosystem processes.

Future Research Potential ________

Based on current research activity in the Sevilleta region,

as well as on the research activity projections considered

internally and with potential visiting researchers, several

major avenues of future research are anticipated. First are

ecosystem- and community-level studies addressing the

effects of climate change on biotic systems. These will include both seasonal, annual, decadal (and longer time scales)

fluctuations and trends in climatic variables, and the eventual responses in ecosystem structure and function among

the various biomes represented in the Sevilleta region.

Second, a dramatic increase in population- and organismlevel studies can be expected in response to the increasing

concern about world-wide patterns of declining biodiversity.

Included in this category of research are studies concerning

the genetic variability of existing plant and animal species,

and the historical implications. As mentioned above, the

Sevilleta is an extremely species-rich region, and many

species therein occur near the boundaries of their range

distributions. As such, they are subjected to environmental

conditions that, for them, may be extreme. In some cases, for

example, a species of desert millipede, the region contains

only isolated, relict populations that are widespread elsewhere. Comparisons of genetic similarity among these and

other species populations that, over time, have colonized

marginal habitats in the Rio Grande Basin, will be of prime

importance in LTER studies.

Third, an increase in the number of studies concerning the

relationship between ecosystem restoration and biodiversity
USDA Forest Service Proceedings RMRS-P-7. 1999 169

is anticipated. The Rio Grande Basin as a whole has been

overexploited in a number of ways, particularly in the past

century. Currently, however, much discussion and some

research has centered on restoration of the region’s semiarid grasslands and on the marshes and gallery forests

associated with the Rio Grande itself. The Sevilleta NWR

contains extensive grasslands that have been free of livestock grazing for nearly two decades. Studies of the effects of

livestock removal on the diversity of grassland biotas are

underway and more are planned. The Rio Grande Valley has

lost most of the marshland that made it one of North

America’s most important migration routes for birds. The

introduction of salt cedar and Russian olive trees in this

century has greatly compounded that loss in terms of habitat

alteration. Significant strides to correct these alterations

have been made by the Fish and Wildlife Service at the

Bosque del Apache NWR, where federal and UNM biologists

have begun collaborative studies on restoration of the original wetlands.

Fourth, a number of current and planned research projects

on the Sevilleta concern the research and development of

new technologies for use in ecological studies, and the

application of current technologies to field research. For

example, the development of field FTIR (Fourier-Transform

Infra-Red) technology to measure trace atmospheric gas

production over km2 areas of natural ecosystems has been

and continues to be an active program on the Sevilleta. In

addition, Sevilleta researchers are developing a 3-dimensional, advanced image processing system that will calculate plant biomass from stereoscopic photographs of permanent study plots. An example of integration of existing

technologies is the collaborative effort between UNM and

NMIMT to correlate lightning activity during thunderstorms with realized precipitation. A 20 km2 grid of 25

tipping-bucket rain gauges, each gauge instrumented with

a data logger, provides rainfall timing and distribution data

that are integrated with temporal and spatial lightning data

collected simultaneously by Langmuir’s Lightning Detection System. As future technology is made available for

scientific use, Sevilleta LTER researchers will continue to

develop practical applications of technology for ecological

research.

Educational Activities: REU and

UMEB Programs ________________

The Sevilleta Research Experiences for Undergraduates

Program and the Undergraduate Mentorships in Environmental Biology Program continues to operate in collaboration with the Sevilleta LTER. As in prior years, the goals of

these programs are to (1) instruct undergraduates in the

principles of scientific research, (2) expose the students to a

wide variety of ecological research techniques and career

opportunities, (3) facilitate individual student research

projects, and (4) encourage students to continue their scientific education in upper-division courses and graduate

school. To accomplish these goals, the programs include (1)

orientation meetings and a seminar series devoted to the

variety of scientific opportunities in ecological research at

the Sevilleta, (2) faculty-student one-on-one instruction of

hypothesis development and research protocols in ongoing

Sevilleta LTER projects, (3) field and laboratory experiences in sampling and data collection, (4) implementation of

individual student research projects, carried out under the

guidance of student-selected faculty members, (5) a Sevilleta

REU Symposium for project presentations by the students,

(6) attendance at scientific meetings, and (7) preparation

and submission of project manuscripts to scientific journals. These activities integrate all theoretical and technical

aspects of the LTER and promote a holistic approach to

large-scale ecological studies.

Applications of Sevilleta LTER

Databases _____________________

The following is a brief description of how Sevilleta LTER

results to date have been incorporated by agencies, resource

planners, etc., into their management plans or processes.

(1) Public Health — Hantavirus: Sevilleta LTER data

have been used by Public Health officials and the Federal

Centers for Disease Control and Prevention in assessing the

causes and circumstances of the 1993 Hantavirus epidemic

in the Southwest. In addition, the CDC continues to collaborate with the Sevilleta LTER, via a separate grant to Co-P.I.

Terry Yates, to monitor rodent populations and hantavirus

prevalence in wild rodents.

(2) Land Management — Fire ecology: LTER studies of

ecological responses to fires in Sevilleta’s grasslands have

yielded data on plant and animal survivorship and

recolonization. These data have convinced the Fish and

Wildlife Service to discontinue fire suppression in grassland/shrubland areas of the refuge, and allow lightningcaused fires to burn in a natural fashion. FWS will continue

to stop fires in woodlands, but they have recognized the

value of fires in grasslands in maintaining open grass

habitats and curtail shrub invasions and desertification.

(3) River Management — Flooding on the Rio Grande:

With additional funding from FWS, UNM Biologists Cliff

Crawford and Manuel Molles are investigating the role of

artificial flooding in restoration efforts along the Rio Grande.

Floods are essential for reseeding cottonwood forests, and

influence various ecosystem processes, such as wood and

leaf litter decomposition and soil nutrient cycling. Sevilleta

LTER data from the LTER site at Bosque del Apache NWR

are being used in this project. Results from the study are

being incorporated into the river management plan by the

various state and Federal agencies responsible for flow

regulation of the Rio Grande.

(4) Water Use Policies — El Niño: LTER researchers have

provided to the public and the state and local governments

a continuous stream of data on the ecological and hydrological effects of the El Niño - Southern Oscillation (ENSO)

dynamic in New Mexico. Considerable press and TV news

coverage has raised the public awareness of the ENSO

phenomenon, and some planning decisions by the State

Water Engineer have been based on ENSO predictions (for

example, reduction of irrigation water allowances in 1992

after sufficient water was predicted during the El Niño of

that year; extra water was allowed to flow to Texas, to pay

off part of New Mexico’s water debt).

(5) Rangeland Resource Use — Grazing Issues: LTER

studies of livestock grazing on private ranchland adjacent to

the Sevilleta NWR have been incorporated into the ongoing

debate on use of western Federal lands for grazing. Policies

on grazing are currently being considered at Federal and

State levels.
170 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Todd R. Caplan is Resource Ecologist, Santa Ana Pueblo, Bernalillo, NM.

Heather A. Pratt is with the Department of Biology, University of New

Mexico, Albuquerque. Samuel R. Loftin is Ecologist, Rocky Mountain Research Station, Albuquerque, NM.

Abstract—Mycorrhizal fungi are crucial elements in native plant

communities and restoring these fungi to disturbed sites is known

to improve revegetation success. We tested the seedball method of

plant dispersal for restoration of plants and mycorrhizal fungi to

disturbed ecosystems. We tested the seedball method with a native

mycorrhizal fungi inoculum, and a commercial inoculum. We found

that the native culture and commercial inoculum were not viable

sources of mycorrhizae.

The role of mycorrhizal fungi in ecological restoration

has been a topic of great interest to scientists for more than

two decades. Mycorrhizal fungi are known to aid plants in

acquiring water and nutrients, most notably phosphorus, in

exchange for carbohydrates and sugars provided by the

plants through photosynthesis. This relationship is thought

to benefit not only individual plants, but entire plant communities (Allen and others 1995; Francis & Read 1994;

Francis & Read 1995). However, human activities which

cause severe soil disturbance may result in the reduction or

complete loss of mycorrhizal propagules from the soil (Allen

& Allen 1980; Allen and others 1987; Reeves and others

1979). Several ecologists, including Allen and others (1987)

and Reeves and others (1979), believe that successful

plant community restoration may ultimately depend upon

the re-establishment of this mycorrhizal relationship.

Unfortunately, few methods have been developed for reintroducing mycorrhizal fungi to disturbed soils. The

method most typically employed involves inoculating nursery plants with the fungi prior to field planting. While this

method has been shown highly successful in forest/shrub

land restoration, planting nursery raised plants is expensive, labor intensive and impractical when attempting restoration of grass and forb dominated plant communities

(i.e. tundra and grassland). Practical and affordable methods for restoring mycorrhizal plants to disturbed grassland

and tundra environments are greatly lacking. In fact, we

Influence of Mycorrhizal Source and

Seeding Methods on Native Grass Species

Grown in Soils from a Disturbed Site

Todd R. Caplan

Heather A. Pratt

Samuel R. Loftin

know of no published research investigating such methods.

However, a method developed by an organic farmer in Japan

may provide an excellent tool for restoring herbaceous mycorrhizal plants to disturbed landscapes.

For over fifty years, Masanobu Fukuoka, a Japanese

scientist and farmer, has been practicing a method of sustainable organic farming which centers around the planting of seedballs (Bones 1996). Seedballs are simply a mixture of clay, soil humus, and plant seed rolled into small balls

the size of deer droppings. Fukuoka combines seed from

over 100 species of vegetables and fruits into these balls

and scatters them by hand throughout his field. The clay

provides a barrier against seed herbivory, re-dispersal of

seeds by wind, and exposure to harsh environmental conditions. The soil humus provides an immediate source of

mineral nutrients and soil micro-organisms. The purpose of

including seed from a high number of plant species is to

provide a soil seed bank from which any number of seeds

may germinate in a given year depending upon current

climatic conditions. Fukuoka’s crop productivity has consistently rivaled or surpassed those of neighboring farmers

employing more labor intensive and costly practices that

utilize more traditional farming methods (fertilizer inputs,

tilling, flood irrigation, etc.).

While seedballs have primarily been used for growing food

crops, the concept is intriguing for use in native plant

community restoration. By substituting native grass and

forb seeds for agricultural crop seeds, land managers restoring disturbed areas with seedballs may benefit from increased ground cover and native plant diversity compared to

seeding using traditional broadcasting methods. Seedballs

may also be an effective means of restoring a much needed

seed bank to severely disturbed soils. Furthermore, by

incorporating mycorrhizal fungi into the seedball mixture,

emerging seedlings will benefit from the increased water

and nutrient uptake in disturbed soils supplied by the

mycorrhizal fungi. These methods for restoring mycorrhizal

grasses and forbs, however, have never been experimentally

tested.

It is important to note that limited options for reestablishing mycorrhizal grasses and forbs to disturbed

ecosystems is not the only problem facing restoration ecologists. A difference of opinion has recently surfaced over the

best methods for developing mycorrhizal inoculum for

restoration plants. The few companies known to us who

engage in the production of mycorrhizal inoculum, utilize a

method which involves promoting reproduction of

arbuscular mycorrhizal (AM) fungi collected from a single
USDA Forest Service Proceedings RMRS-P-7. 1999 171

source. One to a few fungal species are carefully selected

and progeny from this “mother” culture are used to inoculate

plants for different restoration sites. Inoculum developed

from AM collected in the Pacific Northwest, therefore, may

be used to inoculate plants for a restoration site in New

Mexico. The fungal species bred for these bulk cultures are

generally selected because they are aggressive root

colonizers, are relatively easy to grow and are present in

soils world-wide.

Bulk inoculum containing one to a few ubiquitous fungal

species may not be the best approach to inoculating restoration plants. One argument is based upon the fact that

different mycorrhizal fungi may be active on the same host

plant at different times in the year (Allen and others 1995;

Sanders & Fitter 1992; Siguenza and others 1996). Inoculum containing only one or two species, therefore, may

provide little or no functional benefit to its host during

certain times of the growing season or under variable environmental conditions. Another argument is that even

though a given AM fungi species is ubiquitous, different

genotypes probably exist which influence plant function

differently depending on the biome from where it was collected. For example, Allen and others (1995) found that

similar morphotypes of AM fungi collected from different

sites confer different physiological benefits to the same plant

species. These arguments have led us to ask the question:

Will plants used in ecological restoration efforts derive

greater benefit (increased growth and survival) from local

AM fungi inoculum compared to non-local, commercial inoculum containing one or a few AM fungi species?

We addressed this question in a controlled greenhouse

experiment while simultaneously investigating the seedball

seeding method for seed germination and inoculation. We

believe these methods, once perfected, have great promise

for large scale application.

Methods _______________________

Greenhouse

Soils used for the greenhouse experiment were collected

from several locations within a 200 acre Saltcedar (Tamarix

chinensis) / Russian olive (Elaeagnus angustifolia) stand on

Santa Ana Pueblo in Bernalillo, NM. The soil was collected

Table 1—Analyses of untreated, and sterilized soil samples for pH, electro-conductivity,

nutrient content, and texture.

Test parameter Untreated Sterilized

pH 7.75 7.48

Electro-conductivity 2.20 mmhos/cm 2.55 mmhos/cm

Magnesium 2.40 meq/L 3.25 meq/L

Calcium 6.31 meq/L 8.44 meq/L

Sodium 12.05 meq/L 13.10 meq/L

Sodium Absorbtion ratio 5.77 5.42

Calculated Exchangeable NA pct-ESP 6.8 6.3

Organic material - pct 1.29 1.61

NO3-N 1:5 (soil:water) extract 1.1 ppm 1.1 ppm

Phosphorus (NaHCO3 extracted 17.6 ppm 8.1 ppm

K 1:5 (soil:water extract) 64 ppm 63 ppm

Texture of soil by feel sand sand

from 27 random sites from an area of known low salinity.

We sieved the soil through 2 mm sieves to remove organic

debris. We sterilized the soil by microwaving it for 150

seconds per kilogram of soil. The soil reached mean temperatures of 97 °C (s.d. 10.7). One untreated, and one

sterilized representative sample were sent to the SWAT

Laboratory at New Mexico State University, Agronomy

and Horticulture Department and analyzed for macro and

micro nutrients, organic matter, pH, texture, and electroconductivity (table 1).

The soils were placed in flat cedar boxes (15" x 20" x 12") in

the Rocky Mountain Experiment Station greenhouse and

seeded with three locally native grassland species according to the following treatments: 1) seedballs with cultured

native AM fungi inoculum; 2) seedballs with commercial

AM fungi inoculum; 3) seedballs with sterilized inoculum

(control); and 4) broadcast seeding. We planted each box on

July 30, 1997. The species of grass utilized were Sporobolus

crytandrus, Hilaria jamesii, and Bouteloua gracilis. Each

treatment was replicated five times, yielding twenty boxes

(samples) total.

We made seedballs by combining specific quantities of

clay, soil humus, plant seed and water, then rolling them

into small balls the size of elk droppings. These quantities

follow methods outlined by Harris (1996). In addition,

mycorrhizal fungi from two sources were incorporated into

the seedball mix. Seedballs in treatment 1 had native AM

fungi inoculum cultured in Santa Ana greenhouse and

seedballs in treatment 2 had commercial AM fungi inoculum

purchased from a bulk producer and distributor. Methods

for culturing indigenous AM fungi followed Menge (1984)

and Morton (1996).

Bioassays

Plant contents from each sample were harvested when

the majority of plants approached senescence on October 19,

1997. Upon harvest, individual plants were separated and

species composites were formed. We collected 0.3 g of root

segments from these composites to determine percent

mycorrhizal root infection. In addition, oven dry weight

measures of root biomass and shoot biomass were measured

for each composite sample. Finally, portions of the dried

shoots from each composite sample were ground and sent to

the SWAT laboratory for tissue phosphorus and nitrogen

analysis.
172 USDA Forest Service Proceedings RMRS-P-7. 1999

The 0.3 g root segments used for percent root infection

were immediately placed in tissue cassettes and immersed

in 50 percent ethanol solution. We cleared the roots prior to

staining by alternating them between a 10 percent potassium hydroxide solution and a 1 percent hydrogen peroxide

solution for approximately 50 hours or until each sample

was observed to be cleared. The samples soaked in each

solution for at least 1 hour and up to 10 hours before

changing to the other solution. After clearing, we stained the

roots in a 5 percent trypan blue solution in lactoglycerin.

Fungal colonization of the roots was evaluated using the

gridline intersection method described in Brundrett and

others (1994).

Samples of the commercial inoculum, cultured inoculum,

and microwaved soil were sent to Joe Morton’s lab at West

Virginia University in Morgantown, WV for an infectivity

assay. The assay determined the presence, quantity and

identity of mycorrhizal spores by utilizing a mean infection

percentage assay (Morton, 1996).

Results ________________________

Treatment Effects

A one-way ANOVA test was performed for analysis of

treatment effects on each of the following variables; percent

of root length colonized by arbuscular-mycorrhizal (AM)

fungi, root biomass, shoot biomass, tissue nitrogen, and

tissue phosphorus. The treatment effects were analyzed

across all species (table 2).

The commercial inoculum treatment resulted in relatively

high percent AM colonization, but there were no significant

treatment effects. The values obtained for percent AM colonization were so low as to be negligible in all treatments.

No significant treatment effects were recorded for root or

shoot biomass.

There were significant treatment effects for the plant

tissue nitrogen. The highest accumulation occurred in the

native inoculum treatment followed by the commercial inoculum treatment. The control treatment and the broadcast

treatment were not significantly different. The tissue

phosphorus values did not differ significantly between the

treatments.

Species Effects

A T-Test was used to test for species effect since the

H. jamesii plants were inadvertently removed from the

boxes during the experiment. Plant tissue phosphorus

was significantly greater in the S. crytandrus than in the

B. gracilis, but there were no significant species effects for

plant tissue nitrogen (table 3). Other analyses were not

performed due to missing data. All tests were conducted on

Statistical Software for the Social Sciences (SPSS 5.0).

Infectivity

The infectivity assays for the cultured inoculum, the

commercial inoculum and the microwaved soil all had the

same result: there were no viable spores in any of the

samples.

Discussion _____________________

In this experiment we attempted to test two new techniques for restoring mycorrhizal plants to disturbed areas,

the seedball method of dispersal, and utilizing either native

Table 2—Means and standard errors of percent AM fungi colonization, root biomass,

shoot biomass, tissue N, tissue P for each of the treatments; control (sterilized

inoculum), cultured native inoculum (native), commercial inoculum

(commercial), and broadcast seeding. F-probability statistic shown for each

variable. Letters reflect significant groupings by one way ANOVA analysis.

Treatment Per. colonized Root biomass Shoot biomass

Control 0.40 (s.e. 0.30) 40.89 (s.e. 5.20) 35.8 (s.e. 3.6)

Native 0.99 (s.e. 0.38) 46.65 (s.e. 5.01) 43.9 (s.e. 4.2)

Commercial 4.51 (s.e. 2.14) 54.14 (s.e. 5.06) 38.4 (s.e. 2.7)

Broadcast 1.50 (s.e. 0.58) 56.89 (s.e. 2.62) 36.5 (s.e. 1.6)

F-prob 0.055 0.097 0.30

Treatment Tissue N Tissue P

Control 0.61 (s.e. 0.03) C 0.08 (s.e. 0.01)

Native 1.04 (s.e. 0.05) A 0.09 (s.e. 0.01)

Commercial 0.82 (s.e. 0.08) B 0.09 (s.e. 0.01)

Broadcast 0.58 (s.e. 0.04) C 0.09 (s.e. 0.01)

F-prob 0.0000 0.86

Table 3—Means and standard errors for tissue N and tissue P for two

of the grass species, Bouteloua gracilis and Sporobolus

crytandrus. F- probability statistic is shown for each variable.

Letters reflect significant groupings by T-Test.

Species Tissue N Tissue P

Bouteloua gracilis 0.73 (s.e. 0.06) 0.08 (s.e. 0.00) B

Sporobolus crytandrus 0.74 (s.e. 0.052) 0.10 (s.e. 0.00) A

F-prob 0.91 0.002
USDA Forest Service Proceedings RMRS-P-7. 1999 173

or commercial AM fungi inoculum. Both of these techniques

have great potential, and further work may address the

complications we encountered in this experiment.

Seedball Method

We made seedballs with a commercially available red

pottery clay substrate. None of the seedballs dissolved completely during watering in the greenhouse though the boxes

were thoroughly soaked daily. We attribute this to adding

too much clay to the seedball mixture. The plants that grew

in the seedball treatments sprouted directly out of the

seedballs but only the seeds on the periphery of the seedballs

germinated. Although there was no significant difference in

biomass between treatments, we observed that grasses from

the seedball treatments were substantially larger in size

than the broadcast treatments. The observed size difference

between plants in seedball and broadcast treatments is

attributed to fewer numbers of individuals in the seedball

treatments and greater competition for nutrients in the

crowded broadcast treatment samples.

AM Fungi Inoculum

The question of using an AM fungi inoculum in the

seedball is complicated. Although we found significant treatment effects in the tissue nitrogen analysis, the infectivity

assay results showed that our inoculums, both cultured and

commercial, had no viable spores.

AM fungi propagates by two methods, spores and hyphae.

The spores are the sexually produced propagules. Hyphae

are the “body” of the fungi and penetrate the root cortex

cells of the host plant and extend out into the rhizosphere.

Often hyphae will extend from one host plant’s roots to the

roots of another neighboring plant. By this “vegetative”

means, the hyphae of a single fungi are spread throughout

a community.

We attempted to infect our experimental grasses with AM

fungi spores harvested from the native culture we generated

in the Santa Ana Greenhouse, and from AM fungi spores we

ordered from a commercial supplier. Both of these sources

were later found to be unreliable for viable spores. We

checked the roots of the native culture host plants for

percent of root length colonized by AM fungi prior to the

experiment and found them to be highly mycorrhizal (mean

45.7 percent). So why were there no viable spores in the

native inoculum? It has been hypothesized that sporulation

will not occur for an individual AM fungi until root colonization reaches values of 30- 40 percent of root length (Morton

1998, personal comm.). Southwestern AM-fungi has high

levels of diversity, and although the root length colonized in

the native culture host plants appeared to be high enough to

have sporulation, there were no spores. This phenomenon

may be explained by the presence of more than one species

of AM fungi colonizing the roots although it is not possible to

identify AM species without spores. Multiple species occupying the same host plant has been observed in other studies

(Allen and others 1995; Sanders & Fitter 1992; Siguenza

and others 1996). In our culture host plants, one species of

AM fungi may be colonizing 20 percent of the root length,

another may be colonizing 10 percent, while a third species

may occupy the remaining 15 percent. It is nearly impossible

to distinguish between species of AM fungi in this type of

assessment. So what we thought was extensive colonization

by one species of AM fungi may have been 2 to 3 different

species colonizing the same plant. Given this hypothesis,

AM fungi in the Southwest would rely more on hyphal

propagation than sporulation due to the high diversity of

AM fungi available for colonization. Future attempts to

inoculate restoration plants using seedballs may require

relying upon AM hyphae by mixing segments of the roots of

the native culture host plants into the seedballs, rather than

relying upon spore production. The hyphae within these root

segments, therefore, will then colonize the roots of target

plants “vegetatively.”

We returned the commercial inoculum for a refund. Repeated analyses of various commercial inoculums have

shown similar results. Commercial sources of mycorrhizal

inoculum should be tested for viable propagules prior to

experimental or practical application.

The differences we observed in our experimental treatments between tissue phosphorus were probably not due to

mycorrhizal effects, evidenced by the extremely low values

of root colonization. They may be attributed to competitive

effects related to the clumped dispersal of the plants emerging from the seedballs.

We still believe that seedballs can be excellent method of

seed dispersal for restoration projects. Incorporating root

segments of the native culture host plants containing

hyphae into the seedballs may accomplish both goals of

restoring not only the seeds of native plants, but the native

AM fungi that have been removed from a disturbed area.

Acknowledgments ______________

The researchers thank the Rocky Mountain Experiment

Station for funding and use of greenhouse and laboratory

space to conduct this research. We also thank the U.S. Fish

& Wildlife Service for providing additional funding for supplies and some laboratory analysis. Special thanks to Randi

Paris and Gary Desselle for their assistance with this project.

References _____________________

Allen, E.B. and M.F. Allen. 1980. Natural re-establishment of

vesicular-arbuscular mycorrhizae following strip-mine reclamation in Wyoming. Journal of Applied Ecology, v.17:139-147.

Allen, E.B., Allen, M.F., Helm, D.J., Trappe, J.M., Molina, R. and

E. Rincon. 1995. Patterns and regulation of mycorrhizal plant

and fungal diversity. Plant and Soil, v.170(1):47-62.

Allen, E.B., Chambers, J.C., Connor, K.F., Allen, M.F., and R.W.

Brown. 1987. Natural re-establishment of mycorrhizae in

disturbed alpine ecosystems. Arctic and Alpine Research,

v.19(1):11-20.

Bones, J. 1996. Light Writings, Microsoft Internet Explorer;

http:\\www.rt66.com\~jimbones

Bundrett, (spelled Brundrett in text) M., L. Melville, and L. Peterson,

eds. 1994. Practical Methods in Mycorrhiza Research. Mycologue

Publications, Ontario.

Francis, R. and D.J. Read. 1995. Mutualism and antagonism in

the mycorrhizal symbiosis, with special reference to impacts on

plant community structure. Canadian Journal of Botany, v.73

(Suppl. 1):S1301-S1309.

Francis, R. and D.J. Read. 1994. The contributions of mycorrhizal

fungi to the determination of plant community structure. Plant

and Soil, v.159:11-25.
174 USDA Forest Service Proceedings RMRS-P-7. 1999

Harris, S. 1996. Faith in a Seedball. In: Dialogue, a publication of

the New Mexico Water Dialogue, v.4(2):16-17.

Menge, J.A. 1983. Utilization of vesicular-arbuscular mycorrhizal

fungi in agriculture. Canadian Journal of Botany, v.61:1015-1024.

Morton, J. 1998. Personal Communication. Department of Biology,

West Virginia University, Morgantown, WV.

Morton, J. 1996. INVAM Protocols for Producing Bulk Cultures.

Microsoft Internet Explorer, http:\\invam.caf.wvu.edu.

Reeves, F.B., Wagner, D., Moorman, T., and J. Kiel. 1979. The role

of endomycorrhizae in revegetation practices in the semi-arid

west: A comparison of incidence of mycorrhizae in severely

disturbed vs. natural environments. American Journal of Botany,

v.66(1):6-13.

Sanders, I.R. and A.H. Fitter. 1992. The ecology and functioning

of vesicular arbuscular mycorrhizas in coexisting grassland

species: Seasonal patterns of mycorrhizal occurrence and morphology. New Phytologist, v.120 (4):517-524.

Siguenza, C. Espejel, I., and E.B. Allen. 1996. Seasonality of

mycorrhizae in coastal sand dunes of Baja-California. Mycorrhiza v.6 (2):151-157.
USDA Forest Service Proceedings RMRS-P-7. 1999 175

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Joy Rosen and Roy Jemison are with the Rocky Mountain Research

Station, USDA Forest Service, Albuquerque, NM 87106. David Pawelek is

with the Cibola National Forest, USDA Forest Service, Albuquerque, NM

87113. Daniel Neary is with the Rocky Mountain Research Station, USDA

Forest Service, Flagstaff, AZ 86001.

Abstract—A Cibola National Forest wet meadow restoration was

implemented as part of the Forest Road 49 enhancement near

Grants, New Mexico. An Arc/View 3.0 Geographic Information

System (GIS) was used to track the recovery of this ecosystem.

Layers on topography, hydrology, vegetation, soils and human

alterations were compiled using a GPS and commonly available

data. Cartographic information allows visual interaction of natural

features that could not be interpreted from tabular data sets. First

results indicate that stream confinements by the railroad trestle,

old channel fill, old two-track roads, Forest Road 49, and mis-graded

construction affected the flow and location of spring floodwaters in

1998.

Agua Fria meadow is a small, 2.6 km2 forest opening

located in the Zuni Mountains 32 km southwest of Grants,

New Mexico, and bisected by Forest Road (FR) 49 (Jemison

and others 1998). It is representative of numerous fourth

order streams in the Rio Grande basin affected by grazing,

water erosion and changes in water flow due to human

impacts (Jackson 1994a). The lower end of the meadow

was blocked 3-15,000 years ago by one of the El Malpais

sequence of lava flows (Mabery, 1997). Thick organic soil

layers recently exposed by channel erosion suggest the area

was a typical ‘wet meadow’, retaining much of the water that

flowed into the area. Circa-1900 logging in the upper

watershed, and the location of transportation routes could

have contributed to prerestoration conditions of increased

surface runoff, elevated channel flow rates and channel

erosion. The decreased elevation of the old channel could

have lowered the water table across the meadow, with the

net effect being a change towards a more xeric ecosystem.

Funds to reroute Agua Fria Creek were provided in 1995

via a Forest Road improvement project with the Federal

Highway Department. The goal of the restoration design

was to increase the period of flow through the meadow

(Jackson, 1994b). Slower water velocity and more water

absorption over a larger area of the meadow were planned

through construction of a highly sinuous channel (fig. 1).

Using GIS Technology to Analyze and

Understand Wet Meadow Ecosystems

Joy Rosen

Roy Jemison

David Pawelek

Daniel Neary

The new channel runs down the center of the meadow,

2-3 m in elevation above the old channel. It is only .60-.75 m

deep in contrast to the old channel which was incised as

much as 3 m in places (fig. 2). Thus the new channel has a

much smaller cross sectional area which encourages flooding and water retention in the meadow.

Importance of GIS _______________

As a technology, GIS is an information management and

analysis tool (Harlin and Lanfear, 1993). Map layers and

associated databases can be complied and serve as reference

tools for effective communication of past, present and potential conditions. Data incorporated into a GIS can include

point data, such as photo-points or the location of objects and

spatial data, such as historical landuse maps and vegetation

coverages.

Environmental data frequently collected in wetland monitoring projects includes vegetation, soil moisture, stream

channel profile and water table level (Brinson, 1996 and

Harlin and Lanfear, 1993). The location and/or extent of

these data can be mapped with a Global Positioning System

(GPS) unit and presented in 2- and 3-dimensional models.

GPS mapped data can be easily combined with existing

GIS map layers to increase previous coverages and analyze

spatial interactions between mapped features.

Questions that can be addressed using GIS/GPS are:

• How does elevation affect water flow across the meadow?

• Are the new channel elevations and grades adequate to

meet restoration specifications?

• Why is the channel breached in some areas?

• What is the potential extent of the new wet meadow?

• How does soil moisture distribution across the meadow

change over time?

• How does vegetation adjacent to the channel change

over time?

• How does channel morphology change over time?

• How do past and present land uses (railroad, roads,

borrow pits, etc.) affect current conditions?

Methods _______________________

A Trimble Geoexplorer II GPS with post-processing differential correction and Arc/View GIS 3.0 software were used to

acquire the locations of the project fence perimeter, FR 49,
176 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 1—This photo shows the “green belt” surrounding the meanders of the newly

installed channel. This channel is shallow and wide with 37 meanders in the study area.

The old channel show in figure 1 is relatively straight and more deeply incised.

Figure 2—Previous restoration projects amplified erosion in the old channel on the south

side of the meadow. This photo shows the ensuing escarpment, looking upstream.
USDA Forest Service Proceedings RMRS-P-7. 1999 177

two-track roads, stream channels, train trestle, borrow pit

location, and the 1998 spring flood extent for Agua Fria

meadow. In conjunction with a laser leveller, the GPS unit

recorded point locations for a submeter accuracy surface

elevation map. Point data collected includes the locations of

stream flow measurements, head cutting, core sampled

trees, rock weirs and carbon dated soils.

Results ________________________

A map of the flood water extent in the spring of 1998 was

created by walking the perimeter of the flood areas with a

GPS unit (fig. 3). The extent of the flood was visually

identified by standing water, wet soils, soil deposits and

soggy vegetation. Major breaches of the new channel are also

identified on the map. This information will be important to

track the success of the new channel, the vegetative response, and the reoccurrence of seasonal flooding. Previous

human alterations act as constraining features to the water

in Agua Fria meadow. Flooding is at least partially confined

by the railroad bed, roads, and the old channel.

Personal observations during 1998 spring runoff demonstrated that rates of erosion and deposition can be very rapid

at Agua Fria. Soil carbon dates for soil samples collected

between 75 and 90 cm below the soil surface at the lower end

of the project area were dated at AD 1430-1670 and AD 770-

380. Combined with other information about the area this

information could help us determine the sequence of events

that have taken place in the meadow.

Runoff water flowed at Agua Fria for approximately 2-3

months in the spring of 1998. Flood waters flowed above the

bankfull stage and across the meadow for more than half the

time. Variations in the gradient of the new channel from the

project design caused water to flow into areas not predicted.

For example, less slope than expected directly downstream

of FR 49 and fill materials placed in the old channel, higher

than the adjacent surface, directed over-bank flows away

from the new channel into a two-track road.

Two-track roads above and below FR 49 partially diverted

water away from the new stream channel. Above FR 49, a

two-track that crossed the new channel caused more water

to flow across rather than around a constructed channel

meander. Below FR 49, flood water diverted onto a two-track

road by gradient and fill variations flowed into the borrow

pit (fig. 3). These diversions of water increased the area of

the lands projected to be inundated with floodwaters, a

major goal of the restoration. However, while increasing the

extent of the areas flooded, these two-track roads have the

Figure 3—1998 spring Flood Map.
178 USDA Forest Service Proceedings RMRS-P-7. 1999

potential to be eroded into straight channel sections. Straight

channel sections would allow water to flow quickly through

them and could over time return the channel and meadow to

pre-project conditions.

The over-bank flows downstream of FR 49 that were

diverted into the borrow pit, filled the pit and flowed toward

the lower end of the project area (fig. 3). These flows ran

across the surface and followed the course of the old stream

channel, most of which had been previously filled in with

soil from the borrow pit. Increased surface slope at the lower

end of the study area caused overland flows to initiate

erosion and headcutting in the area where the diverted

water rejoined the new channel (fig. 4). By the time runoff

stopped, headcuts had formed up to 1.50 m deep and 30 m to

50 m long (fig. 5).

Figure 5—Major erosion due

to spring 1998 flooding. This

photo is taken looking upstream from the fenceline

project boundary. The second

to last constructed concrete

weir is in the center of the

photograph.

Figure 4—Downstream of

the new channel breach, below Forest Road 49, standing

water and sheet flow cover

the reseeded and filled old

channel, during the spring of

1998.
USDA Forest Service Proceedings RMRS-P-7. 1999 179

Management Implications ________

GIS and GPS technology is becoming more commonly used

as management and reference tools in the Southwest Region

of the USFS. Currently an interoffice IBM system with Arc/

Info, database management and statistical software is being

by the USFS nationwide. This hardware and software upgrade will facilitate data transfer, analysis, storage, analysis and the creation of GIS products. This project will

demonstrate how the successes and failures of ecosystem

alterations can be studied and documented. This information will provide guidance for other projects that address

similar issues and have access to similar technologies.

Future Work ____________________

GPS and GIS will continue to be used to collect, analyze

and store information about Agua Fria meadow. In addition

to the stream flow and climatic data being collected, continuous monitoring of watertable levels and soil moisture will be

initiated in 1998. Vegetation cover and stream channel

longitudinal profiles will be surveyed every spring and fall.

GIS coverages of natural and human induced attributes

and interactions will continue to be complied and analyzed

to increase our understanding of the ecosystem functions at

work in Agua Fria meadow. Perhaps using GIS elevation

maps and groundwater observation well information, water

table elevations can be geographically hypothesized. Soil

moisture and groundwater data may help validate possible

ecosystem changes.

References _____________________

Brinson, M. 1996. Assessing Wetland Functions Using HGM. National Wetlands Newsletter, Jan.-Feb. 1996, pg. 10-16.

Harlin, J.M. and K.J. Lanfear (editors). 1993. Proceedings of the

Symposium on Geographic Information Systems and Water Resources. May 14-17, 1993 Mobile, Al. Published by the American

Water Resources Association, Bethesda, MD. pg 640.

Jackson, F. (1994a) Zuni Mountains Road Reconstruction, Channel

Restoration—Initial Studies. U.S. Department of Agriculture,

Forest Service, Cibola National Forest, Albuquerque, NM.

Jackson, F. (1994b) Zuni Mountains Road Reconstruction—

Agua Fria Bridge Site Channel Restoration Design. U.S. Department of Agriculture, Forest Service, Cibola National Forest,

Albuquerque, NM.

Jemison, R., D. Neary, and D. Pawelek. 1998. Effect of Geomorphic

Controls and Human Interventions on Riparian Meadow

Ecosystems in the Zuni Mountains of New Mexico—Study

plan. Rocky Mountain Research Station, US Forest Service.

Albuquerque, NM.

Mabery, Ken. 1997. Natural History of El Malpais National

Monument, Bulletin 156, New Mexico Bureau of Mines and

Mineral Resources, Albuquerque, NM.
180 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Maria L. Sonett is Senior Reclamation Specialist, McCulley, Frick &

Gilman, Inc., Albuquerque, NM.

Abstract—Integrated surface management techniques for pipeline construction through arid and semi-arid rangeland ecosystems

are presented in a case history of a 412-mile pipeline construction

project in New Mexico. Planning, implementation and monitoring

for restoration of surface hydrology, soil stabilization, soil cover,

and plant species succession are discussed. Planning phases included baseline survey for native plant community composition and

noxious weed populations, seed mixture design, critical area identification, construction specifications for seeding, weed control and

erosion controls, and information meetings. Implementation

phases included daily inspection of equipment, seed quality and

quantity, planting, mulch cover and anchoring, erosion control

blankets, water diversion structures, and arroyo stabilization structures. Monitoring commitments for seeding success, noxious weed

spread, and condition of erosion controls on public land were

established for three years following project completion. Two years

of noxious weed monitoring showed that most noxious weed populations appear to have been contained by project-specific weed

management. One population of halogeton (Halogeton glomeratus)

was contained after the first year but increased in area after the

second year. Monitoring of seeding success will occur in a one-time

assessment three growing seasons after completed seeding ( 1998).

With adequate time, drastically disturbed lands will heal

unassisted by human intervention through successional

development of plant communities. The rate of natural

recovery in semi-arid environments is sometimes too slow to

prevent an accelerated rate of soil erosion (Munshower,

1994). Further, natural recovery of a disturbed site may be

arrested in the early stages of succession as first-stage exotic

invaders develop into mono-cultures, and compete with

desirable seral species for available resources (Richard Lee,

personal communication).

Pipeline construction projects are commonly subject to

environmental commitments in National Environmental

Protection Act (NEPA) documentation. Environmental commitments frequently include requirements for the establishment of protective ground cover in the form of native perennial vegetation within a mandated period of time, often three

years or less (Mid-America Pipeline Four Corners Project

Environmental Assessment, Plan of Development, 1995). In

semi-arid environments, where mean annual precipitation

Integrated Surface Management for Pipeline

Construction: the Mid-America Pipeline

Company Four Corners Project

Maria L. Sonett

is low, it is unlikely that these requirements can be met

without the help of reclamation science and subsequent

surface management.

The role of reclamation science is to augment the critical

early stages of natural succession in a plan for re-establishment of a self-sustaining plant community. The plan should

include three phases: 1) planning and design, 2) implementation, and 3) monitoring and evaluation. The plan should

address the following surficial conditions and processes:

1) plant communities and vegetative cover, 2) surface soil

condition and erosion control, and 3) invasive weed control.

The success of any project utilizing such a method depends

on both the quality of the individual components, and the

degree to which these components are successfully integrated. Further, we found that plan integration must also

mean that all three phases are integrated into the overall

construction project schedule.

Mid-America Pipeline Four Corners

Project ________________________

The Mid-America Pipeline Four Corners Project provides

a case study of a surface reclamation and management effort

that was successfully integrated into a well-executed pipeline construction project.

The project, starting at Huerfano, New Mexico and ending in Seminole, Texas, was constructed under a permit from

the Farmington District of the United States Department of

the Interior Bureau of Land Management. A new 12 inch

line was installed into an existing right-of-way. Total project

length was 412 miles, including a 10-mile lateral line.

Project planning began in December 1994, and construction

was completed in December 1995.

Pre-work Measures

Communication about desired goals and planned actions

for reclamation and management of surface conditions is a

critical component in successful implementation. Pre-job

meetings with contractors and inspection personnel were

used as a forum to introduce reclamation topics and required

actions and to clarify coordination between construction

personnel and reclamation personnel. This type of early

communication made integration to a larger project easier.

Planning and design began with field reconnaissance to

identify plant communities, areas of high erosion potential,

and presence of noxious weed infestations (table 1). This

information was then used to create reclamation specifications including seed mixtures, seeding techniques and

equipment, erosion control techniques, and noxious weed

management.
USDA Forest Service Proceedings RMRS-P-7. 1999 181

Revegetation

Seven broad plant community classifications were done

after William Dick-Pedie (1993). These included: PlainsMesa Grassland, Plains-Mesa Sand Scrub, Southern Desert

Grassland, Juniper Savanna, Coniferous and Mixed Woodland, Great Basin Desert Scrub, and Northern Desert

Grassland. Project seed mixes included native, warm season

perennial grasses, cool-season perennial grasses, perennial

and annual forbs, and woody species referenced by DickPedie as major plants comprising the selected plant community types. All seeded species were selected for ecological

suitability and for palatability as forage or browse.

Revegetation efforts began in the first phase of construction with an operation called “double-ditching”. “Doubleditching” is an industry term for topsoil removal during

the right-of-way clearing and smoothing. Topsoil was removed and placed to one side of the pipeline trench. The next

layer of soil was removed and placed in a separate pile.

Several months later, after the pipe is laid, the soil is

replaced in the trench in the same order that it was

removed, with the more fertile topsoil on top. These areas

were then re-graded to match original site contours, and

finish graded with a moto-grader. The moto-grader left a

rough, deeply imprinted soil surface that was approved as

the seedbed condition. Large soil particles and a rough

surface provided excellent water infiltration, and protected

the light, fluffy seed from high winds.

Seeding techniques and equipment were recommended

based on soil type and slope conditions. The majority of the

pipeline area was seeded with a heavy-duty rangeland drill,

followed by application of vegetative mulch material such as

straw or corn stalk in some areas.

During pre-construction mapping, the observed density of

annual and perennial invasive weed species was greater at

the edges of the right-of-way, possibly where seeding from

previous pipeline construction had not extended into existing vegetation. This may have left a strip of unseeded,

disturbed ground that was more susceptible to weed invasion. Seeding and mulching operations therefore were specified to be “knit” into the existing vegetation, in order to

assure that no disturbed soil was left untreated.

Quality control was required for all re-vegetation materials. Mulch material was inspected at the producer’s fields

for weed content. Project requirements specified that materials be purchased from a producer who regularly managed

for weeds, and whose fields were located in a designated

“weed district,” under the supervision of a county weed

agent.

A random section of the project seed lots was also sampled

for weed seed content. Although required standard testing

was done by the seed supplier at certified laboratories, seed

was “double-certified” to assure absence of potential problem species. Of the seed lots sampled, invasive weed species

were found in two lots. These species were omitted from the

seed mixes, and an appropriate replacement was approved

by the permitting agency.

Erosion Control

Erosion control for upland areas included mulching with

straw or chopped corn stalks, construction of water bars to

direct flow off the right-of-way, and installation of erosion

control blankets on steep slopes. Areas with slopes of greater

than 15 percent were identified as high erosion risk, and

were designated for broadcast seeding and application of

Table 1—Weed species identified for control and management on the Mid-America Pipeline Four

Corners Project, 1995. This list is based on a list of candidate species for the New Mexico

noxious weed list for New Mexico, from Dr. Richard Lee, New Mexico State University Weed

Control Scientist, November 1994.

 Common name Scientific name Life cycle Origin

African Rue Peganum harmala P I - North Africa

Camelthorn Alhagi pseudalhagi P I - Asia

Canada Thistle Cirsium arvense P I - Eurasia

Dalmation Toadflax Linaria genistifolia ssp. dalmatica P I - Europe

Diffuse Knapweed Centaurea diffusa P I - Med.

Halogeton Halogeton glomeratus A I - Asia

Jointed Goatgrass Aegilops cylindrica A I - S. Europe

Leafy Spurge Euphorbia esula P I - Eurasia

Malta Starthistle Centaurea melitensis A I - Europe

Musk Thistle Carduus nutans or Carduus thoermeri B I - S. Europe

Perennial Pepperweed Lepidium latifolium P I - S. Europe

Purple Loosestrife Lythrum salicaria P I - Europe

Purple Starthistle Centaurea calcitrapa A I - Europe

Russian Knapweed Acroptilon repens P I - Eurasia

Scotch Thistle Onopordum acanthium B I - Europe

Spotted Knapweed Centaurea maculosa P I - Eurasia

Teasel Dipsacus fullonum B I - Europe

Whitetop or Hoary Cress Cardaria draba P I - Europe

Yellow Starthistle Centaurea solstitialis A I - Europe

Yellow Toadflax Linaria vulgaris P I - Eurasia

“A” - Annual, “B” - Biennial, “P” - Perennial, “I” - Introduced
182 USDA Forest Service Proceedings RMRS-P-7. 1999

erosion control blankets. As the revegetation project progressed, other areas of high erosion risk were identified,

and were stabilized with erosion control blankets.

Erosion control for riparian areas began with the preservation of existing riparian vegetation for habitat and bank

stabilization. Three large rivers, the Rio Grande, the Rio

Puerco, and the Pecos River, were crossed by a directional

drilling method that minimizes impacts to the river channel

and eliminates impacts to riverbank vegetation. The directional drill begins several hundreds of feet back from one

bank, angles down and under the river bed, and re-emerges

several hundred feet back from the opposite bank.

Where riparian vegetation was removed, banks were

stabilized with rip-rap and seeded with native grass species.

Riparian restoration included pole plantings of willow and

cottonwood, at a replacement ratio of 10:1.

Ephemeral arroyo systems of sufficient magnitude to

warrant concern about erosion were stabilized with small

grade control structures made from either gabion baskets, or

by native rock mined during trench excavation. Gabion

baskets were placed following formal engineering designs,

and rock was generally placed in smaller arroyos by informal

field design.

Noxious Weed Management

Noxious weed management was intended to reduce or

eliminate the spread of noxious weeds through earth-disturbing construction activities. Management included preconstruction mapping, chemical treatment of target weed

populations, specifications requiring equipment cleaning,

soil management during construction, and post-construction monitoring.

Four populations of noxious weed species were identified

during pre-construction mapping. These populations are

listed in table 2.

A mixture of Garlon (triclpyr) and 2,4-D was applied by a

licenced applicator. Chemical application techniques varied

according to the size and density of weed infestations. In

some areas, target weed populations had not crowded out all

other vegetation, so a spot spray was used to help conserve

surrounding vegetation. In other areas, dense infestations

that had out-competed desirable vegetation required a broadcast spray.

The small colony of musk thistle was removed by hand.

Plants were placed in a sealed container, allowed to dry

within that container, and were subsequently burned in a

50-gallon drum by blow torch.

To limit the potential of weed spread by seed-infested soil

on equipment, soil to a depth of 6"-8" was scraped and

stockpiled at the edge of the working area. Stockpiled soils

were flagged to prevent their re-location and to prevent

access by vehicular traffic.

Equipment used for soil removal was cleaned immediately

after use. Cleaning was performed by hand, and took place

in the same general location as the stockpiled soils. Hand

cleaning by brush and scraper was approved by the permitting agency as an alternative, cost-effective method for the

bulldozer used in weed areas. The tracks and blade of the

bulldozer were brushed off by hand-held brooms, and caked

dirt was scraped off with a hand-held scraper blade. This

method took an average of one-half hour per location.

Both plant and soil removal was planned to limit the

distribution of seed by equipment into un-infested areas of

the right-of-way.

Post-Construction Monitoring and

Management

Post-construction monitoring for noxious weeds and for

erosion control was carried out for three growing seasons

following job completion.

Seeded stand success appeared promising in many areas

after two growing seasons. In other areas, livestock utilization, lack of precipitation, and poor soils were noted as the

probable causes of poor stand success. Final monitoring for

seeded stand success will be carried out in 1998 by Bureau

of Land Management range staff.

Prevention of noxious weed spread on the right-of-way

was successful for Russian knapweed (Acroptilon repens) for

all three years, and these populations were successfully

eliminated by the third year. The population of halogeton

(Halogeton glomeratus) was apparently contained for the

first year after construction, but increased in area in the

second year. Since the direction of population spread was

opposite that of the direction of construction, livestock rather

than equipment may be the agent of spread. The small

colony of the biennial, musk thistle (Carduus nutans), was

hand removed in the second year following construction and

did not reoccur in the third year.

Table 2—Weed species identified on the Mid-America pipeline right-of-way during pre-construction

survey, July-August, 1995.

Approximate Approximate density

Scientific name Common name size of infestation of infestation

Halogeton glomeratus Halogeton scattered colonies 1-5/ft2

over100-200 acres

Carduus nutans Musk thistle 4000 ft2 15-20 individuals

Acroptilon repens Russian knapweed 720 ft2 1/ft2

Acroptilon repens Russian knapweed 3 scattered colonies 2.5/ft2

of approx. 3000 ft2

over 3 acres
USDA Forest Service Proceedings RMRS-P-7. 1999 183

Erosion control measures (erosion blanketed slopes and

grade control structures) were assessed by air survey. Areas

showing erosion or damaged measures were reported to an

on-call contractor, who carried out repairs.

Conclusions____________________

Integrated surface management provides a comprehensive method to assist early stages of natural plant community succession and site stabilization. An integrated approach includes three phases: 1) pre-construction measures,

such as coordination, site survey, and design of seed mixtures and erosion control requirements; 2) implementation

of plans and designs during construction; and, 3) postconstruction monitoring and adjustment of non-satisfactory

areas.

The term “integrated” applies to the integration of three

closely related surficial processes: 1) soil erosion; 2) plant

community dynamics; and 3), control of exotic invasive plant

species. It also applies to the integration of the reclamation

effort into the overall construction project, particularly in

terms of scheduling and cooperation of different construction phases.

References _____________________

Bureau of Land Management, Environmental Assessment for the

Mid-America Four Corners Pipeline Loop Project. June 1995.

Volume 1

Dick-Pedie, William A. 1993. New Mexico vegetation, past present

and future. University of New Mexico Press, Albuquerque, New

Mexico.

Munshower, Frank F. 1994. Practical Handbook of Disturbed

Land Revegetation. CRC Press, Inc. pp. 2-4.

Lee, Richard Personal Communication, 1995. New Mexico State

Cooperative Extension Service Weed Scientist, New Mexico

State University, Las Cruces, New Mexico.

Biodiversity and

Endangered Species

USDA Forest Service Proceedings RMRS-P-7. 1999 187

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Alice Chung-MacCoubrey is a Research Wildlife Biologist, USDA Rocky

Mountain Research Station, 2205 Columbia SE, Albuquerque, NM.

Abstract—Historic and recent changes in the structure, composition, and distribution of riparian forests have likely influenced

populations of bats through their effects on habitat quality for

reproductive females. This project seeks to identify natural structures used by maternity colonies, determine criteria used in the

selection of these roosts, and interpret how historic and current

human activities may positively or negatively impact bat populations in the bosque. This paper reports first season results from this

ongoing project. Thirteen reproductive female bats (5 little brown

myotis, 5 Yuma myotis, 1 red bat, and 2 pallid bats) captured on the

Bosque del Apache National Wildlife Refuge in the summer of 1997

were radiotracked daily to their maternity roosts. Four little brown

and Yuma myotis colony roosts were found. Colony size ranged

from 90 to over 1800 bats. Two colonies were in manmade structures. Two other colonies and numerous solitary roosts were found

in natural structures (dead cottonwoods). A pallid bat roosted in a

rocky butte, and the red bat roosted in the foliage of a large, live

cottonwood. Six of the nine tree roosts were in burned areas of

forests directly along the river. Individuals and colonies of little

brown and Yuma myotis used under-bark crevices and snags rather

than more permanent types of roosts. Additional data from subsequent years will help determine whether the use of ephemeral bark

roosts, snags, and riverside forests are characteristic of bat roost

selection in the bosque.

Riparian-associated bats may be found in the bosque

where suitable foraging and roosting habitat exists along

relatively permanent bodies of water. However, historic and

recent human activities have changed the structure, composition, and distribution of these forests in New Mexico. The

effects of these changes on the population status of bats have

yet to be determined. Because of their unusually low reproductive rate (typically one offspring per year), bat populations can easily be affected by events that alter the availability and distribution of resources to reproductive females.

Suitable roosts and a sufficient diet are critical to successful

reproduction by females (Humphrey 1975, Racey 1982).

Historic and ongoing changes in riparian forest structure,

composition, and distribution due to agriculture, flood control, channelization, demand for fuel and wood products, and

exotic plant invasion (Scurlock 1995) have undoubtedly

Maternity Roosts of Bats at the Bosque Del

Apache National Wildlife Refuge: a

Preliminary Report

Alice Chung-MacCoubrey

affected the abundance and diversity of roosts and foods

available to female bats during the summer. Hence, the

reproductive success and status of bat populations along

the Rio Grande have likely been impacted. Yet it is difficult

to assess the magnitude of these historic impacts or abate

future impacts because the resources critical to successful

reproduction by bats in bosque habitats are not known. The

goal of this project is to identify roost structures used by

reproductive females, determine how historic, ongoing, and

future changes in the structure and composition of the

bosque may benefit or harm the resident bat communities,

and provide recommendations on how to improve bat

habitat.

Specific objectives of this project in progress include 1)

identifying and characterizing structures used as colony and

solitary maternity roosts by bats and the general environment surrounding roosts and 2) describing roost behaviors

of reproductive female bats in the bosque. With this information, recommendations will be made on how land management activities may be used to positively affect critical

resources for bats and how to abate negative effects on bat

habitat in the bosque.

Methods _______________________

Maternity roosts were identified by radiotagging reproductive female bats and locating them at their daytime

roosts. Field work was conducted on the Bosque del Apache

National Wildlife Refuge (Bosque del Apache NWR) from

June to August 1997. Reasons for the selection of this site

include the presence of native bosque, remoteness from

urban influences, and the potential to collaborate with other

ongoing wildlife and vegetation studies. Candidates for

radiotagging were captured by placing mist nets over various types of water following the method of Kunz and Kurta

(1988). Net sites throughout the refuge included flooded

water management units, canals, shallow sections of the Rio

Grande, and flight corridors. Nets were opened at sunset

and closed after midnight. Information on the species, sex,

age, reproductive status, and weight of all bats captured was

recorded.

To identify maternity roosts, pregnant, lactating, or

postlactating females were fitted with radiotransmitters.

One to four reproductive females were radiotagged in a

single night. Fur was clipped from between the shoulder

blades, and a 0.50 - 0.67 g radiotransmitter (Holohil Systems Ltd.) was glued to the back of the bat with surgical

adhesive (Skin-Bond®) (Wilkinson and Bradbury 1988). Bats

were released after the glue dried (approximately 30 minutes). Radiotagged bats were located each day until signals

were lost or radios were retrieved.
188 USDA Forest Service Proceedings RMRS-P-7. 1999

Each roost and its immediate surroundings were evaluated, and the number of bats exiting at dusk was counted to

determine total roost occupancy. Information on the number

of roosts used by each bat, the type and location of roosts, and

roost fidelity were collected. Roost locations were recorded

with a global positioning system units (Trimble Geoexplorer

GPS and Pathfinder Basic Plus).

Preliminary Results and

Discussion _____________________

Mist Net Captures

From 11 June to 30 July 1997, we mist netted 13 nights at

9 sites. These sites included 4 flooded water management

units, 2 streams along flight corridors, 2 sections of river,

and 1 section of canal. During the earlier part of the netting

period, capture success was low because water was available

throughout the refuge (river level was up and many management units were flooded). However, as the summer progressed, river level went down, many management units

were drained, and overall water availability decreased on

the refuge. Accordingly, capture success improved. From the

13 net nights, we captured and identified 130 bats of 6

species (table 1). The most abundant species caught was the

Mexican free-tailed bat (Tadarida brasiliensis). Moderate

numbers of little brown myotis (Myotis lucifugus) and Yuma

myotis (M. yumanensis) were captured. A small number of

pallid bats (Antrozous pallidus) and a single small-footed

myotis (M. ciliolabrum) and red bat (Lasiurus borealis or L.

blossevilli) were captured. At the time of capture, field

identification of the red bat, a lactating female, to one of the

two species (L. borealis or blossevilli) was not possible. This

individual was radiotagged and thus not available for a

voucher specimen. Seventy-seven percent of the total bats

captured were female, and 62 percent of these females were

reproductive (pregnant, lactating, or postlactating).

Little brown myotis, Yuma myotis, hoary bats (L. cinereus)

and Mexican free-tailed bats were reported previously on

the refuge by Findley and others (1975). Reith (1982) later

identified pallid bats as also present on the refuge. Recently, Valdez and others (in press) reported four previously undocumented species on the refuge: fringed myotis

(M. thysanodes), silver-haired bat (Lasionycteris noctivagans), eastern red bat (L. borealis), and Townsend’s bigeared bat (Corynorhinus townsendii). The female eastern

red bat captured by Valdez and others (in press) was not

reproductive. The present study is the first to document the

presence of a small-footed myotis and a reproductive red bat

on the refuge.

Maternity Roosts Located

From bats captured during these mist netting sessions,

13 pregnant or lactating females were selected for

radiotracking. Five little brown myotis (2 pregnant, 3 lactating), five Yuma myotis (1 pregnant, 3 lactating, 1 postlactating), two pallid bats (both lactating), and one lactating

red bat were radiotagged. A radiotransmitter weight not

exceeding 5 percent of the bat’s body weight has been

recommended to minimize effects on behavior and activities

(Aldridge and Brigham 1988). In this study, transmitter

weight was well below the recommended maximum of 5

percent for the larger species (pallid bats and red bat). For

the smaller bats (little brown and Yuma myotis), transmitter weight ranged from 5.1-8.6 percent of the bat’s body

weight. Brigham and others (1997) did not report any adverse effects on reproductive female Myotis californicus

tagged with transmitters 8-9 percent of their body weight.

Additional research is needed to clarify the effects on and

tolerances of bats to variable loads, and further miniaturization in transmitter size will allow researchers to minimize

the effects of radiotagging on bats.

Eighteen roosts were located from the 13 radiotagged

bats. One pallid bat was not relocated. Only one or two

roosts were typically found per bat because either the signal

disappeared after the second roost was found or some bats

rarely moved during the entire tracking period. Two colony

roosts were found repeatedly from 7 independently

radiotagged bats. Thus only 13 unique roosts were found.

Four were maternity colonies, and nine were solitary roosts.

Two of the colony roosts were in manmade structures.

The lactating red bat was the second red bat captured at

the Bosque del Apache NWR and the first to be radiotracked

in the state. The red bat roosted high within the canopy of a

large, live Fremont’s cottonwood (Populus fremontii)

(table 2). This cottonwood was part of a small, isolated

cottonwood stand along the river surrounded by dense

saltcedar (Tamarix spp.). The roosting behavior of this red

bat is consistent with the foliage roosting behavior of this

genus (Barbour and Davis 1969).

Table 1—Species, sex, and reproductive statusa of 130 bats captured during 13 mist netting events at the Bosque del Apache National

Wildlife Refuge between June and August 1997.

Female Male Total

Species Nonrepro Repro Juvenile Nonrepro Repro Juvenile individuals

Tadarida brasiliensis 23 39 0 3 4 0 69

Myotis lucifugus 4 12 4 5 2 3 30

Myotis yumanensis 2 6 6 1 0 7 22

Antrozous pallidus 1 31 1 0 1 7

Myotis ciliolabrum 0 10 0 0 0 1

Lasiurus borealis 0 10 0 0 0 1

 or L. blossevilli

a

Nonrepro = nonreproductive adult female or male. Repro = pregnant, lactating, or postlactating adult female or scrotal adult male. Juvenile = juvenile

male or female young of the year.
USDA Forest Service Proceedings RMRS-P-7. 1999 189

Table 2—Description of roosts used by radiotagged, reproductive females of 4 species of bats at the Bosque del Apache National

Wildlife Refuge.

 Bat speciesa Colony/solitary # of bats Roost type D.b.h.(cm)b Height(m) Status

Myotis lucifugus (L) Colony 507 Populus fremontii 80 14.4 dead

Myotis lucifugus (P) Colony 90 Populus fremontii 50 21.6 dead

Myotis lucifugus (P) Solitary — Populus fremontii 22 4.4 dead

Myotis lucifugus (L) Solitary — Populus fremontii 63 26.0 dead

Myotis lucifugus (L) Solitary — Populus fremontii 53 22.2 dead

Myotis lucifugus (L) Solitary — Populus fremontii 32 20.2 dead

Myotis yumanensis (L) Colony >250 Concrete bridge — — —

Myotis yumanensis (P) Solitary — Populus fremontii 28 16.5 dead

Myotis yumanensis (L) Solitary — Populus fremontii — — dead

M. lucifugus & Colony >1800 Church roof/steeple — — —

 M. yumanensis (P, L)

Antrozous pallidus (L) Solitary — Rock crevice — — —

Antrozous pallidus (L) Solitary — Rock crevice — — —

Lasiurus borealis/ Solitary — Populus fremontii 76 18.0 live

 blossevilli (L)

a

Reproductive status of the radiotagged bat is in parenthesis. P = pregnant, L = lactating

b

D.b.h. = diameter at breast height

The lactating pallid bat was found in 2 separate rock

crevices on the 2 days that is was relocated (table 2). These

roosts were approximately 200 m apart on a lone rocky

butte surrounded by grassland approximately 0.75 km east

of the river. The use of crevices in vertical rock faces and cliffs

is typical roosting behavior for pallid bats (Vaughan and

O’Shea 1976).

Ten little brown and Yuma myotis roosts were found,

four of which were colonies (table 2). Two little brown

myotis colonies were found under the sloughing bark of

cottonwoods killed in the 1996 fire. Occupancy at these two

colonies declined from 507 and 90 bats in late June/early

July to 50 and 0, respectively, in the first week of August.

The 90-bat colony roost stood in the middle of an open

grassy field. The 507-bat colony stood amongst a burned,

dead stand of large and small cottonwoods along the river.

The third colony, which consisted of over 250 Yuma myotis,

roosted in deep, vertical crevices (1.5 cm wide) running the

length of the underside of a small concrete bridge close to the

river. The fourth colony roost was located 8 miles north of the

refuge in the steeples and under the corrugated metal

roofing of a local church. Over 1800 Yuma and little brown

myotis shared this roost, but it is not known whether the two

species segregated within the building. A dead Mexican freetailed bat of unknown sex was also found in one of the

steeples, suggesting that Mexican free-tails may also occasionally share this roost.

Six solitary roosts of Yuma and little brown myotis were

located under the bark or in hollows of smaller cottonwood

snags, also killed by the 1996 fire (table 2). The trees used as

solitary roosts were generally of smaller d.b.h. ( x = 39.6,

SE = 7.84 cm, N = 5) than trees used as colony roosts ( x= 65

cm, N = 2)

Most of the tree roosts (7 of 9 roosts) were in forests

bordering the east and west side of the river. Within the

Bosque del Apache NWR, forests directly along the river are

relatively contiguous and unmanipulated. Forest types along

the river include dense saltcedar stands, mixed cottonwood

and saltcedar habitat, patches of mature cottonwood, and

burned cottonwood stands with new saltcedar saplings. To

the west of the river and its associated riverside forest, the

refuge is a mix of wetland, grassland, agricultural, and

forested habitats. Forests patches are of small to medium

size, scattered, and disconnected relative to the forest along

the river. Only one colony and one solitary roost were found

in these patches, perhaps due to their discontinuity with

other forest or perhaps as a result of the sampling error. If

not the result of sampling error, the predominance of roosts

in riverside forest may indicate the need for contiguous

forest stands which provide food and cover for roosting,

commuting, and foraging. The capture of several Yuma and

little brown myotis in riverside forest 8 miles south of the

church colony they used indicates that these bats travel

substantial distances while feeding in this habitat. Roosts

were not found in pure saltcedar stands or mixed cottonwood/saltcedar stands, perhaps due to the dense understory

that would make flight difficult.

The manmade structures used as colony roosts by little

brown and Yuma myotis in this study are consistent with the

known roosting habits of these species. Nursery roosts of

Yuma myotis are commonly found in buildings, under bridges,

and in caves and mines (Barbour and Davis 1969). Nursery

roosts of little brown myotis have been found in buildings,

under roofs, in attics, tree hollows, and other crevices with

suitable temperature regimes (Fenton and Barclay 1980).

Ephemeral roosts are associated with high roost lability

in bats, and more permanent structures are associated with

high roost fidelity (Lewis 1995). Roosts of little brown myotis

found in forest along the Rio Grande were under the bark or

in crevices of dead trees within burned cottonwood stands.

Reasons for using these ephemeral roosts may include decreased commuting costs to foraging areas, lower ectoparasite levels and a higher abundance and availability of ephemeral sites (Lewis 1995). The use of ephemeral tree roosts

(for example under bark of snags) rather than more permanent tree roosts (for example hollows in live cottonwoods)

may be due to a lower availability or suitability of the latter

type. Permanent structures such as the church and bridge
190 USDA Forest Service Proceedings RMRS-P-7. 1999

allow higher roost fidelity, the benefits of which include

reduced costs in roost searching, greater site familiarity,

and the ability to maintain social relationships (Lewis 1995).

Year to year site fidelity of these roosts will be assessed by

returning to colony roosts in subsequent years and assessing

occupancy.

The results of this single season of radiotracking give

preliminary data on the roosting habits of Yuma and little

brown myotis, red bats, and pallid bats on the Bosque del

Apache NWR and its surrounding area. Additional maternity colony and solitary roosts must be located to better

understand which roosts are selected by reproductive females, what characteristics make roosts suitable, how site

fidelity or lability is associated with roost type, and how

roost resources may be partitioned among species. With

future field seasons, roost selection and behavior of these

species on the Bosque del Apache NWR will be better and

more conclusively characterized.

References _____________________

Aldridge, H. D. J. N. and R. M. Brigham. 1988. Load carrying and

maneuverability in an insectivorous bat: a test of the 5 percent

“rule” of radiotelemetry. J. Mammal. 69:379-382.

Barbour, R. W. and W. H. Davis. 1969. Bats of America. University

Press of Kentucky, Lexington.

Brigham, R. M., M. J. VonHof, R. M. R. Barclay, and J. C. Gwilliam.

1997. Roosting behavior and roost-site preferences of forestdwelling California bats (Myotis californicus). J. Mammal.

78:1231-1239.

Fenton, M. B. and R. M. R. Barclay. 1980. Myotis lucifugus. Mammalian Species 142: 1-8.

Findley, J. S., A. H. Harris, D. E. Wilson, and C. Jones. 1975.

Mammals of New Mexico. University of New Mexico Press,

Albuquerque.

Humphrey, S. R. 1975. Nursery roosts and community diversity of

nearctic bats. J. Mammalogy 56:321-346.

Kunz, T. H. and A. Kurta. 1988. Capture methods and holding

devices. Pp. 1-30 in T. H. Kunz, ed. Ecological and behavioral

methods for the study of bats. Smithsonian Institution Press.

Washington, D.C.

Lewis, S. 1995. Roost fidelity of bats: a review. J. Mammalogy

76:481-496.

Racey, P. A. 1982. Ecology of bat reproduction. Pp. 57-104 in T. H.

Kunz, ed. Ecology of bats. Plenum Press, New York.

Reith, C. C. 1982. Insectivorous bats fly in shadows to avoid

moonlight. J. Mammal. 63: 685-688.

Scurlock, D. 1995. Environmental history. Pp.12-28 in D. M. Finch

and J. A. Tainter, eds. Ecology, diversity, and sustainability of

the Middle Rio Grande Basin. USDA Forest Service, Rocky

Mountain Forest and Range Experiment Station, General Technical Report RM-GTR-268. Ft. Collins, CO. 186 pp.

Valdez, E. W., J. N. Stuart, and M. A. Bogan. In press. Additional

records of bats from the Middle Rio Grande Valley, New Mexico.

Southwestern Naturalist.

Vaughan, T. A. and T. J. O’Shea. 1976. Roosting ecology of the

pallid bat, Antrozous pallidus. J. Mammalogy 57:19-42.

Wilkinson, G. S. and J. W. Bradbury. 1988. Radiotelemetry: techniques and analysis. Pp. 105-124 in T. H. Kunz, ed. Ecological

and behavioral methods for the study of bats. Smithsonian

Institution Press. Washington, D.C.
USDA Forest Service Proceedings RMRS-P-7. 1999 191

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Michael D. Means and Deborah M. Finch are with the USDA Forest

Service, Rocky Mountain Research Station, 2205 Columbia SE, Albuquerque,

NM 87106.

Abstract—Expanding human populations in the middle Rio Grande

have increased demands on water, land, and other resources,

potentially disrupting bird migration activities. From 1994 to 1997,

a total of 26,350 birds of 157 species were banded and studied.

Results include species composition, timing of migration, and habitat use. Recommendations for managers are included.

Although quantitative accounts of landbird migration

along the middle Rio Grande riparian corridors in the

literature are rare, the use of the Rio Grande as a migratory

route by landbirds is an acknowledged behavior of southwestern birds (Yong and Finch 1997, Yong and others 1998,

Finch and Yong in press). The availability of food, water,

cover, resting sites and a suitable north-south route along

the river provides potential stopover resources for neotropical

migrants such as flycatchers, warblers, and vireos and

short-distance migrants such as many sparrow species.

Expanding human populations in the middle Rio Grande

have placed increasing demands on water, land, and other

resources associated with riparian habitats. Water management, recreation, transportation, grazing, urban development, and invasion of exotic plant species alter these riparian habitats, potentially disrupting bird migration activities.

How habitat changes have affected or will affect landbirds

migrating through the middle Rio Grande is unclear (Finch

and others 1995).

In spring 1994, we initiated a study to investigate the use

of the middle Rio Grande riparian corridors as stopover

habitat by neotropical and short-distance landbird migrants.

This study is now in its fifth year. We have also been

cooperating with Rio Grande Bird Research, Inc. by adding

to and analyzing a 17-year (1981-1997) capture data set of

migrating landbirds at the Rio Grande Nature Center in

Albuquerque, New Mexico. The objective of this paper is to

update our earlier reports (Finch and others 1995, Finch and

Yong in press) on species composition, relative abundance,

timing of migration, and general habitat use along the

middle Rio Grande.

Bird Migration Through Middle Rio Grande

Riparian Forests, 1994 to 1997

Michael D. Means

Deborah M. Finch

Methods _______________________

Study Sites

Our study sites were located at the Bosque del Apache

National Wildlife Refuge (N33° 48' and W106° 52'), Socorro,

NM, and the Rio Grande Nature Center (N35° 07' and W106°

41'), Albuquerque NM (fig. 1). Data were collected in spring

(early April through early June) and in fall (early August

through early November) 1994-1997. The Rio Grande Nature Center site was not studied during the spring of 1997.

Both sites contained older Fremont cottonwood (Populus

fremontii) forests and some younger forests of cottonwood,

Gooding willow ( Salixgooddingii), Russian olive (Elaeagnus

angustifolia) and salt cedar (Tamarix pentandra). Sites also

contained agricultural fields and riparian edges of coyote

willow (Salix exigua). The Bosque del Apache site also

included a homogeneous stand of salt cedar. Vegetation

structure, plant species composition and tree size were

measured to compare habitat characteristics.

Mist Netting

Between 20 and 40 nylon mist-nets (12 x 2.6 meter with 30

mm and 36 mm mesh) were used at each site to capture (and

recapture) landbird migrants. Each net was set up 15 minutes before official sunrise and closed 6 hours later. The

birds were removed from the nets, identified, measured and

released as quickly and safely as possible. For more information about netting and banding procedures at our sites, see

Kelly and Finch (1999 in this volume) and Finch and Kelly

(1999 in this volume).

Point Counts

Sixteen transects were established in the dominant vegetation types in these areas: agricultural field edges, cottonwood, screwbean mesquite (Prosopis pubescens), mixed cottonwood, salt cedar and coyote willow. Each transect was 1

kilometer long and had point count stations located at 200

meter intervals (6 stations per transect). Birds were counted

for five minutes at each station and birds detected between

stations were also recorded. Behaviors and habitat use by

birds were also recorded.

Results and Discussion __________

Numbers of Species and Captures

We banded a total of 26,350 birds of 157 species from 1994-

1997, of which 6,000 (22.7 percent) of these were recaptures

(table 1). Fewer spring birds were banded (21 percent) than
192 USDA Forest Service Proceedings RMRS-P-7. 1999

fall birds (79 percent). This is because large numbers of

hatch-year birds migrate south in the fall, increasing the

number of fall captures. The majority of recaptures were

resident breeders or winter residents. The most abundant

neotropical migrants that return each year to breed at these

sites were Common Yellowthroat (Geothlypis trichas), Blue

Grosbeak (Guiraca caerulea), Black-Headed Grosbeak

(Pheucticus melanocephalus) and Summer Tanager (Piranga

rubra). The two most commonly recaptured short-distance

migrants breeding in the areas were Spotted Towhee (Pipilo

erythrophthalmus) and Bewick’s Wren (Thryomanes

bewickii).

Figure 1—Study Sites: Bosque del Apache National Wildlife Refuge and Rio Grande Nature Center, NM.

We detected year-to-year fluctuations in species richness,

numbers of captures, and age and sex ratios for our two sites.

These fluctuations appeared to correspond to amounts of

rainfall before and during the migration periods and may

have influenced how concentrated migrants were relative to

water sources. For example we have had much higher

capture rates in drought years than wetter years. In addition, capture rates were generally higher at the Rio Grande

Nature Center site in Albuquerque NM than at the Bosque

del Apache. The Nature Center is surrounded by urban

development whereas the Bosque del Apache is in a rural
USDA Forest Service Proceedings RMRS-P-7. 1999 193

Table 1—Total number of birds captured and banded, by family, at the Bosque del Apache National Wildlife Refuge and Rio Grande Nature Center

from 1994 through 1997.a

Common name Family Captures Common name Family Captures

(con.)

Sharp-shinned Hawk Accipitridae 16.00

Red-tailed Hawk Accipitridae 14.00

Cooper’s Hawk Accipitridae 9.00

Swainson’s Hawk Accipitridae 5.00

Ferruginous Hawk Accipitridae 4.00

Northern Harrier Accipitridae 2.00

Common Bushtit Aegithalidae 51.00

Belted Kingfisher Alcedinidae 8.00

Common Nighthawk Caprimulgidae 1.00

Lazuli Bunting Cardinalidae 635.00

Blue Grosbeak Cardinalidae 512.00

Black-headed Grosbeak Cardinalidae 366.00

Indigo Bunting Cardinalidae 36.00

Lark Bunting Cardinalidae 14.00

Painted Bunting Cardinalidae 6.00

Pyrrhuloxia Cardinalidae 4.00

Rose-Breasted Grossbeak Cardinalidae 3.00

Dicksissel Cardinalidae 2.00

Brown Creeper Certhiidae 29.00

Killdeer Charadriidae 7.00

Mourning Dove Columbidae 47.00

White-winged Dove Columbidae 3.00

Common Ground Dove Columbidae 1.00

Chihuahuan Raven Corvidae 24.00

Scrub Jay Corvidae 24.00

Western Scrub Jay Corvidae 3.00

American Crow Corvidae 1.00

Yellow-billed Cuckoo Cuculidae 16.00

Greater Roadrunner Cuculidae 7.00

Chipping Sparrow Emberizidae 2722.00

Gambel’s White-crowned Sparrow Emberizidae 1660.00

Oregon Junco Emberizidae 779.00

Lark Sparrow Emberizidae 576.00

Brewer’s Sparrow Emberizidae 557.00

Song Sparrow Emberizidae 468.00

Lincoln’s Sparrow Emberizidae 464.00

Mountain White-crowned Sparrow Emberizidae 405.00

Savannah Sparrow Emberizidae 317.00

Spotted Towhee Emberizidae 297.00

Vesper Sparrow Emberizidae 251.00

Green-tailed Towhee Emberizidae 241.00

Clay-colored Sparrow Emberizidae 213.00

Gray-headed Junco Emberizidae 168.00

White-crowned Sparrow Emberizidae 58.00

White-throated Sparrow Emberizidae 15.00

American Tree Sparrow Emberizidae 6.00

Canyon Towhee Emberizidae 6.00

Black-throated Sparrow Emberizidae 4.00

Dark-eyed Junco Emberizidae 3.00

Grasshopper Sparrow Emberizidae 3.00

Sage Sparrow Emberizidae 3.00

Slate-colored Junco Emberizidae 3.00

Swamp Sparrow Emberizidae 3.00

Golden-crowned Sparrow Emberizidae 2.00

Cassin’s Sparrow Emberizidae 1.00

Fox Sparrow Emberizidae 1.00

Harris’ Sparrow Emberizidae 1.00

American Kestrel Falconidae 50.00

Prairie Falcon Falconidae 1.00

Pine Siskin Fringillidae 1687.00

Lesser Goldfinch Fringillidae 397.00

House Finch Fringillidae 335.00

American Goldfinch Fringillidae 297.00

Cassin’s Finch Fringillidae 6.00

Evening Grosbeak Fringillidae 1.00

White-winged Crossbill Fringillidae 1.00

Barn Swallow Hirundinidae 41.00

Northern Rough-winged Swallow Hirundinidae 27.00

Bank Swallow Hirundinidae 1.00

Violet-green Swallow Hirundinidae 1.00

Red-winged Blackbird Icteridae 255.00

Bullock’s Oriole Icteridae 87.00

Brown-headed Cowbird Icteridae 55.00

Great-tailed Grackle Icteridae 17.00

Yellow-headed Blackbird Icteridae 14.00

Western Meadowlark Icteridae 9.00

Common Grackle Icterida 8.00

Orchard Oriole Icteridae 3.00

Northern Mockingbird Mimidae 22.00

Gray Catbird Mimidae 18.00

Brown Thrasher Mimidae 1.00

Crissal Thrasher Mimidae 1.00

Sage Thrasher Mimidae 1.00

Mountain Chickadee Paridae 41.00

Black-capped Chickadee Paridae 31.00

Plain Titmouse Paridae 1.00

Wilson’s Warbler Parulidae 3771.00

MacGillivray’s Warbler Parulidae 1372.00

Orange-crowned Warbler Parulidae 871.00

Audubon’s Warbler Parulidae 822.00

Yellow Warbler Parulidae 572.00

Common Yellowthroat Parulidae 279.00

Virginia’s Warbler Parulidae 265.00

Yellow-breasted Chat Parulidae 73.00

Myrtle Warbler Parulidae 60.00

Northern Waterthrush Parulidae 37.00

Townsend’s Warbler Parulidae 17.00

Ovenbird Parulidae 15.00

Nashville Warbler Parulidae 10.00

Lucy’s Warbler Parulidae 8.00

American Redstart Parulidae 5.00

Black-throated Gray Warbler Parulidae 5.00

Black-and-white Warbler Parulidae 4.00

Prothonotary Warbler Parulidae 4.00

Hooded Warbler Parulidae 3.00

Kentucky Warbler Parulidae 3.00

Magnolia Warbler Parulidae 3.00

Blue-winged Warbler Parulidae 2.00

Chestnut-sided Warbler Parulidae 2.00

Golden-winged Warbler Parulidae 2.00

Yellow-rumped Warbler Parulidae 2.00

Bay-breasted Warbler Parulidae 1.00

Black-throated Blue Warbler Parulidae 1.00

Blackburnian Warbler Parulidae 1.00

Canada Warbler Parulidae 1.00

Lawrence’s Warbler Parulidae 1.00

Mourning Warbler Parulidae 1.00

Prairie Warbler Parulidae 1.00

Tennessee Warbler Parulidae 1.00

Western Palm Warbler Parulidae 1.00

House Sparrow Passeridae 60.00

Red-shafted Flicker Picidae 52.00
194 USDA Forest Service Proceedings RMRS-P-7. 1999

setting. Urban development may narrow the corridor width

available to migrants, causing them to concentrate as they

funnel through a narrower band of vegetation at the Nature

Center than at the Bosque del Apache. Annual fluctuations

in numbers of juvenile birds also influenced overall numbers

of captures.

Species Composition

A total of 272 species were detected using both mistnetting and point counts. Of those, 222 species were landbirds

and the remainder were waterbirds and shorebirds. Of the

landbirds, 98 species were neotropical migrants (44.4 percent); 107 species were short-distance migrants (48.2 percent); 6 were crossborder breeders (2.7 percent) and 11

species were year-round residents (5.0 percent). Many of the

short-distance migrants were winter residents at our study

sites.

Number of Species by Family

Of the 157 species of landbirds banded, 64 species (40.8

percent) and 22,400 individuals (84.9 percent) were common; 52 species (33.1 percent) and 4,100 individuals (15.6

percent) were uncommon and 41 species (26.1 percent) and

117 individuals (0.4 percent) were rare in New Mexico (table

1). The Family Parulidae (warblers) had the most species

captured (32) followed by the family Emberizidae (sparrows,

grosbeaks, blackbirds) with 26 species. The third most

dominant family, Tyrannidae (flycatchers) had 13 species

captured. Species with over 1,000 individuals captured were

the Wilson’s Warbler (Wilsonia pusilla), Chipping Sparrow

(Spizella passerina), White-crowned Sparrow (Zonotrichia

leucophrys), Pine Siskin (Carduelis pinus) and MacGillivray’s

Warbler (Oporornis tolmiei) (table 1). For capture rates of

individual species standardized by constant mist-netting

effort, see Kelly and Finch (1999 in this volume).

Timing of Migration

Spring migration occurred primarily during the middle of

April through the end of May with a core period of 5 weeks.

Average captures/day at each site showed little fluctuation

by week within the core period (fig. 2). The mean number of

captures at the Nature Center from 1994-1997 tended to be

higher than at the Bosque del Apache in early spring. The

peak period of spring migration was about a week later at the

Nature Center which is 150 km north of the Bosque del

Apache.

Fall migration was more prolonged than spring migration

(fig. 2). Mean number of captures peaked during the first 2

weeks of September at both sites. The mean number of

captures from 1994-1997 was lower in fall at the Bosque del

Apache NWR than at the Rio Grande Nature Center. The

Nature Center had small fields containing nutritional crops

(sunflower and corn) that were located within and near the

mist-netting study area. This may have influenced capture

rates at the Nature Center by drawing more birds into the

vicinity than at the Bosque del Apache.

Table 1 (Con.)

Common name Family Captures

Downy Woodpecker Picidae 22.00

Red-naped Sapsucker Picidae 11.00

Hairy Woodpecker Picidae 8.00

Ladder-backed Woodpecker Picidae 6.00

Williamson’s Sapsucker Picidae 2.00

Northern Flicker Picidae 1.00

Northern Flicker Intergrade Picidae 1.00

Ruby-crowned Kinglet Regulidae 787.00

Golden-crowned Kinglet Regulidae 6.00

Verdin Remizidae 6.00

White-breasted Nuthatch Sittidae 24.00

Red-breasted Nuthatch Sittidae 13.00

Burrowing Owl Strigidae 8.00

Great Horned Owl Strigidae 8.00

Western Screech-owl Strigidae 7.00

Flammulated Owl Strigidae 2.00

European Starling Sturnidae 5.00

Blue-gray Gnatcatcher Sylviidae 14.00

Western Tanager Thraupidae 144.00

Summer Tanager Thraupidae 118.00

Hepatic Tanager Thraupidae 4.00

Scarlet Tanager Thraupidae 1.00

Black-chinned Hummingbird Trochilidae 4.00

Rufous Hummingbird Trochilidae 1.00

Bewick’s Wren Troglodytidae 198.00

House Wren Troglodytidae 161.00

Marsh Wren Troglodytidae 11.00

Cactus Wren Troglodytidae 2.00

Rock Wren Troglodytidae 2.00

Carolina Wren Troglodytidae 1.00

Winter Wren Troglodytidae 1.00

American Robin Turdidae 307.00

Hermit Thrush Turdidae 259.00

Swainson’s Thrush Turdidae 12.00

Townsend’s Solitaire Turdidae 4.00

Dusky Flycatcher Tyrannidae 436.00

Willow Flycatcher Tyrannidae 255.00

Western Wood-Pewee Tyrannidae 225.00

Western Flycatcher Tyrannidae 77.00

Gray Flycatcher Tyrannidae 73.00

Black Phoebe Tyrannidae 67.00

Ash-throated Flycatcher Tyrannidae 48.00

Western Kingbird Tyrannidae 42.00

Hammond’s Flycatcher Tyrannidae 41.00

Say’s Phoebe Tyrannidae 12.00

Olive-sided Flycatcher Tyrannidae 10.00

Brown-crested Flycatcher Tyrannidae 5.00

Least Flycatcher Tyrannidae 4.00

Common Barn-owl Tytonidae 15.00

Warbling Vireo Vireonidae 259.00

Solitary Vireo Vireonidae 67.00

Gray Vireo Vireonidae 2.00

Red-eyed Vireo Vireonidae 2.00

Bell’sVireo Vireonidae 1.00

Yellow-throated Vireo Vireonidae 1.00

a

See Kelly and Finch (this volume) for scientific names of bird species and for

summaries of mist-netting standardized by number of netting hours.
USDA Forest Service Proceedings RMRS-P-7. 1999 195

Habitat Use

Results of point counts in different dominant vegetation

types suggested differential use of habitats by migrating

species. More birds were detected in agricultural-edge habitats than in other habitats, particularly in the fall when the

crops had matured. Second highest bird counts were in the

two cottonwood habitat types (fig. 3). Birds were counted

more frequently in willow habitat in spring than in fall.

Point count results differed from netting results in terms

of species dominance patterns. We suggest that counts in

open habitats (agricultural edge and cottonwood) may overrepresent open-habitat species whereas counts in denser

habitat (willow) may under-represent shrub bird species.

For example, small, quiet passerines that stop in dense

willow thickets during migration may not be readily heard

or seen during point count sessions but may be detected

through netting efforts. Also, birds and nets are more visible

in open habitats than in closed habitats, and presumably

therefore, more birds may be detected by sight in open

habitats during point counts that at nets which, if easily

seen, will be avoided.

Many migrants stayed at sites to breed. We have many

records of individual birds returning year after year to the

same areas to breed. Also, at the start of spring season and

Figure 2—Weekly averages of Neotropical migrant bird captures at the Bosque del Apache NWR and the

Rio Grande Nature Center Spring and Fall 1994-1997.

the end of fall season, we encountered many birds that

winter at the sites. Stopover times for most of the migrants

were limited to one or two days except for the winter

residents and resident breeders. Because stopover times

were short and low numbers of neotropical migrants were

recaptured, it is difficult to determine the underlying basis

for stopover habitat selection (i.e., habitat structure, food

supply, presence of water). Nevertheless, it was clear that

certain species were observed or captured more often in

some habitats than in others. For example, the Wilson’s

Warbler, a very abundant species, was most frequently

caught or counted in willow habitats each year even though

willow is less common at our sites than many other habitats,

suggesting that Wilson’s Warbler preferentially selected

willow during stopover.

Habitats at our study sites have not been altered during

our period of study except for willow which is periodically

mowed along irrigation ditches and water conveyance channels (see Kelly and Finch 1999 in this volume). Given that

willow habitat is used by many migrants, we suggest that

managers evaluate their mowing designs to determine if

mowing is really needed, and if so, whether the schedule or

protocol can be modified to allow willows to grow high

enough to enhance bird use.
196 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 3—Use of habitats during spring and fall migration in the middle Rio Grande Riparian Corridor 1994-1997.

Acknowledgments ______________

We thank Dr. Wang Yong and Dr. Jeff Kelly for their

contributions to this study. David Hawksworth, Gus Bodner,

and Susan Allerton have done a large amount of the technical field work associated with this study. Rio Grande Bird

Research, Inc. ( Nancy and Steve Cox) cooperated and

shared their data on the Rio Grande Nature Center portion

of this study. We are grateful to the Bosque del Apache

National Wildlife Refuge, Rio Grande State Park, and the

City of Albuquerque Open Spaces Division for their interest

and support. This study was funded by the Bureau of

Reclamation, the New Mexico Department of Game and

Fish, and the Rocky Mountain Research Station.

References _____________________

DeLay, L.; Finch, D.M.; Brantley, S.; Fagerlund, R.; Means, M.D.;

Kelly, J.F. 1999. Arthropods of native and exotic vegetation and

their association with Willow Flycatchers and Wilson’s Warblers.

(This volume.)

Finch, D.M.; Wolters, G.L.; Yong, W.; and Mund, M.J. 1995. Plants,

arthropods, and birds of the Rio Grande. Pp. 133-164 in D.M.

Finch and J.A. Tainter (eds.), Ecology, diversity, and sustainability of the Middle Rio Grande Basin. USDA Forest Service, Rocky

Mountain Forest and Range Experiment Station, Fort Collins,

CO. General Technical Report RM-GTR-268.

Finch, D.M.; Kelly, J.F. 1999. Status and migration of the Southwestern Willow Flycatcher in New Mexico. (This volume).

Finch, D.M.; Yong, W. 1996. Use of willow habitat along the LowFlow Conveyance Channel by willow flycatchers and other migratory landbirds. 1996 Progress Report to the Bureau of Reclamation, Albuquerque, NM.

Finch, D.M.; Yong, W. In press. Landbird migration in riparian

habitats of the Middle Rio Grande: A Case Study. Studies in

Avian Biology.

Kelly, J.F.; Finch, D.M. 1999. Use of saltcedar vegetation by landbirds

migrating through the Bosque del Apache National Wildlife

Refuge. (This volume.)

Kelly, J.F.; Finch, D.M.; Means, M.D. 1997. 1997 Annual report on

bird migration along the Low-Flow Conveyance Channel in the

Bosque del Apache NWR. Progress report to the Bureau of

Reclamation, the NM Game and Fish Department, and the

Bosque del Apache National Wildlife Refuge.

Kelly, J.F.; Smith, R.; Finch, D.M.; Moore, F.R.; Yong, W. (in

review). Influence of summer biogeography on wood warbler

stopover abundance. Condor.

Yong, W.; Finch, D.M. 1998. Age-related population trends of

landbirds migrating through Southwestern semi-arid grassland.

Pp. 81-93, in B. Tellman, D.M. Finch, C. Edminster, and R.

Hamre, (eds.), The Future of Arid Grasslands: Identifying Issues,

Seeking Solutions. USDA Forest Service, Rocky Mountain Research Station. Proceedings RMRS-P-3.

Yong, W.; Finch, D.M. 1997. Populations trends of migratory

landbirds along the middle Rio Grande. Southwestern Naturalist

42:137-147

Yong, W.; Finch, D.M.; Moore, F.R.; Kelly, J.F. (in press). Stopover

ecology and habitat use of migratory Wilson’s Warblers. Auk.
USDA Forest Service Proceedings RMRS-P-7. 1999 197

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Deborah M. Finch and Jeffrey F. Kelly are with the Rocky Mountain

Research Station, USDA Forest Service, 2205 Columbia SE, Albuquerque,

NM 87106.

Abstract—In the Southwestern United States, recent degradation

of riparian habitats has been linked to decline of the Southwestern

subspecies of the Willow Flycatcher. During a 2-year banding effort,

migration patterns and bird fat content were analyzed. Recommendations for managers, and outlines for conservation plans, are

included.

The Willow Flycatcher (Empidonax traillii) is a neotropical migratory landbird that breeds throughout the

United States and southern Canada and is fairly abundant

in the northern portion of its range. The species winters in

the Choco Lowland, Gulf-Caribbean Slope, and the Pacific

Arid Slope zoogeographic regions of Latin America and

South America (Stotz and others 1996), although the

limits of its winter distribution are poorly known. Regional

variation among breeding individuals has long been considered prominent enough to warrant subspecies designations (Phillips 1948). Currently, most experts recognize 4 or

5 subspecies of the Willow Flycatcher (Unitt 1987, Browning

1993).

Recent degradation of riparian habitats in the southwestern United States is believed to be linked to the decline

of the southwestern subspecies of the Willow Flycatcher

(Empidonax traillii extimus). The Southwestern Willow Flycatcher breeds in Arizona, New Mexico, southern California,

and southern parts of Utah, Nevada, and Colorado. Owing to

its small population size, the southwestern subspecies was

listed as federally endangered in 1995 and critical habitat

was designated in 1997. Although used for migration and

breeding, none of habitat associated with the Rio Grande

was included in the critical habitat designation. While the

majority of the flycatcher monitoring programs focus on

breeding surveys, nesting success, and cowbird parasitism,

it is widely acknowledged that declines in the abundance of

this species may also be attributable to poor quality habitats

visited in winter or during migration stopover.

In the Southwestern U.S. riparian corridors attract a

concentration of migrating songbirds including Willow

Flycatchers. The Rio Grande is the second largest riparian system in the Southwest and maintains the largest

Status and Migration of the Southwestern

Willow Flycatcher in New Mexico

Deborah M. Finch

Jeffrey F. Kelly

cottonwood forest in North America (Whitney 1994). This

river system is also a primary source of agricultural and

municipal water in both New Mexico and Texas. Cottonwood-willow habitats along the Rio Grande were historically

associated with a braided river channel that meandered

across a broad floodplain. The need to deliver water in a

reliable manner and to limit damage due to flooding have

resulted in management to reduce the meandering of the

channel and the variability in river flow. Hence, riparian

vegetation is restricted to the permanent watercourses that

include the Rio Grande and associated water conveyance

channels.

This paper gives a brief overview of Willow Flycatcher

breeding status throughout the state of New Mexico and

describes its migration pattern through the middle Rio

Grande valley. We also summarize information on conservation plans underway.

Breeding Surveys 1994 to 1996 ____

Breeding sites of the Southwestern Willow Flycatcher

have been documented in New Mexico on the Upper Rio

Grande and Rio Chama (Taos and Rio Arriba County), the

Zuni River (McKinley County), the Middle and Lower Gila

River (Grant County), the Middle Rio Grande (Valencia

and Socorro Counties), and the Lower Rio Grande (Dona

Ana County) (Williams 1997a). During flycatcher surveys

from 1994 through 1996, at least 22 territories were found

each year on the Upper Rio Grande (Tierra Azul, Taos

Junction, Orilla Verde, Velarde, and San Juan Pueblo), 5 on

the Chama, 17 on the Middle Rio Grande (Isleta, Peralta Dr.,

Bosque del Apache, San Marcial), 5 on the Zuni River, 5 on

the Canadian River, 2 on the Lower Rio Grande (Radium

Springs), and over 140 on the Gila River (Fort West Ditch, UBar Ranch, Redrock, Gila Lower Box). By 1998, the number

of flycatcher territories jumped to over 220 (Dennis Parker

and Scott Stoleson personal communications) owing to greater

survey coverage in the Cliff-Gila Valley.

Number of known flycatcher sites, i.e., sites with at least

one territory, varied by year, with 17 sites detected in 1994;

13 in 1995; and 19 in 1996 (Williams 1997a). Of these, 16

sites had breeding attempts in one or more years. In 1996,

18 sites had 1-4 territories, with breeding observed at 11 of

them; 4 sites had 5-14 territories, with breeding at all of

them; and only 1 site had greater than 15 territories. This

latter site was on the U-Bar Ranch along the Gila River

between Cliff and Gila.

The Rocky Mountain Research Station initiated a research study in 1997 on the U-Bar Ranch to determine

flycatcher nesting success and rates of cowbird parasitism in

different-sized patches of habitat. Based on 1997 results,
198 USDA Forest Service Proceedings RMRS-P-7. 1999

flycatchers selected box elder (Acer negundo) more frequently than other woody plants including willow to nest in

and placed their nests higher on average than any other

known E. traillii population in the United States (Scott

Stoleson and Deborah Finch unpublished data). Box elder

foliage is dense, and its twigs are structured in a way that

was apparently highly suitable for nest placement by Gila

River flycatchers. The Cliff-Gila breeding site had a high

abundance of flying insects, moist soils, and numerous

irrigation ditches criss-crossing the property. Larger habitat patches were closed to livestock during the breeding

season. Brown-headed cowbirds (Molothrus ater) were

present, but brood parasitism rates at flycatcher nests

whose contents could be monitored were low (17 percent)

relative to other hosts such as yellow-breasted chats (Icteria

virens) and yellow warblers (Vermivora celata) (Stoleson

and Finch unpublished data).

Lessons learned from studying the habitat conditions

used by the Cliff-Gila population may be helpful for recovering the flycatcher and its habitats elsewhere in New

Mexico, such as in the bosque of the middle Rio Grande. For

example, the wet, “buggy” ditch habitats of densely-foliated,

small-diametered shrubs or trees found on the U-Bar Ranch

can potentially be simulated elsewhere. Similar conditions

can be created through the manipulation of water in irrigation channels, alteration of channel mowing schedules, creation of backwater ponds, revegetation with native woody

plants at suitable sites, and control of salt cedar (an alien

plant that dries soils). To evaluate the potential of ditches

to support flycatchers along the Rio Grande, let us turn to

our migration study to determine if and how migrating

Willow Flycatchers use channels during stopover.

Migration Study 1996 to 1997______

Low Flow Conveyance Channel

To investigate the use of the Low Flow Conveyance

Channel (LFCC) by Willow Flycatchers (Empidonax trailii)

and other migrant songbirds, the Bureau of Reclamation

(BOR) initiated a study in cooperation with the USDA-FS’s

Rocky Mountain Research Station in 1996. The objective of

this study was to determine the effects of a rotational

mowing system on the use of the Low Flow Conveyance

Channel (LFCC) by migrant Willow Flycatchers and other

songbirds. In the 1950’s the LFCC was built to carry water

from the Rio Grande at San Acacia to Elephant Butte

Reservoir. This diversion was necessary because too little

water was reaching Elephant Butte Reservoir and salt cedar

had invaded the river channel and blocked flow in several

sites. The LFCC was designed to carry 2,000 cubic feet per

second (cfs) from the river to the reservoir with maximum

hydraulic efficiency. Water has not been diverted into the

LFCC since 1985 and currently the LFCC is used to capture

irrigation return flows and as a shallow groundwater drain.

The vegetation along the LFCC’s is comprised of primarily

coyote willow (Salix exigua) and seep willow (Baccharis sp.).

This vegetation was mowed annually from 1959 through

1994. As part of an agreement with the U.S. Fish an Wildlife

Service the mowing of the LFCC was placed on a rotational schedule in 1996. Under this schedule 21 to 30 percent

of the LFCC will be mowed annually. This schedule will

result in multiple age classes of willow vegetation that are

potential habitat for migrant birds. For instance, in our

study area vegetation has grown rapidly and resulted in

dense stands of 6-15 ft tall vegetation that was 8-25 ft wide.

While these willow stands have not been historically

available to migrating birds like Willow Flycatchers they

may represent an important resource for this endangered

subspecies.

Study Site and Mist Net Operation

In both 1996 and 1997 field data were collected in the

first week of April through the first week of June and from

the first week of August through the first week of November.

In 1996 and 1997 nets were operated in willow, agricultural

edge, cottonwood bosque and along the LFCC. Standard

nylon mist nests (12 m x 2.6 m) were used. Mist nets were

operated 5 days a week. Unless rain, high winds, or temperature dictated a change, mist nets were opened 15 minutes

before sunrise and operated approximately six hours each

banding mourning. Each captured individual was weighed

to the nearest 0.1 g using a digital electronic balance. We

estimated fat stores of each bird by observing the subcutaneous fat deposits in the interclavicular fossa and abdomen

according to a six-point scale developed by Helms and Drury

(1960). Unflattened wing chord, tarsus, tail length relative

flight feather length (for wing formula calculation), presence

of notch and emargination of primaries, bill width, bill

length, lower mandible color, wingspan, and tail shape

were measured according to Svensson (1984) and Pyle (1997).

The amount of skull ossification was examined in fall to

identify age. Plumage color and relative contrasts between

body parts were recorded by referring to the color standard

of Smithe (1975). Each bird was banded with a numbered

aluminum leg band.

The same 14 net sites along the LFCC were used in 1996

and 1997. These net sites were located on the west bank of

the LFCC, immediately south of the North Bosque del

Apache National Wildlife Refuge Check Structure. We selected this location for the following reasons: 1) the willow

growth in this section was typical of the LFCC, i.e., data

collected from the area would be relatively representative

of the entire LFCC; 2) the area was close to our original

study site, therefore, this data set could be used as a spatial

control for comparisons and it also made it possible to

operate both net site concurrently. 3) the site was inside the

Refuge boundary and, therefore, the probability of nets

being vandalized was reduced. To maximize capture rate,

nets were set up approximately perpendicular to the LFCC

at 30-50 m intervals.

In addition, the 5 net sites established in salt cedar

habitat adjacent to the LFCC in 1996 were also operated in

1997, and 2 additional nets were operated in this habitat

bringing the total to 7. Of the 14 nets operated in the

cottonwood habitat in 1996, 7 were operated in 1997. The

number of nets in the willow habitat was increased from 3 in

1996 to 4 in 1997. Netting effort remained constant at 3 nets

in the agricultural edge habitat. In total 39 nets were

operated in during 1996 and 35 nets were operated in 1997.

Because some of our net sites changed between 1996 and
USDA Forest Service Proceedings RMRS-P-7. 1999 199

1997 we needed to standardize our capture data to make

comparisons. For this purpose we calculated our banding

effort in each season in terms of net-hours. A single mist net

operated for one hour is a net-hour.

Willow Flycatcher Identification

Willow Flycatchers are difficult to distinguish from Alder

Flycatchers (Empidonax alnorum) in the field (Stein 1963,

Pyle 1997). Most individuals (90 percent) of these species

can however be separated based on Steins formula, which

combines several wing measurements and bill length

(Stein 1963). Alder flycatchers have not previously been

recorded in New Mexico (Williams 1997b), but to demonstrate that the birds that we captured were Willow Flycatchers rather than Alder Flycatchers we undertook this analysis. We also identified Willow Flycatchers to subspecies in

the field. These identifications were based on a number of

morphological and coloration measurements. Because there

is no proven method of validating these subspecies identifications, they should be applied with caution (Yong and Finch

1997). It is unlikely that every individual was classified

correctly and the total accuracy cannot be estimated. Here

we report some analyses designed to uncover potential

distinctions among subspecies. We distinguished four subspecies (Browning 1993): Empidonax traillii adastus,

E.t. brewsteri, E. t. traillii, and the Southwestern form E. t.

extimus. For most of this report we distinguish only those

birds categorized as endangered Southwestern Willow Flycatchers and lump those of other subspecies.

Banding Effort

In 1996 we netted for 7,997 net hours in the spring and

13,085 net hours in the fall for a total of 21,092 net hours.

The majority of this effort was concentrated on the LFCC

(2,491 net-hours in spring and 4,673 net hours in fall) and in

cottonwood bosque (3,217 hrs in spring and 4,698 net hours

in fall). Our overall netting effort in 1997 was very similar to

that in 1996. We netted for 7,691 net hours in the spring and

12,938 net hours in the fall for a total of 20,629 net hours in

1997 which is 98 percent of our 1996 effort. A larger majority

of our 1997 effort was focused on the LFCC (8,183 net hrs; 40

percent of total effort). Cottonwood and salt cedar habitats

were the next most intensely banded sites with about 4,151

net hours each.

Results of Migration Study

Analysis by Stein’s formula indicated that 88.5 percent of

the birds that we have identified as Willow Flycatchers can

be confirmed as Willow Flycatchers rather than Alder Flycatchers. Several factors indicate that birds whose species

could not be confirmed on the basis of Stein’s formula were

also Willow Flycatchers. First, this formula only separates

90 percent of birds known to be Willow Flycatchers (Stein

1963). Thus a pure sample of Willow Flycatchers would not

have more separation than our sample. Second, the presence

of an Alder Flycatcher has never been confirmed in New

Mexico (Williams 1997b). Third, young Willow Flycatchers

have been shown to be less distinguishable from Alder

Flycatchers on the basis of Steins formula (Hussell 1991).

For these reasons we are confident that our identification of

these birds as Willow Flycatchers is accurate.

A total of 92 Willow Flycatchers have been captured in

the 2 years of the study and 13 of these were categorized as

belonging to the endangered Southwestern subspecies. A

total of 41 Willow Flycatchers were caught along the LFCC

of which 5 were categorized as southwestern subspecies. It

appears that the primary characteristic that we used to

categorize flycatchers to subspecies was back color (table 1).

Principal Components analysis of tail length, wing length,

bill length, wing formula, tarsus length (table 2) did not

reveal a single or combination of morphological features that

readily distinguishes among the subspecies of Willow Flycatchers. Thus, the accuracy with which subspecies assessment can be made in the field remains unclear.

Because of the low number of captures of Southwestern

Willow Flycatchers it is impossible for us to make any

generalizations about habitat use of this subspecies that

are distinct from the rest of the species. As was true for most

species, the capture rate of Willow Flycatchers declined

from 1996 (2.4 birds/100 net hours) to 1997 (2.0 flycatchers/

100 net hours). The greatest number of Willow Flycatchers

were consistently captured in the LFCC habitat although

capture rates were higher in the willow habitat (fig. 1).

Table 1—Back colors of 77 Willow Flycatchers caught while migrating along the Middle Rio Grande between

1994 and 1996. Color numbers and descriptions refer to those in the Naturalist’s Color Guide

(Smythe 1975). Individuals were assigned to color categories by matching the color of their back

feathers to the most similar color sample. Individuals were assigned to subspecies in the field.

Numbers in parentheses are the percent of individuals in each color category that were assigned

to each subspecies.

Subspecies

Color Number Description Adastus Brewsteri Extimus Trailii

29 Brownish Olive 2 (18) 1 (2) 0 0

43 Grayish Olive 1 (9) 2 (4) 19 (100) 2 (100)

46 Olive Green 1 (9) 0 (0) 0 0

47 Olive Green 0 1 (2) 0 0

48 Olive Green 1 (9) 40 (89) 0 0

49 Greenish Olive 6 (54) 1 (2) 0 0
200 USDA Forest Service Proceedings RMRS-P-7. 1999

To assess the relative habitat use of Willow Flycatchers we

compared the percent of birds captured in each habitat to the

percent of banding effort (net hours) devoted to each habitat.

In each season except fall 1996 a larger percentage of

Willow Flycatchers were captured along the LFCC than the

percent effort devoted to that habitat. This indicates that

Willow Flycatchers were relatively abundant in this habitat. This pattern was also evident in the willow habitats in

all seasons and the salt cedar habitat in the fall of 1996 and

the spring of 1997. Both the agricultural edge and the

cottonwood habitats consistently captured fewer Willow

Flycatchers than the amount of effort expended (fig. 1).

Willow Flycatcher migration peaked in the 1st week of

June during the spring and in the 1st week of August in the

fall (fig. 2). The peak of migration appears to be more

narrow in the spring than in the fall. There does not appear

to be a clear difference among habitats in the timing of

migration. The majority of birds had little fat as indicated by

fat scores of zero or one (fig. 3). Again there were no obvious

differences in fat scores among birds captured in different

habitats. This lack of pattern also was apparent in the mass

of birds captured in different habitats (table 2).

Recommendations for the

Future _________________________

It is clear from our data that Willow Flycatchers are

using the LFCC as a stopover habitat during both the spring

and the fall. By intensely studying an area of the LFCC we

have been able to document both yearly variation in habitat

use and the progression of change that follows rest from

mowing. The fairly well developed willow stands that have

developed in the absence of mowing since 1995 indicates

that a rotational mowing system may be a viable means for

providing habitat for migrant birds while not compromising the function of the LFCC. To understand the compatibility of these uses at a broad scale, however, it is necessary to

have a broad view of the conditions that exist on the LFCC.

That is, our study has been useful in documenting the

potential to use rotational mowing to benefit migrant birds,

but to understand how much of that potential can be realized

we need to sample a broader portion of the LFCC.

To achieve this broader view of the LFCC we propose to

continue our study of the same area that we have investigate over the past 2 years, but with reduced effort (3 days per

week). On the remaining 2 sampling days per week we will

measure vegetation and establish temporary netting sites

at a spectrum of sites along the LFCC. This approach will

give us a broader sample of vegetative structures, mowing

histories and bird use data from which we can infer the

relationship between mowing schedule and bird use along

the LFCC. At the same time by maintaining some effort at

the sites we have sampled previously we will be able to

compare bird capture, vegetation, and arthropod abundance

data collected in 1998 with that collected in previous years.

Conservation Plans and Research

Needs _________________________

In January 1998, the U.S. Fish and Wildlife Service

assembled a Recovery Team for the Southwestern Willow

Flycatcher that is comprised of a technical subgroup and

seven stakeholder implementation subgroups. The technical subgroup is made up of technical experts from universities, research institutions, agencies, and other organizations. Implementations teams are composed of stakeholders

from special interest groups, conservation organizations,

state and federal agencies, and other entities having a stake

Table 2—Mean (sd) mass and wing, tail, and tarsus, lengths of Willow Flycatchers caught in the Bosque del Apache

in 1996 and 1997. N is number of birds measured.

Mass (g) Wing (cm) Tail (cm) Tarsus (cm)

x (sd) n x (sd) n x (sd) n x (sd) n

1996.00 FA AG 13.0 (—). 1 66.0 (—) 1 56.0 (—) 1 18.5 (—) 1

CO — (—) 0 66.5 (0.7) 2 55.5 (0.7) 2 16.5 (0.8) 2

LF 11.4 (1.0) 8 66.7 (3.4) 8 54.4 (4.2) 8 15.4 (1.3) 8

SS 12.6 (0.8) 7 65.9 (2.0) 7 55.7 (2.0) 6 16.2 (1.4) 7

SW 12.1 (0.6) 4 67.2 (1.8) 5 53.8 (2.4) 5 16.6 (1.0) 5

SP AG 11.9 (0.4) 2 68.2 (2.5) 2 58.5 (2.1) 2 16.0 (0.3)

CO — (—) 0 — (—) 0 — (——) 0 — (——) 0

LF 12.1 (0.8) 12 67.3 (3.1) 13 56.7 (1.8) 13 16.4 (0.7) 13

SS 12.9 (—) 1 68.0 (—) 1 59.0 (——) 1 16.8 (——) 1

SW 12.1 (1.0) 11 68.1 (3.3) 11 58.1 (2.8) 11 16.5 (0.9) 11

1997.00 FA AG 14.2 (——) 1 70.0 (——) 1 58.0 (——) 1 16.6 (——)

CO — (——) 0 — (——) 0 — (——) 0 — (——) 0

LF 11.3 (0.8) 7 66.1 (2.6) 7 55.6 (3.2) 7 15.5 (1.7) 7

SS 12.3 (0.5) 2 65.0 (4.2) 2 55.0 (2.8) 2 15.5 (0.2) 2

SW 11.5 (0.2) 3 65.3 (3.1) 3 53.3 (2.9) 3 16.0 (0.2) 3

SP AG — (——) 0 — (——) 0 — (——) 0 — (——) 0

CO 12.1 (1.5) 4 72.6 (3.0) 4 61.3 (3.9) 4 16.8 (0.6) 4

LF 12.8 (0.9) 13 69.5 (3.3) 13 57.2 (3.5) 13 16.5 (0.8) 13

SS 12.4 (0.6) 6 69.0 (2.5 7 59.4 (3.1) 7 16.4 (1.1) 7

SW 13.5 (1.2) 5 69.4 (2.9) 5 57.8 (2.6) 5 16.6 (0.8) 5
USDA Forest Service Proceedings RMRS-P-7. 1999 201

Figure 1—Percent of Willow Flycatchers and banding effort in each of 5 habitat of the Bosque del Apache. Relative

abundance of flycatchers among habitats can be assessed by comparing the percent effort with the percent of captures

within and among habitats. Habitats in which the percent captures bars are larger than the percent effort bars likely have

higher abundances of flycatchers.

in, or affected by management of, the Willow Flycatcher and

its habitats. A first draft of the recovery plan will be submitted to the Fish and Wildlife Service by October 1999.

A Conservation Assessment prepared by technical experts (many of whom are now on the Recovery Team) was

financed by the U.S. Forest Service in 1997-98 and will be

published or in press in a technical monograph series by

1999. The goal of this assessment is to review and synthesize

the state of knowledge about the flycatcher and formulate

recommendations for managing its populations and habitats throughout the Southwest. Designed to support the

recovery plan, the review is composed of chapters on southwestern riparian history, flycatcher status, threats, winter

and migration biology, breeding ecology, demography, effects of cowbird parasitism, flycatcher habitat use, management recommendations, and research needs. Some of the

relevant management recommendations in the conservation assessment include:

• Close occupied sites to recreational use during the

breeding season.

• Remove cows from occupied sites during the breeding

season.

• Trap cowbirds at sites having parasitism rates that

exceed 10 percent.

• Discourage spread of exotic woody plants such as salt

cedar.

• Prevent wildfires in riparian areas and develop fire

plans in advance of wildfires.

• Develop and conserve water for stimulating riparian

vegetation growth.

• Reduce “phreatophyte” control on irrigation ditches and

channels.

• Restore riparian areas near source populations of Willow Flycatchers.

The conservation assessment has also identified critical

gaps in knowledge that prevent experts and managers

from being fully effective in designing approaches for
202 USDA Forest Service Proceedings RMRS-P-7. 1999

recovering flycatcher populations and habitats. Research

needs include:

• Understanding the relationships between landscape

attributes, habitat occupancy patterns and nesting success of the Southwestern Willow Flycatcher.

• Understanding how cowbird travel distances and parasitism rates pertain to livestock presence and absence,

and Willow Flycatcher nesting sites.

• Developing knowledge of the direct effects of land use

(grazing, ditching, recreation, exotic plant control, channel mowing, water management) on Willow Flycatchers.

• Evaluating flycatcher nesting success and migration

stopover use in exotic and native vegetation.

• Designing and modifying methods to restore and

sustain riparian habitats and recover flycatcher

populations.

Figure 2—Number of Willow Flycatchers caught in

the Bosque del Apache during the spring and fall

by week and habitat.

Figure 3—Fat scores of Willow Flycatchers caught in

the Bosque del Apache in the spring and fall by

habitat.

Conclusions____________________

In summary, survey data indicated that the majority of

Southwestern Willow Flycatchers breeding in New Mexico

are found in the southwestern portion of the state, mostly

on private property along the Gila River. In 1998, more

than 200 territories were detected on the U-Bar Ranch

alone in the valley between the towns of Cliff and Gila.

Several breeding sites were also located on the Rio Grande

but only two (San Juan Pueblo and San Marcial) had more

than 5 flycatcher territories in 1995 and 1996. To recover

flycatchers, more attention to habitat restoration along the

middle and upper Rio Grande and associated tributaries is

needed. Linking research knowledge of flycatcher habitat

use in the Cliff-Gila valley to ongoing and new restoration

efforts along the Rio Grande may be of benefit to recovering

the flycatcher in the middle and northern regions of New

Mexico. In addition, our study of flycatcher migration along
USDA Forest Service Proceedings RMRS-P-7. 1999 203

the Low Flow Conveyance Channel suggests that ditches

and channels are important stopover habitat, particularly if

water is present and bankside willows are allowed to grow.

Based on our evaluation of stopover habitat use and Gila

River breeding habitat use, we suggest that habitats for

breeding Willow Flycatchers can be created along the Rio

Grande if specific habitat conditions are supplied. These

conditions include at minimum slow or still water, vegetation that supplies a suitable twig structure for nest placement (for example shrub willow, box elder), moist soils

(unlikely where large salt cedar thickets have established),

and a high abundance of flying insects.

Aknowledgments _______________

We thank the Bureau of Reclamation in Albuquerque, the

Bosque del Apache Wildlife Refuge, the Center for Field

Research, and New Mexico Game and Fish Department for

financial assistance, field grants, housing, and site access

for conducting our bird migration study. We are grateful to

the many field assistants, Earthwatch volunteers and volunteer interns who have helped us with this study. In

particular, we thank Mike Means, Dave Hawksworth and

Gus Bodner, for their dedication and length of service to

the study.

References _____________________

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Yong, W. and D.M. Finch. 1997. Migration of the Willow Flycatcher

along the Middle Rio Grande. Wilson Bulletin 109:253-268.
204 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Peter B. Stacey is Research Professor, Department of Biology, University

of New Mexico, Albuquerque, NM, and Angela Hodgson is Research Associate, Wildlife Conservation Society, P.O. Box 1512, Haines, AK.

Abstract—Although usually considered to be a bird of old growth

mixed conifer forests, the Mexican spotted owl historically occurred

in a wide range of habitats from lowland cottonwood bosques to

montane canyon systems. In a recent study of habitat use in central

New Mexico, we found that owls roost primarily in canyon bottoms,

and that they select sites that are characterized by deciduous trees

and high structural complexity of vegetation, rather than by large

diameter conifer trees per se. Intact riparian areas in montane

canyons typically have considerable structure, yet, as in the lowlands, these habitats have undergone extensive modification and

reduction. The unexpected diversity of habitat use of the Mexican

spotted owl suggests that historic changes in upland riparian

systems in the Rio Grande Basin may have impacted more species

than originally believed.

Although the Mexican spotted owl (Strix occidentalis

lucida) is often considered to be a species that depends

primarily upon mature mixed-conifer forest, it actually is

known to have historically nested in a surprisingly large

range of habitats. For example, spotted owls once occurred

in the lowland cottonwood bosques of New Mexico and

Arizona (Bailey 1928, Phillips and others 1964), and even

today they can still be found in some Arizona cypress and

Maderan oak forests in SE Arizona (USDI Fish and Wildlife

Service 1995). At the present time, however, most spotted

owls in the Rio Grande Basin and throughout the southwest

are restricted to canyon habitats at higher elevations in

the mountains. The topography of these mountain systems

can be extremely complex, and exposure, soil types and

moisture regimes often vary over extremely short spatial

scales. As a result, the vegetation communities within a

particular owl territory may actually consist of a complex

mosaic of plant associations that range from mixed conifer

forests (usually dominated by Douglas-fir, Pseudotsuga

menziesii, and southwestern white pine, Pinus strobiformis)

on north facing slopes, ponderosa pine (P. ponderosa)forests

on east and west facing slopes, and pinyon-juniper (P. edulis

and Juniperus spp.) forests or scrub oak (Quercus) thickets

on south facing slopes. In the canyon bottoms themselves,

vegetation may range in some locations from relative intact

Biological Diversity in Montane Riparian

Ecosystems: the Case of the Mexican

Spotted Owl

Peter B. Stacey

Angela Hodgson

riparian forests dominated by narrow-leaf cottonwood

(Populus angustifolia) and oak (primarily Gambel oak,

Quercus gambelii and gray oak, Q. grisea), to open pine-oak

meadows in areas that have been heavily impacted by

livestock grazing (for a detailed description of these associations, see Dick Peddie 1993). Because of the floristic complexity that exists within most spotted owl territories in the

southwest, it has not always clear which plant associations

within the mosaic are actually important to the birds, and

therefore which types of habitat modification may be most

likely to adversely affect their continued survival.

Because the spotted owl has played a central role in

controversies over timber harvests on public lands in the

southwest and elsewhere, most previous studies of habitat

selection in this subspecies have focused upon their association with large and/or commercially important conifer trees

(Ganey and Balda 1994, Zwank and others 1994, Seamans

and Gutierrez 1995). These studies found that spotted owls

tend to roost or nest in areas that have more or larger

diameter conifer trees than when compared to randomly

chosen sites, and that they tend to use unmanaged conifer

forests more often than would be expected by chance alone.

However, these studies did not specifically examine the

importance of other species such as the deciduous oaks and

cottonwoods that often occur in the understory of canyon

bottoms, although most authors have noted that oaks are

common at many roost sites (see also Ganey and others

1992). Rinkevich and Gutierrez (1997) found that in Zion

National Park in Utah, Mexican spotted owls are found only

in canyon bottom habitats with well-developed riparian

vegetation, and that they are absent from the pure mixed

conifer forests on the plateaus at the tops of the cliffs.

Similarly, there are no established nesting territories of

spotted owls in the extensive mixed conifer forests on the

Kiabab Plateau in northern Arizona, even though there are

a number of birds in the canyons that radiate from the

plateau (J. Goodman, pers. comm.; R. Silver, pers. comm.).

These observations, when combined with the historical

records of owls nesting in lowland riparian forests in the

complete absence of mixed-conifer, suggest that tree species

or vegetative characteristics other than, or in addition to,

large diameter conifer trees, may be important in habitat

selection in this subspecies.

The goal of this project was to explore this question for

spotted owls that occur in montane canyon habitats in the

middle Rio Grande basin of west-central New Mexico. Although we used the same general methods to study habitat

selection as most prior studies (Ganey and Balda 1994,

Zwank and others 1994, Seamans and Gutierrez 1995), we

expanded our analysis in several ways. First, we included
USDA Forest Service Proceedings RMRS-P-7. 1999 205

both conifer and deciduous trees when sampling vegetation

composition and structure in the roosting and randomly

selected plots. Second, we recorded the presence in our plots

of smaller diameter trees (>5 cm D.B.H.) than were included

in previous studies (usually >10 cm D.B.H.), since many

deciduous trees, particularly oaks, have small stem diameters and would otherwise be excluded from our analysis.

And finally, in recognition of the high degree of spatial

heterogeneity in the vegetation of owl territories, we undertook two different statistical comparisons. First, as was done

in previous studies, we compared occupied owl roost sites

with randomly chosen sites that were located within all of

the different plant community types within the owls’

territories (for example, pinon-juniper, ponderosa pine, deciduous/riparian, etc.). However, since we found that the

owls did not actually use all of these associations for roosting, we conducted a second analysis in which we restricted

the comparison of roost sites to only the subset of random

plots that were located within the same vegetation associations used by the owls (mixed conifer/deciduous and mixed

conifer; see below). The first comparison will reveal the

general types of habitats or plant associations that the owl

uses for roosting, while the second analysis examines the

specific characteristics of the vegetation that appear to be

important for habitat selection within that particular

association(s). This second analysis is particularly useful in

management, because it can give detailed information on

the important habitat characteristics of the associations

that are actually used by the owls, and therefore might be

affected by different management activities within those

associations.

Methods _______________________

Study Areas

The data reported here were collected as part of a longterm study of the Mexican spotted owl in west central New

Mexico (Arsenault and others 1997, Kuntz and Stacey 1997).

Our primary location for the roost-site analysis was located

in the West Red canyon area of the San Mateo Mountains, 40

km west of the Rio Grande near Truth or Consequences, NM.

Owls have been recorded in this canyon since at least the

early 1900’s (Ligon 1926) and we believe it represents

habitats typical of those now occupied by this species in

many of the mountain ranges in the southwest. The topography is characterized by deep forested canyons that extend

from a central ridge of peaks that runs north-south along

the length of the mountain chain. Elevations at the study

site vary from 1800-3200 m, and the vegetation is a mix of

scrub oak, pinyon-juniper, ponderosa pine, mixed conifer,

and limited aspen and spruce-fir at the highest elevations

(see Dick-Peddie 1993). Remnant riparian vegetation, consisting primarily of Gambel oak and scattered mature narrow-leaf cottonwood trees, occurs along all canyon bottoms.

At the present time, there is little or no regeneration of the

cottonwoods and most have died off. However, dense stands

of cottonwood, willows (Salix spp.) and other riparian species can be found within livestock exclosures in West Red

and elsewhere in the San Mateo Mountains, and we believe

this to be the original vegetation association in the canyon

bottoms. But because the current vegetation has been extensively altered from its original condition, we refer to this

association as “mixed-conifer/deciduous”, since it is now

dominated by conifers and oak trees, with mature cottonwoods in some locations. Most of the pure ponderosa pine

and mixed-conifer forests in the San Mateos have been

logged at least once during the past 50-100 years, although

there is no timber harvest at present. The current land uses

are primary livestock grazing (both summer and fall seasons) and recreation.

Detailed observations were made within three adjacent

owl territories in the West Red Canyon watershed with a

combined area of approximately 36 km2. Additional qualitative assessments of owl roost areas were made in three other

mountain ranges in west-central New Mexico, including the

Black Range, the Magdalena Mountains and the Zuni Mountains. Vegetation in these ranges was similar to that of the

San Mateo Mountains.

Habitat Analysis

We examined roosting habitat use from May through

November, 1993-94. Spotted owls were first located during

night surveys using standard techniques (Foresman 1983)

and roost locations then determined the following day. We

captured adult and juveniles at the roost using either a Balchatri trap or a 3.4 m noose pole. Each bird was then banded

with an US Fish and Wildlife Service aluminum leg band

and one color band. A 5 or 7.5-gram radio transmitter

(Holohil Systems, Ltd., Woodlawn, Ontario, Canada) was

then mounted on a central tail feather. The radio-tagged

owls were then located 2-3 times per week while roosting,

using a TRX 1000S radio telemetry receiver and a threeelement Yagi antenna (Wildlife Materials, Inc., Carbondale,

IL). The telemetry data were used to map the owls’ breeding

season home ranges using the minimum convex polygon

method and the computer program CalHome (California

Department of Fish and Game, Sacramento, CA). We

marked the location of all roost locations, and all habitat

measurements were taken at a later time when owls were

not present. Roost sites within 50 meters of each other were

considered part of the same cluster, even if they were used

in different years. We did not include in the analysis any

roost sites that were within 50 m of active nests, since

spotted owls do not make their own nests, and instead must

use either natural platforms in trees or caves, or the abandoned stick nests of other species. Since this could limit

habitat choice, we examined roost locations of only nonbreeding owls, or of family groups that had moved at least

100 meters from their nests.

We examined microhabitat characteristics within 0.04 ha

circular plots at 64 breeding season (1 March-15 October)

roost sites of radio-tagged owls and 69 random sites in the

West Red Canyon study area. All random plots were located

within the breeding season home ranges of the owls as

determined by the radio-tracking. We used a random number table to generate UTM coordinates and then located the

plot in the field using a Trimble global positioning system

(Trimble Navigation, Sunnyvale, CA) with an accuracy of

approximately 10-15 meters. Sample plots were centered on

the roost tree or on the potential roost tree closest to the
206 USDA Forest Service Proceedings RMRS-P-7. 1999

center of each random plot. The number of sites measured

was limited by time constraints and was not determined by

statistical methods.

We measured 27 variables within each plot. A complete

description of each variable and additional details of sampling methods is given in Hodgson and Stacey (1996). We

recorded the species identity, height, and diameter at breast

height (D.B.H.) for each tree > 5 cm D.B.H. within each plot

using a D.B.H. tape and clinometer. We then calculated

the basal area (m2/ha) and density (trees/ha) for each species, and height and diameter classes of trees. We used a

compass to measure the aspect at the center of the plot and

placed each plot in one of eight directional categories. Canopy

closure was measured as the average of four densitometer

readings taken 5 meters from the center of the plot in each

of the four cardinal directions, as well as the position of the

plot along the slope (upper 1/3, middle 1/3, lower 1/3 of slope,

or drainage bottom) and height of the owl roost. Each plot

was also assigned to one of four forest general types: mixedconifer, ponderosa pine woodland, pinyon/juniper woodland,

or mixed-conifer/ deciduous, as defined above. Juniper, pinyon pine and shrub live oak are the characteristic species of

the pinyon/juniper woodland in this area, and we combined

density and basal area of these species and designated the

total as pinyon/juniper basal area and density.

Statistical Analysis

Means (± SD) were calculated reported for all habitat

variables. Most variables were not normally distributed and

could not be normalized using standard transformations. To

determine if there was non-random selection for habitat

characteristics associated with roost sites, we compared

random and roost plot variables using the non-parametric

Mann-Whitney U test (SAS 1988). Since there was a total of

45 individual variables that could be tested with the same

data set (Hodgson and Stacey 1996), the significance level

for each test was conservatively set at p ≤ 0.005, using the

Bonferroni correction for 50 tests (Manly 1992). We analyzed the categorical variables, direction, position and forest

type using Chi-square goodness-of-fit tests (SAS 1988).

Two different analyses were performed. First, to examine

habitat selection within the entire range of vegetation associations present within the owls’ home ranges, we compared

roost sites to all of the random plots. Second, to determine if

there was also non-random selection of roost sites within

used forest types, the statistical influence of random plots in

unused forest types (see Results) was removed by eliminating all plots that were in ponderosa pine or pinyon/juniper

habitats from the random plot data set, since owls were

never actually observed roosting in these forest types. All

statistical analyses were then repeated using the subset of

random plots that were located within mixed-conifer or

mixed-conifer/ deciduous oak (n = 36).

Results ________________________

Roost Locations

As part of our overall study, we located roosting sites

between 1993 and 1995 in 30 different spotted owl territories

in four mountain ranges in addition to the three primary

territories in West Red Canyon area. Owls in these areas had

strong fidelity to breeding season roost sites: owls in 10

territories were found in the same roost areas for each of the

three consecutive years, and for two years in nine other

territories. In only three territories were owls found in

different roost areas in consecutive years. Not every territory was occupied every year, and four occupied territories

were checked during only one year. Four territories were

checked for three consecutive years but owls were only

located in those territories during only one year.

Twenty-eight (85 percent) of 33 different roost areas

were located in canyon bottoms. Five roost areas (15 percent) were not associated with drainage bottoms and owls

roosted on the upper or middle third of the slope in or

adjacent to large rock cliffs. All 28 roost areas located in

canyon bottoms had conifers (predominately Douglas-fir,

ponderosa pine, and/or southwestern white pine) and deciduous trees within 30 meters of the roost site. Gambel oak

was always present, and four roost areas also contained

remnant cottonwoods. Sixteen of the canyon bottom roost

areas were located in main (2nd or 3rd order) canyons and 12

were located in narrow first order drainages off of the main

canyon. Of the five roost areas located in or near cliffs, four

had only conifer trees within 30 meters of the roost site,

while one also had Gambel oak.

Habitat Selection

The roost sites of six adult and three juvenile radio-tagged

owls from the three territories in the San Mateo Mountains

were used for the detailed habitat analysis. Habitat use by

these birds was clearly non-random. Over two-thirds of

the roost sites were located in the mixed-conifer/ deciduous

association (49 of 64) and the remaining sites were in mixedconifer (15/64). No owls were found to roost in pinon-juniper

or ponderosa pine forests. The distribution of roost plots

among forest types was significantly different from the

distribution of random plots within the owls’ home ranges

(χ2 = 230.8, df=3, p < 0.001, fig. 1). Percent canopy closure in

roost plots ( x = 59.2 ± 17.2 ) was significantly greater than

in the full set of random plots representing all forest types

( x = 42.6 ± 20.1, p < 0.001) but was not significantly different

from mean canopy closure in the random plots in only the

mixed-conifer and mixed-conifer/ deciduous associations

( x = 51.9 ± 18.7, p = 0.0751). The density of live trees was

significantly greater in roost sites ( x = 773.1 ± 328.4) then in

random sites in all forest types ( x = 577.9 ± 354.1, p < 0.001)

but did not differ from random sites in mixed-conifer and

mixed conifer/deciduous associations ( x = 703.5 ± 380.3, p >

0.05). Mean roost tree D.B.H. was 31.1 ± 14.3 cm, mean roost

tree height was 18.4 ± 6.8 meters, and mean owl roost

height was 5.3 ± 2.2 meters. Most Mexican spotted owls

roosted in live Douglas-fir (47 percent), Gambel oak (19

percent), or Southwestern white pine trees (13 percent).

A comparison of the basal area of tree species found in

roost plots to that in random plots in all forest types (the

overall comparison; table 1) found significantly higher basal

area of Douglas-fir, southwestern white pine, and Gambel

oak/ other deciduous trees, and significantly lower pinon/

juniper, in the roost plots. In contrast, when the roost plots

were compared only to the subset of random plots within

used habitats, the differences in Douglas-fir and white pine
USDA Forest Service Proceedings RMRS-P-7. 1999 207

Figure 1—Distribution of Mexican spotted owl roost and randomly located sites among different forest association types

in the San Mateo Mountains, Middle Rio Grande Basin, New Mexico.

Table 1—Basal areas of tree species in Mexican spotted owl roosting sites in the San

Mateo Mountains, New Mexico (n = 64), compared with those in randomly

selected plots within the owls’ territories. Because the owls were never

observed roosting in pinyon/juniper or ponderosa pine forests at our study

area, we present two comparisons. First, random plots located in all forest

association types in the territory (n = 69), and second, the subset of random

plots that were located in forest types actually used by the owls for roosting

(mixed conifer and deciduous, MC/D, and mixed conifer, MC; n = 36). Note

that when the statistical influence of sample plots located in the unused

forest types was removed, the difference between occupied roost sites and

random plots in a higher basal area of Douglas-fir and southwestern white

pine was no longer significant.

Means ± SD

Random Plots MC/D, MC

Basal Area (m2/ha) Roost All Forest Types Forest Types

Douglas-fir 7.5 ± 6.5 3.9 ± /5.5** 6.9 ± 6.2

Southwestern White Pine 2.9 ± 6.3 0.8 ± 1.8** 1.4 ± 2.3

Pinyon/Juniper 0.2 ± 0.8 2.5 ± 4.5** 0.4 ± 1.9

Ponderosa Pine 2.9 ± 3.6 7.0 ± 7.2* 6.5 ± 5.9*

White Fir 0.6 ± 1.9 1.4 ± 4.2 2.7 ± 5.5*

Total Conifer Trees 14.2 ± 10.0 15.6 ± 8.7 18.0 ± 9.0

Gambel Oak and other 5.5 ± 4.7 1.1 ± 2.0** 1.4 ± 2.4**

Deciduous

Total Live Tree 19.7 ± 9.8 16.9 ± 8.6 19.4 ± 8.9

Snags 1.8 ± 2.8 3.0 ± 4.8 4.1 ± 5.4

*,**. Statistically significant differences between occupied roost plots and random plots. Because

of the large number of comparisons possible, the Bonferroni correction was used to set significance

levels to * p ≤ 0.005 and ** p ≤ 0.001.
208 USDA Forest Service Proceedings RMRS-P-7. 1999

basal areas were no longer significant, and the only a greater

basal area of Gambel oak and other deciduous species

distinguished the occupied and random sites (table 1).

Deciduous trees also accounted for nearly three times

more basal area in the roost sites than in either set of random

plots, which were not different from one another: 52 percent

of the total live tree basal area at roost sites versus 21

percent and 18 percent of total basal area in the random sites

in all forest types and mixed-conifer or mixed-conifer/deciduous forest types, respectively.

Analysis of deciduous and coniferous tree densities in

different D.B.H. classes showed significantly greater densities of small deciduous trees in the understory of roost

plots, and significantly lower densities of conifers in the

15-30 cm D.B.H. class, than in either set of random plots.

Surprisingly, the density of larger trees in roost plots was

not significantly different from the surrounding forest matrix in either analysis. However, large deciduous and coniferous trees were only found in a few habitat plots so the

power to detect a significant difference for the largest height

and D.B.H. classes was low (power = 0.03-0.50). Snag densities in roost plots were only significantly different from

random plots in the smallest height class (2-5 m, p < 0.001);

these were primarily oak stems.

Discussion _____________________

Our results suggest that the habitat requirements of

Mexican spotted owls may be more complicated that previously suspected. The territories of the owls in the southwest

are large, often ranging from 250 to 1500 ha (USDI Fish and

Wildlife Service 1995). At our study sites in both the San

Mateo Mountains, as well as in the other mountain ranges,

each owl territory contained 3-4 different forest types. As

with most previous studies (Ganey and Balda 1994, Zwank

and others 1994, Seamans and Gutièrrez 1995), we found

that the birds roosted in the mixed-conifer or mixed-conifer/

deciduous forest associations. No roost sites were located in

pure ponderosa pine or pinyon/juniper woodlands. Like the

prior studies, we also found that when we compared the

characteristics of roost sites to random plots in all forest

types, including those in the associations that were not used

by the birds, roost sites had greater canopy closure, and

greater density of Douglas-fir, southwestern white pine,

Gambel oak and total live trees. But when tree species at

roost sites were compared only to their availability in the

used habitat types (mixed-conifer and mixed-conifer/deciduous forest types), the specific habitat characteristics important to spotted owls became even more pronounced. In

this analysis, we found no significant difference in total live

tree, total conifer, Douglas-fir or southwestern white pine

density, or canopy closure. Roost sites and random sites in

mixed conifer associations did not differ except that the

occupied sites were most often in canyon bottoms or on the

lower portion of slopes where there was a higher density of

Gambel oak and other deciduous trees, and where deciduous

trees in general made up over one-half (52 percent) of the

total basal area of all live trees present. Although the

detailed analysis of habitat use was conducted on only three

owl territories, it is corroborated by the limited data from

roost sites on 30 other territories in four mountain ranges in

southwest New Mexico. In this larger sample, 84 percent of

roosting areas were in canyon bottoms and contained

deciduous trees.

The results of this analysis are similar to those of Rinkevich

and Gutierrez (1996), who found that in Zion National Park

owls occurred only in canyon bottoms with well-developed

riparian vegetation, and of Johnson (1997), who found that

owls in a number of different locations in Colorado always

roosted in the narrow parts of canyon bottoms in areas of

high canopy closure.

On the surface, our results appear to differ somewhat

from those of several prior studies which have emphasized

the importance of large diameter conifer trees in habitat

selection (Ganey and Balda 1994, Zwank and others 1994,

Seamans and Gutièrrez 1995). There are a number of reasons that may account for this. First, it is clear that the

spotted owl has always occupied a number of different

habitats types, including lowland bosques, and different

aspects of the vegetation may be important in different parts

of its range (see below). However, this study is one of the

first to specifically include and quantify the basal area and

densities of deciduous trees in roosting habitat, although

others have noted the importance and prevalence of these

species in spotted owl habitat (Ganey and others 1992,

Ganey and Dick 1995, Seamans and Gutièrrez 1995, Tarango

and others 1997). It also is the first to look at roost site

selection only within used habitat types. Comparing roost

plots to random plots throughout a study area often results

in comparing roost plots in mixed-conifer forest to random

plots that are located in pinyon/juniper or ponderosa pine

forests. For example, approximately 30 percent of the random plots measured by Seamans and Gutièrrez (1995) at

their study area in New Mexico, and 29 percent of the

random plots measured in the present study, were in

pinyon/juniper woodland. Only rarely have Mexican spotted

owls been documented to utilize pinyon/juniper forest (Skaggs

and Raitt 1988, Seamans and Gutièrrez 1995). Typical

pinyon/juniper woodlands have tree cover of only 30-50

percent and the height of the tallest trees is usually only 4-

8 meters (Moir and Carleton 1987). Therefore, due to the

large statistical influence the unused random habitat plots

may have on determining which variables are significant

different among plots, it could be difficult to determine the

specific habitat characteristics within the mixed-conifer

habitat that actually affect habitat selection by the owls.

What all of these studies have in common is that they have

found that Mexican spotted owls select roosting habitats

are characterized by a high level structural complexity in

the vegetation, just as they do in the other parts of the

species range in California and the Northwest (Gutierrez

and others 1995). In some parts of the southwest, this

structure may be provided by old growth or mature mixed

conifer forests, or by a well-developed understory of Gambel

oak in ponderosa pine-oak woodlands. In many canyon

habitats, however, deciduous vegetation, particularly riparian, may be the most important factor determining structural complexity. Mature montane riparian communities

historically contained a wide variety of tree species, including Gamble and other oaks, cottonwoods, maples (Acer

grandidentatum) and even conifer species such as Douglasfir and white pine (Dick-Peddie 1993). Even today, remnant

riparian habitats often contain a substantial component of

Gambel oak that can provide vertical layering and vegetative structure for the birds.
USDA Forest Service Proceedings RMRS-P-7. 1999 209

Understanding the characteristics of suitable roosting

habitat for spotted owls may be extremely important for a

number of reasons. The birds are relatively “heat intolerant”, and must find cool and shady places to roost during the

summer (Barrows 1981). Intact riparian habitats, and other

mature forests, are often substantially cooler than the surrounding areas. The owls simply may not be able to survive

hot seasons in areas that do not have the appropriate

thermal micro-environment. Spotted owls also sleep during

much of the day, and during this period adult and particularly juvenile owls can be very vulnerable to diurnal and

crepuscular avian predators, such as Northern goshawks

(Accipiter gentilis) and great horned owls (Bubo virginiana).

Typically, the owls roost in locations where multiple layers

of vegetation make them difficult to detect, and they often

perch on a horizontal branch next to a large tree trunk where

a goshawk or great horned owl would run the risk of considerable injury if it attacked and missed its target (see also

Buchanan and others 1995). Since caves and shaded sites

near large cliffs can provide the same type of cool microhabitat and protection from aerial predators as do riparian areas,

this may explain why the owls in our study always roosted

in or near cliffs when they were not in the canyon bottoms.

As in the lowlands, canyon bottom riparian habitats in the

mountains have undergone extensive alteration as a result

of human activities. Many plant and animal species characteristic of this zone have become rare, and a number have

been listed or been proposed for listing under the Endangered Species Act. While 88 percent of roost areas that we

located, including all the canyon bottom sites, contained

deciduous trees, Gambel’s oak, a species found both in

upland areas and canyon bottoms, was often the only deciduous species present in the immediate vicinity of roost sites.

All of the canyons, however, had remnant cottonwoods and

maples near the roost areas, indicating that these areas

probably had more riparian characteristics before intensive

grazing and other disturbances (Krueper 1993). Both our

study and the results of earlier work suggest that within the

mixed-conifer zone, spotted owls are selecting roost areas in

canyon bottom microhabitats where deciduous trees offer

the greatest vertical forest structure and canopy cover.

Recognition of the canyon bottom habitat in the mixedconifer zone as montane riparian, and monitoring of the

effects of disturbance to this habitat (including grazing, road

building and fire), may aid in the management of these

sensitive areas. The apparent importance of deciduous vegetation in the roosting habitat selection of Mexican spotted

owls suggests that the decline of montane riparian areas

may have an even greater effect on biological diversity in the

southwest than was originally suspected.

Acknowledgments ______________

We thank N. Cervantes, T. Epps, L. Graham, J. Hobson,

K. Marty, C. Thompson and M. Watson for their dedicated

help with the field work. J. Ganey, W. Block, J. Berger, M.

Gomper, and K. Obermeyer provided helpful discussion of

the ideas. We thank S. Spangle of the U.S. Fish and Wildlife

Service, Albuquerque, N.M. and W. Block of the Rocky

Mountain Forest and Range Experiment Station, U.S. Forest Service, for facilitating this study. Funding was provided

by U.S. Forest Service, Rocky Mountain Forest and Range

Experiment Station Cooperative Agreement 28-C3-741

and National Science Foundation Grant DEB 9302247 to

PBS, and a Cooper Ornithological Society Mewaldt-King

Student Research Award to AH.

References _____________________

Arsenault, D.A.; Hodgson, A; Stacey, P.B. 1997. Dispersal movements of juvenile Mexican spotted owls (Strix occidentalis lucida)

in New Mexico. In J.R. Duncan, D.H. Johnson, and T.H. Nichols,

eds. Biology and Conservation of Owls of the Northern Hemisphere. USDA Forest Service Gen. Tech. Rept. NC-190, St. Paul,

MN: 47-57.

Bailey, F.M. 1928. Birds of New Mexico. New Mexico Department

of Game and Fish. Santa Fe, NM.

Buchanan J.B; Irwin L.I.; McCutchen E.L. 1995. Within-stand

nest-site selection by spotted owls in the eastern Washington

Cascades. J. Wildlife Manage. 59:301-310.

Dick-Peddie, W.A. 1993. New Mexico vegetation, past present and

future. Albuquerque, NM: University of New Mexico Press. 246p.

Forsman, E.D. 1983. Methods and materials for locating and

studying spotted owls. USDA Forest Service Gen. Tech. Rept.

PNW-162, Pacific Northwest Research Station, Portland, OR.

Forsman, E.D.; Meslow, E.C.and Wright, H.M. 1984. Distribution

and biology of the spotted owl in Oregon. Wild. Monogr. 87:1-64.

Ganey, J.L.; Balda, R.P. 1994. Habitat selection by Mexican spotted

owls in northern Arizona. Auk 111:162-169.

Ganey, J.L.; Dick, J.L. Jr. 1995. Habitat relationships of the Mexican spotted owl: Current knowledge. Chapter 4. In USDI Fish and

Wildlife Service. Recovery plan for the Mexican spotted owl (Strix

occidentalis lucida), Vol. 2. Albuquerque, NM.

Ganey, J.L.; Duncan, R.B.; Block, W.M. 1992. Use of oak and

associated woodlands by Mexican spotted owls in Arizona. In

Folliott, P.F., G.J. Gottfried, D.A. Bennett, V.M. Hernandez C.,

A. Ortega-Rubio, and R.H. Hamre [tech. coords.], Ecology and

management of oak and associated woodlands: perspectives in

the southwestern United States and northern Mexico. USDA

Forest Service Gen. Tech. Rept. RM-218, Rocky Mountain Forest

and Range Experiment Station, Fort Collins, CO.

Hodgson, A.; Stacey, P.B.1996. Dispersal and habitat use of

Mexican spotted owls in New Mexico. Final Report, USDA Forest

Service, Cooperative Agreement 28-C3-741. Rocky Mountain

Experiment Station, Fort Collins, CO.

Johnson, C.L. 1997. Distribution, habitat and ecology of the

Mexican spotted owl in Colorado. Master’s Thesis, University of

Northern Colorado, Greeley, CO.

Krueper, D.J. 1993. Effects of land use practices on western riparian

ecosystems. In D.M. Finch and P.W. Stangel [eds.], Status and

management of neotropical migratory birds. USDA Forest Service Gen. Tech. Rept. RM-229, Rocky Mountain Forest and

Range Experiment Station, Fort Collins, CO.

Kuntz, W.A.; Stacey, P.B. 1997. Preliminary investigation of vocal

variation in the Mexican spotted owl (Strix occidentalis lucida):

Would vocal analysis of the four-note location call be a useful tool

for field identification? In J.R. Duncan, D.H. Johnson, and T.H.

Nichols, eds. Biology and Conservation of Owls of the Northern

Hemisphere. USDA Forest Service Gen. Tech. Rept. NC-190,

North Central Research Station, St. Paul, MN: 562-568.

Ligon, J.S. Habits of the spotted owl (Syrnium occidentale). Auk

43:421-429.

Manly, B.F.J. 1994. Multivariate statistical methods: a primer,

2nd ed. Chapman and Hall, London, UK.

Moir, W.H.; Carleton, J.O. 1987. Classification of pinyon-juniper

(P-J) sites on National Forests in the Southwest, p. 216-226. In

Proceedings Pinyon-Juniper Conference. USDA Forest Service

Gen. Tech. Rept. INT-215, Intermountain Research Station,

Ogden, UT.

Phillips, A.; Marshall, J.; Monsen, G. 1964. Birds of Arizona.

University of Arizona Press. Tucson, AZ.

Rinkevich S.E.; Gutierrez R.J. 1996. Mexican spotted owl habitat

characteristics in Zion National Park. J. Raptor Research. 30:74-

78.
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Sas Institute. 1988. SAS/STAT User’s Guide, Release 6.03. SAS

Institute, Cary, North Carolina, USA.

Seamans, M.E.; Gutièrrez, R.J. 1995. Breeding habitat of the

Mexican spotted owl in the Tularosa Mountains, New Mexico.

Condor 97:944-952.

Skaggs, R.W.; Raitt, R.J. 1988. A spotted owl inventory of the

Lincoln National Forest, Sacramento Division, 1988. Unpublished Report to the New Mexico Department of Game and

Fish, Santa Fe. 12 pp.

Tarango L.A.; Valdez R.; Zwank P.J.; Cardenas, M. 1997. Mexican

spotted owl habitat characteristics in southwestern Chihuahua,

Mexico. Southwestern Nat. 42:132-136.

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wildlife and plants; final rule to list the Mexican spotted owl as a

threatened species. Federal Register 58:14248-14271.

USDI Fish And Wildlife Service. 1995. Recovery plan for the

Mexican spotted owl (Strix occidentalis lucida), Volume 1.

Albuquerque, NM. 172 pp.

Willey, D.W. 1993. Home-range characteristics and juvenile dispersal ecology of Mexican spotted owls in southern Utah. Unpublished Report to the Utah Division of Wildlife Resources, Salt

Lake City.

Zwank, P.J.; Kroel, K.W.; Levin, D.M.; Southward, G.M.; Romme,

R.C. 1994. Habitat characteristics of Mexican spotted owls in

southern New Mexico. J. Field Ornithol. 65: 324-334.
USDA Forest Service Proceedings RMRS-P-7. 1999 211

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Jean-Luc E. Cartron and Scott H. Stoleson are with the Rocky Mountain

Research Station, USDA Forest Service, Albuquerque, NM. R. Roy Johnson

is with Johnson and Haight Environmental Consultants, Tucson, AZ.

Abstract—Riparian habitats and wetlands represent less than 2

percent of the land area of the Southwest, but they support the

highest density and abundance of plants and animals in that region

(Dahms and Geils 1997). Since the latter part of the 19th century,

riparian and wetland ecosystems have been severely impacted by

human activities such as woodcutting, mining, livestock grazing,

and water diversion and pumping (Phillips and Monson 1964,

Johnson and Carothers 1982, Tellman and others 1997). In this

paper, we examine the likelihood of species endangerment in obligate and preferential riparian-nesting landbirds of the Southwest.

Population trends are also reviewed with respect to biogeography,

as we distinguish between birds that reach the end of their distribution in the Southwest and those that do not. We report local

extirpations and/or population declines for a higher proportion of

those species occurring at the northern periphery of their geographic range. We also show an increased likelihood of endangerment for obligate vs. preferential riparian birds. Ultimately, the

large number of Southwestern species depending on riparian habitats and/or represented by peripheral populations only underscores the sensitivity of the regional avifauna to riparian habitat

degradation.

With a disproportionate percentage of the nation’s vertebrate species, the southwestern United States is known as a

region of high biodiversity (Hubbard 1977). A relatively low

latitude, a varied topography, a unique biogeographic and

geologic history (MacMahon 1985, Flather and others 1994),

and the local occurrence of most of the vegetative life zones/

biotic communities of the western U.S. (Carleton and others

1991, Brown 1994) all contribute towards high species richness. An important feature of biodiversity in the Southwest,

however, is that much of the wildlife is concentrated in

riparian habitats and wetlands, which constitute less than

2 percent of the land area (Johnson and Haight 1985, Szaro

and Jakle 1985, Dahms and Geils 1997). Birds in particular

show a close association with riparian habitats and wetlands, as 78 (47 percent) of the 166 avian species nesting in

the Southwest lowlands are completely dependent on these

Riparian Dependence, Biogeographic

Status, and Likelihood of Endangerment in

Landbirds of the Southwest

Jean-Luc E. Cartron

Scott H. Stoleson

R. Roy Johnson

habitats during the breeding season (Johnson and others

1977).

Another important feature of the regional wildlife relates

to biogeography: many of the vertebrate species (for example, birds, bats) represented in the Southwest reach the

end of their distribution in this region. Because population

density tends to decline (Hengeveld and Haeck 1982,

Rapoport 1982, Brown 1984, Emlen and others 1986, Teleria

and Santos 1993, Maurer and Villard 1994, Brown and

others 1995) and distribution may be patchier (Brown 1984)

towards the edge of the geographic range, peripheral populations tend to be small and isolated. Hence, they may be

associated with a higher risk of occasional decline or even

local extirpation due to stochastic variation in local conditions (see Petterson 1985, Simberloff 1988, Clark and others

1990). Ultimately, the high concentration of wildlife in only

a small portion of the land area, combined with the large

number of species represented by peripheral populations -

which, too, may concentrate near bodies of water- suggests

that biological diversity in the Southwest may be particularly vulnerable to the loss of riparian habitat and wetlands.

In this study, we examine the influence of biogeography

and extent of riparian dependence on the prevalence and/or

likelihood of endangerment in landbirds nesting at low and

mid elevations in Arizona and New Mexico. As it turns out,

riparian habitats have been severely altered by human

activities since the end of the 19th century. Due to groundwater pumping, livestock grazing, water management activities, urban expansion, woodcutting, invasion by exotic

species, and mining (Phillips and Monson 1964, Rea 1983,

Johnson and Simpson 1988, Tellman and others 1997), an

estimated 90 to 95 percent of the original riparian habitat

has been lost or degraded (Johnson and Carothers 1982,

Fleishner 1994). Altogether, the history of riparian habitats

in the Southwest has been called one of destruction and

desertification (Phillips and Monson 1964, Johnson and

Simpson 1988).

Methods _______________________

We first compiled a list of all 74 obligate and preferential

riparian/wetland landbird species breeding at low or mid

elevations (i.e., desertscrub and desert grasslands) in Arizona and New Mexico (table 1). Obligate riparian species

were those nesting (almost) exclusively in riparian habitats,

while preferential riparian birds were those breeding most

frequently and in highest numbers along rivers and streams.

The differentiation between obligates and preferentials, as
212 USDA Forest Service Proceedings RMRS-P-7. 1999

Table 1—List of obligate and preferential riparian and wetland landbird species nesting at low and mid-elevations in the

Southwest (Arizona and New Mexico).

Species (Federal and State status)a Geographic statusb Population decline/extirpationc

Obligate riparian and wetland

Mississipi Kite (AZ)

Bald Eagle (FT) SE

Cooper’s Hawk EEE

Common Black-Hawk (AZ, NM) NE E

Gray Hawk (AZ) NE E

Zone-tailed Hawk NE E

Yellow-billed Cuckoo (AZ) DDDD

Broad-billed Hummingbird (NM) NE

Violet-crowned Hummingbird (AZ) NE

Belted Kingfisher (AZ) SE extirpated in the lowlands

Northern Flicker (Red-shafted race)

Northern Beardless-Tyrannulet (NM) NE

Western Wood Pewee

Willow Flycatcher (FE) SE EEEE

Black Phoebe

Vermilion Flycatcher NE EEED

Tropical Kingbird (AZ) NE

Cassin’s Kingbird

Thicked-billed Kingbird (AZ, NM) NE

Western Kingbird

Rose-throated Becard (AZ) NE E

Bank Swallow SE

Cliff Swallow

White-breasted Nuthatch

Bewick’s Wren

Marsh Wren SE

Yellow Warbler

Common Yellowthroat

Yellow-breasted Chat EED

Red-winged Blackbird

Yellow-headed Blackbird SE

Summer Tanager NE EEED

Blue Grosbeak

Lazuli Bunting SE

Indigo Bunting SE

Painted Bunting NE

Song Sparrow

Abert’s Towhee (NM)

Bronzed Cowbird NE

Northern Oriole

Lesser Goldfinch

Preferential riparian

Harris’ Hawk NE EEEE

American Kestrel

Peregrine Falcon (FE)

Gambel’s Quail

White-winged Dove NE

Mourning Dove

Common Ground Dove (NM) NE

Greater Roadrunner

Common Barn Owl

Western Screech-Owl

Ferruginous Pygmy-Owl (FE) NE EEEE

Elf Owl NE DDDD

Black-chinned Hummingbird

Anna’s Hummingbird NE

Gila Woodpecker (NM) NE D

Ladder-backed woodpecker

Ash-throated Flycatcher

Brown-crested Flycatcher NE EEE

(con.)
USDA Forest Service Proceedings RMRS-P-7. 1999 213

Preferential riparian (con.)

Northern Rough-winged Swallow

Verdin NE

Black-tailed Gnatcatcher NE

Northern Mockingbird

Curve-billed Thrasher

Crissal Thrasher NE

Phainopepla NE

European Starling

Bell’s Vireo NE DDED-E

Lucy’s Warbler

Northern Cardinal NE

Pyrrhuloxia NE

Brown-headed Cowbird

Hooded Oriole NE EEE

House Finch

Data compiled from Monson and Phillips (1981), Hunter and others (1987), Johnson and others (1987), Arizona Game and Fish Department

(1988, 1996), U.S. Fish and Wildlife Service (1996), New Mexico Department of Game and Fish (1997).

a

FE: federally listed as endangered in Arizona and/or New Mexico, FT: federally listed as threatened in Arizona and/or New Mexico, AZ:

listed by the Arizona Game and Fish Department as endangered, threatened, or candidate (i.e., species or subspecies for which threats are

known or suspected and substantial population declines probably occurred but have not been documented), NM: listed by the New Mexico

Department of Game and Fish as endangered, threatened, or sensitive. b

NE: occurs at the northern edge of its geographic range in the Southwest, SE: occurs at the southern edge of its geographic range in the

Southwest. c

E: extirpated from the upper basin of one major river (Salt, Verde, Gila, Colorado, Santa Cruz, San Pedro rivers, Rio Grande) and its

tributaries, EE: extirpated from the upper basin of two major rivers,... D: population decline documented within the upper basin of one major

river, DD: population decline documented within the upper basin of two major rivers,...

Table 1 (Con.)

Species (Federal and State status)a Geographic statusb Population decline/extirpationc

presented here, was specific both to low and mid-elevations

and to Arizona and New Mexico only. The Yellow-billed

Cuckoo (Coccyzus americanus), for example, is widespread

in a variety of mesic habitats in the eastern states, but it is

restricted to riparian woodlands in the Southwest. The

Cassin’s Kingbird (Tyrannus vociferans) is an obligate riparian bird at lower elevations, but in pinyon-juniper woodlands it often nests away from water.

We also determined the biogeographic status of each

species in relation to the northern and southern ends of its

distribution. Birds were divided into three categories: a)

species that reach the northern end of their range in the

Southwest, b) species that reach the southern end of their

range in the Southwest, and c) all other species. For each

species, likelihood of endangerment was then examined

using two indicators: (1) population decline or local extirpation documented in the lower basin of one or several major

watersheds (Colorado, Gila, Salt, Verde, San Pedro, Santa

Cruz, Rio Grande) and (2) federal or state listing as endangered, threatened, candidate, or sensitive species. The second indicator did not reflect endangerment per se, as listing

can also be based on scarcity in the absence of population

decline. However, scarcity may determine the potential risk

for future population decline and/or extirpation (see introduction). Differences in the number of species exhibiting

population decline or local extirpation were tested across the

categories defined above. Differences in the number of species listed on the Federal Register and/or by states were

tested between obligate and preferential birds. All statistical tests consisted of Chi-square analyses of contingency

tables.

Results and Discussion __________

Of all 74 species listed in our table (table 1), 41 (55 percent)

were found to be riparian obligates, 33 (45 percent)

preferentials. A total of 37 (50 percent) birds reached the

northern or the southern end of their geographic range in the

Southwest. Population decline and/or extirpation was documented for 18 (24 percent) species, while federal or state

listing was reported for 18 (24 percent) birds -but not

necessarily the same species exhibiting decline or extirpation. Results indicated a significantly higher (P<0.005) proportion of species exhibiting population decline and/or local

extirpation among those occurring at the northern end of

their geographic range than among those not occurring at

the end of their distribution (fig. 1). The difference in the

proportion of species showing population decline/local extirpation between biogeographic categories b -represented by

only 8 species- and c was three-fold, but failed to achieve

significance (P>0.05). No significant difference (P>0.05) was

detected in the proportion of obligate versus preferential

riparian species showing population decline and/or local

extirpation. However, the proportion of species listed versus

not listed was significantly higher (P<0.05) in obligate birds

than in preferential birds. Combining indicators 1 and 2 (see

methods), the proportion of obligate species exhibiting endangerment and/or scarcity was marginally significantly

higher (P<0.1) than that of preferential species (fig. 2).

Overall, our study underlines the fragile nature of the

southwestern avifauna: if biogeographic status and extent of riparian dependence influence the likelihood of
214 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 1—The influence of biogeography. The Y axis represents the

number of bird species exhibiting versus not exhibiting population

decline and/or local extirpations across three biogeographic categories: (1) birds that reach the northern end of their range in the

Southwest (Periph. [N]), (2) birds that reach the southern end of their

range in the Southwest (Periph. [S]), and (3) all other species.

Figure 2—The relationship between extent of riparian dependence and population scarcity and/or endangerment. The Y axis

represents the number of riparian birds state/federally listed

and/or exhibiting population decline or local extirpation across

two categories: (1) obligate riparian birds and (2) preferential

riparian birds.
USDA Forest Service Proceedings RMRS-P-7. 1999 215

endangerment, then a high number of species—those exhibiting a high degree of dependence on riparian habitats

and/or those represented by peripheral populations—may

be at risk for becoming extirpated in the Southwest if

habitat degradation continues. The study may also be useful

for predicting which birds may be vulnerable to further

degradation of riparian habitats. In our view, conservation

planning for peripheral populations may be more important

than generally advocated by biologists: reduced gene flow

between isolated peripheral populations and core populations may well signify a greater potential for speciation at

the edge of the geographic range (Brown 1984). Continued

habitat loss may then mean not only reduced biodiversity

but also decreased potential for speciation—arguably one

key determinant of future biodiversity.

References _____________________

Arizona Game and Fish Department. 1988. Threatened native

wildlife in Arizona. Phoenix, AZ: Arizona Game and Fish Department. 32 p.

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and Endangered Wildlife Program, Arizona Game and Fish

Department. 40 p.

Brown, D. E. (ed.). 1994. Biotic communities of the southwestern

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Brown, J. H., D. W. Mehlman, and G. C. Stevens. 1995. Spatial

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Carleton, J. O., W. A. Robbie, G. T. Robertson, C. L. Spann, H. G.

Brown, III, J. Glass, D. W. Shaw, T. Robison, W. H. Moir, D.

Potter, R. A. Fletcher, R. Galeano-Popp, and G. J. Miller. 1991.

General ecosystem survey. Albuquerque, NM: U.S. Department

of Agriculture, Forest Service. 188 p. plus maps.

Clark, T. W. , R. M. Warnecke, and G. G. George. 1990. Management

and conservation of small populations. In: T. W. Clark and J. H.

Seebeck, eds. Management and conservation of small populations. Brookfield, IL: Chicago Zoological Society.

Dahms, C. W., and B. W. Geils, eds. 1997. An assessment of forest

ecosystem health in the Southwest. Gen. Tech. Rep. RM-GTR295. Fort Collins, CO: U.S. Department of Agriculture, Forest

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Emlen, J. T., M. J. DeJong, M. J. Jaeger, T. C. Moermond, K. A.

Rusterholz, and R. P. White. 1986. Density trends and range

boundary constraints of forest birds along a latitudinal gradient.

Auk 103:791-803.

Flather, C. H., L. A. Joyce, and C. A. Bloomgarden. 1994. Species

endangerment patterns in the United States. Gen. Tech. Rep.

RM-241. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment

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Fleishner, T. L. 1994. Ecological costs of livestock grazing in western

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Hengeveld, R., and J. Haeck. 1982. The distribution of abundance.

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Hubbard, J. P. 1977. Importance of riparian ecosystems: biotic

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eds. Importance, preservation, and management of riparian

habitat: a symposium. Gen. Tech. Rep. RM-43. Fort Collins, CO:

U.S. Department of Agriculture, Forest Service, Rocky Mountain

Forest and Range Experiment.

Hunter, W. C., R. D. Ohmart, and B. W. Anderson. 1987. Status of

breeding riparian-obligate birds in southwestern riverine systems. Western Birds 18(1):10-18.

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216 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Linda DeLay is with the New Mexico Natural Heritage Program, Department of Biology, University of New Mexico. Deborah Finch, Michael Means,

and Jeff Kelly are with the Rocky Mountain Research Station, USDA Forest

Service, Albuquerque, NM. Sandra Brantley is with the Department of

Biology, and Richard Fagerlund is with Environmental Services, University

of New Mexico.

Abstract—We compared abundance of migrating Willow Flycatchers and Wilson’s Warblers to the abundance of arthropods in exotic

and native vegetation at Bosque del Apache National Wildlife

Refuge. We trapped arthropods using glue-boards in 1996 and 1997

in the same cottonwood, saltcedar, and willow habitats where we

mist-netted birds during spring and fall migration. There were

fewer arthropods, particularly flies, in saltcedar. We have mixed

evidence that Willow Flycatchers and Wilson’s Warblers respond to

variation in insect numbers. Wilson’s Warblers appear to be more

abundant in willow than in other vegetation types in response to the

abundance of small flies.

Desert riparian forests in the Southwestern United States

attract a higher concentration of migrating passerines and

are a valuable resource for breeding birds (Ohmart 1994,

Finch and others 1995). Little is known about what types of

habitats are most important during landbird migration or

how habitat alteration may affect migrating birds (Moore

and others 1995). The Rio Grande is the second largest

riparian system in the Southwest and supports the largest

cottonwood forest in North America (Whitney 1994). Exotic

tree species are a major component of riparian forests. We

are evaluating the relative importance of exotic and native

vegetation types to migrating landbirds and the relationship of arthropod prey to avian use of vegetation at Bosque

del Apache National Wildlife Refuge.

Methods _______________________

We captured passerine birds using mist-nets and sampled

their potential arthropod prey using glue-boards in three

adjacent vegetation types at Bosque del Apache National

Wildlife Refuge (33°48'N, 106°52'W), New Mexico.

Arthropods of Native and Exotic Vegetation

and Their Association with Willow

Flycatchers and Wilson’s Warblers

Linda DeLay

Deborah M. Finch

Sandra Brantley

Richard Fagerlund

Michael D. Means

Jeffrey F. Kelly

Vegetation Types—We classified the vegetation as:

Fremont cottonwood (Populus fremontii) forest, coyote willow (Salix exigua) stringers along water conveyence structures, and saltcedar (Tamarix ramosissima) forest. The

cottonwood forest had a mature cottonwood overstory of

30 percent coverage with a fairly closed middle story of exotic

saltcedar and Russian olive (Eleagnus angustifolia) and

young cottonwood and Gooding willow (S. gooddingii). The

tree-shrub layer, approximately 5 meters in height, was

sparse and included seepwillow (Baccharis spp.) and pale

wolfberry (Lycium pallidum). The willow stands along water conveyance channels were fairly homogeneous, dense,

periodically mowed, and reached only 5 meters in height.

Two separate conveyance structures were studied, but were

combined as a single willow vegetation type. The saltcedar

forest was dominated by a tree-shrub layer (5 meters in

height) of saltcedar. There were as many dead stems as live

ones and the forest structure was a mixture of densely

clumped shrubs and open ground (M. Means, pers. obs.).

Bird abundance—We estimated bird relative abundance

as captures per net-hour using nylon mist nets (12 meters x

2.6 meters) opportunistically placed in each habitat. We set

up between 28 to 31 nets distributed as follows: 6 to 7 in

cottonwood, 16 to 18 in willow, and 5 to 7 in saltcedar. Nets

were opened 15 minutes before dawn and left open for an

average of 6 hours each day for 5 days a week. Field data

were collected in 1996 and 1997 during spring migration

(late April to early June) and fall migration (early August to

early November). We selected two Neotropical migrant passerines for our in-depth analysis of bird-arthropod associations: a commonly captured, primarily foliage gleaning bird

(Wilson’s Warbler, Wilsonia pusilla) and a rarer, primarily

aerial forager (Willow Flycatcher, Empidonax traillii).

Arthropod prey abundance—Glue-board traps were used

to sample arthropods for one 24 hour period each week.

These glue-boards were placed at a subset of mist-nets

within each vegetation type where they were randomly

attached to the vegetation 1.5 meters from the ground

within 10 meters of a mist-net. Glue-boards were yellow,

approximately 13 cm x 18 cm, and coated with TanglefootTM.

Arthropods trapped on glue-boards were counted and grouped

into size categories, small (≤6 mm), medium (>6 to 12 mm),

and large (>12 mm), and identified to Order and Family.

Our arthropod sampling scheme (see Hutto 1980, Cooper

and Whitmore 1990 for discussion on the efficiency of this
USDA Forest Service Proceedings RMRS-P-7. 1999 217

method) was set up primarily for ease of operation and to

estimate general abundance of arthropods in relation to the

relative abundance of birds captured in the immediate

vicinity. With this single sampling method, we do not claim

to be sampling the same prey species that aerial gleaning

and foliage gleaning insectivores are capturing. We are

assuming that prey numbers correlate with those of arthropod availability. For a more adequate picture of availability

(see Hutto 1985), we incorporated differences in vegetation

density (foraging-substrate availability) among vegetation

types into our estimates of arthropod availability. Assuming

independence of arthropods captured and vegetation density between vegetation types, we calculated a relative index

of arthropod numbers adjusted by a measure of shrub

density (<5 meters in height). We calculated the average

number of shrub stems for a habitat from 0.04 ha areas

around each net and divided the number by 1000. We then

multiplied that vegetation density by the number of

arthropods per trap.

Analysis—Statistical analyses were performed with SPSS/

PC+ (SPSS 1994) or SAS/PC (SAS Institute 1990). Normality and homogeneity were examined prior to applying parametric and nonparametric tests. Univariate analysis of

variance was performed using PROC GLM (SAS Institute

1990) to test for differences in arthropod abundances among

vegetation types for each year and season. Numerically

important orders of arthropods were identified, and separate ANOVA tests were performed for each group. Duncan’s

multiple range test was used to determine which mean

values from each vegetation type were different, and

Bonferroni adjustments in significance levels were made

when needed (Rice 1989). The arthropod count data were

log-transformed for the ANOVA tests. Associations between arthropod abundance and bird abundance were tested

with the nonparametric Spearman’s rank correlation test

(SPSS 1994). A Wilcoxon 2-tailed test was used to examine

differences in two size classes of flies. An alpha level of

0.05 was used to signify significance.

Results ________________________

Fifteen orders of arthropods were represented on glueboards set out in cottonwood midstory, stands of willow, and

stands of saltcedar forest. Coleopteran, Dipteran, Hemipteran, Homopteran, Hymenopteran, and adult Lepidopteran

were represented in samples in both seasons and years in all

three habitats (table 1).

There were significant year and season differences among

the relative abundances of insects (2-way ANOVA: F=1.24,

df= P=0.002) and the seasonal difference depended on the

year (year*season, F=9.24, df= P=0.003). Subsequent comparisons between vegetation types were therefore examined separately by year and season. The relative abundance

of arthropods was significantly less in saltcedar than in

willow or cottonwood midstory in most years and seasons.

Arthropod numbers per trap were highly variable in saltcedar

during fall, 1997, and did not differ from those in willow or

cottonwood (fig. 1, table 2). Patterns in the data differed

when we corrected arthropod abundance for shrub density

(arthropod-shrub index, table 2). There were significantly

fewer arthropods (arthropod-shrub index) in the cottonwood

understory than in willow for most comparisons.

Flies were less abundant in the homogenous stands of

saltcedar than in the other vegetation for both years and

seasons. There were more orders (5 out of 6) in the fall of

1997, in which differences among vegetation were evident

(table 2).

Beetles (Coleoptera) and plant bugs (Homoptera) are

primarily foliage inhabiting insects and made up the largest

proportion (83 percent in 1996 and 77 percent in 1997) of

that group. Flies (Diptera) and wasps, etc. (Hymenoptera)

made up the greatest proportion of aerial insects (99 percent,

both 1996 and 1997). We examined the association of both

aerial insects (flies and wasps) and foliage insects (beetles

and plant bugs) with Wilson’s Warblers (WIWA) and Willow Flycatchers (WIFL) over time for 1996 and 1997. Over

time there was a positive association between the relative

Table 1—Orders of arthropods represented by season (S=spring, F=fall) in the three habitats

sampled, 1996 and 1997.

Cottonwood Willow Saltcedar

Order 1996 1997 1996 1997 1996 1997

ACARINA (mites) S F F F F

ARANEIDA (spiders) S F S F S F S F S F F

COLEOPTERA (beetles) S F S F S F S F S F S F

DERMAPTERA (earwigs) F

DIPTERA (flies) S F S F S F S F S F S F

EPHEMEROPTERA (mayflies, etc.) F

HEMIPTERA (true bugs) S F S F S F S F S F S F

HOMOPTERA (plant bugs) S F S F S F S F S F S F

HYMENOPTERA (wasp, etc.) S F S F S F S F S F S F

LEPIDOPTERA (adult butterflies,etc.) S F S F S F S F S F S F

ODONATA (dragonflies, etc.): F S

ORTHOPTERA (grasshoppers, etc.): F S F S

THYSANURA (bristletails): S F

THYSANOPTERA (thrips): S F S F S F S F S F S F

TRICHOPTERA (caddisflies): S F F S F
218 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 1—The mean relative abundance of all arthropods found in three vegetation types during spring

and fall, 1996 and 1997.

abundance of Willow Flycatchers and the relative abundance of aerial insects in 1996 (Spearman’s rho 0.89, P=0.001,

N=9) but not in 1997 (Spearman’s rho 0.12, P=0.60, N=15).

In spring of 1997, WIFL numbers tended to correspond with

that of aerial insects, although this pattern was not significant (Spearman’s rho 0.7, P=0.17, fig. 2).

Wilson’s Warblers were not associated with aerial insects

over all weeks sampled in 1996 (Spearman’s rho 0.42,

P=0.26, N= 9) and tended to show only a trend in 1997

(Spearman’s rho 0.50, P=0.06, N=15). However, Wilson’s

Warbler numbers appeared to respond to temporal changes

in aerial and foliage insect numbers over the spring season

of both years (fig. 3). There was a positive association

between their relative abundance with that of aerial

(Spearman’s rho= 0.90, P=0.04, N=5) and foliage (Spearman’s

rho= 0.99, P=0.0001, N=5) insects in the spring.

Wilson’s Warbler numbers showed a corresponding association with aerial insects only in the willows in 1997

(Spearman’s rho= 0.65, P=0.009, N=15). There were significantly more small flies (<6mm) than mid to large flies (>

6mm) in the willows in 1997 (Wilcoxon 2-tailed, P=0.0001).

The greatest proportion of small flies consisted of Humpbacked flies (Phoridae) and Long-legged flies (Dolichopodidae); flies that tend to hover about the foliage. Together

they comprised 31 percent of flies in the spring and increased

to 67 percent in the fall. Gnats, chironomids, mosquitoes and

other swarming nematocerans comprised 61 percent of the

flies in spring and dropped to 19 percent in the fall.

Discussion _____________________

Migration is energetically stressful and migrants must

stopover between breeding and wintering habitats to forage,

rest, and replenish fat deposits (Moore and others 1995).

Decisions involved in habitat selection by landbird migrants

may depend on the spatial scale examined. The decision to

stop along a particular route on the way between wintering

and breeding grounds may be driven by such extrinsic

factors as genetics or associated with the benefits of the

shortest distances and most favorable wind patterns. Selection of a particular habitat may occur once migrants settle in

an area and may involve intrinsic factors such as characteristics of that vegetation type or habitat (for review see: Hutto

1985a and Moore and others 1995). Physical structure of the

habitat, including plant species composition and foliage

density, may influence how birds move through the habitat,

see and capture prey, and may determine how susceptible
USDA Forest Service Proceedings RMRS-P-7. 1999 219

migrants are to predation (Robinson and Holmes 1982,

1984). Several studies indicate a relationship exists between

food availability and avian selection of different habitats

(reviewed in Moore and others 1995).

We examined measures of arthropod availability of cottonwood habitat, stands of willow and stands of exotic

saltcedar. We found a difference among arthropod orders

and their abundance among vegetation types. Typically,

saltcedar harbored fewer total arthropods, particularly flies,

compared to the cottonwood understory, and willow stands.

When we extrapolated from numbers of arthropods caught

on traps to what might be available on the vegetation by

using a shrub density index, we instead found fewer

Table 2—Comparisons, between habitats at a different year and season, of relative abundance of arthropods

and an index of arthropod abundance adjusting for shrub density. ANOVA results using logtransformed data. Duncan groupings provide comparisons of each habitat (C = Cottonwood, S = Salt

Cedar, W = Willow). Letters not underscored by the same line are significantly different. Asterisks

denote that significance (P < 0.05) remains and ns denotes its removal after a sequential bonferroni

adjustment.

Arthropod numbers/trap Arthropod-Veg Indexa

Duncan Groups: Duncan Groups:

N = no. ANOVA High mean to ANOVA High mean to low

weeks P value Low mean P value mean

All individuals

Spring 1996 3 0.0001 W C S 0.0001 W S C

Fall 1996 5 0.0001 C W S 0.0001 W S C

Spring 1997 5 0.001 W C S 0.0004 W S C

Fall 1997 10 0.014 W S C 0.0001 S W C

Spring 1996 Six top ranking Orders (abundance of individuals)

Beetles 0.039ns

Flies 0.001* W C S

True Bugs 0.0005* W S C

Plant Bugs 0.068

Wasps, etc. 0.002* W C S

Thrips 0.237

Fall 1996 Six top ranking Orders (abundance of individuals)

Beetles 0.62

Flies 0.0002* C W S

True Bugs 0.278

Plant Bugs 0.046ns

Wasps, etc. 0.03ns

Thrips 0.301

Spring 1997 Six top ranking Orders (abundance of individuals)

Beetles 0.002* C W S

Flies 0.001* W C S

True Bugs 0.552

Plant Bugs 0.012* W C S

Wasps, etc. 0.08

Thrips 0.353

Fall 1997 Six top ranking Orders (abundance of individuals)

Beetles 0.0001* C W S

Flies 0.0001* W C S

True Bugs 0.0001* W S C

Plant Bugs 0.009* W S C

Wasps, etc. 0.0001* W C S

Thrips 0.759

a

Arthropod-veg index = (number arthropod individuals/trap)* number shrub stems.

arthropods in the cottonwood midstory. This pattern might

be explained by the fact that the cottonwood midstory, a

large portion of which is saltcedar, is less dense than that of

the monotypic saltcedar stand. In the future we plan to

include vegetation species diversity and spatial aspects of

vegetation to refine the relationship of arthropods to our

vegetation types.

Sudbrock (1993) stated that arthropod populations on

individual saltcedar plants fluctuate more in saltcedar monocultures than in mosaics of native vegetation. Those

fluctuations may have negative impacts on wildlife that feed

on arthropods. Contrary to what several other authors have

reported (Cohen and others 1978 and Crawford and others
220 USDA Forest Service Proceedings RMRS-P-7. 1999

Figure 3—The relationship of Wilson’s Warbler with

that of aerial insects (Orders: Dip=Diptera,

Hym=Hymenoptera) and foliage insects (Orders:

Col=Coleoptera, Hom=Homoptera) over time in 1997.

Asterisks denote a significant (*P=0.04, **P=0.0001)

association between bird abundance and aerial insect

abundance in spring.

Figure 2—The relationship of Willow Flycatchers with

that of aerial insects (Orders: Dip=Diptera,

Hym=Hymenoptera) over time in 1997

1993), Mund-Meyerson and others (in Mund-Meyerson,

1998) report that arthropod density on saltcedar, based on

fogging tree canopies, was not significantly different from

cottonwood trees over most of the breeding season of migrant

birds (May, June, and August samples). Our arthropod

sampling in cottonwood habitat included only midstory

trees and shrubs: saltcedar, Russian olive, and cottonwood.

In order to evaluate possible migrant bird selection of exotic

and native habitats during their migration, we need to

examine more components of each habitat that may influence prey availability. These elements would include arthropod abundance and diversity in relation to both overstory

and understory layers of a habitat (structural complexity),

plant or arthropod species diversity of a habitat, and vegetation density. These factors may influence numbers of

arthropods as well as their accessibility to avian predators.

We will also incorporate information on foraging behaviors

within our habitat designations in order to aid our evaluation and interpretation of vegetation use.

Our data suggest that migrating Wilson Warblers (WIWA)

and, perhaps, Willow Flycatchers (WIFL) respond to variation in arthropod abundance over time, especially during

spring migration. There was an association of WIWA capture rates with both aerial and foliage insects over time.

WIWA capture rates were associated with aerial insects in

the willows in 1997. The association of WIFL capture rates

with aerial insects was weak. Future analyses will examine

the correlation of bird capture rates to those of arthropods on

a net-to-trap basis. After completing our identification of

glue-board arthropods for 1996 and sampling from 1998, we

will have a more comprehensive data set from which to

evaluate bird-arthropod associations in each of our habitat

categories.

Depending on the migrant species, different taxa of

arthropods may determine avian vegetation use. Our future

analyses will include the examination of different families of

arthropods and their association to migrant capture rates

within each vegetation type. Raley and Anderson (1990)

found, for example, that riparian birds, one of which was the

WIWA, selected arthropod prey disproportionately to availability in willow. They also found that very small arthropods

were consistently underrepresented in WIWA diets. We

found an association with insect abundance and WIWA in

willow and hypothesize that this association may be in

response to a similar temporal change in abundance of small

dipterans such as gnats and chironomids. We need to examine data on avian prey-foraging behavior and prey selection

within each vegetation type to better understand possible

factors underlying vegetation and habitat use.

One school of thought suggests that food is only loosely

exploited and is not important in determining bird species

abundance (Wiens 1981); one might only expect a close

association between bird population densities and food resource levels during times of resource shortages (Wiens

1977). However, Hutto (1985b) found that insectivorous

migratory bird densities matched insect densities across

habitats within a season and across seasons within a habitat

during years with normal rainfall and thus probably not at

a time of resource stress. We speculate that migrant birds at
USDA Forest Service Proceedings RMRS-P-7. 1999 221

Bosque del Apache Wildlife Refuge may have been resourcestressed on a large scale, in relation to arthropod numbers,

in 1997. Fires in the summer of 1996 reduced a large

proportion of riparian habitat at the refuge (J. Taylor, pers.

comm.) and consequently would have reduced larger-scale

availability of foraging habitat and arthropod prey. Capture

rates of birds netted at the same sites have decreased during

the two years following the fire (J. Kelly, pers. obs.). Weekly

relative abundances of arthropods trapped on glue-boards

were lower in 1997 than in 1996 (L. DeLay, pers. obs.).

Perhaps less available foraging habitat caused migrating

insectivores to disperse over a larger area in search of insect

prey, and those stopping over at our sites were more responsive to differences in arthropod abundances. It has been

suggested that migrants assess alternative habitats during

an initial exploratory phase shortly after arrival (Moore and

others 1990) and possible cues to prey availability may be

feeding activity or high numbers of other migrant birds in

the vegetation (Moore and others 1995). Perhaps, there were

sufficient numbers of WIWA arriving weekly in our netting

area during spring to respond to greater concentrations of

other WIWA feeding in willow vegetation. Even though

WIFL capture rates were greatest in willow (Kelly and

others 1997), their relatively few numbers may be an insufficient cue to feeding activity.

Acknowledgments ______________

We thank J. Taylor, P. Norton and the staff of Bosque del

Apache National Wildlife Refuge for access, housing, and

assistance with our migratory bird studies. We thank

Wang Yong for assistance in developing the bird and

arthropod sampling methods. We thank our crew leader,

D. Hawksworth, and crew members for work and data

entry for 1996 and 1997: S. Allerton, L. Balin, G. Bodner,

M. Connolly, C. Mandras, and B. Rasch. We also thank

Earthwatch International for supplying us with a volunteer workforce in 1997.

References _____________________

Cohen, D.R., R.D. Ohmart, and B.W. Anderson. 1978. Avian population responses to saltcedar along the lower Colorado river.

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Crawford, C.S., A.C. Cully, R. Leutheuser, M.S. Sifuentes, L.H.

White, and J.P. Wilber. 1993. Middle Rio Grande ecosystems:

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Hutto, R.L. 1985b. Seasonal changes in the habitat distribution of

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arthropods, and birds of the Rio Grande. In D.M. Finch and J.A.

Tainter, technical eds., Ecology, Diversity, and Sustainability of

the Middle Rio Grande Basin. USDA Forest Service General

Technical Report 268:133-164.

Kelly, J.K., D.M. Finch, and M.D. Means. 1997. Annual report on

bird migration along the low flow conveyance channel in the

Bosque del Apache NWR. Prepared for: The Bureau of Reclamation and The Bosque del Apach NWR.

Mund-Meyerson, M.J. 1998. Arthropod abundance and composition

on native vs. exotic vegetation in the Middle Rio Grande riparian

forest as related to avian foraging. Master’s Thesis. Department

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coast barrier island by spring trans-Gulf migrants. Wilson Bulletin 102: 487-500.

Moore, F.R., S.A. Gauthreaux, P. Kerlinger, and T.R. Simons. 1995.

Habitat requirements during migration: important link in conservation. In T.E. Martin and D.M. Finch, eds., Ecology and

Management of Neotropical Migratory Birds: a synthesis and

review of critical issues. Oxford Univ. Press.

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avifauna of western riparian habitats. Studies in Avian Biology

15:273-285.

Raley, C.M. and S.H. Anderson. 1990. Availability and use of

arthropod food resources by Wilson’s Warblers and Lincoln’s

Sparrows in southeastern Wyoming. Condor 92:141-150.

Rice, W. 1989. Analyzing tables of statistical tests. Evolution 43:

223-225.

Robinson, S.K. and R.T. Holmes. 1982. Foraging behavior of forest

birds: the relationship among search tactics, diet, and habitat

structure. Ecology 63: 1918-1931.

Robinson, S.K. and R.T. Holmes. 1984. Effect of plant species and

foliage structure on the foraging behavior of forest birds. Auk 101:

672-684.

SAS Institute. 1995. Statistical Analysis Systems, version 7. SAS

Institute Inc. Cary, North Carolina.

SPSS Inc. 1994. SPSS/PC+. Marija J. Norusis/SPSS Inc. Chicago,

Illinois.

Sudbrock, A. 1993. Tamarisk Control I. Fighting back: An overview

of the invasion, and a low-impact way of fighting it. Restoration

and Management Notes 11(1): 31-34.

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Future Conditions for Southwest Riparian Ecosystems: Bringing

interests and concerns together. General Technical Report RMGTR-272. Rocky Mountain Experiment Station, Fort Collins, CO.

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222 USDA Forest Service Proceedings RMRS-P-7. 1999

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Jeffrey F. Kelly is Wildlife Biologist, Rocky Mountain Research Station,

Albuquerque, NM. Deborah M. Finch is Project Leader, Rocky Mountain

Research Station, Albuquerque, NM.

Abstract—We compared diversity, abundance and energetic condition of migrant landbirds captured in four different vegetation types

in the Bosque del Apache National Wildlife Refuge. We found lower

species diversity among migrants caught in exotic saltcedar vegetation than in native willow or cottonwood. In general, Migrants were

most abundant in agricultural edge and least abundant in cottonwood. There were no consistent patterns in energetic condition of

common species among vegetation types. Ninety percent of statistical tests for variation in mass and fat score among vegetation types

showed no significant difference. The few significant tests indicated

that (1) Chipping Sparrows caught in saltcedar tended to be in

poorer energetic condition than those caught in other vegetative

types; (2) Ruby-crowned Kinglets captured in saltcedar tended to be

in better energetic condition than those in other vegetative types; (3)

The relationship between energetic condition of Wilson’s Warbler’s

and vegetation type varied with year and season. The mixed evidence we report on the effects of exotic saltcedar on migrant birds

parallels the existing literature on this topic. It is important to

consider the configuration of vegetation types on the landscape

when evaluating the effects of saltcedar on migrant birds.

Riparian vegetation that comprises the bosque of the

Middle Rio Grande Valley is an important habitat component for both resident and migrant birds (Finch and Yong in

press, Yong and others in press). Large numbers of en-route

migrants use these riparian areas as stopover habitat and

they likely represent a critical resource for successful migration (Farley and others 1994, Wauer 1977). The bosque was

historically dominated by cottonwood-willow vegetative associations, but the abundance of these plants has been

declining due to changes in the hydrograph of the Rio

Grande and the invasion of saltcedar (Tamarisk ramosissima;

Howe and Knopf 1988). Saltcedar has become a dominant

component of lowland desert riparian communities of the

Southwest (Hunter and others 1988). In addition to the

obvious effects of saltcedar on native plant communities,

there is also concern over its effects on the quality of riparian

habitat for birds and other animals.

One of the primary concerns has been the potential loss of

biodiversity that could result if many bird species cannot

sustain themselves in saltcedar dominated habitats. For

Use of Saltcedar Vegetation by Landbirds

Migrating Through the Bosque Del Apache

National Wildlife Refuge

Jeffrey F. Kelly

Deborah M. Finch

instance, over 240 species of birds are known to breed in the

Middle Rio Grande Valley (Hink and Ohmart 1984). These

species represent a large fraction (49 percent) of the 493 bird

species that occur in New Mexico (Williams 1997). Furthermore, the concentration of endangered species in the Southwest is higher than in most other regions (Flather and others

1994, Reid 1998) and many of these species are riparian

obligates. This loss of biodiversity may also have economic

impacts. In New Mexico, 1.6 million people spent $428

million on activities associated with watching wildlife in

1996 (USDI and USDOC 1997). Bird watching and hunting

alone generated $90 million in retail sales in New Mexico in

1991 (Inter. Assoc. Fish. & Wildl. Agencies 1992). So, there

is substantial commerce that is derived from game and nongame wildlife in New Mexico. Thus, saltcedar has the potential to negatively impact both the biodiversity of New Mexico’s

fauna and the commerce that it supports.

For these reason’s, there have been a number of studies on

the effects of saltcedar on bird communities in the southwestern U.S. (Anderson and others 1977, Carothers 1974,

Ellis 1995, Hunter and others 1985, Hunter and others

1988). The majority of these studies have found mixed

results relative to the impact of saltcedar on bird communities. Interestingly, nearly all of these studies are based on

community metrics and use point counts or other visual

surveys as the primary means of assessing the response of

birds to vegetation structure. While the results we report

here are also derived from a community approach, our study

differs from previous work in that we use data from mist nets

to assess the relationship between vegetation structure and

migrant diversity, abundance, and energetic condition. We

reasoned that if saltcedar was poor migrant habitat, then we

should catch fewer total number of birds of fewer species in

this vegetation and these birds should in poorer energetic

condition than those caught in native willow (Salix spp.) and

cottonwood (Populus spp.) vegetation.

Methods _______________________

Our study area was at the north edge of the Bosque del

Apache National Wildlife Refuge (N33°48', W106°52'; hereafter Bosque del Apache). This mist-net area was chosen

because it contained a diversity of vegetation types in close

proximity. That is, all nets were within a 1 km radius circle

of the banding station. We used mist nets (12 m x 2.6 m, 30

or 36 mm mesh) to capture spring and fall migrants at the

Bosque del Apache. We placed nets in four vegetation types.

These types were: (1) cottonwood (Populus fremontii) forests

with mixed native and exotic understory (14 nets in 1996

and 7 nets in 1997); (2) saltcedar monocultures (5 nets in

1996 and 7 nets in 1997); (3) willow strips along irrigation

canals (18 nets in both years); and along an agricultural edge
USDA Forest Service Proceedings RMRS-P-7. 1999 223

(con.)

(3 nets in both years). Agricultural edge nets were located in

strips of cottonwood (2 nets) and in fourwing saltbush

(Atriplex canescens; 1 net). Nets were operated from mid

April to early June (referred to hereafter as spring) and from

early August until early November (referred to hereafter as

fall) each year. Nets were operated 5 days per week, and

were opened 15 minutes prior to sunrise for about 6 h/d

except during inclement weather. Nets were checked at 20-

30 minute intervals. Each bird captured was marked with a

uniquely numbered aluminum leg band. The mass, morphological features (for example, unflattened wing chord, tarsus, and culmen lengths) and the fat condition of each bird

were measured. Fat condition was scored on an integer scale

from zero to six (Helms and Drury 1960).

To compare the diversity of birds captured among vegetation types we used rarefaction curves (James and Rathbun

1981, Ludwig and Reynolds 1988). These curves represent

the number of species that we would expect to catch in any

sample of individuals. These expected values were generated from the relative abundance of all species in the capture

data. Comparison among rarefaction curves is limited by the

number of individuals captured in the sparest subsample

(James and Rathbun 1981). For this reason, we compared

expected number of species in samples of 100 individuals

from each vegetation type.

To compare abundance of migrants among vegetation

types we calculated capture rates as number of birds/1000

net h. A single mist net operated for 1 hour equals one net

hour. We calculated capture rates for: (1) all captures; (2) for

the 5 most common families; and (3) for seven individual

species that represented the most common families and had

relatively large numbers of captures in saltcedar. These

species were Brewer’s Sparrow (Spizella breweri), Chipping

Sparrow (Spizella passerina), Dark-eyed Junco (Junco

hyemalis), Dusky Flycatcher (Empidonax oberholseri), Ruby

Crowned Kinglet (Regulus calendula), White-crowned Sparrow (Zonotrichia leucophrys), Wilson’s Warblers (Wilsonia

pusilla). We also compare mass and fat score among vegetation types for these seven species. We used Kruskal-Wallis

tests to compare capture rates, mass, and fat scores among

vegetation types. We conducted separate tests for each year

and season.

Results ________________________

We operated mist nets for a total of 41,652 net hrs. Effort

was evenly divided between the two years; 21,082 net hrs (51

percent) in 1996 and 20,570 net hrs (49 percent) in 1997.

More effort was used to catch birds in the fall (26,023 net hrs;

63 percent) than in the spring (15,629 net hrs; 37 percent).

We captured a total of 5,466 birds in the two years. Unlike

our effort, these captures were not evenly divided between

the two years. Many more birds were captured in 1996

(3,732 individuals; 68 percent) than in 1997 (1,734 individuals, 32 percent). While we also captured more individuals in

the fall (3,184 individuals; 58 percent) than in the spring

(2,282 individuals; 42 percent), this pattern parallels the

difference in effort between the seasons.

We captured individuals of 118 species that represented 25 families (table 1). Five families accounted for 80

percent of captures. These were: Warblers (Parulidae; 2,234

Table 1—Number of captures for 118 species of birds mist-netted at the Bosque del Apache during 1996 and 1997.

1996 1997

Common name Scientific name Spring Fall Total Spring Fall Total Grand total

HAWKS

Northern Harrier Circus cyaneus 0 1 0 0 00 1

Sharp-shinned Hawk Accipiter striatus 0 0 0 1 01 1

Coopers Hawk Accipiter cooperii 0 1 1 0 00 1

DOVES

Mourning Dove Zenaida macroura 0 0 0 1 34 4

White-winged Dove Zenaida asiatica 0 0 0 1 01 1

Common Ground Dove Columbina passerina 0 0 0 1 01 1

CUCKOOS

Greater Roadrunner Geococcyx californianus 0 1 1 2 13 4

Yellow-billed Cuckoo Coccyzus americanus 2 2 4 0 22 6

HUMMINGBIRDS*

Black-chinned Hummingbird Archilochus alexandri 42 10 52 67 27 94 146

Calliope Hummingbird Stellula calliope 0 0 0 0 11 1

Broad-tailed Hummingbird Selasphorus platycercus 5 1 6 2 02 8

Rufous Hummingbird Selasphorus rufus 0 6 6 0 33 9

KINGFISHERS

Belted Kingfisher Ceryle alcyon 0 0 0 0 22 2

WOODPECKERS

Hairy Woodpecker Picoides villosus 1 0 1 1 01 2

Downy woodpecker Picoides pubescens 0 0 0 0 11 1

Ladder-backed Woodpecker Picoides scalaris 0 0 0 1 01 1

Red-naped Sapsucker Sphyrapicus nuchalis 0 2 2 0 11 3

Williamson’s Sapsucker Sphyrapicus thyroideus 0 1 1 0 00 1

Northern Flicker Colaptes auratus 0 4 4 0 22 6
224 USDA Forest Service Proceedings RMRS-P-7. 1999

FLYCATCHERS

Western Kingbird Tyrannus verticalis 0 1 1 1 12 3

Brown-crested Flycatcher Myiarchus tyrannulus 0 1 1 0 00 1

Ash-throated Flycatcher Myiarchus cinerascens 13 0 13 12 0 12 25

Say’s Pheobe Sayornis saya 1 1 2 0 00 2

Black Pheobe Sayornis nigricans 8 1 9 9 2 11 20

Western Wood-pewee Contopus sordidulus 20 20 40 7 3 10 50

Western Flycatcher Empidonax difficilis 5 10 15 1 4 5 20

Willow Flycatcher Empidonax traillii 27 23 50 29 12 41 91

Hammond’s Flycatcher Enpidonax hammondii 9 5 14 0 0 0 14

Dusky Flycatcher Empidonax oberholseri 102 21 123 31 7 38 161

Gray Flaycatcher Empidonax wrightii 10 2 12 1 2 3 15

VIREOS

Red-eyed Vireo Vireo olivaceus 1 0 1 0 00 1

Warbling Vireo Vireo gilvus 45 46 91 12 18 30 121

Yellow-throated Vireo Vireo flavifrons 1 0 1 0 00 1

Solitary Vireo Vireo solitarius 13 5 18 2 1 3 21

Gray Vireo Vireo vicinior 1 0 1 0 00 1

JAYS

Western Scrub Jay Aphelocoma californica 0 0 0 0 11 1

SWALLOWS

Barn Swallow Hirundo rustica 7 5 12 4 2 6 18

Northern Rough-winged Swallow Stelgidopteryx serripennis 3 0 3 6 06 9

CHICKADEES

Mountain Chickadee Poecile gambeli 1 1 2 0 00 2

VERDINS

Verdin Auriparus flaviceps 0 2 2 0 00 2

BUSHTITS

Common Bushtit Psaltriparus minimus 0 1 1 0 19 19 20

NUTHATCHES

White-breasted Nuthatch Sitta carolinensis 1 0 1 0 00 1

Red-breasted Nuthatch Sitta canadensis 0 3 3 0 00 3

CREEPERS

Brown Creeper Certhia americana 0 11 11 0 0 0 11

WRENS

Cactus Wren Campylorhynchus brunneicapillus 0 0 0 0 01 1

Rock Wren Salpinctes obsoletus 0 1 1 0 00 1

Carolina Wren Thyrothorus ludovicianus 1 0 1 0 00 1

Bewick’s Wren Thyromanes bewickii 15 24 39 13 22 35 74

House Wren Troglodytes aedon 33 11 44 7 2 9 53

Winter Wren Troglodytes troglodytes 0 1 1 0 00 1

Marsh Wren Cistothorus palustris 1 2 3 0 00 3

GNATCATCHERS

Blue-gray gnatcatcher Polioptila caerulea 3 0 3 2 02 5

THRUSHES

Townsend’s Solitaire Myadestes townsendi 1 1 2 1 01 3

Swainson’s Thrush Catharus ustulatus 3 2 5 1 01 6

Hermit Thrush Catharus guttatus 15 9 24 3 1 4 28

American Robin Turdus migratorius 13 2 15 11 0 11 26

Ruby-crowned Kinglet Regulus calendula 25 132 157 30 115 145 302

MIMIC THRUSHES

Northern Mockingbird Mimus polyglottos 6 0 6 1 01 7

Gray Catbird Dumetella carolinensis 2 3 5 0 00 5

WOOD WARBLERS

Black and White Warbler Mniotilta varia 1 2 3 0 00 3

Prothonotary Warbler Protonotaria citrea 0 2 2 0 11 3

Blue-winged Warbler Vermivora pinus 1 0 1 1 01 2

Golden-winged Warbler Vermivora chrysoptera 0 0 0 2 02 2

Table 1 (Con.)

1996 1997

Common name Scientific name Spring Fall Total Spring Fall Total Grand total

(con.)
USDA Forest Service Proceedings RMRS-P-7. 1999 225

WOOD WARBLERS (Con.)

Lucy’s warbler Vermivora luciae 1 0 1 2 02 3

Virginia’s Warbler Vermivora virginiae 18 34 52 5 12 17 69

Nashville Warbler Vermivora ruficapilla 3 0 3 0 11 4

Orange-crowned Warbler Vermivora celata 32 37 69 10 30 40 109

Yellow Warbler Dendroica petechia 44 77 121 48 34 82 203

Black-throated Blue Warbler Dendroica caerulescens 0 1 1 0 00 1

Yellow-rumped Warbler Dendroica coronata 53 39 92 9 7 16 108

Magnolia Warbler Dendroica magnolia 2 0 2 0 00 2

Chestnut-sided Warbler Dendroica pensylvanica 2 0 2 0 00 2

Bay-breasted Warbler Dendroica castanea 0 0 0 1 01 1

Black-throated Gray Warbler Dendroica nigrescens 1 0 1 0 11 2

Townsend’s Warbler Dendroica townsendi 2 1 3 0 22 5

Prairie Warbler Dendroica discolor 1 0 1 0 00 1

Ovenbird Seiurus motacilla 4 0 4 0 00 4

Northern Waterthrush Seiurus noveboracensis 0 8 8 0 4 4 12

Kentucky Warbler Oporornis formosus 1 0 1 0 00 1

MacGillivray’s Warbler Opornis tolmiei 234 62 296 30 41 71 367

Common Yellowthroat Geothylpis trichas 63 19 82 45 21 66 148

Yellow-breasted Chat Icteria virens 26 4 30 10 8 18 48

Hooded Warbler Wilsonia citrina 2 0 2 0 00 2

Wilson’s Warbler Wilsonia pusilla 348 380 728 124 294 418 1146

Canada Warbler Wilsonia canadensis 1 0 1 0 00 1

American Redstart Setophaga ruticilla 1 1 2 1 12 4

TANAGERS

Western Tanager Piranga ludoviciana 4 31 35 2 3 5 40

Hepatic Tanager Piranga flava 0 2 2 0 00 2

Summer Tanager Piranga rubra 13 37 50 6 10 16 66

SPARROWS

Vesper Sparrow Pooecetes gramineus 2 1 3 1 23 6

Savannah Sparrow Passerculus sandwichensis 0 4 4 1 8 9 13

Lark Sparrow Chondestes grammacus 4 7 11 0 8 8 19

Harris’ Sparrow Zonotrichia querula 0 0 0 1 01 1

White-crowned Sparrow Zonotrichia leucophrys 77 211 288 132 60 192 480

White-throated Sparrow Zonotrichia albicollis 0 2 2 0 00 2

Chipping Sparrow Spizella passerina 33 265 298 9 17 26 324

Clay-colored Sparrow Spizella padilla 0 0 0 0 11 11 11

Brewer’s Sparrow Spizella breweri 57 32 79 6 33 39 118

Dark-eyed Junco Junco hyemalis 40 133 173 9 29 38 211

Black-throated Sparrow Amphispiza bilineata 1 0 1 0 11 2

Sage Sparrow Amphispiza belli 0 0 0 0 11 1

Song Sparrow Melospiza melodia 3 115 118 2 28 30 148

Lincoln’s Sparrow Melospiza lincolnii 14 125 139 4 34 38 177

Swamp Sparrow Melospiza georgiana 0 1 1 0 00 1

Fox Sparrow Passerella iliaca 0 2 2 0 00 2

Spotted Towhee Pipilo maculatus 22 37 59 10 19 29 98

Green-tailed Towhee Pipilo chlorurus 18 12 30 6 8 14 44

Canyon Towhee Pipilo fuscus 1 0 1 0 11 2

GROSBEAKS & BUNTINGS

Pyrrhuloxia Cardinalis sinuatus 0 1 1 0 00 1

Black-headed Grosbeak Pheucticus melanocephalus 31 25 56 25 3 28 84

Blue Grosbeak Guiraca caerulea 25 61 86 14 76 90 176

Indigo Bunting Passerina cyanea 7 4 11 8 7 15 26

Lazuli Bunting Passerina amoena 5 31 36 2 11 13 49

Painted Bunting Passerina ciris 0 2 2 0 00 2

BLACKBIRDS

Brown-headed Cowbird Molothurus ater 8 0 8 21 0 21 29

Red-winged Blackbird Agelaius phoeniceus 1 2 3 0 22 5

Northern Oriole Icterus galbula 5 3 8 3 0 3 11

Common Grackel Quiscalus quiscala 0 0 0 1 01 1

Great-tailed Grackel Quiscalus mexicanus 0 0 0 3 03 3

FINCHES

House Finch Carpodacus mexicanus 15 1 16 7 1 8 24

American Goldfich Carduelis tristis 2 1 3 1 01 4

Lesser Goldfinch Carduelis psaltria 6 12 18 0 2 2 20

*Note that hummingbirds were not banded, So some of the captured birds may be repeats.

Table 1 (Con.)

1996 1997

Common name Scientific name Spring Fall Total Spring Fall Total Grand total
226 USDA Forest Service Proceedings RMRS-P-7. 1999

individuals; 41 percent), Sparrows (Emberizidae; 1,572 individuals; 29 percent of all captures), Flycatchers (Tyrannidae;

399 individuals: 7 percent), Thrushes (Turdidae; 368 individuals; 7 percent), and Grosbeaks (331 individuals; 6 percent). The remaining 20 families accounted for only 20

percent of all captures (562 individuals). We caught >200

individuals of seven species: Wilson’s Warbler, MacGillivray’s

Warbler (Oporornis philadelphia), Yellow Warbler

(Dendroica petechia), White-crowned Sparrow, Chipping

Sparrow, Dark-eyed Junco, and Ruby Crowned Kinglet.

Rarefaction curves indicate that the diversity of migrants

captured in saltcedar was lower than that captured in native

cottonwood and willow in 3 of the 4 seasons examined (fig. 1);

the exception was spring 1997. There was also a tendency for

diversity of birds captured to be lower in agriculture edge

than in native bosque vegetation.

Capture rates were higher in all vegetation types during

1996 than in 1997 (fig. 2) There was significant variation in

capture rates among vegetation types in spring (χ2 = 27.8,

df = 3, p<0.001) and fall (χ2 = 6.3, df = 3, p<0.1) of 1996 and

in fall 1997 (χ2 = 6.9, df = 3, p<0.08), but this variation was

not significant in spring 1997. Cottonwood had the lowest

capture rate in both seasons of both years and saltcedar had

the second lowest capture rate in both seasons of 1997 and

Figure 1—Rarefaction curves that describe how many migrating bird species we would expect to capture

in a sample of individuals from vegetation types at the Bosque del Apache. The letters to the right of the

curves indicate vegetation types (AG = agricultural edge, CO = cottonwood, SC = saltcedar, WI = willow).

These curves indicate that diversity of migrants in saltcedar was generally lower than in willow or

cottonwood habitat. Spring 1997 is the exception to this generality.

spring of 1996. Agricultural edge had the highest capture

rates in both seasons of 1997 and in the fall of 1996.

Significant variation in capture rates among vegetation

types was also evident in some of the common families in

some seasons (table 2).

Of the seven species examined, six showed significant

variation in abundance among vegetation types in at least

one sampling period (table 3). All four sparrows showed

significant variation in capture rates in spring and fall 1996,

but the only significant pattern among these species in 1997

was for Dark-eyed Juncos in the fall. Chipping, Whitecrowned, and Brewer’s sparrows tended to be most abundant in the agricultural edge and least abundant in the

cottonwood. Dark-eyed Juncos differed from the other sparrows by being most abundant in cottonwood and saltcedar.

Wilson’s Warblers tended to be most abundant in willow, but

were also abundant in the agricultural edge in 1996 and in

saltcedar in both falls. While, Ruby-crowned Kinglets tended

to be most common in willow, there was no significant

variation in their abundance among vegetation types in any

season. Finally, Dusky Flycatchers tended to be most abundant in saltcedar, followed by willow (3 of 4 seasons). However, significant variation in capture rates of Dusky Flycatchers among vegetation types was evident only in spring
USDA Forest Service Proceedings RMRS-P-7. 1999 227

Figure 2—Capture rates/1000 net hours for en-route migrants in vegetation types at the Bosque del Apache.

Vegetation types were agricultural edge (AG), cottonwood (CO), saltcedar (SC), and willow (WI). Note that (1) capture

rates were higher in 1996 than in 1997; (2) agricultural edge tends to have the highest capture rates; and (3) cottonwood

tends to have the lowest capture rates.

Table 2—Vegetation specific capture rates ( x ± SD) for the five most common families of migrants

in the Bosque del Apache of the Middle Rio Grande Valley. Differences among

vegetation types were assessed with Kruskal-Wallis tests. Lines that are in boldface

type had significant variation in capture rates among habitats.

Vegetation type

Family Year Season AG CO SC WI

Flycatcher 1996 Spring*** 2.4 ± 0.7 0.9 ± 1.0 2.3 ± 0.5 4.0 ± 2.3

Fall 0.8 ± 0.6 0.6 ± 0.4 1.2 ± 0.6 0.5 ± 0.5

1997 Spring 0.7 ± 0.6 1.1 ± 0.7 1.9 ± 1.5 0.9 ± 0.8

Fall 0.2 ± 0.3 0.2 ± 0.3 0.2 ± 0.2 0.7 ± 0.6

Thrush 1996 Spring 1.0 ± 0.9 0.9 ± 0.7 0.3 ± 0.3 0.6 ± 0.7

Fall 1.2 ± 0.5 0.8 ± 0.6 0.9 ± 0.4 1.5 ± 1.5

1997 Spring 1.4 ± 2.4 0.5 ± 0.5 0.4 ± 0.5 0.6 ± 1.0

Fall 0.3 ± 0.3 0.5 ± 0.6 1.3 ± 0.9 1.0 ± 1.3

Warbler 1996 Spring*** 9.9 ± 6.5 2.5 ± 2.0 3.3 ± 0.4 20.0 ± 17.0

Fall 10.0 ± 13.0 3.8 ± 2.6 2.8 ± 2.4 5.9 ± 4.6

1997 Spring 2.0 ± 3.0 2.5 ± 3.2 2.4 ± 1.9 4.8 ± 5.9

Fall* 1.1 ± 0.5 0.7 ± 1.1 3.5 ± 3.3 5.1 ± 5.7

Sparrow 1996 Spring*** 8.7 ± 3.4 1.2 ± 1.1 2.5 ± 1.2 4.8 ± 3.2

Fall** 20.1 ± 17.8 2.3 ± 3.1 14.7 ± 4.5 5.7 ± 6.9

1997 Spring 5.0 ± 4.3 1.5 ± 1.5 2.0 ± 1.5 1.3 ± 1.5

Fall 6.1 ± 9.5 0.6 ± 0.5 2.1 ± 0.7 2.0 ± 1.7

Grosbeak 1996 Spring*** 1.8 ± 0.8 0.3 ± 0.3 0.1 ± 0.3 1.6 ± 1.8

Fall 4.8 ± 4.0 0.8 ± 0.9 0.4 ± 0.6 0.5 ± 0.9

1997 Spring 0.2 ± 0.3 0.6 ± 0.3 0.5 ± 0.5 0.7 ± 0.8

Fall* 3.1 ± 3.0 0.4 ± 0.4 0.1 ± 0.2 0.8 ± 1.1

* indicates P < 0.05; ** P < 0.01; ***P < 0.001
228 USDA Forest Service Proceedings RMRS-P-7. 1999

of 1996 when this species was most abundant in willow. It

appears that differences in abundance among vegetation

types were more evident in 1996 when most species were

more abundant than in 1997.

We conducted a total of 80 Kruskal-Wallis tests to detect

variation in mass and fat score among the seven common

species; 40 test for variation in fat and 40 tests for variation

in mass. Of these 80 tests, eight showed significant variation

among vegetation types (two for variation in mass and six for

variation in fat; table 4). In three of the eight significant

tests, after-hatch-year Chipping Sparrows caught in saltcedar had lower mass or fat score than those caught in other

vegetation types. This relatively strong indication that

saltcedar was associated with poor Chipping Sparrow habitat was not evident in other species. The only other indication that saltcedar might be poor quality vegetation for

migrants was that after-hatch year male Wilson’s Warblers

caught in saltcedar in Spring 1996 had lower fat scores than

those caught in other vegetation types. This pattern is

interesting because in the following year after-hatch year

male Wilson’s Warblers caught in saltcedar had higher fat

scores that those caught in other vegetation types. Overall

there were three instances in which birds caught in saltcedar had higher fat scores than those captured in other

vegetation types (two in Wilson’s Warbler and one in Rubycrowned Kinglets). Three of the seven species tested showed

no significant variation in mass or fat score among vegetation types in either year or season.

Discussion _____________________

In general, migrants were more abundant in 1996 than in

1997. This pattern seems difficult to explain on the basis of

changes in local habitat condition. That is, there was little

change in the vegetation in our net area between years.

There was a substantial fire in the Bosque del Apache NWR

in 1996 that burned bosque habitats south of our netting

area. It is possible that the loss of these nearby habitats

affected captures in our net area, but we have no direct

evidence of this effect. In addition, capture rates in 1997

were similar to those from 1994 and 1995 in this same area

(D.M. Finch unpub data), which suggest that unusually high

capture rates in 1996 are the phenomenon that requires

explanation rather than the low capture rates of 1997.

Any likely explanation for annual variation in capture

rates would have to include large scale weather patterns

that affect both the condition of stopover habitats locally and

regionally and the ability of migrants to get to those sites.

Table 3—Mean captures per 1000 net-h (SD) by vegetation type for 7 species of landbirds that migrate through the Middle Rio Grande.

Kruskal-Wallis tests were used to examine differences among vegetation types.

Vegetation type

Species Year Season Ag. Edge Cottonwood Saltcedar Willow P<

Sparrows

Chipping Sparrow 1996 Spring 5.9 (6.0) 0.9 (2.5) 3.2 (4.8) 7.9 (7.5) 0.02

Fall 71.2 (84.9) 5.7 (13.7) 71.5 (34.1) 7.8 (12.2) 0.01

1997 Spring 1.5 (2.7) 0.6 (1.7) 1.3 (3.4) 1.3 (3.1) 0.95

Fall 1.8 (3.1) 0.0 (0.0) 1.9 (2.0) 1.5 (3.5) 0.20

White-crowned Sparrow 1996 Spring 32.5 (26.7) 1.9 (3.7) 0.0 (0.0) 16.3 (15.3) 0.01

Fall 41.4 (59.3) 1.1 (1.9) 23.2 (16.8) 13.9 (20.2) 0.01

1997 Spring 39.3 (34.3) 7.7 (13.0) 10.2 (9.8) 10.2 (13.4) 0.50

Fall 21.7 (35.2) 1.2 (3.1) 3.5 (2.6) 5.3 (7.7) 0.30

Brewer’s Sparrow 1996 Spring 10.3 (14.2) 1.2 (2.0) 16.3 (12.8) 8.8 (15.4) 0.05

Fall 4.0 (3.4) 0.2 (0.8) 6.5 (8.8) 2.1 (2.7) 0.05

1997 Spring 1.5 (2.6) 0.0 (0.0) 0.7 (1.8) 0.0 (0.0) 0.10

Fall 3.6 (6.3) 0.0 (0.0) 3.9 (3.4) 2.9 (4.1) 0.07

Dark-eyed Junco 1996 Spring 22.2 (19.4) 5.3 (4.9) 2.2 (4.9) 2.1 (6.5) 0.02

Fall 3.0 (3.0) 13.4 (15.2) 27.4 (15.7) 3.2 (4.3) 0.01

1997 Spring 0.0 (0.0) 3.8 (8.3) 1.3 (2.2) 0.3 (1.1) 0.35

Fall 0.9 (1.6) 2.3 (4.3) 6.5 (4.4) 0.8 (1.6) 0.01

Warblers

Wilson’s Warbler 1996 Spring 35.6 (35.6) 4.3 (10.6) 8.7 (8.3) 85.4 (105.5) 0.01

Fall 65.2 (3.0) 29.2 (23.4) 18.4 (16.7) 25.3 (23.9) 0.90

1997 Spring 4.5 (7.8) 14.2 (28.1) 12.2 (8.8) 20.1 (30.4) 0.15

Fall 5.4 (2.7) 5.0 (6.9) 25.4 (25.2) 31.6 (40.8) 0.05

Thrushes

Ruby-crowned Kinglet 1996 Spring 1.5 (2.6) 3.4 (4.3) 0.0 (0.0) 3.6 (4.7) 0.25

Fall 10.9 (6.2) 5.5 (4.8) 7.1 (3.4) 14.5 (15.2) 0.10

1997 Spring 0.0 (0.0) 3.2 (4.9) 2.5 (5.0) 5.3 (9.8) 0.35

Fall 2.7 (2.7) 5.0 (6.1) 12.3 (8.6) 9.8 (13.2) 0.15

Flycatchers

Dusky Flycatcher 1996 Spring 3.0 (2.6) 4.7 (6.2) 15.3 (7.2) 20.8 (11.3) 0.01

Fall 1.0 (1.7) 1.1 (1.5) 4.2 (3.4) 1.4 (1.9) 0.15

1997 Spring 1.5 (2.7) 3.2 (4.2) 10.3 (12.8) 2.3 (2.8) 0.40

Fall 0.0 (0.0) 0.0 (0.0) 1.2 (1.4) 0.6 (1.8) 0.15
USDA Forest Service Proceedings RMRS-P-7. 1999 229

As we expected, we found evidence that migrants were

less diverse in exotic saltcedar than in native cottonwood

and willow. This pattern appeared to be more pronounced in

1996. It is possible that the larger distinction in diversity

between saltcedar and native habitats in 1996 is related to

the occurrence of rare eastern migrants. That is, in 1996 we

captured a relatively large number of uncommon eastern

migrants and we might expect that these migrants would be

more familiar with wet deciduous habitats rather dry desert

scrub habitats. If so, the affinity of these uncommon species

for willow and cottonwood habitats could account for the

pronounced difference in diversity between saltcedar and

native vegetation types in 1996.

Contrary to our expectations, we found that migrant

abundance tended to be greatest in agricultural edge areas

and intermediate in both saltcedar and willow. Cottonwood

tended to have the lowest abundance of migrants. Variation

in abundance among vegetation types was generally greater

in 1996 than in 1997. This pronounced variation in 1996 may

have been related to the density of migrants. Increased

numbers of migrants may have increased competition for

resources and forced individuals to be more selective in the

vegetation types that they occupied.

Another consideration for comparing capture rates among

vegetation types is that our ability to sample vegetation

types is related to their morphology. Because of the short

stature of agricultural, willow, and saltcedar vegetation our

sampling of these vegetation types is fairly uniform in

contrast to cottonwood forests where our samples reflect

largely just the understory avifauna. So, variation in capture rates among habitats may reflect sampling bias as well

as the distribution of birds. In particular, the low capture

rates in cottonwoods may be a reflection of sampling bias.

Our evidence on the effects of saltcedar on energetic

condition of migrants was mixed. Chipping Sparrow energetic condition provided some evidence that saltcedar

was a component of poor stopover habitat. Other species

(Dark-eyed Juncos, Brewer’s sparrows, and Dusky Flycatchers) showed no variation among vegetation types.

Wilson’s Warbler was the only species for which evidence on

the effects of saltcedar on energetic condition was conflicted.

Finally, Ruby-crowned Kinglets provided evidence that at

some times for some species, birds caught in saltcedar

vegetation were in better energetic condition than those

caught in native vegetation.

There are several potential causes for the general lack of

consistent variation in energetic condition of migrants among

vegetation types. For instance, perhaps there is no difference in the availability of arthropod food among vegetation

types. This pattern would diminish the potential for variation in energetic condition of migrants among vegetation

types. Evidence consistent with this explanation has been

found by Mund-Meyerson and others. They found that, in

general, the arthropod fauna of cottonwood, Russian olive,

and saltcedar were similar and fairly stable during May

through August in the Bosque del Apache NWR. In contrast

to this evidence DeLay and others (this volume) show that in

our net area there was significant variation in arthropod

communities among vegetation types. Specifically there

were fewer arthropods, primarily flies (diptera), in saltcedar

than in the native vegetation types. Further, Delay and

others (this volume) provide some evidence that migrants

track the abundance of arthropods through time. Even with

this evidence, however, it is difficult to link variation in total

arthropod abundance to the availability of specific species of

arthropods that comprise the diets of specific migrants.

Another difficulty in interpreting patterns in energetic

condition is the close proximity of the vegetation types to one

another. A single individual bird could readily move among

these vegetation types. Thus, a birds’ energetic condition

might reflect the quality of the entire study area (or larger

area), rather than the vegetation that it was captured in. We

have some evidence that this is not a large problem. For

instance, Yong and others (1998) show that, for Wilson’s

Table 4—Significant results of Kruskal-Wallis tests for variation in fat and mass among

vegetation types in the Bosque del Apache National Wildlife Refuge. Number of

tests conducted for each species is in parentheses following the species name. Age

categories are after-hatch year (AHY), hatch-year (HY), and Unknown (UNK).

P-valuesa

Species Season Year Age Sex Fat Mass

Sparrows

Chipping Sparrow (8) Spring 1996 AHY UNK NS 0.05*

Fall 1996 AHY UNK 0.01* 0.03*

White-crowned Sparrow (12) Spring 1997 AHY UNK 0.04 NS

Brewer’s Sparrow (4) — — — — — —

Dark-eyed Junco (8) — — — — — —

Warblers

Wilson’s Warbler (32) Spring 1996 AHY Male 0.02+ NS

Spring 1997 AHY Male 0.03* NS

Fall 1996 HY Female 0.01+ NS

Thrushes

Ruby-crowned Kinglet (12) Fall 1996 UNK Female 0.01+ NS

Flycatchers

Dusky Flycatcher (4) — — — — — —

a

Asterisks indicate where birds caught in saltcedar habitat had the lowest mass/fat score and Plus signs

indicate where birds caught in saltcedar had the highest mass/fat score.
230 USDA Forest Service Proceedings RMRS-P-7. 1999

Warblers in spring, 88 percent of recaptures occur in the

same vegetation type where the original captured occurred;

this pattern was weaker (53 percent) in the fall. Nonetheless, it is important to recognize that individuals captures in

a particular vegetation type might not depend solely on that

vegetation. For these same reasons, any negative effects

that saltcedar may have on migrants would likely be less

apparent when it is part of a mosaic of different vegetation

types.

In summary, we found evidence that saltcedar contained

a lower diversity of migrants, but that overall bird abundance in saltcedar was intermediate among other vegetation

types. Evidence on the effects of saltcedar on mass and fat

score of migrants was mixed. The mixed nature of our results

is similar to those of other studies done on the effects of

saltcedar on bird communities. An important consideration

in interpreting these results is the configuration of the

vegetation types on the landscape.

Acknowledgments ______________

We thank the Bosque del Apache National Wildlife Refuges, particularly John Taylor and Phil Norton. M. D. Means

provided masterful database management and technical

support. For field work we thank S.E. Allerton, G.R. Bodner,

D.L. Hawksworth, M. D. Means, B.R. Rasch and H. Walker.

References _____________________

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along the middle Rio Grande, New Mexico. Conservation Biology

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economic contributions of bird and waterfowl recreation in the

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USDA Forest Service Proceedings RMRS-P-7. 1999 231

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Bob Calamusso is Fisheries Biologist and John N. Rinne is Fisheries

Research Biologist, Rocky Mountain Research Station, U.S. Department of

Agriculture, Forest Service, Flagstaff, AZ.

Abstract—Between 1994 and 1997, research was conducted on

three native, montane species of the Middle Rio Grande Ecosystem,

in the Carson and Santa Fe national forests. The focus of study was

on abiotic and biotic factors that affected status, distribution,

biology and habitat of these species. Results of study suggest

negative interactions with non-native species and, secondarily,

habitat loss as the main factors contributing to the decline of these

three native species. An inverse relationship in relative abundance

between Rio Grande cutthroat trout and brown trout, extirpation of

Rio Grande sucker when in sympatry with white sucker, and

predation experiments documenting brown trout as efficient predators of juveniles of all three species, document both the real and

potential impact of non-native species.

To sustain the Rio Grande cutthroat trout (Oncorhynchus clarki

virginalis), and the Rio Grande sucker (Catostomus plebeius) and

chub (Gila pandora) we must 1) protect stocks of native fishes with

barriers to migration of non-native fishes, 2) renovate and restock

streams with native fish assemblages, and 3) conduct management

strategies on a watershed scale to facilitate inter-mixing of populations and subsequent gene flow, and enhance the degree of security

of populations in the presence of stochastic natural disasters.

When the first Europeans arrived (ca. 1540) in what is now

New Mexico, 27 native fish species were believed to be in

existence in the Rio Grande basin. Of these 27 species, 13

have been extirpated in all or portions of this drainage

(Sublette and others 1990). For the area known as the

Middle Rio Grande Ecosystem (MRGES) Sublette and others (1990) recognize 21 native species present, whereas

Rinne and Platania (1995) recognize 17 as native and Smith

and Miller (1986) recognize only 16. All of these authors

recognize 6 species as endemic. Human influences since this

historic period have dramatically changed the palette of our

native Rio Grande fish fauna. Presently, there are 43-45

species extant in the Middle Rio Grande Basin (10 native, 28

non-native) and though 10 native species still persist, their

range and numbers have been much reduced (Rinne and

Platania 1995).

Native Montane Fishes of the Middle

Rio Grande Ecosystem: Status, Threats,

and Conservation

Bob Calamusso

John N. Rinne

Although loss of native fish species has been more pronounced in the lower elevation tributaries and the Rio

Grande mainstream, decrease in the ranges and abundance

of native species also has occurred in upper elevation,

montane areas of the MRGES. For example, Rio Grande

cutthroat trout (RGCT), Oncorhynchus clarki virginalis,

now occupies only 9 percent of its historic range in the Rio

Grande basin (Stumpff and Cooper 1996). Rio Grande sucker

(RGS), Catostomus plebeius, is listed as endangered by the

state of Colorado and is declining in New Mexico in the

northern portion of its range (Calamusso 1992; Langlois and

others 1994). Although Rio Grande Chub (RGC), Gila

pandora, are yet widespread and abundant in the New

Mexico portion of its historic range, the species is becoming

reduced in range and numbers in the Colorado portion

(Zuckerman and Langlois 1990). Numerous factors have

been hypothesized as causing the decline of the three native

upland, Rio Grande species, the major factors being the

introduction of non-native species and habitat loss.

The primary objective of this paper is to present an

overview of the status, threats and conservation strategies

for three native, montane species based on research funded

by the MRGES program and conducted in the Carson (CNF)

and Santa Fe (SFNF) national forests located in northcentral New Mexico (fig. 1). The first five years of research

will not be finalized until autumn 1998. More detailed and

specific results of research on abiotic and biotic factors

affecting the three native species, that cannot be addressed

in this outlet, will be reported in the future. Accordingly,

initial results of research are used to document and support

recommendations.

Status _________________________

Rio Grande Cutthroat Trout

The Rio Grande cutthroat trout is one of two salmonids

native to New Mexico and one of four salmonids native to

Colorado (Sublette and others 1990; Alves 1998). It is a

member of the inland cutthroat trouts (Behnke 1991), and is

the southern most occurring of the group. While the historic

range of the RGCT is not definitely known, it is likely that

the species occupied all waters capable of supporting trout

in the Rio Grande drainage and the headwaters of the

Canadian and Pecos River drainages of New Mexico and

south-central Colorado (Sublette and others 1990). Stumpff

and Cooper (1996) speculate that this distribution may

have covered approximately 40 hydrologic sub-basins in

Colorado and New Mexico and may have extended as far
232 USDA Forest Service Proceedings RMRS-P-7. 1999

south as Mexico (Behnke 1992). Ninety-two populations of

genetically pure RGCT exist today, 53 in New Mexico and

39 in Colorado. Most of these populations are found within

United States Forest Service (USFS) lands. In New Mexico,

the RGCT occupies only 9 percent of its former range

(Stumpff and Cooper 1996). Most streams inhabited by

RGCT are small, low productivity headwater streams where

space and resources are limited. Gene flow among these

disjunct and isolated populations is almost non-existent.

Currently, only 47 populations of pure RGCT remain in

the Upper Rio Grande Ecosystem (URGES) and MGRES of

Figure 1—Study area including the current distribution of Rio Grande cutthroat trout relative to brown trout

and the distribution of Rio Grande sucker and chub in the Rio Grande drainage of the Carson and Santa

Fe National Forests, New Mexico as of January 20, 1998.

New Mexico (fig. 1). All are listed as “at risk/stable” by the

New Mexico Department of Game and Fish (NMDGF). Nine

additional populations pure and putative RGCT, representing a 19 percent increase in known populations, were identified by our surveys from 1994-1997 (table 1).

In response to the decline in RGCT stocks, the subspecies

has been classified by the Colorado Division of Wildlife

(CDOW) as a “species of special concern”, and by the NMDGF

as diminishing— “A species that is absent from significant

portions of its historic range, yet self-sustaining populations

exist.” The USFS classifies the subspecies as a sensitive
USDA Forest Service Proceedings RMRS-P-7. 1999 233

species (Rinne and Medina 1996)—”A species that is in

jeopardy of becoming threatened with extinction.” In

1989, the RGCT was listed in a federal “notice of review”

as a “category C” subspecies—“taxa that are now considered

to be more abundant and/or widespread than previously

thought.” (Williams and others 1989). It currently is under

consideration for listing as a threatened species.

Rio Grande Sucker

The Rio Grande sucker, an obligate riverine fish, was once

common in the Rio Grande and its tributaries from southern

Colorado to southern New Mexico (Cope and Yarrow 1875;

Ellis 1914; Minckley 1980; Koster 1957, Zuckerman and

Langlois 1990; Sublette and others 1990). At present, RGS

are extant in the Rio Grande, primarily north of the 36th

parallel and its tributaries primarily north of the of the 33rd

parallel (Sublette and others 1990; Calamusso, unpublished

data). Populations of this small mountain sucker have declined throughout the MRGES (Calamusso 1992; Calamusso

and Rinne 1996) and are listed by the CDOW as endangered

in the URGES of Colorado (Langlois and others 1994). After

sampling over 250 streams in the early 1990’s, Zuckerman

and Langlois (1990) reported only two locations for RGS in

the URGES. Since that time one of these populations has

been extirpated and one persists (Hot Creek). Recently, the

CDOW has restored two streams for RGS (Kelly 1997). The

decline in RGS stocks have been attributed to the introduction and expansion of non-native white sucker, Catostomus

commersoni, however, empirical data which identifies the

competitive advantages of white sucker are needed to support this hypothesis.

Stream surveys conducted by the CNF and USFS Rocky

Mountain Research Station (RMRS) (1992-1997) identified

a total of 14 populations of RGS in the study area. Three

streams on the CNF and eleven streams on the SFNF

contain the native sucker (fig. 1). Surveys of streams which

were determined to have suitable RGS habitat on the SFNF

(Jemez Drainage) revealed robust populations of RGS.

Streams on the SFNF draining into the Chama River were

found to have populations of pure RGS or RGS in sympatry

with white sucker. Only three populations of RGS were

found on CNF where 5 populations once were known to exist.

Many Rio Grande tributaries draining the CNF and adjacent lands exhibited habitat characteristics suitable for RGS

but did not contain the species. These tributaries now are

inhabited by the white sucker. In contrast to the CNF,

Table 1—New distributions for Rio Grande cutthroat trout, CNF and

SFNF, 1994-1998.

Stream UTM Elevation (m)

American Creek 338460E,3984710N 2,500

Canada de Osha 446050E,4002240N 2,400

Comales Creek 447750E,4001190N 2,583

Agua Piedras 452640E,3998770N 2,583

Rio de las Trampas 429450E,4001150N 2,209

Rio San Leanardo 439360E,3988900N 2,720

Rito de las Palomas 338260E, 3984350N 2,488

Italianos Creek 455620E, 4048670N 2,652

Yerba Creek 453430E,4046970N 2,497

streams in the Jemez drainage of the SFNF do not contain

white sucker due to the barrier to migrating non-native

fishes from the Rio Grande mainstem created by the Jemez

Canyon dam. Similar to RGCT, populations of RGS are often

fragmented which limits genetic exchange among populations. Based upon the endangered status of RGS in Colorado

and its decline on the CNF we consider the RGS as “imperiled” in the northern portion of its range.

Rio Grande Chub

Inhabiting both riverine and lacustrine habitats, the endemic Rio Grande chub is widely distributed throughout the

MRGES and URGES. It is found in the Rio Grande and its

tributaries primarily north of the 33rd parallel (Sublette

and others 1990; Calamusso, unpublished data). Declines

for this species have been greater in the URGES than the

MRGES (Zuckerman and Langlois 1990).

RGC were found in 17 streams in the study area; 9 on the

CNF and 8 on the SFNF and were found at all historic

locations. Elevations in these streams ranged from 1,717 to

2,810 meters. RGC were commonly sampled in streams

exhibiting habitat characteristics that are preferred by the

native chub (fig. 1). In contrast to both the RGS and RGCT,

gene flow among chub populations is fluid. The status of the

RGC is listed as stable and reproducing for New Mexico

(Sublette and others 1990; Calamusso and Rinne 1996).

Co-occurrence of Native Fishes

Co-occurrence of two or more of the native species was

documented in only 10 streams within the study area

(table 2). Streams exhibiting co-occurrence for all three

native species was greatest in the Jemez drainage of the

SFNF and lowest on the CNF. RGC and RGS were found in

sympatry at lower elevations, whereas RGCT and RGS were

found in sympatry at higher elevations. When RGCT were

found occurring with the native cypriniforms their numbers

were very low due to an abundance of non-native salmonids

present in the lower elevation reaches. The low number of

streams (n=3) exhibiting co-occurrence of all three of the

formerly sympatric species reflects the degree of fragmentation to which the natives have been subjected.

Table 2—Co-occurrence of Rio Grande cutthroat trout, sucker and/or

chub, Carson and Santa Fe National Forests, 1994.

Rio Grande Rio Grande Rio Grande

 Stream cutthroat trout sucker chub

Carson NF

Rio Tusas X X

Canjilon Creek X X

El Rito X X

Rio San Antonio X X

Rio Nutrias X X

Santa Fe NF

Rio de las Vacas X X X

Rito de las Palomas X X X

American Creek X X X

Canones Creek X X
234 USDA Forest Service Proceedings RMRS-P-7. 1999

Threats ________________________

Habitat degradation, dewatering and grazing have all

been cited as factors contributing to the decline of many

native species (Rinne and Minckley 1991). We can assume

that RGCT populations are limited due to declining habitat

conditions. Grazing studies, however, are limited for the

Southwest and none have shown a direct link to the decline

in native fishes, especially cypriniform fishes (Rinne 1988;

Rinne 1998; Rinne in press). For example, in our habitat

studies of RGS, two streams, the Rio Tusas and Rio de las

Vacas exhibited severely grazed riparian stream reaches

with a high width to depth ratio, but had the greatest

relative abundance of all streams surveyed that contained

RGS. Thriving populations of RGS and RGC have been

reported in a reach of the Rio San Jose which receives sewage

discharge from Grants, New Mexico (AquaScience 1982).

Dewatering of montane streams for irrigation and acequia

systems has and will continue to occur. We view these as

contributing-secondary factors in the reduction in range and

numbers of montane Rio Grande native fishes. Our research

indicates that the principal threat to these native fishes is

the expansion in range and numbers and continued introduction of non-native fishes.

Rio Grande Cutthroat Trout

Except for the westslope cutthroat trout, native to the

Salmon and Clearwater drainages in Idaho and to the John

Day River drainage in Oregon, interior cutthroat trout

evolved apart from rainbow, Oncorhynchus mykiss, and

redband trout, Oncorhynchus mykiss gairdneri. They lack

innate isolating mechanisms that would allow them to

coexist with those forms and with non-native trout species

(Behnke 1992). Of the 86 populations of RGCT (Grade A - F)

recognized in the study area 24 (28 percent) are considered

to be introgressed with rainbow trout genes or some form of

non-native cutthroat trout (NMDGF, Unpublished Data).

Snake River cutthroat trout, Oncorhynchus clarki subsp.

were stocked in New Mexico until the late 1980’s, whereas

rainbow trout continue to be stocked within the native range

of RGCT. In an evaluation of historic RGCT streams in

Colorado that were experiencing declines in populations, 72

percent were declining due to non-native trout, 14 percent to

failed barriers (hence invasion from non-native fishes),

whereas only 14 percent of the RGCT populations experiencing declines were attributed to poor habitat conditions

(Alves 1998). The threat of introgression by non-native

Oncorhynchus remains ever constant.

No less of a threat to the sustainability of RGCT are nonnative brown, Salmo trutta, and brook trout, Salvelinus

fontinalis. Preliminary information suggest this impact may

be great. In American Creek, Rito Cafe, and the Rio de las

Vacas there appears to be an inverse trend of density and/or

biomass between the native cutthroat and the introduced

brown trout (table 3). Of the 41 streams in the study area

draining into the Rio Grande containing pure populations of

RGCT only 13 (32 percent) are occupied solely by the cutthroat native, whereas 28 (68 percent) have brown trout cooccurring (usually in lower reaches) with RGCT. Of these 26

streams only 15 (54 percent) have pure populations of RGCT

which are protected by barriers to non-native trout.

Table 3—Relative density (D) (n/hectare) and biomass (B) (kilogram/

hectare) of Rio Grande Cutthroat trout (RGCT) and brown

trout (BT) in study reaches in American Creek and Rito Cafe,

Rio de las Vacas, Santa Fe National Forest, 1995.

RGCT BT

Study section D B D B

American Creek

1 324 9 279 22

2 702 32 0 0

3 90 6 90 13

4 488 13 195 9

5 300 9 486 12

6 89 5 714 58

7 56 5 617 46

Rito Cafe: Below Barrier

1 676 14 2801 241

2 400 15 2300 182

3 0 0 3200 144

4 0 0 3875 96

Rito Cafe: Above Barrier

5 2545 30 91 30

6 2608 36 0 0

7 1080 22 83 5

Rio de las Vacas: Below Barrier

1 0 0 318 18

2 117 2.7 233 10

3 0 0 595 60

4 156 2.4 739 43.3

5 0 0 1468 83.7

6 61 .55 1908 118.9

Rio de las Vacas: Above Barrier

1 3905 133.3 0 0

2 2827 153.7 0 0

3 3386 121.4 0 0

4 2548 121.0 0 0

Rio Grande Sucker

Little information exists on interactions of RGS with nonnative species. Zuckerman and Langlois (1990) speculated

that declines in RGS abundance in Colorado were due to

genetic swamping by white sucker. They reported capturing

hybrids of RGS and white sucker in two streams in southern

Colorado. Recent genetic studies, however, found no evidence of hybridization of RGS with white sucker (Sue Swift,

USFS, Pers. Com.) and while the mechanism of decline in

RGS populations is unknown, RGS populations have been

observed to decline across their range when in sympatry

with the non-native white sucker.

In the 1980’s five streams in the CNF were listed as

containing RGS. Our surveys found only two streams inhabited solely by RGS (Rio Tusas, Little Tusas), one stream had

white sucker in co-occurrence with the native (Rio Vallecitos),

and in two streams the native sucker had been completely

replaced by the white sucker (Rio Costilla, Rio Grande del

Rancho). Presently, a beaver dam protects the Tusas system

from intrusion by white sucker and while the Rio Tusas and

Little Tusas appear free of white sucker, the Rio Vallecitos

has white sucker established in the lower and middle reaches

(up to Canon Plaza). The absence of white sucker in the
USDA Forest Service Proceedings RMRS-P-7. 1999 235

upper reaches of the Rio Vallecitos near Hopewell Lake may

only be temporary as white sucker were found further

upstream in 1995 than in 1992. Without a physical barrier

to migration between Canon Plaza and the upper reaches,

intrusion by white sucker would seem imminent. At present,

all streams draining into the Rio Grande and Rio Chama

from the CNF have been or are susceptible to colonization by

white sucker.

Streams within the Jemez drainage (SFNF) are safe from

intrusion by the white sucker due to the migrational barrier

created by Jemez Canyon Dam. The potential for unintentional introduction of white sucker into this system could

occur from its use by fisherman as bait. White suckers have

been found in the Rio Chama and in its southern tributaries

(for example Canones Creek) originating on the SFNF.

These streams are currently vulnerable to invasion by

white sucker.

Rio Grande Chub

Probably least studied of the three native species is the Rio

Grande chub. While the RGC is considered to be common

and is abundant throughout the study area a general decline

in this native cyprinid has been observed in the URGES

(Zuckerman and Langlois 1990). RGC are capable of exploiting both lentic and lotic habitats, this may allow the RGC to

maintain its general abundance in the MRGES. Factors

such as dewatering and grazing in riparian areas may have

a negative effect on RGC populations since the species is

commonly associated with aquatic vegetation, instream

woody debris, and overhanging riparian vegetation.

Interactions of Brown Trout with

Cypriniformes

As with RGCT, brown trout have been suspected in contributing to the decline in RGS and RGC populations, although no published data existed prior to this study. To test

this predation hypothesis we used instream experimental

cages in which brown trout, RGS, and RGC were placed

together. Results from this experiment were dramatic yet

perhaps inconclusive. In the instream cages, predation on

the natives by brown trout was severe. Yet in light of these

results if one examines electrofishing data from the Rio de

las Vacas an inverse relationship between brown trout

abundance and cyprinid abundance is not evident (fig. 2). It

may be that brown trout do not extirpate these cyprinids, but

do depress the natural abundance that would occur in the

absence on the non-native predator. What the abundance of

these cyprinids would be in the presence of the native

cutthroat can only be speculated since there are so few

instances where healthy populations of RGCT, RGS, and

RGC co-occur.

In summary, our data indicates that non-native fishes are

the main vector of demise for the three native species in our

study area. Non-native salmonids can be directly linked to

the decline of RGCT stocks in the study area and throughout

its historic range. The impact of white sucker through

potential genetic swamping, aggression, or greater fecundity along with predation by brown trout may act in concert

to extirpate stocks of RGS. Habitat degradation and overall

environmental decline may play a role in the demise of

native fishes in the montane reaches of the MRGES. Declining habitat conditions may make the natives less fit to

compete with non-natives, however data is not available to

support this hypothesis. At present our ability to measure

and identify these mechanisms may be lacking.

Conservation and Management:

Current Management ____________

Rio Grande Cutthroat Trout

Management directed toward the sustainability of the

RGCT has been ongoing since the 1970’s when extensive

distributional surveys were conducted by the CDOW,

NMDGF and the USFS. The search for unknown populations of pure RGCT continues. Both the CDOW and the

NMDGF have developed and are implementing RGCT

management plans (Stumpff and Cooper 1996; Alves 1998).

To insure the persistence of existing stocks of RGCT, agencies continue to build and identify sites for migrational

barriers to non-native salmonids. In an effort to increase the

number of RGCT populations, renovation of streams for the

reintroduction of RGCT into its historic range is one of the

major management practices presently being used by both

states. Two brood stocks are maintained in Colorado, one in

Haypress Lake and the other at the Fish Research Hatchery

in Fort Collins. The NMDGF is in the process of developing

a RGCT brood stock at the Seven Springs Hatchery. The

RMRS continues to conduct research aimed at identifying

habitat variables that influence RGCT productivity, spawning success, and recruitment and is beginning to evaluate

population characteristics to develop population viability

analyses that will help predict the sustainability of specific

RGCT populations. Progress toward the goal of sustaining

RGCT stocks, however, is slow and may be losing ground.

Funding of restoration and protection programs is still a

limiting factor.

Figure 2—Relative abundance of RGS, RGC and

brown trout in the Rio de Las Vacas.
236 USDA Forest Service Proceedings RMRS-P-7. 1999

Rio Grande Sucker

In response to the decline of the RGS in the URGES the

CDOW initiated a Rio Grande Sucker Recovery Plan partially funded by Great Outdoors Colorado Lottery monies

(Kelly 1997). Population and habitat surveys were conducted in Hot Creek, the one remaining stream that contained RGS along with examining streams in New Mexico

where RGS are abundant. In 1996 the CDOW captured 200

RGS from the Rio Tusas (CNF) and released them in Medano

Creek, which flows into a closed basin where access by nonnative fishes is impossible. Prior to RGS being released in

this drainage, the CDOW had restored this stream for

RGCT. If the transplant of RGS is successful, RGC will be

transplanted into this drainage to complete the native fish

assemblage. In an effort to create a third population, 54 RGS

were transplanted from Hot Creek to San Francisco Creek,

a nearby drainage. Identification of suitable reintroduction

sites in Colorado is ongoing.

Although the RGS is in general decline in the MRGES of

New Mexico it is still considered common and is not afforded

any special protection or status by the NMDGF. We speculate, however, that there will be a further decline in RGS in

the CNF, tributaries of the Chama River (CNF, SFNF) and

in any remaining unprotected drainages emptying into the

Rio Grande drainage. Because of the threat of decline, the

RMRS continues its efforts to identify remaining populations of RGS in the MRGES and in Rio Grande tributaries of

southern New Mexico. The RMRS also has plans to develop

population viability models for RGS populations in New

Mexico.

Rio Grande Chub

Currently, RGC are not actively managed or afforded

protection in New Mexico, however, efforts are being made

in the URGES by the CDOW to restock the chub in historic

waters. The CDOW continues to search for streams where

the native fish assemblage (RGCT, RGS, RGC) can be

reintroduced. The RMRS will continue to conduct distributional and habitat surveys to further define the role of RGC

in the aquatic ecosystems of the MRGES.

Management Recommendations

and Future Conservation Goals____

To sustain the native montane fishes of the MRGES we

believe management and research should proceed by evaluating the specific requirements of each species and their

requirements in the context of the aquatic community. To

that end we suggest the following for each species and the

aquatic ichthyofuanal community:

Rio Grande Cutthroat Trout

To conserve the Rio Grande cutthroat trout resource,

managers of all agencies must have the latest information on

this cutthroat subspecies’s distribution and status. Distributional and population data for this rare southwestern

trout are dynamic. The addition of 7 new populations of

RGCT during the 1994 field season and the confirmation of

the Rito de las Palomas and American Creek as pure in 1998

suggests that despite almost two decades of effort toward

sustaining this Southwestern cutthroat subspecies, much is

yet unknown about its distribution and status. Continued

effort toward defining the distribution of this subspecies in

New Mexico and Colorado is warranted. Of primary importance is the protection of existing pure stocks of RGCT.

Placement and the maintenance of barriers to upstream

migration from non-native salmonids, though reducing gene

flow among populations, appears to be the only viable

method in light of the wide distribution of non-native salmonids in the Southwest. Accordingly, there is an urgent and

continuing need to define the extent and degree of impact of

introduced salmonids, especially brown , on RGCT. Restoration of streams will be necessary to increase the number of

pure populations in the subspecies’ former range. Hatchery

facilities need to be dedicated to the maintenance of a variety

of high quality RGCT genetic strains which can be combined

to replicate gene flow that is now not viable in nature due to

the a lack of connectivity among cutthroat populations.

Stocking of non-native trout in watersheds that contain pure

populations of RGCT must cease. All too often unknowing

fisherman inadvertently stock non-native fishes above barriers not realizing the consequence of their actions. Research

to define population dynamics (fecundity, recruitment, age

class structure, longevity) is needed to begin to develop

population viability analyses to determine the potential long

term persistence of pure populations of RGCT.

Rio Grande Sucker

Surveys to identify unknown populations of RGS need to

continue. Similar to RGCT, known populations of RGS

warrant protection from invasion by the white sucker and

non-native salmonids. Instream barriers need to be constructed for tributaries draining to the Rio Grande and

Chama River.

While streams within the Jemez drainage are currently

safe from intrusion by the white sucker due to Jemez Canyon

Dam white sucker may eventually be introduced into this

system via bait bucket. Regulations may be warranted to

limit any use of non-native bait or to prohibit the use of bait

in the Jemez system above the Jemez Canyon Dam. White

sucker have been found in the Rio Chama and in its southern

tributaries (for example Canones Creek). Here, the only way

to prevent white sucker from expanding its range into

streams containing RGS would be the placement of barriers.

Due to the precarious status of northern populations of RGS

protection of populations of RGS in isolated Rio Grande

tributaries in southern New Mexico should be considered.

Restoration efforts should identify those waters having

modest gradients (<2.5 percent) with well developed glide/

pool habitat within a mosaic of various habitat types.

Rio Grande Chub

Continued delineation of the distribution of the RGC

throughout the MRGES and its entire range is warranted.

Monitoring of RGC populations is also necessary to ensure

long-term sustainability.
USDA Forest Service Proceedings RMRS-P-7. 1999 237

Further, the recommendations suggested for the individual species should be incorporated on a watershed scale.

Management or stream renovation of isolated reaches will

not be enough to sustain the native fishes of the MRGES.

Managing on a watershed scale incorporates a greater diversity of aquatic habitats, thereby increasing ichthyofaunal

diversity. Gene flow among various stocks of native fishes is

enhanced and the effects of stochastic events is dampened.

The Rio de las Vacas (SFNF) of the Jemez River drainage is

a watershed that has the potential to be managed on this

large landscape approach. Currently, all three native species, along with the native longnose dace, Rhinichthys

cataractae, occur and are abundant in this drainage. At the

lower reaches of the Jemez River the system is protected

from intrusion from non-native fishes from the Rio Grande

by Jemez Canyon dam. A migrational barrier would have to

be constructed at the lower reaches of the Rio de las Vacas

and subsequent stream renovations would be needed to

remove non-native fishes, primarily brown and rainbow

trout. The monetary and logistical costs of this project would

be substantial, however the benefits to the sustainability of

native fishes would be great.

Conclusions____________________

To sustain native fishes of the MRGES protection of its

aquatic habitats and the resultant aquatic community should

be the primary goal of any management plan. Future management must address the threats from non-native species

identified by this research. Restoring native species to their

former range and managing aquatic communities on a

watershed scale will address the losses realized over decades

of misguided fish introductions and habitat degradation .

With additional funding and management plans incorporating these two approaches future persistence of native fishes

may be assured.

References _____________________

Alves, J. 1998. Status of Rio Grande Cutthroat trout in Colorado.

Unpublished Report of the Colorado Division of Wildlife. 10 pp.

AquaScience, Inc. 1982. Suitability of Rio San Jose water for fish.

Report No. 301-312, March 1982.

Behnke, R. J. 1992. Native trout of western North America. Amer.

Fish Soc. Monograph 6: 1-275.

Calamusso, B. 1992. Current distribution of Catostomus plebeius

and Gila pandora on the Carson National Forest, New Mexico

with preliminary comment on habitat preferences. Proc. Desert

Fishes Council 24:63-64.

Calamusso, B. and J. N. Rinne. 1996. Distribution of the Rio Grande

cutthroat trout and its co-occurrence with the Rio Grande sucker

and Rio Grande chub on the Carson and Santa Fe national

forests. pp. 157-167 In: Shaw, D. W. and D. M. Finch, (tech

coords.), Desired future conditions for Southwestern riparian

ecosystems: Bringing interests and concerns together. 1995 Sept.

18-22,1995; Albuquerque, NM. Gen. Tech. Rept. RM-GTR-272.

Fort Collins, CO: U.S. Department of Agriculture, Forest Service,

Rocky Mountain Forest and Range Experiment Station. 359 pp.

Cope, E. D. and H. C. Yarrow. 1875. Report upon the collections of

fishes made in portions of Nevada, Utah, California, Colorado,

New Mexico, and Arizona during the years 1871-1874. Chapter 6.

pp. 635-703 In: United States Army Engineers Dept. Report, in

charge of George M. Wheeler Geog. and Geol. of the Expl. and

Surveys west of 100th meridian, 5, 1-1021.

Ellis, M. M. 1914. Fishes of Colorado. Univer. Colorado Studies,

11(1): 5-135.

Kelly, Brighed. 1997. Colorado Outdoors. Sucker Saving. Jan/Feb

1997. pp. 10-14.

Koster, W. J. 1957. Guide to the fishes of New Mexico. Univ. of

New Mexico Press, Albuquerque.

Langlois, D., Alves, J., and J. Apker. 1994. Rio Grande sucker

recovery plan. Colorado Div. Wildl., Denver. 22 pp.

Minckley, W. L. 1980, Catostomus plebeius Baird and Girard, Rio

Grande sucker, p. 387. In: Lee and others (Eds.), Atlas of North

American Freshwater Fishes. North Carolina State Mus. Nat.

Hist., Raleigh.

Rinne, J. N. 1988. Grazing effects on stream habitat and fishes:

Research design considerations. N. Amer. J. Fish Manage.

8:240-247.

Rinne, J. N. 1998. Grazing and fishes in the Southwest: Confounding factors for research. In, AWRA/SRM Specialty Conference on

Rangeland and Water Resources. May 26-30, Reno, Nevada.

Rinne, J. N. In press. Fish and Grazing Relationships: Southwestern United States. In, Jamison R., Raish, C, and D. Finch (eds)

Ecological and Socioeconomic Aspects of Livestock management

in the Southwest.

Rinne, J. N. and A. L. Medina. 1996. Implications of multiple use

management strategies on native southwestern (USA) fishes, pp.

111-124. In: Meyer, R. M., C. Zhang, M. L. Windson, B. J. McCay,

L. J. Husha, and R. M. Muth (editors). Fisheries resource utilization and policy. Proc. of the World Fish. Congress, Theme 2.

Oxford & IBH Publ. Co., New Delhi, India.

Rinne, J. N. and W. L. Minckley. 1991. Native fishes of arid lands:

A dwindling resource of the desert Southwest.

Rinne, J.N. and S.L. Platania. 1995. Fish Fauna, pp. 165-175. In:

Finch, D. M. and J.A. Tainter (tech eds.) 1995. Ecology, diversity,

and sustainability of the Middle Rio Grande Basin. Gen. Tech.

Rep. RM-GTR-268. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 186 p.

Rinne, J. N. and W. L. Minckley. 1991. Native fishes of arid lands:

A dwindling resource of the desert Southwest.

Rinne, J.N. and S.L. Platania. 1995. Fish Fauna, pp. 165-175. In:

Finch, D. M. and J.A. Tainter (tech eds.) 1995. Ecology, diversity,

and sustainability of the Middle Rio Grande Basin. Gen. Tech.

Rep. RM-GTR-268. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 186 p.

Stumpff, W. K. and J. Cooper. 1996. Rio Grande Cutthroat trout,

Oncorhynchus clarki virginalis. in D.E. Duff (editor), Conservation Assessment for Inland Cutthroat Trout. USDA Forest Service, Intermountain Region, Ogden, Utah.

Sublette, J. E., M. D. Hatch, and M. Sublette. 1990. The fishes of

New Mexico. Univ. of New Mexico Press, Albuquerque.

Williams, J.E., J.E. Johnson, D.A. Hendrickson, S. ContrerasBalderas, J.D. Williams, M. Navarro-Mendoza, D. E. Mcallister

and J.E. Deacon. 1989. Fishes of North America endangered,

threatened, or of special concern: 1989. Fisheries 14(6):2-20.

Zuckerman, L. D. and D. Langlois. 1990. Status of Rio Grande

sucker and chub in Colorado. Unpublished report, Colorado Div.

Wildl., Montrose, CO. 44 pp.

Workshop Summary

USDA Forest Service Proceedings RMRS-P-7. 1999 241

In: Finch, Deborah M.; Whitney, Jeffrey C.; Kelly, Jeffrey F.; Loftin,

Samuel R. 1999. Rio Grande ecosystems: linking land, water, and people.

Toward a sustainable future for the Middle Rio Grande Basin. 1998 June 2-5;

Albuquerque, NM. Proc. RMRS-P-7. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Barbara A. Coe is a consultant with Daystar Associates, Albuquerque, NM.

Abstract—Because decisions made today about the Middle Rio

Grande will influence future conditions, symposium participants—

the stakeholders—collaborated in a final session to plan improvements for the watershed and river corridor. The result included

several action plans focusing on desired future conditions and

actions to achieve them.

How can a sustainable future for the Middle Rio Grande

Basin be achieved? What exists now that you would like to

preserve? What would you like to restore? What would you

like to get rid of or change? These are some of the questions

addressed by participants in the Workshop portion of the

Middle Rio Grande Rio Grande Ecosystems Symposium.

Decisions made in the past by many stakeholders have

produced the current state, those things that are perceived

as good or bad. Likewise, decisions made now by many

stakeholders will influence the future state. Although individuals alone cannot control everything that happens, working collaboratively toward common goals can help symposium participants move much more effectively in the desired

direction.

The final item on the agenda for the Symposium was a

process to help participants think about and plan how to

enhance the future of the Middle Rio Grande Basin. This

was intended as input to the Bosque Management Plan and

also to stimulate collaborative actions by participants, with

this session as a start at organizing those actions. The

workshop had three main purposes — to identify the desired

future of the Basin, to plan some joint actions toward

improvement of the Rio Grande watershed and river corridor, and to introduce an innovative and powerful way to

work together to achieve goals — that can be applied to any

situation.

Workshop Approach: The Path of

Least Resistance ________________

The specific process used as a framework is one designed

to use the “Path of Least Resistance” to help groups successfully achieve the goals they set. Sometimes plans get

implemented; sometimes they don’t. Many groups (and

individuals) who use this process report that it makes a

major difference in their capacity to achieve their goals.

Future of the Middle Rio Grande

Barbara A. Coe

The intended outcomes of the workshop were:

a. Improved understanding of one’s own and others’ desires for the future of the Middle Rio Grande Basin.

b. Improved understanding of the current state of the

Middle Rio Grande Basin.

c. Preliminary action plans for elements of the desired

future.

d. Introduction to an innovative but tested way to achieve

goals collaboratively.

The approach used is drawn from discoveries about the

elements of successful implementation or “the creative process” by Robert Fritz, author of The Path of Least Resistance (1989), Corporate Tides (1996), and other books and

the elements of successful collaboration by Barbara A. Coe,

author of articles in the Journal of the Community Development Society and others. It was based on extensive “grounded

theory” research — discovering the principles through observation of many cases. Fritz discovered that a foundational structure underlies and determines action, not only in

physical systems, but also action by individuals, organizations, and groups. For example, the motion of the water in

the Rio Grande is guided by such elements as the path,

depth, and slope of the riverbed, obstructions such as boulders, and barriers such as levies. The water moves along

the “path of least resistance.”

So too, individuals, organizations and groups are guided

by their structures along this path of least resistance. In the

case of organizations and multi-organizational groups or

communities such as this one, the elements of the path, or

structure, include such things as individual or organizational goals, relative power relationships, information, organizational reporting relationships, or all sorts of other things.

With individuals, the elements of the structure include

cognitive elements such as beliefs and assumptions, along

with the actual circumstances. It is necessary to look at the

specific action to know what elements are guiding it. However, once the structure is identified, actions can often be

predicted. Sometimes the path of least resistance leads to

successful implementation, sometimes not.

Events Events Events

Patterns

Structure

Oscillating or Advancing Patterns of

Action _________________________

Two structures are common: One structure leads to a

pattern of success, advancing steadily toward the goals. The

other leads to a pattern of oscillation, moving toward the

goals, then away, then toward again, sometimes over a long,
242 USDA Forest Service Proceedings RMRS-P-7. 1999

sometimes over a short, period of time. The reason for

advancement is that when the desired future state and the

current state are in disequilibrium, energy tends to be

generated between them, so that people tend to be motivated

to move toward the goals. When desires for the future are set

against a clear view of the current state, this produces a sort

of dynamic tension or “structural tension.” (Fritz, 1989).

This tension energizes groups and helps them take and

sustain the action necessary to achieve their goals. To

maintain this energy requires staying clear about the current state on an ongoing basis, as it changes, as well as

staying focused on the goal. Although conditions or events

may sometimes preclude achievement of certain goals, the

chances of success are greatly enhanced if the pattern is one

of continued advancement.

When in a structure designed to lead to oscillation, however, groups take action, such as creating a plan, and then

later find themselves in the same place again, perhaps

creating another plan because the first one was not implemented. The reason for oscillation is that the structure has

inherent contradictions among its elements, so that action

cannot be focused consistently toward the goal. As Fritz

says, “it is a design problem.” A structure can, however, be

designed and created that leads toward the goal.

An accurate assessment of the current situation is an

essential ingredient of a structure designed for successful

goal implementation, but the view of the current situation is

often distorted. Sometimes blanks are filled in when the

information is unknown; other times assumptions are made

about reality or about the future; or beliefs about how the

world works distort reality. Different people tend to see

things differently — this is known from many situations —

for example, different people witnessing an accident will

describe that accident in very different ways. Distortions of

the current situation tend to contribute to oscillation. To see

the current state clearly, groups must identify what is

factual about the current situation, relative to the desired

condition. Assumptions, beliefs, and conjectures are set

aside for the purpose of creating the desired outcome.

Goal

Goal

Advancement

Oscillation

Having the goals and the current state clearly in mind

allows for flexibility of actions. Often what will lead to the

desired future cannot be predicted at the outset. In the case

of sustainable basins, the information is not necessarily

available at the beginning. Experimentation with different

approaches may be needed before reaching the goal.

Action

Interim

Result

Feedback loop

When the interim result is observed and evaluated, actions may then be adjusted accordingly and then the new

actions monitored and evaluated to learn if they lead toward

the goals or are more efficient. This is the approach advocated in Adaptive Management.

When results, either interim results or the desired future,

have been achieved, groups find that when they acknowledge this completion and actually celebrate it in some

meaningful way, their energy for the next step or the next

project is considerably enhanced.

The process used in the workshop was designed to produce

a structure leading to advancement toward the goals for the

Rio Grande; one in which the path of least resistance leads

naturally toward plan implementation. The four primary

elements of such a structure are:

1. A clear picture of the desired future state

2. An accurate description of the current state

3. Experimental actions (or adaptive management)

4. Completion and celebration

In a situation requiring the participation of different

agencies and stakeholders, a structure designed to advance

also tends to include the elements of linking communication,

collaborative vision, and evocative leadership (1988, 1990,

and 1998).

The Process ____________________

The group gathered at about 10:30 p.m. for the workshop

to begin the work of producing a preliminary plan for the

future of the Middle Rio Grande Basin. Groundrules for

working together were suggested and agreed-upon by the

group:

Listen to learn and understand

Share the spotlight

Talk one at a time

Respect all ideas

1. Looking for Common Ground. In this process, participants looked for their “common ground” — what they

shared — regarding their desired future of the Rio Grande

Ecosystems. Participants formed into five small groups

(organized based on the animal logos on their folders) and

began to address their Desired Future Condition or Future

State of the Middle Rio Grande Basin.

They first selected a timekeeper, recorder, reporter, then

introduced themselves briefly, indicating their name, a

major activity related to the Rio Grande and a one word

descriptor of something they appreciate about the Middle

Rio Grande Basin.

They then brainstormed about the elements of the desired

future state, making sure everyone had a chance to speak,

and using the flipcharts to make the notes so as to help

everyone focus on the same thing at the same time and make

it easier to process the ideas.

The next step was to get clarification about the items when

necessary, and then to find “common ground” on five to seven

elements of the desired future upon which they agreed and

to write each on a half sheet of paper. They were cautioned

that they might identify some items upon which they didn’t

agree — but to ignore those or to put them on aside on a

disagree list.

They followed these guildelines for identifying Desired

Future Conditions:

End result, not a means

Specific enough to know it when it is achieved, not

vague
USDA Forest Service Proceedings RMRS-P-7. 1999 243

What you want, not a problem to solve or something you don’t want

Example: the Rio Grande River Basin is _ _ _ _ _

or the Rio Grande River Basin has _ _ _ _ _

The groups then reported out their desired future conditions as follows: One of the groups was asked to name one

element of their desired future conditions. Their half sheet

was placed on the wall. Other groups with that same element were asked to place theirs with the first one. The next

group was asked for the name of one of their elements and

the process was repeated until the names of all elements

were on the wall. The elements were consolidated into six

major elements which became the topics for the afternoon

work.

2. Clearly Identify the Current State. The second step

was to examine the current status of the Rio Grande Ecosystems, so as to be able to determine what the appropriate

actions would be. Given a clear picture of the baseline,

groups can devise appropriate action steps. Otherwise, actions may be taken that are unnecessary, unwise, or ineffective. Furthermore, a clear and objective view of the current

conditions is a necessary aspect of successful implementation, setting up and using the disequilibrium and “structural

tension” between the desired and current conditions to

motivate action.

To address the second step the groups were asked to “vote

with their feet,” to move to that element on which they would

like to do further work. The next step was to describe the

Current Conditions or state, that is:

What is already in place vis a vis the desired future

state — what is the baseline or current state —

• not how it got that way or

• what is next, just what is

3. Experiment with Actions and Adjust. The last part

of this process was to think of some actions to try — to

experiment with. Often action steps are set in concrete, but

another key to successfully creating the goals is to be flexible

in regard to means — similar to Adaptive Management.

Some actions are taken, then evaluated to see if they get

closer to the goal. If not, other actions are tried.

Groups were asked to think of at least 3 or 4 steps that they

considered would lead in the direction of the desired future

state. Also, they were asked, if time allowed, to write on the

chart who would need to do the action and by when. They

organized the results of their work into “structural tension

charts” to illustrate how to get from the current state to the

future state and how it sets up the energy state. Several

participants indicated the need to take action and observe

the results, adjusting as necessary as more information is

available.

4. Complete and Celebrate. An important part of creating the desired results is to acknowledge the completion,

whether of an interim step or subgoal, or of a final goal. To

complete the process, each of the groups reported out its

results to the other groups and asked for feedback and

questions. They discussed next steps followed by concluding

remarks by Jeff Whitney.

Report Out. Each group then reported on the elements of

their structural tension chart as follows:

Action Plans for Achieving a

Sustainable Middle Rio Grande

Basin _________________________

Desired Future Condition: Sustainable local economy

and agriculture and the environment and economy in dynamic equilibrium.

Actions:

• Personal choice as consumers

• Develop regulations that constrain growth based on

available water supply (determine water available for

development)

• Have more regulation on water use (i.e. watering lawns

and washing cars with potable water)

• Promote new economic paradigms (i.e. natural capitalism); destruction of environment is economically detrimental; market regulation

• Internalize environmental costs

• Shift subsidies to environmental benefits

• Need measures of economic goods and bads in terms of

ecology

• Farm days (public education)

• Reaching out to children

Current Conditions:

An artificial dichotomy between economic and ecological

health

Inadequate incentives for agricultural producers to protect

environment

Development that disregards the local environmental conditions (i.e. water/arid climate)

Current demands on water exceed supply

Inefficient/wasteful uses of water

Economy not constrained by the supply of water

Agriculture is given little value; no incentive to keep water

on the farm

Ecological values of agriculture and nature are not

recognized

Urban development is seen as economically more beneficial

than other uses of resources

Perceived economic value of using future capital today

Consuming too much

Ecological services (solar energy, etc.) highly undervalued

Desired Future Condition:

Enough water of sufficient quality to sustain human

culture and natural processes: a sustainable water

supply; good water quality; and water conservation

Actions:

• Increase hazardous waste recycling opportunities

• Extend water conservation — municipalities now

• NPO’s intensify and implement regional planning efforts — MRGCOG and local, state and federal governments, acequias, tribes, conservancy districts — via

media and schools — now

• Reduce/minimize water consumption and demand —

everyone, now
244 USDA Forest Service Proceedings RMRS-P-7. 1999

• Increase wetland development — public agencies, private landowners — now

• Implement NPDES non-pointsource program — EPA

and NWED — now

• Manage public lands for sustainable water supply —

public agencies, public water — now/5 years

• Economic incentives for turf/agricultural irrigation efficiency — State Engineer’s Office/legislature and governor — next legislative session

• Increase cost of municipal and industrial water —

adjust rate structure — public water suppliers — phased

in now

• Re-engineer Conservancy’s drainage system — Conservancy District/BOR — now

Current Conditions:

Too little processing

Too much sediment

Dependent on ground water — urban uses

Inefficient irrigation systems

Poor upland water retention

Large areas of irrigated turf

Urban run-off into Rio Grande

People think they live in Ohio not the Desert Southwest

Water Use Excessive: irrigation/sprinklers

– Flood irrigation leads to high water

– Urbanization moves water off rather than retains

– recycling/reuse minimal!

Attitudes/public awareness changing

City water conservation effort

Agriculture improvements

Intel et al., recycle/reuse

Improving technology and ongoing research

Planning and public Education initiatives

– Regional planning

– Evaluation

Desired Future Condition

An ecologically aware and informed citizenry: public

thinks like a watershed; people connected to the river

Actions:

• Getting the public out to the river with people who know

about it

(school kids, media, elected officials) — RGNC, ABQ

Open Space, Rio Grande

• Restoration, MRGCD, FWS, NM G&F, NM Forestry,

Tribes — ongoing

– special events

– restoration projects

– river institute

– mentor programs

• Take River to people: take knowledgeable people to

public forums, outreach programs

– creative advertisement

– continuing education class, UNM

– Elder Hostel — consortium of experts, TAG Team

— by year 2000

• Media/elected officials outreach — Alliance for Rio

Grande Heritage — Conservation Lobbyists — ongoing

• Foster New Partnerships among existing education and

conservation programs, including tribal— Non-government activists/interested parties, local level, grass roots

— 2000?

Current Conditions:

Disconnected from the river

– can’t see/experience river

– Insular/out of context from the whole

Urban people don’t feel an emotional attachment to the river

People don’t understand there’s a problem with the river

Ignorance about watershed — “water comes from the tap”

Take river for granted

Seeds of interest/growing awareness and fears routed in

misconception

Overwhelmed/immobilized

Confusion due to hype (El Niño)

Grass roots activity

Desired Future Condition:

Bosque composed of diverse native vegetation: native, self-sustaining biological communities; healthy

native wildlife population and habitat; salt-cedar free

by 2003!

Actions:

• Increase restoration efforts

• Coordinated effort on river dynamics to enhance establishment of native vegetation — reach by reach over

next 20 years, based on 20 year half life for existing

cottonwood forest

Hydrograph

Sediment

Physical barriers — channel characteristics

Exotics removal/impact reduction

Salt cedar

Russian olive

Pheasants, oryx

Cattle

Fishes

Protect what we’ve got

Effective for management to maintain native biota

Corridors

Control over known

detrimental interspecies

relationships

Application of existing knowledge

Targeted habitat restoration for specific SPP.

Monitor wildlife/habitat response to restoration efforts

Current Conditions:

Exotics replacing natives

Lack of effective native species reproduction

Declining wildlife and habitat

Monocultures

Lack of a diverse mosaic of habitats

Limited/underfunding of wildlife-habitat relationships
USDA Forest Service Proceedings RMRS-P-7. 1999 245

Desired Future Condition:

Collaborative Efforts: good people interaction to create win-win solutions; legal framework for sustainable uses (i.e. urban planning, water conservation,

water adjudication, preservation of agricultural lands;

governance that is innovative and inclusive of people

Actions:

• Train community mediators

• Conduct institutional analysis

• Create collaboration plan — for agencies

• Break down institutional boxes

• Demo projects: win-win solutions are possible

• Test pilot projects to hold management accountable

• Citizen review board: Referendum #9

• Hold management accountable to implement collaborative process: clean house

• Fund agencies to implement collaborative processes

• Reform institutional missions toward collaborative

processes

• Train people to be responsible citizens: of services to

communities; mediation skills, etc.

• NEPA CEQ: rewrite implementing regs go through fear

and danger

Current Conditions:

Command control paradigm

One lawsuit after another

Competition for resources

Wasteful use of resources

Legal framework weighted toward consumptive uses of

resources

Decisions made by elites

Water flows uphill to $

General public feels powerless and apathetic and uninformed

Other interests unwilling to acknowledge validity of other

points of view

No meaningful process in place to get diverse interests

together to understand other points of view

Lack of legislative involvement

Action happens only in crisis mode

Desired Future Condition:

A functional river/riparian ecosystem capable of supporting a mosaic of habitats with viable and diverse

native species: restore function potential; a reconnected river and bosque; river and watershed are

healthy; functioning river systems including uplands

to Rio Grande corridor; minimal physical and institutional constraints on river dynamics

Actions:

• coordinate agency management basinwide — 3 years

(2001)

• Floodplain management for a sustainable Bosque — as

soon as possible

– Exotic species control

– little removal/fire suppression

– selective habitat restoration

• Select sites for mechanical restoration

– remove bank vegetation

– rework banks by channel

– provide flows

• Augment hydrograph to ensure periodic overbank

flooding — within 10 years (2008)

– peak flows

– timing and duration

• Monitoring — immediately

Current Conditions:

Complex infrastructure

Controlled hydrograph

Narrowing and structural constraints

Stable channel

Lack of sediment supply

Less water

Narrow floodplain

Large stands of non-native vegetation

Stands of mixed native-non-native vegetation

Disconnected River & Bosque floodplain

High fire frequency

Reduced native fish species

Lack of mosaic of successional stages

High consumer demands on water

Fragmented water allocations/drainage

Wrap up _______________________

In the wrap-up, participants expressed concern that the

word “river” was heard much more than “basin.” The statement was made that ninety-five percent of the attention is

being placed on five percent of the land mass because the

river is a charismatic resource that captures attention.

People have lost sight of where the water comes from and

need to regain that awareness. People could substitute the

word food for river, as well: urban people are disconnected

with the source of their food. As with water, the need to

reconnect with the land and the food supply is apparent.

The group also discussed the urgency of restoration of the

Bosque. Of particular concern is the possibility of a very

large, devastating flood, as some cities have experienced

because of lack of riparian area. At the same time, the group

expressed concern that actions taken with too little knowledge, especially concerning the long-term consequences of

actions, may have detrimental effects. They agreed about

the need to be opportunistic, to take advantage of the

knowledge available, and to be flexible about how improvement is achieved.

The Rocky Mountain Research Station develops scientific information and technology to improve management, protection, and use of

the forests and rangelands. Research is designed to meet the needs

of National Forest managers, Federal and State agencies, public and

private organizations, academic institutions, industry, and individuals.

Studies accelerate solutions to problems involving ecosystems,

range, forests, water, recreation, fire, resource inventory, land reclamation, community sustainability, forest engineering technology,

multiple use economics, wildlife and fish habitat, and forest insects

and diseases. Studies are conducted cooperatively, and applications

may be found worldwide.

Research Locations

Flagstaff, Arizona Reno, Nevada

Fort Collins, Colorado* Albuquerque, New Mexico

Boise, Idaho Rapid City, South Dakota

Moscow, Idaho Logan, Utah

Bozeman, Montana Ogden, Utah

Missoula, Montana Provo, Utah

Lincoln, Nebraska Laramie, Wyoming

*Station Headquarters, 240 West Prospect Road, Fort Collins, CO 80526

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