Sierra Nevada Ecosystems in the Presence of Livestock

A report to the

Pacific Southwest Station and Region

USDA Forest Service

Rangeland Science Team

Barbara Allen-Diaz, UC Berkeley, Chair

Reginald Barrett, UC Berkeley

William Frost, UC Cooperative Extension

Lynn Huntsinger, UC Berkeley

Ken Tate, UC Cooperative Extension

March 22, 1999
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Executive Summary

This document was prepared by a group of scientists with expertise in California rangeland

ecosystems. The group was asked to critically review the Sierra Nevada Ecosystem

Project (SNEP 1996), Forest Service Sierra Nevada Science Team (SNST 1998) report,

and other literature in order to provide an assessment of the current science base for

addressing rangeland issues in the Sierra Nevada. The Range Science Team (RST)

prepared a draft report in 5 weeks as requested, which was reviewed by scientists,

managers, users, and other interested publics. This final report adds to the literature base

provided by SNEP and incorporates many of the reviewer comments.

This report stops short of synthesizing the vast amount of peer-reviewed and gray

literature concerning the response of Sierra Nevada ecosystems in the presence of

livestock. We believe that this synthesis is the most important next step, and we are

committed to such an effort. However, we intend to enlist additional expertise to the team

and devote the time such an effort requires in order to make a credible, sound, and useful

synthesis for managers.

Our effort does point out the deficiencies in current knowledge of ecosystem response to

livestock. To paraphrase a recent article by Hamilton (1997), human understanding of a

phenomenon, such as ecosystem response to grazing, improves by building on the work of

the past. Sometimes, however, it is necessary to reevaluate the firmness of the foundation

on which we stand. The intellectual history of the interactions of grazing and ecosystem

response forms a cautionary tale where force of personalities and uncritical acceptance of

hypotheses have sometimes overshadowed data and squelched open debate so important

for the progress of science.

Our findings are summarized below:

Grazing is a polarized issue with some people arguing for removal of grazing based

“science” and others supporting grazing based on “science.” The evaluation of grazing

effects is not so black and white.

“Grazing” is most often treated as a yes or no proposition, but it really is a complex

process where timing, frequency, duration, season of use, and intensity matter. The terms

“grazing” and “overgrazing” are not defined in most of the statements where they are

used. Kattelmann (SNEP1996; V 2 Ch 30) makes an attempt to define overgrazing as

when more than half the available forage is consumed (50% utilization). However, this

definition is not strongly supported by the references cited. In many studies it is also

difficult to determine when “historic grazing” is being discussed versus “current grazing.”

Without detailed descriptions of grazing season, frequency, intensity, and system as well

as a quantitative description of the range site, riparian type, or stream class it is difficult to

interpret the work with regard to current livestock management in the Sierra Nevada.

Unfortunately, this problem permeates much of the existing rangeland literature.

Much of the existing work on grazing continues to be conducted as case studies. Although

lacking in statistical and experimental design rigor, case studies do serve to
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provide a wealth of applied information. The key to learning from the tremendous amount

of case study work occurring is the development and use of standard pre-treatment and

post-treatment monitoring, standard reporting of “grazing” management tested, standard

reporting of stream characteristics, and standard reporting of watershed history and

characteristics. Such information would allow the resources management community as a

whole to benefit from individual case study efforts. Case studies (and all forms of “gray”

literature) conducted in the Sierra Nevada need to be collected, evaluated and synthesized.

It is also important to remember that observations of phenomena are valid, and

observation is the first step in the scientific method. Observations of grazing effects range

from defecation in a creek to reducing fire hazard. Ideally, formulating hypotheses from

observations is next; then testing hypotheses to build confidence in their general

applicability. Unfortunately, testing of hypotheses is not often done before people leap

from observation directly to the conclusion that grazing is the primary source of resource

degradation.

Tracing SNEP-cited literature back to the original sources has provided varying degrees of

support for each statement cited (see Appendix 1). We have found citations that are valid

interpretations of research work as well as citations that are completely irrelevant to the

statement. We found citations that were based on the author’s conjecture in the discussion

section of a paper (not data), and we found SNEP authors offering opinions with no

citations, and for which we found no experimental basis in the literature available to us. A

key problem with the grazing literature cited in SNEP and SNST is that the authors do not

always differentiate between peer-reviewed original research, non-peer-reviewed

proceedings, editorials, position statements, or informational pamphlets, etc. when

supporting statements. Obviously, non-peer-reviewed proceedings, editorials, position

statements, and informational pamphlets are often valuable sources of information and are

one means by which science and management interface. In tracing statements back to their

original source we found a tendency to extend research results far beyond their original

findings. This limits the utility of the document for resource managers.

We did find that there is a large amount of relevant, primary scientific literature that is

missing completely from both the SNEP and SNST report. Thus, we were able to add to

the research base for making decisions about grazing effects in the Sierra Nevada in this

report.

One solution to improve resource management is to more closely link scientific research,

extension, and on-the-ground management, so that the feedbacks between them can result

in adaptive management strategies (Walters 1986) and lead to better policy decisions.

Obviously, experimental research will not keep up with the needs of managers to identify

and understand the success and failure of grazing management strategies. If science is to

form a basis for ecosystem management decisions, then more thought must be paid to the

proportion of management dollars available for research support.

Table of Contents
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Executive Summary..........................................................................................................i

Part I: Introduction.......................................................................................................... 1

Background................................................................................................................. 1

Structure and approach of this study............................................................................ 2

The Theoretical Framework for Understanding Grazing Effects................................... 3

Part II: State of Our Knowledge: Links between Livestock and Water Resources............ 5

Interception and Infiltration ......................................................................................... 6

Overview of the literature ........................................................................................ 6

Interception and Soil Cover.................................................................................. 7

Infiltration............................................................................................................ 8

Summary ....................................................................................................... 11

Stream Channel Stability and In-stream Flow Processes............................................. 12

Overview of the Literature ..................................................................................... 13

Summary ....................................................................................................... 14

Watershed Water Quality and Pathogens ................................................................... 15

Overview of the Literature ..................................................................................... 16

Summary ....................................................................................................... 17

Water Quality (Water Temperature) .......................................................................... 18

Overview of the Literature ..................................................................................... 19

The impact of temperature variations on aquatic biota........................................ 19

The effects of temperature on other processes within streams............................. 20

Factors contributing to temperature increases..................................................... 20

Models for predicting temperature change.......................................................... 21

Summary ....................................................................................................... 21

Part III: State of Our Knowledge: Links between Livestock and Plant Resources .......... 22

Meadows and Riparian Resources.............................................................................. 22

Overview of the Literature ..................................................................................... 23

Grazing system .................................................................................................. 23

Grazing intensity................................................................................................ 24

Grazing season................................................................................................... 25

Rooting potential ............................................................................................... 26

Problems with Research ................................................................................. 26

Foothill oak woodlands.............................................................................................. 27

Overview of the Literature ..................................................................................... 27

Residual Dry Matter........................................................................................... 28

Summary ....................................................................................................... 30

Woodland Overstory Management Recommendations........................................ 30

Grazing Management Recommendations............................................................ 30

Grazing Management for Blue Oak Regeneration............................................... 31

Long term vegetation change in oak woodland .......................................................... 31

Overview of the literature ...................................................................................... 31

Part IV: State of Our Knowledge: Links between Livestock and Wildlife Resources...... 33

Overview of the literature ...................................................................................... 34
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Amphibians........................................................................................................ 34

Reptiles.............................................................................................................. 34

Willow flycatcher............................................................................................... 34

Brown-headed cowbird...................................................................................... 35

Mammals........................................................................................................... 36

Part V: Historic and Current Ranching Use of the Sierra Nevada ................................... 37

Abstract/summary...................................................................................................... 37

Overview of the Literature ..................................................................................... 39

Grazing in the nineteenth century ....................................................................... 39

Early grazing and fire......................................................................................... 42

Land tenure........................................................................................................ 43

Twentieth century history................................................................................... 44

Current ranching and ecosystem management..................................................... 46

Attitudes and values of the ranching community and land use change ................. 46

Part VI: Social Impacts of Sierra Livestock Grazing on Forest Service Land.................. 50

Abstract/summary...................................................................................................... 50

Overview of the Literature ..................................................................................... 50

Impacts of grazing on recreation ........................................................................ 50

Impacts of packstock use ................................................................................... 51

Part VII: Summary ........................................................................................................ 53

Cited Literature ............................................................................................................. 55

Appendix I: Evaluation of SNEP Statements about Livestock........................................ 98

Livestock and Water Resources..................................................................................... 98

SNEP Statements Concerning Upland Soil Cover, Soil Compaction and Infiltration:.. 99

A review of the Literature Cited in SNEP ............................................................ 100

SNEP Statements Concerning Channel Stability and In-stream Flow Processes:....... 102

A review of the Literature Cited in SNEP ............................................................ 105

SNEP Statements Related to Pathogens and Nutrients............................................. 116

A review of the Literature Cited in SNEP ............................................................ 116

SNEP Statements Concerning Water Temperature................................................... 116

A review of the Literature Cited in SNEP ............................................................ 117

Livestock and Plant Resources .................................................................................... 117

SNEP Statements Concerning Meadow and Riparian Resources.............................. 117

A review of the Literature Cited in SNEP ............................................................ 119

SNEP Statements Concerning Blue oak................................................................... 119

A review of the Literature Cited in SNEP ............................................................ 120

SNEP Statements Concerning Oak Woodland Vegetation Community Change ........ 121

A review of the Literature Cited in SNEP ............................................................ 121

Livestock and Wildlife Resources................................................................................ 122

SNEP Statements Concerning Amphibians............................................................... 122

A review of the Literature Cited in SNEP ............................................................ 123

SNEP Statements Concerning Birds ........................................................................ 124

Willow flycatcher............................................................................................. 125

Brown-headed cowbird.................................................................................... 126
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A review of the Literature Cited in SNEP ............................................................ 127

Historic and Current Ranching Use.............................................................................. 127

Rangeland History....................................................................................................... 130

Appendix II: Supplement to Part IV: Livestock and Wildlife........................................ 132
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Part I: Introduction

Background

The Forest Service (FS) requested a review of the science base for understanding the

biological and social effects and interactions of grazed rangeland ecosystems in the Sierra

Nevada. Public concern had been raised, and echoed by the FS own internal Science Team

review (1998), that existing information found in Sierra Nevada Ecosystem Project (SNEP

1996) documents concerning rangelands and grazing effects was insufficient to serve as

the base for developing a Sierra Nevada wide EIS and amending Forest Plans. This effort

is part of the documentation in the pre-NEPA public participation part of the Forest

Service’s Sierra Nevada Framework for Conservation and Collaboration, 1998.

The Rangeland Science Team (RST) was chaired by Dr. Barbara Allen-Diaz. Members

include Drs. Reginald Barrett, William Frost, Lynn Huntsinger, and Ken Tate. Criteria

used to select the team included 1) expertise, 2) academic credentials, 3) no previous

authorship of SNEP documents, and 4) availability to participate in an initial 5-week turna-round time. The RST was in-place on August 24, 1998; the first draft was issued

October 1, 1998. Team expertise included plant ecology and management including oak

woodland, meadow and riparian systems, inventory and monitoring, wildlife ecology and

management, and watershed hydrology. In-stream vertebrate and invertebrate resources

were not included in this report because we did not successfully recruit a fish biologist or

an aquatic insect expert because they either did not fit the criteria or because they believed

that they were unable to effectively deal with the issue of fish habitat in the short time

frame allowed for this review.

The RST initially focused its efforts on a review and evaluation of the science base for

statements made about grazing in SNEP documents. This approach was taken because the

RST was led to believe that this information would serve as the foundation for building

grazing management direction during the Forest Service Ecosystem Conservation

Framework EIS process. We first asked the question: Is the information in SNEP

concerning grazing sufficient to develop alternative grazing management direction? Our

conclusion based on the review of statements concerning grazing made in SNEP was no.

Since the vast majority of statements we evaluated concerning grazing were negative, any

objective evaluation of the scientific foundation of those statements most likely would be

considered “pro” livestock. Indeed many reviewer comments considered the draft RST

report to be pro-livestock.

Reviewers rightly criticized the incompleteness of the draft report. In fact, in order to meet

the original deadline, the RST did not finish an evaluation of additional literature, topics of

importance were left out, and the RST did not make any attempt at synthesis or

recommendations. This report does add to the literature base, however. Reviewer

comments and criticisms can be found at web site: www.psw.fs.fed.us/sierra.
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Structure and approach of this study

The RST charter with the Forest Service stated that the RST will review existing sciencebased knowledge about Sierra Nevada rangeland ecosystems in the presence of livestock.

The RST will critically examine existing research literature and other information,

including the SNEP rangeland chapter and FS Science Team report, in order to provide an

assessment of the quality of the current science base for addressing rangeland issues. As

much as possible, in the short time frame allowed, the RST will point out what we know

based on experimental evidence as well as what we don’t know about Sierra Nevada

ecosystems grazed by livestock.

Science is a process for accumulating knowledge about the natural world; it is not always

straightforward. The first step is often to propose testable hypotheses based on

observations of events in the natural world that suggest patterns, or based on theoretical

constructs. A second step may be to make further observations based on comparisons to

detect correlation, which may or may not indicate causal relationships. The final step is a

series of experiments or controlled observations designed to test hypotheses.

The Forest Service has embarked on an effort to tie scientific discovery and management

goals and decisions through the use of an Ecosystem Management Framework. Ecosystem

Management has been defined as the management of “communities of organisms working

together with their environments as integrated units...places where all plants, animals,

soils, waters, climate, people, and processes of life interact as a whole” (Salwasser and

Canta 1993 in Haynes et al. 1998).

Four basic scientific principles have been proposed to guide FS ecosystem management

efforts (Haynes et al. 1998):

1. ecosystems are dynamic,

2. ecosystems can be viewed spatially and temporally within organization levels,

3. there are limits to ecosystem’s ability to withstand change and still maintain

integrity, and

4. there are limits to people’s ability to predict change.

SNEP was an effort supported by Congress to conduct an independent science assessment

of the conditions and trends in ecosystems and communities of the Sierra Nevada. The

effort was enormous; more than 50 scientists authored or co-authored articles which

pulled together information on the Sierra Nevada ranging from forest health and

productivity to economic impacts of development and human population growth.

The Sierra Nevada was defined as an “ecosystem” incorporating the headwaters of 24

major river basins and covering any area of 20,663,930 acres (SNEP Summary 1996).

Watersheds were used as the basis for defining Sierra Nevada ecosystem boundaries, even

though SNEP authors recognized that no single boundary adequately defined all the

important ecological or social components. Thirty six percent of the core Sierra Nevada
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ecosystem is privately owned and 66% is in some form of public ownership (SNEP

Summary 1996). Most of the high elevation and eastern Sierra Nevada are in Forest

Service (41%), Bureau of Land Management (13%), or National Park Service (6%)

management. Private land ownership dominates the western portion of the Sierra Nevada

below 3000’ (SNEP Summary 1996).

Diversity of plants, animals, soils, climate, and people and their uses of the land and

resources are extraordinarily high in the Sierra Nevada Ecosystem. More than 3500

species of native plants, 400 terrestrial vertebrates, and 650,000 people occupy the Sierra

Nevada (SNEP Summary 1996).

Domestic grazing animals have utilized Sierra Nevada forage resources since the 1860s. In

the beginning, Sierra Nevada forage resources were open to any and all that could capture

those resources. Early federal policies encouraged open-access use of public land, and

although the exact distribution of grazing by cattle and sheep is unknown, it is clear that it

was widespread and excessive.

Grazing as an ecological process is composed of intensity, frequency, kind and class of

animal, and season of use. Intensity of use is related to stocking rate (number of animals).

Frequency of use is how many times animals are allowed to graze in the same area in one

season. Kind and class of animal refers to the species and age class of animal. Season of

use is the time of year grazing is allowed. These factors shape the various impacts of

grazing – selective consumption of plant materials, trampling and nutrient re-distribution.

The Theoretical Framework for Understanding Grazing Effects

Evaluation of possible responses of Sierra Nevada ecosystems to the presence of livestock

must be organized in such a way such that responses at different spatial and temporal

scales are explicit. Table 1 provides our theoretical framework for evaluating the large

body of information on livestock grazing. The “Ecological Hierarchy” (column 1) focuses

analysis on a specific spatial scale within which ecosystem functioning occurs. For

example, grazing animals select plants and plant parts. Through selective grazing, some

individuals are consumed while others are lightly utilized or not grazed at all. Selective

grazing, depending on the intensity, frequency and season of use can result in destruction

of the most palatable plant populations with changes in plant community composition.

Eventually, with continued “heavy” or “abusive” grazing, ecosystem functioning is altered,

carbon stores removed, and nutrient cycles interrupted. Habitat for other organisms is

altered, and although some species may initially benefit from ecosystem changes, most do

not.

At the same time, the physical system can be affected by grazing intensity, frequency or

season of use. The “Physical System” (column 2) outlines the spatial scales at which the

physical environment is affected and may respond to grazing. For example, the

hydrological cycle starts with precipitation and infiltration. Livestock grazing may affect

infiltration through the removal of vegetation that may leave the soil surface exposed as

well as the physical impact of hoof action that may compact the soil. This results in a loss
4

of soil surface structure and increased erosion through overland flow at a given site. At

the watershed scale this may result in an altered soil moisture regime, increased storm

runoff, and increased sediment deposition or erosion in stream channels.

Column 3, The “Management System”, is a compendium of management regulations,

current practices, and current scales of application which are arranged roughly to align

with our perceived understanding of effects at different ecological scales. For example,

management direction currently requires annual operating plans on allotments. These

operating plans dictate on/off dates (season of use) and number and kind of animals to

graze in a particular allotment. However, allotments are composed of numerous

ecosystems, communities, populations and individual plants and animals that may respond

differently to grazing pressure. The allotment plan is targeted to the landscape or

watershed that may not protect resources at other ecological scales.

Explicit in this organization is the understanding that response to grazing will depend also

on the temporal scale at which grazing is applied. At any spatial scale within Table 1, the

timing of disturbance events (generally season or year, although daily and decade cycles

may be of interest) will often result in different ecosystem response.

Table 1.

Ecological Hierarchy The Physical System The Management System

Individual Soil/Infiltration T&E species

Population Site Key areas

Community Reach Pastures

Ecosystem Stream Grazing systems

Landscape Watershed Allotment

Biome Climate zone Pastoral systems

Many studies have focused on documentation of the effects of abusive (or heavy) grazing

on ecosystem structure and function. The scientific foundation for understanding

ecosystem response to abusive grazing is clear: plant cover is destroyed, soil erodes, water

quality is degraded, individual wildlife species and their habitats are destroyed, biodiversity

declines, invasive plants take hold. Conversely, ample studies have shown removal of

domestic grazing animals generally results in increases in plant cover, biomass, and

diversity to some point. Water quality, streambank stability, wildlife and fish habitat

improve. Again the changes in ecosystem response vary by ecosystem. Arid and semi-arid

systems are generally slow to respond while riparian systems and areas with sufficient

water are the most resilient in general, and improve the fastest. These studies are sufficient

if the goal is to remove livestock grazing. However, if the goal is
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maintain multiple use of the public lands in the Sierra Nevada, then many more studies

quantifying effects at different grazing intensities, frequencies, and seasons of use must be

conducted.

The data exist to support the conclusion made in SNEP and elsewhere that Sierra Nevada

ecosystems suffered from abusive grazing practices through the turn of the century. It

follows then that grazed ecosystems in the Sierra Nevada are now either in static,

improving, or still declining condition because of those past abusive grazing practices. In

addition, abusive grazing was not the only practice affecting ecosystem response. Changes

in fire regime, and changes in hydrology because of mining and road building are other

significant activities. It is hard to determine how these factors interact, as well as what the

likely ecosystem response will be to a change in one practice such as grazing, given the

impact of all the activities. We do know that change in ecosystem condition will not likely

be linear in most ecosystems (Allen-Diaz and Bartolome 1998), and that the rate of

ecosystem response will most likely vary by ecosystem (e.g. Laycock 1991, Friedel 1991,

Kauffman and Krueger 1984).

The question is what practices can managers select in the great middle ground between

abusive grazing and no grazing? The answer might be different depending on whether the

focus is on ecological, social, or economic considerations. The fundamental choices

revolve around grazing systems (rest, season long, deferred, and combinations of short

duration, high frequency, etc.), season of use, number of animals, and kind and class of

animals.

This report should not be seen as a comprehensive discussion of the topic of grazing, but a

contribution towards such an effort. Obviously, unequivocal “scientific” answers to the

many questions concerning Sierra Nevada ecosystems response to grazing can only be had

after many decades of additional, rigorous scientific study, and detailed, careful synthesis

of existing literature. Meanwhile, policy decisions will in most cases be made based on

some experimental evidence, educated guesses, and observations made by scientists,

managers and land users.

Part II: State of Our Knowledge: Links between Livestock and Water

Resources

This section summarizes literature on livestock effects on interception, infiltration, stream

channel stability, in-flow stream processes, and watershed water quality. It generally

follows the elements of the hydrologic cycle as well as the general spatial hierarchy of the

physical system (Table 1). Each subsection below starts with an initial description of how

one would expect the system to respond to livestock grazing based on hydrologic

principles. The literature is then reviewed and summarized, which clearly points out the

weaknesses in uncritically expecting the system as predicted from general hydrologic

principles.
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Interception and Infiltration

When investigating the potential linkages between livestock and upland hydrologic

process, the primary process of concern is infiltration. Any land use or natural event that

reduces infiltration capacity has the potential to effect the hydrology of the entire

watershed. Hydrologic principles tell us that reduced infiltration and increased overland

flow in the uplands can lead to secondary effects on peak flows, erosion, contaminant

transport, and water quality degradation. Documenting these secondary effects via

watershed scale field research is a difficult task.

From reading SNEP (see appendix 1), we conclude that common beliefs about livestock

effects are:

1) Grazing removes vegetation, leaving the soil surface exposed to erosive raindrop

impact, and

2) Livestock physically compact the soil via hoof action.

Potential primary results for the site level are:1) Infiltration would be reduced as soil

surface structure is lost, 2) Erosion would increase as soil particles are detached and

readily transported, 3) Increased soil bulk density, decreased soil porosity and reduced

infiltration capacity would lead to increased overland flow and increased erosive and

contaminant transport potential.

At the watershed scale potential results include: 1) Altered soil moisture regime, 2)

Increased storm flow peaks in streams, 3) Increased stream erosive power, 4) Increased

sediment delivery to stream channels, 5) Increased sediment deposition or erosion in

stream channels.

Overview of the literature

Does the literature base support this common paradigm? If so, under what grazing

management (timing, frequency, intensity, duration, season) are these impacts realized, or

not?

A large body of peer-reviewed, experimental literature exists concerning the linkage

between livestock and upland hydrologic functions such as interception, infiltration and

overland flow. Presented below is a brief glimpse of the amount of literature available, it is

by no means comprehensive.

Blackburn (1984) reviews the impacts of livestock grazing on upland watershed

parameters by major rangeland vegetation types. He reviews information on cover, soil

compaction, infiltration, runoff, and erosion responses and interactions to grazing

management treatments. The review is categorized by range ecosystem, and includes

California annual grasslands, sagebrush/grass, high elevation rangelands, ponderosa

pine/bunchgrass, and pinyon-juniper woodland. The author states “Livestock grazing

affects watershed hydrologic properties by removing protective plant cover and by
7

trampling. Reductions in vegetation cover may: (a) increase the impacts of raindrops, (b)

decrease soil organic matter and soil aggregates, (c) increase surface crusts, and (d)

decrease infiltration rates, and/or increase erosion.” He goes on to state “Existing studies

show no hydrologic advantage to grazing a watershed lightly rather than moderately.

Some studies show no difference in soil loss, infiltration capacity, or soil bulk density

between light, moderate, or ungrazed pastures. Little evidence supports claims for

specialized grazing systems.”

The reader is referred to Blackburn (1984) for a detailed accounting of the 130

publications included in the review. Blackburn has included numerous relationships and

tables of data from the original publications, allowing the reader to draw their own

conclusions. Blackburn’s conclusions include:

1. Hydrologic impacts of livestock grazing result primarily from the interactions of

climate, vegetation, soil, and intensity and duration of livestock use, Thus, grazing

impacts will vary naturally from area to area. Few studies have attempted to

account for these natural variations.

2. Documentation of the intensity and duration of livestock grazing has been poor

or completely ignored in most studies. What is described as moderate grazing

intensity in one study may be the same as heavy grazing in another study.

3. Most livestock grazing studies have compared the impacts of heavy grazing with

no grazing. It is easy to get the impression from the literature that heavy grazing is

a viable management objective or that livestock grazing is universally equivalent to

heavy grazing; however, no such oversimplification is justified.

4. It has been recognized for over 70 years that heavy continuous grazing

accelerates erosion and runoff.

Making the point that more research is required on “proper grazing” rather than

“overgrazing”, Blackburn quotes Love (1958) as writing “There is a large body of

information leading to the conclusion that heavy grazing has bad hydrologic consequences.

It is doubtful that more investigations are needed to emphasize this conclusion.”

Interception and Soil Cover

Gifford (1985) provides a review of the relationship between grazing, soil cover and

erosion in which he references 79 publications. He cites 48 peer-reviewed scientific journal

articles, 24 technical reports, 4 proceedings papers, and 3 dissertations. Despite its

brevity, Gifford’s (1985) review appears to be the most comprehensive, or at least the

most focused, treatment of the literature on cover with regards to upland range hydrology.

He supports the argument that “overgrazing” leads to excessive reduction in vegetative

ground cover, increased runoff and erosion. As the Committee for Rangeland

Classification (1994) points out, bare soil (inverse of cover) is an important indicator of
8

“range health” or condition. However, Allen (1989) points out that cover alone may not

be a good indicator of riparian condition. Gifford concludes the following:

1. Based upon limited data, 50 to 60 % cover is probably sufficient to maximize any

benefits to infiltration and also for minimization of sheet or interrill erosion in the

Intermountain type.

2. Site specific vegetation cover requirements will vary due to cover type (vegetation,

litter, rock, erosion pavement, etc.), seasonal and storm variation, and land use.

3. There is no consistent evidence concerning the importance of one species of

vegetation over another with respect to providing cover to safeguard infiltration or

reduce erosion.

4. There is no evidence to suggest that cover requirements for either infiltration or

erosion should vary depending on class of livestock or wildlife.

Blackburn (1984) reviews numerous papers on the subject of cover. Those of particular

interest include Packer (1953) who studied the interacting effects of cover and artificial

trampling on bluebunch wheat grass in the Boise River watershed of Idaho, as well as

Marston (1952) and Packer (1963). Packer (1953) examines the relative ratios of cover to

trampling required to minimized erosion to “safe” levels. Marston recommends 65%

ground cover for protection of high elevation watersheds in northern Utah. Packer (1963)

recommends that at least 70% plant and/or litter cover is needed to prevent excessive

erosion on the Gallatin Elk winter range in Montana.

Infiltration

Infiltration dynamics on rangelands are driven by interacting ecological, soil, hydrological

and management factors. Gifford and Hawkins (1978) provide a critical review and

statistical analysis of the experiments examining grazing intensity and infiltration capacity

throughout western rangelands available at that time. The authors reference 37 papers in

the review (23 peer-reviewed journal articles, 10 technical reports, and 4 proceedings

papers). Based upon statistical meta-analysis of the available and seemingly comparable

data in the literature, Gifford and Hawkins conclude:

1. There is an influence of grazing on infiltration. Ungrazed [infiltration] rates are

statistically different from grazed at any [grazing] intensity at the 90% level.

2. It is difficult to differentiate between influences of moderate and light grazing.

They may be considered statistically identical.

3. There is a distinct impact from heavy grazing that is statistically different from

that of light/moderate.

4. There is considerable standard error in the data from the literature, which is to

be expected.
9

Although Gifford and Hawkins give detailed definitions of the term “grazing intensity”,

they do not quantify “light”, “moderate”, and “heavy” grazing, leaving the reader

uncertain as to the exact interpretation of this work. The greatest research need identified

in this work was the need for a detailed definition of the long-term effects of grazing (by

year and season) on infiltration rates as a function of site, range condition, and grazing

intensity.

Blackburn’s (1984) review contains the main body of the additional work on infiltration

conducted from the time of Gifford and Hawkins review (1978) until his own in 1984. In

his 1985 review of cover and hydrologic function on rangelands, Gifford (1985) makes the

point that the interaction of range-soil community, plant community, vegetation

successional stage, range condition, and soil properties to determine infiltration and

erosion have not been addressed in the literature. The review also supports the argument

that as range condition increases, there is an upward trend in infiltration with improved

condition class. Finally, he states that spatial and temporal variability in infiltration rates

and erosion have been ignored in most studies.

Recent work has started documenting some of the relationships between soil, vegetation,

range condition, and infiltration through space and time on rangeland. Spaeth et al.

(1996) cite 98 references and likely capture much of what has been done since Gifford and

Hawkins (1978) and Blackburn (1984), but that is not an absolute. Spaeth et al. (1996)

reference 56 peer-reviewed journal articles, 9 technical reports, 14 proceedings papers, 3

dissertations, and 16 texts. The breadth of sources is an appropriate reflection of the

evolution of this field of work into the examination of ecological, soil, and management

influences on rangeland hydrologic processes through space and time.

Subjecting data collected by Rauzi et al. (1968) from 670 plots representing 24 range-soil

groups, 35 plant species, and 8 soil and plant parameter measurements from Northern and

Central Plains rangelands to detrended correspondence analysis, Spaeth et al. (1996)

concluded:

1. Infiltration rates were positively correlated with mulch (cover), percent sand,

soil structure rating and biomass. Infiltration increased as values for these variables

increased.

2. Infiltration rates were negatively correlated with percent clay, percent silt, and

bare ground. Infiltration decreased as values for these variables decreased.

3. Specific plant species such as western wheatgrass, buffalo grass, needle-andthread, prairie sandseed, and sedges were correlated with infiltration rate primarily

because of soil physical properties.
10

4. For all data, soil texture was the parameter most correlated with infiltration

rates. Biomass and mulch cover protect the soil from raindrop energy, but were

secondary to soil texture in predictive models for infiltration rate on a regional

scale.

5. Range managers need to be wary of relating range condition to “hydrologic

health”, given that the two may not be related depending upon the structure and

demography of the plant community. Spaeth et al. (1996) substantiate this

statement with references confirming a negative relationship between range

condition and “hydrologic health” in sagebrush, rabbitbrush, and broom snakeweed

communities (Spaeth 1990, Gutierrez-Castillo 1994, and Spaeth et al. 1994). By

hydrologic health the authors are referring to infiltration capacity, interception,

surface erosion, etc.

Performing the same analysis on data collected by Blackburn et al. (1990) at the Reynold’s

Creek Experimental Watershed in southwest Idaho, Spaeth et al. (1996) examined the

spatial and temporal relationships of soil, vegetation, hydrology, and soil erosion in a

sagebrush community. Data used represent hydrologic relationships for 13 environmental

variables, two soil surface cover types (shrub coppice and interspace between shrubs) over

6 dates. Conclusions are:

1. The shrub coppice was associated with higher infiltration capacity, above

ground biomass, aggregate stability, cryptogam cover, surface soil water content,

and organic carbon.

2. Less silt, litter cover, rock cover, and erosion was found with the shrub coppice

than in interspaces.

3. Infiltration capacity, aggregate stability, above ground biomass, and

cryptogamic cover were lower during the winter months.

4. Despite conflicting reports in the literature, cryptogams were found to be

important to both infiltration and interrill erosion models in this study.

Finally, Spaeth et al. (1996) analyzed data presented in papers by Wood and Blackburn

(1981) on vegetation, soil, infiltration, and sediment production responses to cattle

grazing systems. They compared heavy continuous (4.6 ha au-1), moderate continuous

(6.2 ha au-1), rest deferred rotation (6.2 ha au-1), grazed deferred rotation (6.2 ha au-1),

rested high intensity low frequency (6.5 ha au-1), grazed high intensity low frequency (6.5

ha au-1) and no grazing treatments on Rolling Plains range sites near Throckmorton, TX.

Vegetation communities were mesquite shrub canopy zone, as well as midgrass, and

shortgrass prairie interspaces. Conclusions were:

1. The existing composition of the plant community had more of an effect on

infiltration than grazing treatments.
11

2. The infiltration gradient (high to low) for plant community was shrub canopy zone,

midgrass interspace, and shortgrass interspace.

3. The infiltration gradient (high to low) for grazing treatment was [non-grazed,

grazed and rest deferred rotation], [moderate continuous],[ heavy continuous], and

[rested and grazed high intensity low frequency]. Thus, the authors suggested that

there is no difference in infiltration between no grazing and rested and grazed

rotation grazing systems. Their ranking of moderate and heavy continuous grazing

agrees with Gifford and Hawkins (1978) review, as well as with Blackburn (1984).

Intensive grazing systems were found to reduce infiltration to the greatest extent,

apparently as the result of concentrated hoof impact and soil compaction.

4. Models using plant community type, regardless of grazing treatment explained

74% of the variability in infiltration rates, grazing alone explained 34% of this

variability, and a model containing both plant community and grazing treatment

explained 91%. Plant community can be a major confounding factor in infiltration

experiments and must be considered in management decisions.

Summary

1. There is evidence that “proper” grazing management can maintain upland hydrologic

condition, just as there is evidence that “overgrazing” degrades upland hydrologic

condition. The common paradigm is true if the grazing considered is “over-grazing”.

However, the paradigm is called into question when “proper grazing” is the case.

2. Unfortunately, we are not much closer to defining “proper grazing” than at the

beginning of this exercise. It must be quantified and defined locally, and it must be

quantified in any reports, papers, etc. referring to the project or site.

3. Site specific application of the literature to define management will require knowledge

of both the literature as well as recognition of site specific soil, vegetation, and grazing

information. Site specific application in the form of cover or grazing system

recommendations cannot be broad brushed from the existing literature. Rather the

literature in conjunction with local field experience provides a platform for

knowledgeable first approximations of management recommendations. These first

approximations must be fine-tuned via an active adaptive management program. At a

minimum the literature tells us that critical site specific parameters to consider when

making these first approximations are: a) cover, b) soil texture, c) plant community, d)

grazing intensity.
12

Stream Channel Stability and In-stream Flow Processes

The linkage between livestock, stream channel stability and in-stream flow processes is

complex. Streams themselves are complex, Rosgen (1994) describes almost 100 stream

reach categories. Watershed/landscape position, watershed gradients, soil/geologic

material, climate, and potential/current upland and riparian plant community all interact to

define the “natural” structure and function of a stream reach. Each stream type has a

unique “stable” channel morphology and pattern. Each will support and/or be supported

by different riparian plant communities. Each will respond differently to watershed

disturbances, and specifically each will exhibit differing resiliency to differing grazing

management strategies.

Leopold (1994), Gordon et al. (1992), and Rosgen (1996) are excellent applications of

our basic understanding of stream hydrology and applied river morphology from a

watershed perspective. In addition, a team with USDI-BLM (1998) has developed a

qualitative method to assess the function of lotic areas on western rangelands. The reader

is referred to USDI-BLM (1998) for two reasons: 1) it represents a well thought-out

attempt to merge science-based hydrologic, soil, and ecological information with practical

experience into an efficient assessment tool for trained, objective land managers; and 2) it

is the method used by Menke et al. (1996; SNEP Volume 3, Chapter 22) to assess 24

meadows in the Sierra Nevada. The method cannot be, and was not designed to be, used

to determine cause and effect at the watershed or stream reach scale, nor should it be

utilized for long term trend monitoring. More detailed watershed scale investigations are

required to determine cause and management remedy when streams are identified to be

not functioning or at risk.

Finally, phenomena such as stream bank instability result from interacting watershed scale

mechanisms occurring through time. These phenomena are almost always linked to several

co-occurring natural and human-induced phenomena in the watershed such as wildfire,

large storm events, road construction, urban expansion, etc. This is often termed

cumulative impacts. In that light, it is difficult to pull “grazing” out of the mix of land uses

and natural phenomena occurring in the watershed in recent history and assign some

quantity of cause and effect to it alone. Despite this, an attempt is made to examine both

reach specific and watershed scale concepts linking livestock to stream channel instability

and in-stream flow process.

From reading SNEP, we conclude that the common belief is:

1) Riparian grazing by livestock reduces plant vigor leading to reductions in mass and

depth of roots holding soils and stream banks together against stream flow;

2) Long-term riparian grazing shifts plant community away from species which have

the root structure to hold soils and stream banks together against stream flow; and

3) Livestock trample and break down stream banks by hoof action.
13

Potential primary results for the stream reach would include:

1) Increased storm flow peaks in streams, increased stream erosive power, increased

sediment delivery to stream channels, and increased sediment deposition or erosion

in stream channels.

2) Stream banks become unstable,

3) Stream channels with “hard” bottoms widen,

4) Stream channels with “soft” bottoms down-cut,

5) Stream shading decreases on the widened stream, increasing solar input and water

surface area exposed to solar radiation, and

6) Riparian water table is lowered when stream channel down-cuts changing the site

potential of the adjacent riparian area.

Potential contributing watershed-scale upland mechanisms include:

1) In the uplands overgrazing removes vegetation, leaving the soil surface exposed to

erosive raindrop impact, and

2) Livestock physically compact the soil via hoof action.

Potential watershed scale results of stream bank instability:

1) Entire stream system becomes unstable,

2) Stream widening moves headward from impacted reach(s), expanding throughout

the watershed,

3) Stream channel down-cutting moves headward from impacted reach(s), expanding

throughout the watershed,

4) Watershed drainage efficiency is improved and magnitudes of return interval

storms increase (i.e. 5 year storm increases from 5000 to 10,000 cfs), and

5) Sediment eroded from stream channel is deposited in lower gradient low landscape

position reaches the watershed, leading to instability of down stream reaches.

Overview of the Literature

Does the literature support this common paradigm? If so, under what grazing management

and for which stream types? A large body of literature exists concerning grazing and

riparian system stability. Several reviews have been conducted, and the overwhelming

conclusion is that this literature is inadequate to adequately answer the question above.

There is strong case study evidence documenting the negative impacts of overgrazing on

stream channels, as well as the rapid improvement of these systems when the abusive

grazing is removed completely.
14

Platts (1991) discusses 21 case studies focusing on aquatic habitat, of which channel

stability is a major component. Twenty of these case studies report that riparian and

stream habitats had been degraded by livestock grazing and that these habitats improved

when grazing was prohibited. However, Platts demonstrates that each of these studies was

flawed to a greater or lesser degree and its results were compromised accordingly.

Examples include lack of pre-exclosure data to determine similarities/dissimilarities

between “grazed” and ungrazed stream reaches before livestock exclosure, the stocking of

trout following livestock exclosure, etc. Platts concludes that the weight of evidence from

these studies as a group documents fish abundances and biomasses decline as a result of

habitat degradation in the presence of grazing.

Larsen et al. (1998) reviewed 428 papers on the impacts of grazing on riparian zones. The

authors classified the papers into 3 categories: 1) original data/research, 2)

commentary/opinion, and 3) methodology papers. Eighty-nine of the papers were

classified as experimental, where treatments were replicated and results were statistically

valid. General problems with the literature are reported as: 1) inadequate description of

grazing management practices or treatments, 2) weak study designs, and 3) lack of pretreatment data.

Elmore and Kauffman (1994) discuss historical overgrazing and degradation of riparian

areas. The authors also review riparian grazing management strategies, making general

recommendations for developing these strategies. The authors discuss the results of work

examining grazing strategies involving three pasture rotation, winter grazing, early

growing season, deferred grazing, deferred rotation, rotation grazing, spring-summer

grazing, season long grazing, fall grazing, riparian exclusion, and riparian pastures.

Ohmart (1996) reviews over 250 publications which substantiate the negative effects of

overgrazing, the need for further research on “proper” grazing management strategies, and

the need for increased rigor and consistency in case studies and experiments on these

grazing strategies.

Summary

There are significant problems with the existing literature, making it difficult to interpret

and apply much of it to support or debate the common paradigm developed in SNEP. A

few points seem clear:

1. Each stream will have a different resiliency and response to grazing within the riparian

area as well as within the watershed.

2. There is a substantial body of observation, case study, opinion, and review/viewpoint

papers that support the accepted fact that “overgrazing” leads to streambank instability

and alteration of channel morphology and in-stream flow processes such as sediment
15

trapping. The amount of statistically valid, experimental information examining this

phenomena and explaining the mechanisms which drive it are surprisingly limited.

3. There is also a substantial body of observation, case study, opinion, and

review/viewpoint papers which support the premise that site specific riparian grazing

management strategies can balance riparian “needs” to insure streambank stability and

in-stream flow processes are protected with livestock production. The amount of

statistically valid, experimental information examining the grazing strategies,

explaining the mechanisms which make them successful, and documenting the positive

and negative results of each strategy are also surprisingly limited.

4. Future studies must clearly define the past and current grazing management as well as

study site characteristics such as past and current non-grazing land use, soils, climate,

etc.

5. Additional studies of abusive grazing v. no grazing are of limited value in identifying

proper grazing systems.

6. Funding, time, logistics, as well as watershed and stream variability make it unlikely

that enough long-term, “scientifically valid” experiments will ever be conducted to

examine each grazing system by stream type combination.

7. Identification of “proper” grazing for a given management unit is dependent upon site

specific riparian function objectives and conditions. The literature clearly agrees that

off-the-shelf, one-size-fits-all grazing management standards and riparian grazing

management strategies will not insure that riparian areas are not “overgrazed”. A

successful riparian grazing strategy must be custom designed to fit the specific

circumstances. A clearly defined objective or desired future condition for the riparian

area is the foundation of a successful grazing strategy.

8. New case studies concerning “grazing” and riparian function start every year, yet as a

community of rangeland resource managers we all-to-often learn little about

economically viable, proper riparian grazing from them. Despite this, Larsen et al.’s

(1998) review tells us that case studies are, and will most likely continue to be a large

portion of the literature.

Watershed Water Quality and Pathogens

Concerns regarding pathogen loading to water bodies focus on livestock excrement.

Pollutants from rangeland beef cattle excrement can effect water quality if the pollutants

are directly deposited in the water body or if they are transported to the water body during

storm events. Pathogen dynamics on rangeland watersheds are complex and vary through

time and space. Often background levels of pathogens are unknown. The spatial and

temporal distribution of rangeland beef cattle excrement also varies within and across

watersheds. Cattle distribution is a function of topography, soils, vegetation, air

temperature, animal class, and grazing management.
16

Overview of the Literature

A significant body of literature exists on this subject. Nader et al. (1998a,b) utilize a total

of 66 references. Of these, 46 are peer-reviewed journal articles, 11 are technical reports,

4 are proceedings papers, 3 are text, and 2 are dissertations.

As discussed in Nader et al. (1998b), the primary water-borne protozoa potentially

transmitted by cattle excrement includes Cryptosporidium parvum and Giardia

duodenalis (also known as Giardia lamblia) (Fayer and Ungar 1986, Craun 1990, Atwill

1996). C. parvum is a tiny protozoal parasite that can cause gastrointestinal illness in a

wide variety of mammals, including humans, cattle, sheep, goats, pigs, and horses. It also

occurs in various wildlife species such as deer, raccoons, opossums, rabbits, rats, mice,

and squirrels (Fayer and Ungar 1986). In cattle, shedding of the parasite is usually limited

to calves (Atwill 1998a), but there are a few reports of subclinical shedding in adult cattle

(Lorenzo et al. 1993). Dairy calves are commonly infected with C. parvum and G.

duodenals (Ongerth and Stibbs 1989, Xiao 1994), but little is known of their distribution

in beef cattle herds, particularly in those herds located on open range.

Detailed studies that attempt to link rangeland cattle grazing with the presence of waterborne pathogenic bacteria have for the most part not been done (Atwill 1996). Instead,

indicator bacteria have been used. These studies need to be interpreted with some caution

since indicator bacteria have been shown to be poorly correlated with some pathogenic

bacteria such as Campylobacter jejuni (Carter et al. 1987, Bohn and Buckhouse 1985).

However, an increase in indicator bacteria in waterways, due to cattle grazing has been

documented in many studies (Gary et al. 1983, Robbins 1979, Dixon et al. 1979,

Stephenson and Street 1978). Yet, grazing has also been found to have little or no effect

on fecal indicator counts (Frear 1983, Buckhouse and Gifford 1976). Fecal indicators

may not always signify the presence of pathogens in the water column (Bohn and

Buckhouse 1985). When contamination does occur, it may be temporary and short-lived

(Gary et al. 1983, Robbins 1979), or may persist for several months. (Stephenson and

Street 1978). Furthermore, concentrations tend to decrease downstream (Robbins 1979).

A special concern for bacterial pollutants is their ability to survive in the environment, only

to become a factor in pollution at a later time. Bacteria such as Salmonella newport and

E. coli have been shown to survive several months in freshwater sediments (Burton et al.

1987). Fecal coliforms may survive up to two months in soil, but in the protective

medium of feces, can persist up to a year (Bohn and Buckhouse 1985). Bottom sediments

have been found to harbor concentrations of indicator organisms up to 760 times greater

than the overlying water (Stephenson and Rychert 1982).

Studies that carefully evaluate the association between rangeland cattle and the presence

of these water-borne protozoa have not been conducted. The majority of the existing

literature deals with dairy cattle, or was conducted in laboratory settings. These studies do

not explicitly state how the cattle were managed nor define the cattle’s proximity to

contaminated water bodies. Madore et al. (1987) measured 5,800 Cryptosporidium

oocysts/L in irrigation canal water running through agricultural acreage with cattle
17

pastures compared to 127 oocysts/L in river water subject to human recreation and 0.8

oocysts/L for stream water exposed to ranch land runoff. Unfortunately, the authors do

not specify if the cattle were beef or dairy cattle or if the species of Cryptosporidia was the

of human health concern, parvum.

Atwill et al. (1998a) measure the distribution of fecal shedding of C. parvum from

California cow-calf herds. A total of 1399 (915 calves and 484 yearlings/adults) from 38

herds across the State were tested between Feb. and Aug. 1995. The author’s report a

total of 3.9% of all animals were shedding C. parvum oocysts. Age-stratified prevalence of

shedding among calves ranges from 0-13%. The prevalence of shedding among cattle 12

months or older was 0.6%. Thus, fecal shedding by cow-calf herds is primarily limited to

calves 1-4 months of age. The author concludes that the risk that cattle contaminate

watersheds with appreciable levels of C. parvum is primarily limited to those periods when

young calves are present in the herd. This finding is confirmed in mature dairy cattle as

well (Atwill et al. 1998b).

Along California’s central coast range, Atwill et al. (1997) found that 12 (5.4%) and 17

(7.6%) of 221 feral pigs were shedding C. parvum and Giardia sp. cysts, respectively.

The authors also found that younger pigs (8 months) and pigs from dense populations (> 2

pigs/km2) were significantly more likely to shed oocysts compared to older pigs (>8

months) and pigs from low density populations (< 1.9 pigs/km2). The authors conclude

that given the propensity of feral pigs to focus their activity in the riparian area, feral pigs

may serve as a source of protozoal contamination for surface water.

Johnson et al. (1997) examined the prevalence of shedding of C. parvum and Giardia spp.

by backcountry recreational horses. In fall 1994 the authors collected fecal samples from

91 horses with a history of backcountry use during 1993 and 1994. Five to six horses from

each of 16 locations throughout California were sampled. Horses ranged from 4 to 24

years of age. None of the horses sampled were positive for either of C. parvum and

Giardia spp. The authors conclude that, even accounting for the sensitivity of the test

employed (potential for false negatives), the highest probable prevalence of shedding for

either pathogen was < 3.2% for the cohort of horses studied.

Summary

1. Water quality data should be examined carefully before assigning a cause and effect

relationship between cattle grazing and nonpoint pollution

2. Given the recent prevalence work by Atwill et al. (1998ab, Johnson et al. 1997), it

would be premature to claim that rangeland cattle production is the leading source of

C. parvum or G. duodenalis for surface water contamination.

3. Rangeland beef cattle excrement has been shown to increase pathogen contamination

in waterways beyond background levels. It has also been shown to have no detectable

effect.
18

4. In managing livestock to minimize potential contamination one must consider the age

of the animals, the hydrology of the area, and the proximity of feeders, etc. to

waterways.

5. Livestock’s distribution within a watershed can be manipulated using sound range

management practices such as salting, water location, fencing, and selecting against

cattle that graze riparian areas. Salt, mineral or protein supplements placed next to the

streams can result in direct pollution of the water as well as increase cattle dung, urine

and trampling next to the stream. Alternative water sources, such as windmill or solar

powered wells, reservoirs, and guzzlers, can be developed in upland areas to draw

cattle away from streams.

Water Quality (Water Temperature)

Water temperature is a critical physical property of rivers and streams, influencing a

number of physical, chemical and biological characteristics. Stream temperature

influences solubility of oxygen and other gasses, chemical reaction rates, and sediment

transport capacity (Webb 1996). It has strong impacts on freshwater biota influencing

distribution, growth, reproduction, disease, migration and behavior of both vertebrate and

invertebrate populations (Baltz 1987, Beschta et al. 1987, Ward 1992, Elliot 1994).

Stream temperature effects survival of waterborne pathogens such as Cryptosporidium

parvum and Giardia spp. (Atwill 1996).

As a general rule, stream temperature will rise and fall with air temperature. The amount

of fluctuation will depend on a range of secondary environmental and management

considerations. For instance, shading by streamside vegetation and deep pools can keep

temperatures cooler as well as moderate diurnal extremes. Thus, management activity

which alter streamside vegetation or channel morphology have the potential to alter stream

temperature dynamics. This reasoning assumes that stream temperature in the reach is

actually controlled by streamside shade and channel morphology, rather than flow

dynamics, cool/warm spring-flow input, snow-melt, stream latitude, elevation, stream

order, substrate, etc.

On rangeland watersheds in particular, livestock grazing is believed to increase stream

temperature via removal of riparian vegetation and stream bank instability resulting in

increased channel width-to-depth ratios (Platts 1991).

From reading SNEP, we conclude that the common belief is:

1) Livestock grazing reduces riparian vegetation, and

2) Streambank instability due to grazing causes stream channels to widen, increasing

the channel’s width to depth ratio.

This would result in:
19

1) Increased solar radiation reaches the water surface, and

2) Stream temperature increases.

Overview of the Literature

There is still much we do not know about the basic processes driving stream thermal

dynamics, or the mechanisms by which livestock may impact this dynamic. Existing

research on stream temperature falls into four main areas: 1) the impact of temperature

variations on aquatic biota; 2) the effects of temperature on other processes within

streams; 3) factors contributing to temperature increases; and 4) models for predicting

temperature changes. Although there is a degree of overlap, in the interests of clarity the

four areas will be considered separately.

The impact of temperature variations on aquatic biota.

There has been substantial research into the impact of temperature variations on aquatic

vertebrates and invertebrates, particularly salmonids. Water temperature has both direct

and indirect effects on trout and salmon. Because they are poikilotherms whose body

temperature will average only 2-3oC below ambient temperature, metabolic processes are

driven in large part by water temperature (Berman and Quinn 1991). For example, growth

rates of juvenile rainbow trout (Oncorhynchus mykiss) in laboratory experiments are

highest at temperatures between 15oC and 20oC (Linton et al. 1997). However,

temperatures above 25oC are believed to be lethal to most salmonids (Jobling 1981), and

spawning does not occur unless temperatures are near 9oC. Recent studies have focused

on the impacts of temperature changes on salmonid behaviors such as aggression, feeding,

and swimming (Matthews et al. 1994, Neilsen et al. 1994, Scott and Pointer 1991).

Preliminary results from these studies suggest that age of the study fish is a confounding

factor, and have also raised the possibility that salmonids from warmer climates may have

adapted to a wider range of temperatures than previously thought possible (Matthews et

al. 1994). Matthews et al. (1997) reports field observations of trout at 28 and 29oC, well

above the 25oC lethal limit reported from laboratory studies using commercially available

trout.

Studies on macroinvertebrates indicate that temperature plays a significant role in

community composition which in turn influences prey availability for larger invertebrates

and fish (Murphy and Hall 1981, Hawkins et al. 1983, Lester et al. 1994). Until recently,

research indicated that elevated stream temperatures had a positive impact on food

availability for salmonids, but this research is now being reexamined on three fronts. First,

it appears that the factor which raised stream temperature in the earlier studies (canopy

removal) was itself the driving force behind macroinvertebrate increases, because

increased light levels (not temperature) increased autotrophic production. Second, it has

been pointed out that although stream temperatures increased in the Murphy and Hall

(1981) and Hawkins et al. (1983) studies, it still remained below critical levels for

salmonids and for cold stenothermic macroinvertebrates (Tait et al. 1994). Third, research

by Lester et al. (1996) has raised the possibility that some streamside vegetation,

particularly willows (Salix spp.), exude chemicals which constrain certain
20

macroinvertebrates, and that removal of that vegetation, not resultant temperature

increases or higher periphyton production, is the force behind macroinvertebrate increases.

Consequently, this area of research is currently in a state of some confusion.

The effects of temperature on other processes within streams

Temperature regulates so many biological and chemical processes within streams that the

Federal Water Pollution Control Administration (a precursor of the EPA) once described

it as “a catalysts, a depressant, an activator, a restrictor, a stimulator, a controller, a

(EPA 1986). Aquatic plant respiration and photosynthesis are temperature

dependent, as are microbial processes such as decomposition, chemical reaction rates,

sediment transport, and gas solubility (Allan 1995). One of the most crucial effects of

elevated temperature is that it both increases organismal demand for dissolved oxygen and

decreases its availability, so much so that the real limiting factor for many cold

stenotherms may be oxygen availability at high temperatures, not the temperatures

themselves (Hynes 1970). In some circumstances, oxygen depletion in streams is further

exacerbated when temperatures are sufficiently heightened to increase the decomposition

of organic matter, since that process also draws on available oxygen (Chamberlin 1982).

Similarly, warm water carries considerably more sediment than cold water, and water with

a high amount of suspended sediment absorbs heat more rapidly than clear water (Webb

1996).

Factors contributing to temperature increases

In a relatively undisturbed ecosystem, stream temperatures will be determined by

combination of environmental factors such as air temperature, flow, channel morphology,

substrate, solar radiation and riparian shading. Of these factors, it appears that in the

absence of strong localized inputs from groundwater or snowmelt, the most important

factor driving water temperature is air temperature (Webb 1996). In slow moving streams,

where the water does not mix thoroughly, or in rivers where gravel bars promote deep

pools away from the main channel of the river, thermal stratification may occur. Deeper

levels may maintain a more constant temperature while upper levels fluctuate in response

to air temperature (Matthews et al. 1994, Neilsen et al. 1994).

Because water temperatures are sensitive to a wide range of interacting environmental

factors, human activities that affect these factors have the potential to effect stream

temperature. Temperatures have been shown to be dramatically affected by land use

change within the watershed (Li et al. 1994) particularly by impoundments (Mackie et al.

1983, O’Keeffe et al. 1990) and deforestation (Holtby 1988, Beschta and Taylor 1988,

Rowe and Taylor 1994, Davies and Nelson 1994). While there is widespread agreement

that large-scale watershed deforestation will result in elevated temperatures, there is less

agreement about the impacts of smaller scale disturbances such as grazing in riparian

areas.

Larson and Larson (1996) argue that shade does not cool a stream rather it merely

prevents heating to the degree that watershed attributes and site characteristics allow it.
21

They contend that the air mass characteristics of the watershed, its elevation, surrounding

landscape and instream inputs, coupled with site specific characteristics like flow, aspect,

and slope will be the primary determinants of temperature, and that direct riparian shading

will play at best a small role in rangeland streams. Beschta (1997) challenges these

conclusions, arguing that shade, whether supplied by dense canopies of conifer over larger

streams or by sedges, rushes, and willows along smaller rangeland streams, has historically

been the moderating factor which has allowed salmonid survival in waters of the high

deserts and intermountain West. What both authors agree on, however, is that riparian

vegetation has a significant impact on channel morphology and on nutrient and organic

matter inputs (leaf litter, insect drop, etc.). Fish biologists would further emphasize the

importance of overhanging bank as cover for salmonids (Wesche et al. 1987).

Models for predicting temperature change

Models for predicting stream temperature fall into two broad categories: A). models

designed to assess the effects of particular management alternatives, such as logging or

diversions (Brown 1972, Beschta 1984, Theurer et al. 1984 Bathelow 1989, Weatherley

and Ormerod 1990, Hostetler 1991, Sinokrot and Stefan 1993, Bicknell 1993, Donigian

1995, Chen 1997); and B). models primarily designed to predict the impacts of global

climate change and air temperature on stream temperature (Stefan and Preud’homme

1993, Stefan and Sinokrot 1993, Webb and Nobilis 1997). While each of these models

has its strengths and limitations, a few generalizations can be offered. First, most of the

models intended for use in decision-making are highly complex. For example, the EPA

has developed a computer watershed simulation model capable of predicting stream and

river temperatures in certain situations (Bicknell 1993), but its use requires hourly input

data and considerable technological sophistication from the user (Donigian et al. 1995).

Second, these models are primarily geared towards streams and rivers with substantial

instream flow, and depend on historical flow records; consequently they are not especially

useful for small headwaters streams (Jeppesen and Iversen 1987). Third, several models

infer the impact of shade from temperature measurements taken on either end of a shaded

stream reach (Sinokrot and Stefan 1993) and use the inferred value to predict what would

happen if the shade were eliminated. As a result, these models have limited usefulness in a

restoration context where the question centers on establishment, rather than removal, of

vegetation. Fourth, while the linear regression models based on air temperature have the

advantage of being cheap, easy to use, and reasonably accurate, they are quite sitespecific, since groundwater, snowmelt or other environmental factors not considered by

the model may exert considerable influences on a particular stream or reach (Webb and

Nobilis 1997).

Summary

Comprehensive investigations of stream temperature dynamics, the effect of management

on these dynamics, and the effect of both on fisheries must draw on many disciplines
22

(hydrology, geology, biochemistry, fisheries biology, stream ecology, organismal biology,

range management, forestry, etc).

There remains a wealth of information to be learned about: 1. the factors controlling

stream temperature dynamics, 2. the relative importance of each factor under different

circumstances, 3. how these factors interact at various spatial and temporal scales, and 4.

under what circumstances common range management practices increase stream

temperature and what can be done to avoid stream temperature increases with

economically and socially viable management measures.

From a rangeland management perspective one of the most crucial areas for investigation

is the extent and function of shading on stream temperature.

Many (Platts 1991, Moyle and Liedy 1992) remain firmly convinced that loss of riparian

vegetation due to grazing is one of the most critical problems facing fisheries, some

contend it is not entirely clear that vegetation typical of many rangeland streams can have

significant effect on stream temperature (Larson and Larson 1996). If the role value of

rangeland riparian shading is overestimated, efforts at riparian vegetation restoration may

not achieve desired stream temperature reduction goals.

While it may be true that grazing in riparian corridors is problematic even if it does not

lead to elevated stream temperatures, temperature increase due to vegetation removal is a

testable hypothesis and deserves further investigation. Although a link between livestock

grazing and increased channel width to depth ratios is extremely difficult to establish in a

research setting, the relationship between stream temperature and channel morphological

characteristics is manageable, even if observational, research objective.

Part III: State of Our Knowledge: Links between Livestock and Plant

Resources

Meadows and Riparian Resources

Montane and subalpine/alpine meadows occupy less than .01% of the SNEP study area

(Davis 1996). As described in Shiftlet (1994, SRM Types 213, 216), meadows are

habitats occupied by grass (Poaceae family) and grasslike species primarily of the genera

Carex, Juncus and Luzula. Meadow composition is diverse and Ratliff (1985c) suggests

that over 1500 meadow types, based on species, topography, and hydrology may be

identifiable. The primary environmental characteristic of meadow vegetation is an

associated high water table during all or part of the year (Benedict 1982, Ratliff 1985,

Allen-Diaz 1991).

Montane riparian systems occupy less than .002% of the Sierra Nevada area (Davis and

Stoms 1996, v.II, Chpt 23). As described in Shiftlet (1994, SRM Type 203) riparian

woodlands occur along rivers, streams, and creeks, although some streams in the Sierra

Nevada may not have a woody species component. Species composition and vegetation

structure vary throughout the Sierra Nevada, but the principal overstory associates
23

include willow (Salix spp.), cottonwood (Populus spp.), alder (Alnus spp.), maple (Acer

spp.) and oak (Quercus spp.). The distribution of the type is limited to environments along

water courses, where riparian species are adapted to seasonal inundation by water.

Sucessional studies by McBride and Strahan (1984a, 1984b; Strahan 1984) suggest that

riparian zones never exhibit a stable climax at any one location, rather the riparian zone

should be viewed as a mosaic of establishment, replacement, and destruction controlled by

fluvial geomorphic processes.

From reading SNEP and FS Science Team report, we would conclude:

1. The potential primary result of grazing at the population/community level is: loss

of cover, change in species composition through vegetation removal, invasion of

non-native plants.

2. The potential result at the ecosystem: channel degradation, sedimentation,

increased erosion, loss of native plant species, increase in weedy and/or invasive

species, loss of herbaceous productivity, change in vegetation composition and

structure linked to wildlife and fish habitat.

3. The potential landscape level result: lowering of water table, loss of ecosystem

type (meadow or riparian system).

Overview of the Literature

Skovlin (1984), Platts and Raleigh (1984) who review Skovlin (1984), and Ratliff (1985)

provide somewhat dated but the most comprehensive reviews of the interactions between

livestock (cattle) grazing and meadow/riparian resources. Skovlin reviewed 104 refereed

journal articles, 29 technical reports, 24 dissertations/theses, and 10 unpublished reports in

his review. Ratliff (1985) synthesized his own research and years of experience on Sierra

Nevada meadow ecology and management. The potential effects of grazing on meadow

and other woody vegetation come from animal defoliation, preferential grazing, trampling,

and the redistribution of nutrients. Plant responses can include reduced vigor, lower

productivity, and altered species composition with the potential for erosion, plant invasion,

small mammal interactions and changed fire regimes.

Meadow/riparian research can be organized into several categories. Some studies focused

on grazing system effects, others on grazing intensity or grazing season. Some studies

examined rooting potential to hold streambanks. Finally Skovlin (1984) and Platts and

Raleigh (1984) suggest some problems with existing research.

Grazing system

Davis (1977), Ames (1977) and Behnke (1979) have suggested that no grazing system

short of fencing (total livestock exclusion) has any significant effect on recovery of

riparian habitat. These three articles, although often cited, are opinion pieces with no

experimental evidence to support the authors’ opinions. Szaro (1980) cites Davis (1977)

and Ames (1977) when he states that livestock exclusion is the only effective way of
24

insuring significant recovery of riparian habitat. Other authors (Busby (1979), Kimball and

Savage (1977)) cited by Skovlin suggest that proper grazing and riparian recovery can go

together. However, Busby (1979) is an opinion paper published in a Forum for Trout

Unlimited, while Kimball and Savage (1977) is an unpublished report.

Evidence cited by Skovlin (1984) from clipping studies by Etter (1951) and Pond (1961)

indicate that heavy grazing results a decline in Deschampsia caespitosa and Carex spp.

and increases in the sodforming bluegrass (Poa pratensis). Variations in timing of clipping

in addition to intensity of clipping gave different results. Volland (1978) sampled meadows

in Oregon rested for 11 years and found production increased on rested meadows 4-6

years post grazing, but then declined to grazed area levels. Allen (1989) found no

differences in stringer meadow composition after 7 years rest from grazing.

Elmore and Kauffman (1994) describe potential effects of different grazing systems using

Platts (1989) which are based on Platts personal observations of riparian system response

over his career, not experimental studies. Elmore and Kauffman conclude that complete

removal of livestock is the only viable grazing alternative. These authors say that the

major shortcomings of grazing strategies, that fail to result in restoration of degraded

riparian zones, are that they are cookbook, apply to uplands, and devised to increase

livestock.

Grazing intensity

Skovlin (1984) reviews numerous authors who reported that intensity of grazing has a

much greater effect on vegetation than type of grazing system (Van Poolen and Lacey

(1979), Bryant (1979), Roath (1979), Gillen (1981). Van Poolen and Lacey (1979) did

conclude that herbage production was more affected by intensity of grazing than grazing

system. Bryant (1979) and Roath (1979) are theses, while Gillen (1981) is a PNW Office

Report that we did not review. Skovlin concurs with others’ observation that grazing

systems in general were designed primarily to maintain or improve upland not the riparian

zone or adjacent meadow plots.

Shaw (1991) studied the effects of cattle grazing on willows, Salix eigua and Salix

lasiandra, over a 4-year period under 2 seasons at moderate to light grazing intensities,

continuous season heavy and no grazing. She found no effect on seedling growth under

light/moderate spring and fall grazing and no grazing, but significant decline in density and

growth of S. exigua in heavily grazed pastures. Similarly growth declined under heavy

season continuous grazing in S. lasiandra, but not density. She also found that heavy deer

browsing prevented most seedlings from growing beyond the reach of grazing animals in

year 4 of all treatments. Kay and Chadde (1991) found that native elk grazing resulted in

significant reduction in willow seed production and growth compared to ungrazed

exclosures in Yellowstone. One study conducted comparing differences in willow

palatability in New Zealand (McCabe and Barry 1983) found that their willows contain

different amounts of tannins and lignin suggesting differences in palatability, thus possible

differences in browsing impacts.
25

Skovlin also found in his review that uncontrolled, heavy grazing results in heavy mortality

of seedlings, and concluded that the long-term effect of heavy grazing is on regeneration

of woody species. In our review of Skovlin’s citations we found that Harlow and Halls

(1972) did find this for yellow poplar and dogwood.

Stohlgren et al (1989) conducted a clipping experiment on high elevation/subalpine

meadows in Sequoia Kings Canyon NP. They found clipping for 5 years that repeated

clipping to 1.5cm (0.6 inches), which simulated heavy grazing, negatively affected

productivity in wet/mesic meadows, but not dry Carex exserta meadows. The authors

caution that these results cannot be extrapolated to address grazing at light or moderate

levels.

Grazing season

Skovlin (1984) reviewed numerous papers on the response of shrubs and trees to cattle

grazing. His synthesis of available research showed that moderate/heavy grazing during

winter and moderate/light grazing during the growing season had little effect on shrub

productivity the next year. Our review of Willard and McKell (1978), Harlow and Halls

(1972) and Krefting (1966), that were all cited by Skovlin (1984), generally supports this

view. Wolff (1978 ) however focused on Salix scouleriana response to twig browsing.

He found that overwinter browsing was compensated for by next years growth, but also

cautioned that not all willows will respond in the same way. Skovlin (1984) in his review

found studies that suggested that riparian species of Cornus, Acer, Populus, Salix, and

Betula were more resistant to foliage and twig removal than their upland (presumably

drier zone) counterparts. We did not find evidence for this specific statement.

Some authors (e.g. Elmore and Kauffman 1994) state that livestock grazing has damaged

the willow component beyond repair by reducing cover, eliminating seedling regeneration,

and preventing substrates suitable for willow reestablishment (Kauffman et al. 1983).

Conroy and Svejcar (1991) found that willow location relative to the water table was

more important to survival than season of grazing in the northeastern Sierra Nevada.

Willow response to herbivory varied by intensity and season of use. Knopf and Canon

(1982) studied structural resilience of willows to cattle grazing, but their results were

inconclusive. The authors suggested that willows suffered less damage in winter than

summer grazing. Kauffman et al. (1983) found that late season grazing was worse than

early season grazing on willow communities in northeastern Oregon. Kindschy (1989)

found that willow growth the following year was greater when clipping occurred in early

spring or late fall when the plants were dormant rather than in mid-summer.

Clary and Booth (1993) conducted a study of season of grazing use on mountain meadow

utilization on the Sawtooth National Forest. The study used 2 meadow/riparian pastures

grazed at light stocking rates (1.19 AUM/ha) and 2 at medium stocking rates (2.08

AUM/ha). Authors conducted the study for 6 years, grazing only during the last two
26

weeks of June. They found cattle did not concentrate on the wetter riparian zone during

this season of grazing.

Rooting potential

A recent study examined rooting characteristics of sedge, rush and grass meadow

community types in Nevada and found that sedge and rush communities had significantly

more total live root length per volume of soil compared to other literature and their study

values for grass species (Manning et al. 1989). Their data suggest that root length and

root mass were also greater for wet community types than drier types. The authors

suggest in their abstract that wet community types will have superior site-stabilizing

characteristics, although in their conclusions they state simply that more research will need

to be done to determine how root length and mass influence soil-binding and stability

characteristics of a riparian community.

To determine the role of herbaceous roots in holding trapped sediment in place against

flow, Duneway et al. (1994) and Kleinfelder et al. (1992) examined the effect of

herbaceous plant communities and soil textures on particle erosion of alluvial streambanks,

and the unconfined strength of some streambank soils with herbaceous roots, respectively.

Duneway et al. (1992) report the gradient of erosion from lowest to highest by plant

community to be Nebraska sedge (Carex nebrascensis), baltic rush (Juncus balticus),

mixed sedge (Carex lanuginosa, C. rostrata, and others), and mixed grass (Poa pratensis

with Deschampsia caespitosa). This was attributed to the root-volume density differences

of the plant communities. Root-volume density was negatively correlated with erosion.

Kleinfelder et al. (1992) report that herbaceous roots appear to supply most of the

compressive strength and soil stability found in meadow streambanks, especially those

dominated by Nebraska sedge.

Willows are thought to have differential rooting capabilities (Platts 1987), but little

experimental work has been conducted. Platts (1987) reference to Stabler (1985) which

credited this study with finding that ‘root systems of willow help stabilize stream banks

through binding of soil particles’ was unsubstantiated.

Problems with Research

Skovlin (1984) concluded from his review that:

1. researchers in range management study grazing, forage, soils, and watersheds but

rarely examine effects on wildlife or fisheries;

2. fish and wildlife biologists have tended to use studies that have grazing at the

extremes, very heavy or no grazing; and

3. the literature available on wildlife response to moderate and seasonally controlled

grazing is encouraging.
27

Finally Skovlin states that studies which have used no grazing as a treatment and time

lapse comparisons, although not experimentally sound or statistically reliable, show rather

convincing evidence of improved riparian and aquatic environment in 4-7 years after

protection from heavy grazing. Skovlin’s opinion about potential recovery rates may be

the basis for SNEP quotes.

Platts and Raleigh (1984) in the same National Research Council/National Academy of

Sciences report reiterate many of the research problems identified in Skovlin:

1. Lack of adequate experimental design with before and after or control data,

2. Insufficient frequency and precision of measurement to statistically support

conclusions, and

3. Lack of adequate definition of grazing intensity, season, utilization, and animal

distribution.

Platts and Raleigh (1984) concurred with Skovlin’s assessment that there are few studies

that identify how any present cattle grazing system will adequately restore riparian habitats

in a reasonably acceptable time frame. Platts and Raleigh also concur that range, fish, and

wildlife managers base management decisions on different sets of criteria and thus riparian

condition is in the eye of the beholder; good condition for livestock and range managers is

not necessarily good for other components of the ecosystem. Vegetation is just one

parameter of a healthy stream.

Foothill oak woodlands

The Blue oak woodland and Foothill pine-oak woodland occupy about 15% (Davis and

Stoms1996, v.II, Chpt 23) of the total area of the SNEP study area. Annual grassland

dominated systems occupy another 2.8 - 3.0%. As described in Shiftlet (1994, SRM Type

201), foothill oak woodlands are dominated by blue oak (Quercus douglasii) which form

extensive woodlands, savannas and occasional forests generally between 90 m and 700 m

on the west slope of the Sierra Nevada. The most common associate is foothill pine (Pinus

sabiniana). Composition of understory annuals is highly variable in these oak woodlands,

but is strongly influenced by oak tree cover, solar insolation, and slope angle (Borchert et

al. 1991).

The issues concerning grazing in foothill woodland communities revolve around blue oak

regeneration and conversion of perennial to annual grassland.

Overview of the Literature

Research in the foothill oak woodland has focused on herbaceous productivity and

residual dry matter, oak productivity, and oak regeneration. Numerous studies have

examined herbivore and predator effects on these factors.
28

The following section has been organized to focus on residual dry matter and productivity

issues, and blue oak regeneration. Since recent symposium (PSW 1997) and workshops

(Standiford and McCreary 1996) have presented or synthesized much of the recent

literature in this area, benefits of that synthesis are provided in overstory and grazing

management recommendation sections.

Residual Dry Matter

Research on the impacts of grazing on soils includes bulk density studies. Bulk density is

often inversely related to plant productivity and rooting potential in a given ecosystem. In

the foothill oak woodland, studies have related grazing intensity, residual dry matter

levels, and bulk density. Liacos (1962) found that the bulk density (quote 50) of the

surface horizon on ungrazed Los Osos clay loam soils in the annual grassland hills east of

Berkeley, CA averaged 1.4 g cm-3, while soils grazed heavily for 35 years were more

dense with an average bulk density of 1.6 g cm-3. Sites that were lightly or moderately

grazed were intermediate. The heavily grazed, lightly grazed, and ungrazed sites had

residual dry matter levels of 600, 1250, and 3400 lb/ac on the soil surface at the end of the

grazing season. Asaeed (1982) observed higher bulk densities due to grazing, but only on

swale sites. Bulk density on grazed and ungrazed upland sites were not statistically

different. Swales ungrazed by cattle for 10 years had densities of 1.22 g cm-3, while those

continuously grazed had densities of 1.38 g cm-3. Supporting Asaeed’s (1982) findings,

Van Haveren (1983) reported that bulk densities on fine-textured soils increased with

grazing pressure but coarse-textured soil bulk densities were not affected by grazing

intensity. Frost and Edinger (1991) also found no difference in bulk densities on coarse

sandy loam soils among areas grazed yearly (leaving 800 lb/ac of residual dry matter) and

areas ungrazed for over 50 years.

The effect of livestock grazing on the annual herbaceous plant material is generally

evaluated by the amount of residual dry matter (RDM) left at the end of the dry season.

Management of residual dry matter (the dry plant material left on the ground from the

previous year’s growth) has a significant effect on subsequent year’s herbaceous plant

productivity and composition. RDM works as mulch providing a more favorable

microenvironment for seedling establish through moderation of air and soil temperatures,

and reduction of evaporation from the soil. General guidelines for RDM have been

established which range from 200 pounds per acre on gentle slopes in southern California

to over 1200 pounds per acre on steep north coast slopes (Clawson et al. 1982). The

suggested RDM guidelines were developed using the criteria of herbage productivity,

desired plant species composition, livestock performance, and ground cover.

Research has shown in some areas that reducing RDM to low levels in the fall encourages

higher proportions of silver hairgrass, little quakingrass, nitgrass, broadleaf filaree,

burcolver, redstem filaree, and clover. Leaving large amounts of RDM in the fall

encourages dominance by slender wildoats, soft chess, wild oats, and ripgut brome. In

addition to the influence on species composition, leaving low amounts or very high
29

amounts of RDM will result in lower herbaceous plant production the following year

(Bentley and Talbot 1951, Bartolome et al. 1980, McDougald and Frost 1989).

Blue Oak Regeneration

Livestock grazing has been shown to reduce the survival of blue oak seedlings in some

locations (Davis et al. 1991), while in others grazing did not affect oak seedling survival or

density (Davis et al. 1991, Allen-Diaz and Bartolome 1992). Phillips et al. (1997)

reported no evidence of livestock grazing on blue oak seedlings from their yearly

evaluation over a 5-year period in Kern County. While not addressing seedling mortality,

Hall et al. (1991) did find a differential effect on seedling damage among season of use and

cattle stocking densities in a one year study. Other researchers attribute blue oak seedling

mortality to other factors such as: herbivory by rodents, insects and deer; competition

from herbaceous vegetation; changes in fire regime; and climatic and edaphic factors

(Davis et al. 1991, Gordon et al. 1989, Adams et al. 1997, McCreary and Tecklin 1997).

Furthermore, improved survival and growth has been shown to occur following reduction

of herbaceous plant competition, either through mechanical means or herbicide (Adams et

al. 1997, McCreary and Tecklin 1997), or a combination of protection of individual oaks

combined with livestock grazing (on valley oak seedlings) (Bernhardt and Swiecki 1997).

The ability of blue oak seedlings to progress to the sapling stage, then grow above the

browse line into a tree no longer susceptible to possible grazing effects is a critical element

in oak woodland regeneration. Research on the effects of cattle grazing on saplings, and

their ability to make the transition to tree size above the browse line has produced varying

results. Swiecki et al. (1997a) found that areas with “high levels of vertebrate browsing”

were less likely to have sapling recruitment in 5 of the 13 grazed locations they sampled.

Jansen et al. (1997) found no significant difference in the growth (change in height) of

blue oak saplings over a 3 year period among “traditional moderate” grazing, high

intensity-short duration grazing, and no grazing treatments. Standiford et al. (1998) found

that blue oak sprout growth following harvest was greater in both height and spread in

areas where livestock grazing occurred than in non-grazed areas. Muick and Bartolome

(1987), using sapling to tree ratio to assess successful regeneration, found no difference in

the sapling to tree ratio regardless of grazing history in a statewide assessment of blue oak

regeneration. Bartolome and McClaran (1989) suggested that in areas of moderate

grazing with fire intervals around 7 years, seedlings could take up to 20 years to exceed

the browse line and still become saplings and persist in the stand. In heavily grazed areas,

they hypothesized that seedlings would have to exceed the browse line within 13 years in

order to become saplings and persist.

Long term change in blue oak stands was investigated in 4 biogeographical regions by resampling plots established in the 1930s (Holzman 1993). She found a significant increase

in the mean total basal area of blue oaks. This was attributed to the growth of trees

existing in the 30s and to the introduction of new trees (average of 3 trees per .2 acre plot)

into the stand. These results were consistent across grazed and ungrazed plots (54% and

46% of the sample plots, respectively).
30

Summary

With few exceptions, the studies presented do not define the type of grazing occurring in

the study sites. This makes a clear assessment of “grazing” impacts extremely difficult.

The studies examining saplings indicate that the effect of grazing is variable, perhaps based

upon site differences or grazing management strategies. Evidence from research

examining seedlings also shows differences that may be attributable to site or grazing

management strategies. There is evidence from the long-term changes in blue oak stands

that blue oak regeneration is occurring, in general, with current and past livestock

management strategies.

Research in this area is needed to investigate the long term relationship among differing

grazing management strategies (season, timing, duration, stocking rates) and the effects on

seedling survival, sapling recruitment to tree status, and long term dynamics of oak

woodlands.

Woodland Overstory Management Recommendations

Management recommendations as recent as the 1970's called for removal of blue oaks to

increase forage production for livestock. Much research into this practice, summarized by

Frost et al. (1997) has been used to develop the following guidelines:

1. There is little or no benefit gained from removing blue oaks in areas with less than

20 inches of annual precipitation.

2. In areas with greater than 20 inches or rainfall, thinning oak stands where the

canopy cover exceeds 50 percent will have the greatest effect on forage

production.

3. In areas thinned for forage enhancement, residual tree canopies of 25 to 35 percent

are able to maintain soil fertility, retain some components of wildlife habitat, and

minimize erosion processes.

4. Tree removal activities should always be planned considering all values of trees,

including wildlife habitat, soil stability, etc. in addition to the possible forage

production benefits.

Grazing Management Recommendations

Current grazing management recommendations center around leaving enough RDM to

provide a favorable microenvironment for early seedling growth and adequate soil

protection. The general guidelines presented by Clawson et al. (1982) are commonly

used. It is recommended that locally developed RDM standards be established to account

for local site conditions. In addition, if considerations other than soil protection and

annual herbaceous productivity are important, such as wildlife habitat, oak regeneration,
31

or perennial herbaceous species, different RDM standards may be needed. The overriding

factor is that the RDM standard must result in adequate soil protection.

Specialized grazing management systems adapted to hardwood rangelands have not been

widely used nor have they been the subject of extensive research. Some evidence from the

literature supports year-long grazing rather than a three pasture deferred rotation, where a

different pasture was used during each third of the grazing season (George et al. 1996).

Grazing Management for Blue Oak Regeneration

Standiford and McCreary (1996) concluded that some research studies have shown how

grazing management can be applied to actually encourage the development of young

seedlings. These studies have shown that early season grazing, with cattle removed from

the area prior to the drying up of the annual forages, actually improves moisture available

to the developing seedling and results in higher rates of growth. This grazing activity also

reduces the habitat available for rodents that may be a major source of seedling

depredation. These same grazing studies also show that if cattle are left on an area late

into the spring and summer, that they will preferentially seek out the young oaks, which

are often the only green plants on the site. On areas that have been planted or where

naturally occurring seedlings are found, grazing should be managed in such a way as to

use these pastures early in the season to reduce the competition from annual grasses and

forbs. The cattle should then be moved in the spring to other pastures where regeneration

is not a problem. This rotational system can be continued for several years until the

seedlings have grown sufficiently large to withstand grazing pressure (Standiford and

McCreary 1996).

Long term vegetation change in oak woodland

Overview of the literature

To address the issue of grazing induced changes from perennial to annual grassland, one

must first establish that perennial grasslands were the pre-European vegetation type.

There are many hypotheses about the dominant vegetation type before European influence

and the introduction of exotic annuals in the Sierra Nevada. It is important to note that

these are all hypotheses, with support from examination of relict areas, historical accounts

from early European explorers and settlers, and inference from later research into climatic

and edaphic effects on vegetation communities.

There appears to be no experimental support for the statement that grazing contributed to

a change from perennial grass domination to annual species (if that hypothesis is

accepted). Such statements are based upon historical accounts of large numbers of

livestock, observational reports of "overgrazing" and inferences from research into the

effects on perennial grasses with various levels of grazing pressure. The theory that

overgrazing led to this change is most commonly attributed to Burcham (1982[1957])

who provided a list of effects without supporting documentation. Those effects causing
32

modification of the vegetation of native plant communities were grazing, disturbance of

the soil for cultivation, and development of urban communities (Burcham, 1982[1957],

pg. 185). Burcham also attributed the change of native flora to introduced species to:

1) the composition of the original plant cover, the adaptations of the introduced

species for dissemination and survival,

2) the grazing and agricultural practices employed during development of the range

livestock industry,

3) the climate of the California range lands (Burcham, 1982[1957], pg.189).

Mack (1989), in a review article that addresses changes in the Central Valley, also states

that “the huge numbers of cattle and sheep recorded for the Central Valley from the mid19th century onward testify to the tremendous grazing and trampling these animals must

have exerted on the communities dominated by caespitose grasses.”. Mack, however, cites

Burcham (1982[1957]) as the source.

The most widely adopted hypothesis for pre-European plant communities (Burcham,

1982[1957]; Heady, 1977; and many others) is that areas now dominated by non-native

annual grasses were originally dominated by perennial bunchgrasses, as initially proposed

by Clements (1920). This theory is based upon Clements work using scattered relict

stands, observational evidence of vegetation and applying Clements climax theory. Much

of this hypothesis is based upon relict stands of Stipa setigera and used this species to

support the theory of a grassland climax community over much of this area, and much of

the West. Later Stipa pulchra (now Nassella pulchra) was recognized as a different

species, which lends less credence to the similarity of this community type to others

throughout the West. In addition, Nassella pulchra has been shown to colonize road cuts

(Clements 1934) and to be promoted by fire (Sampson 1944, Jones and Love 1945).

These facts have been used (Hamilton, 1997) to question Clements hypothesis, pointing

out that many of Clements relict stands were along railroad right of ways, many of which

were highly disturbed sites and regularly burned (Biswell 1956).

Cooper (1922) also used relict patches of vegetation and observations, combined with

Clements climax theory, and developed a model in which precipitation zones where

identified which corresponded to various pre-European vegetation types. According to

this model large portions of the foothills of the Sierra Nevada (those with less than about

30 inches of precipitation per year) would have contained a chaparral vegetation type.

Others have supported this hypothesis, such as Naveh (1967) who compared California

with areas of the Mediterranean Basin and concluded that there was a very low probability

that these areas contained a bunchgrass climax community, but were probably dominated

by chaparral.

Jepson (1925) developed a hypothesis that the pre-European vegetation was dominated by

annual plants. Research at the San Joaquin Experimental Range indicates that native

annual grasses were an important part of the flora (Talbot et al. 1939, Talbot and Biswell
33

1942). Based on this work, Bentley and Talbot (1948) concluded that annuals may have

dominated some areas of the foothill grasslands. Research investigating climatic

conditions that favor annual plants over perennial plants has supported the hypothesis of

annual plants dominating in some areas (Blumler 1992). Biswell (1946) proposed that

perennial grasses were the dominant vegetation type along the coast where conditions

were more favorable to them, and native annual were dominant in areas such as the lower

foothills of the western slope of the Sierra Nevada.

Another hypothesis presented is that vegetation types are determined primarily by soil

characteristics, not by climate. This hypothesis, presented by Shreve (1927) indicates that

grasslands were found on deep soils, with different vegetation types on other soils. This

hypothesis is supported by others (Robinson 1971, Keeley 1993) who conclude that Stipa

pulchra (Nassella pulchra) was dominant only on deep soils (agricultural type) or high

clay content soils high in mineral nutrients. They also concluded that well drained sandy

soils and those poor in mineral nutrients probably never supported such associations.

Research on soil moisture (Gordon et al.1989, Holmes and Rice 1996) found that exotic

cool-season annuals completed their life cycle early in the dry season and tend to

concentrate root growth and soil-water utilization in the upper soil profile. In contrast,

native perennial bunchgrasses allocate a high proportion of their biomass to the production

of a deep root system, which allows them to continue soil-water utilization well in to the

dry season and contribute to the formation of a very dry soil profile. They suggest that

these contrasting patterns suggest that the invasion of exotic cool-season annuals might

have produced a corresponding increase in the amount of water present at depth in the soil

profile during the dry season.

Part IV: State of Our Knowledge: Links between Livestock and Wildlife

Resources

There are over 640 regularly occurring terrestrial vertebrate species in California and over

400 of these can be found in the Sierra Nevada. Of these many species, a combination of

scientific and political decisions have been made to focus on a tiny fraction of these in this

review. Hopefully, the species considered below include those most likely to be impacted

by livestock grazing in the Sierra Nevada. However, since the majority of California’s

wildlife is not monitored in such a way as to be confident about it’s status (increasing or

decreasing), we are not able to confidently say that there are no other species of wildlife

that are of interest in this matter. This unfortunate and frustrating situation will continue

as long as the public, which owns the wildlife, is unwilling to fund efforts to systematically

monitor the status of all wildlife species in California. A major policy issue is to what

extent such efforts should be funded and who should bear the cost. The crux of this

debate will center on who should bear the burden of proof on any given question.
34

A brief evaluation of the literature reviewed for the project concerning livestock effects on

wildlife suggests that most studies have found negative responses of wildlife to livestock

grazing (Appendix 2). It is unclear if this is a general pattern since the published literature

provides a small and biased sample of the total wildlife community in the Sierra Nevada.

Also, there are many observational studies and few experiments.

The following summary is provided in “taxonomic” order. This order is not necessarily

the order of political or ecological priority. We note that each species has its own unique

habitat requirements. Therefore it is difficult if not impossible to state that all members of

a group, such as amphibians, will respond to livestock grazing in a similar manner. We

argue that each species must be assessed individually; there are no easy shortcuts.

Overview of the literature

From reading the SNEP and FS Science Team Review, we would conclude that livestock

grazing generally negatively impacts wildlife in the Sierra Nevada.

Amphibians

There is strong evidence that certain species of amphibians, California tiger salamander

(Ambystoma californiense), Yosemite toad (Bufo canorus), California red-legged frog

(Rana aurora draytonii), foothill yellow-legged frog (R. boylii), Cascade frog (R.

cascadae), mountain yellow-legged frog (R. muscosa), and northern leopard frog (R.

pipiens), have declined considerably. Some of these species are likely continuing to decline

(Jennings 1996).

However, we found no peer reviewed, scientific studies dealing with the response of

amphibians to livestock grazing based on experimentation (see Table 1). Most of the

published information is speculative or based on observed changes in species distribution

Reptiles

We found only one reference to a reptile in the SNEP or SNST reports in the context of

grazing. The common garter snake (Thamnopis elegans) may depend on ranid frogs in the

Sierra Nevada (Jennings et al. 1992). If so this snake could be in decline as a consequence

of declines in its required prey. We found no peer reviewed scientific studies dealing with

the response of reptiles to livestock grazing based on experimentation (see Appendix 2 for

a listing of all literature reviewed).

Willow flycatcher

By the 1980s it was clear the willow flycatcher’s (Empidonax trailii) distribution in

California was drastically reduced from it’s original distribution (Serena 1982, Unitt

1987). Repeated and thorough field surveys have confirmed that there are now less than

150 breeding pairs of willow flycatchers in the Sierra Nevada (Harris et al. 1987, Harris et

al. 1988, Sanders and Flett 1989). This habitat specialist is restricted to meadows and
35

riparian areas with willows adjacent to water (Serena 1982, Stafford and Valentine 1985,

Taylor 1986, Taylor and Littlefield 1986, Flett and Sanders 1987, Harris et al. 1987, 1988,

Valentine et al. 1988, Sanders and Flett 1989). Since all willow flycatcher nests found to

date have been in the lower branches of willows within reach of livestock it has been

hypothesized that browsing of willows by livestock, and even livestock movements

through willows, may reduce nesting success (Serena 1982, Stafford and Valentine 1985,

Taylor 1986, Taylor and Littlefield 1986, Flett and Sanders 1987, Harris et al. 1987, 1988,

Valentine et al. 1988, Sanders and Flett 1989).

The most convincing results regarding the response of willow flycatchers to livestock

grazing are from comparative studies along the Blitzen River on the 73,200ha, Malheur

National Wildlife Refuge in Oregon. A decreasing trend in yearlong cattle grazing

intensity (<1.7AUMs/ha) was correlated with increasing relative abundance of willow

flycatchers (Taylor 1986, Taylor and Littlefield 1986). These researchers hypothesized

that the mechanism involved was that cattle grazing reduced willow nesting cover for

willow flycatchers (Taylor 1986, Taylor and Littlefield 1986). Comparative studies along

the Kern River in the southern Sierra Nevada also found a correlation between reduced

cattle grazing and increasing willow flycatcher abundance (Harris et al. 1987, 1988).

Similar patterns were noted in the Dinky Creek region of the Sierra National Forest

(Valentine et al. 1988). Willow flycatchers can be parasitized by cowbirds (Harris 1991)

as discussed below, but it remains unclear if this factor is a major cause of endangerment.

Brown-headed cowbird

The cowbird (Molothrus ater) was originally found throughout the Great Plains of North

America, commonly in association with bison (Bison bison), but since about 1930 has

greatly expanded its range (more than any other native bird in North America) to include

the Sierra Nevada (Rothstein et al. 1980, Laymon 1987, Rothstein 1994). Cowbirds lay

their eggs in the nests of other birds, typically in the morning, then travel up to 7km to

feed on grain in the afternoon (Rothstein et al. 1984, Coker and Capen 1995). During the

nonbreeding season, cowbirds gather in large flocks, often with other species of

granivorous birds in agricultural regions such as the Central Valley. Many species of

native birds have been parasitized by the cowbird, but the significance of this parasitism to

the viability of a host species has rarely been quantified (Rothstein 1994). It is the opinion

of Goldwasser et al. (1980) that cowbird parasitism may have been a major factor in the

extirpation of least Bell’s vireo from the Sierra Nevada. In comparative studies, cowbird

parasitism was suggested to be a contributing factor in the decline of willow flycatcher

numbers in the Sierra Nevada (Harris 1991, Rothstein 1994). It may be important in very

small flycatcher populations already reduced by other factors (Rothstein 1994). Direct

removal of cowbirds has increased populations of least Bell’s vireo (Beezley and Rieger

1987).

Consequently, any factors increasing the abundance of cowbirds (nonnative to the Sierra

Nevada) could be seen in a negative light by those attempting to restore endangered native

species such as the willow flycatcher. The primary factor limiting cowbird numbers in the

Sierra Nevada is unknown. However, a reasonable hypothesis is that any
36

land use providing sources of grain (grass seed) is likely to favor cowbirds. Numerous

observations have been made of cowbirds feeding at cattle feedlots, horse corrals,

meadows with sheep or cattle, clearcuts grazed by cattle, and suburban bird feeders

(Rothstein et al. 1980, Airola 1986, Flett and Sanders 1987, Laymon 1987, Sedgwick and

Knopf 1988), Harris 1991, Gaines 1992, Rothstein 1994, Coker and Capen 1995).

Nesting opportunities do not seem as limited.

Mammals

Concern over competition of “big game” and livestock for available forage has long been

an issue for both wildlife conservationists and the livestock industry (Skovlin 1984).

Interest in the response of other mammals to livestock management practices is more

recent. Given the constraints of this project, we will review only the available information

for mule deer (Odocoileus hemionus) and mountain sheep (Ovis canadensis californicus)

in the Sierra Nevada. These two mammals have been studied sufficiently to make some

statements about their relationship to livestock. As noted for the three other classes of

terrestrial vertebrates, we find that some species will respond positively and some

negatively to livestock grazing practices. We also find that for the majority of mammals in

California, there are no data to indicate whether a species is increasing or decreasing,

much less the cause of any trend. Until monitoring of wildlife distribution and abundance

is more common in California, science can provide little input to political decision making

regarding wildlife matters beyond speculation by wildlife experts.

We found no mention of links between livestock and mule deer in the SNEP or STR

documents. A substantial amount of research dealing with deer-livestock competition has

been published based on studies outside the Sierra Nevada (Mackie 1981). We will focus

here only on recent studies specific to the Sierra Nevada sponsored by the Pacific

Southwest Forest and Range Experiment Station of the USFS. Mule deer are migratory in

the Sierra Nevada, from both the western and eastern slopes. They summer in the higher

mountain meadow-riparian habitats, and they winter in chaparral or oak woodland in the

west and sagebrush-bitterbrush steppe in the east. Livestock and deer occur together

throughout much of the Sierra Nevada, sharing the high country in the summer and low

country in the winter. Descriptions of each deer herd, including speculation regarding the

most important limiting factors, are provided in herd management plans located in the files

of the California Department of Fish and Game, Sacramento. Nearly all herds in the Sierra

Nevada have been declining in size over the past three decades.

We found reference to only two experiments dealing with the relationships between

livestock and mule deer in the Sierra Nevada. Experimental results from the summer

range can be summarized by the following quotations. “Deer spent more time feeding and

less time resting with increased cattle stocking rates [<1.5AUMs/ha]...Time spent feeding

by deer was negatively correlated with standing crop of herbaceous forage...” (Kie et al.

1991). “In the absence of [cattle] grazing, meadow-riparian habitat comprised a greater

proportion of deer home ranges...Within home ranges, deer preferred meadow-riparian

habitat...” (Loft et al. 1991). Deer home ranges increased in area as cattle
37

grazing level increased [<1.5AUMs/ha]...deer and cattle were attracted to the patchily

distributed meadow-riparian and aspen habitats where herbaceous forage was most

available...” (Loft et al. 1993). Finally, Kie (1996) found increased cattle grazing

[<1.5AUMs/ha] caused does to forage beyond their preferred crepuscular activity period.

These results provide strong support for the hypothesis that cattle and deer may compete

for summer forage in meadow-riparian habitat in the Sierra Nevada. Kie and Boroski

(1995) found "...[on winter range] competition with cattle resulted in deer home range

sizes remaining large. In poor forage production years, deer traveled greater distances to

locate adequate forage and home ranges remained large during late winter and spring

regardless of cattle grazing intensity."

The Sierra Nevada mountain sheep, or bighorn, is now limited to three population

fragments totaling less than 100 individuals; it is listed as threatened by the state of

California (Bleich et al. 1990, Ramey 1995, Wehausen 1996). John Wehausen has been

monitoring Sierra Nevada bighorn populations since 1975. Bighorn move from high

elevation summer range, downslope to winter range in sagebrush-bitterbrush slopes east of

the Sierra Nevada crest (Wehausen et al. 1987). Bighorn are very susceptible to infection

by Pasteurella haemolytica carried by healthy domestic sheep (Foreyt and Jessup 1982,

Jessup 1985, Coggins 1988, Onderka et al. 1988, Weaver and Clark 1988, Foreyt 1989,

1990, 1994, Jaworski et al. 1993, Foryet et al. 1994, Pybus et al. 1994, Fitzsimmons et al.

1995). If bighorn populations are to be maintained, domestic sheep cannot be allowed to

come in contact with them. The primary limitation on Sierra Nevada mountain sheep is

now predation by mountain lions (Puma concolor)(Wehausen 1996). Restoration of

Sierra Nevada mountain sheep will require reintroducing them to historic ranges free of

domestic sheep and mountain lions. Captive breeding may now be required to carry out

any reintroductions. One study done elsewhere determined that bighorn moved elsewhere

when cattle were present (Bissonette and Steinkamp 1966).

Part V: Historic and Current Ranching Use of the Sierra Nevada

Knowledge of the history and current status of grazing in the Sierra is important to

understanding the relationship between the Sierra landscape, vegetation, and livestock

grazing. Misunderstandings of history contribute to the misreading of current landscapes.

The first section of Part III discusses the history of grazing in the Sierra reviewing what

has been presented in recent compilations of information about the historical and social

dimensions of livestock grazing in the Sierra, most notably the SNEP report, and

highlighting useful contributions from these and more recent works. The second section

discusses the current status of ranching in the Sierra in relation to ecosystem management.

Abstract/summary

Our understanding of historic grazing and livestock-related management

impacts comes from two main sources: contemporaneous accounts, and

vegetation histories from tree-ring, pollen, and other forms of paleo-botanical

study. Use of the Sierra for summer range as part of the transhumance pattern
38

of grazing began in the 1860s. Anecdotal accounts unanimously lament the

influence of excessive livestock grazing during the period when Sierran public

domain lands were open to all, which peaked sometime in the late 1800’s or

perhaps even early twentieth century. Early federal government policies

effectively imposed what property theorists refer to as an “open-access”

property regime on public domain lands. Only with the establishment of Forest

Reserves and National Parks, and eventually the passage of Taylor Grazing

Act, which led to the development of federal land management institutions and

policy for grazing on public lands, was the open access period ended. Grazing

policies initially favored cattle producers, gradually closing off ranges to use by

sheep and overcrowding the remaining ranges until nomadic sheepherding was

excluded completely.

One grazing-related impact that is much discussed in accounts of the time is

the use of fire by graziers for vegetation management. Sheepherders in

particular are singled out as guilty of burning the forests repeatedly, and for

overgrazing the range. A careful examination of anecdotal accounts reveals

that the situation was far more complex, and that it was part of a struggle for

natural resources between those who owned land, and those who did not. The

literature indicates that cattle grazing was by all indications no less abusive.

Tree-ring data presented in the SNEP report indicate that burning in late 19th

century, while frequent, was not extensive, and probably no more severe than

that caused by a combination of lightning and indigenous burning prior to

Euro-American settlement. In fact, some evidence indicates a thickening of the

underbrush and trees during this period. Anecdotal accounts reviewed here

provide support for this finding.

Knowledge of fire history is important in evaluating the relationship between

grazing, fire frequencies, and vegetation change over time. The more we know

about how and why the vegetation has changed, the better chance we have of

predicting the effects of current and potential management practices. Overall,

stocking rates in the Sierra have declined steadily through the twentieth

century. At the same time, reductions in fire frequency have likely reduced the

amount of forage available to grazing animals over the same time period.

Since the establishment of managed grazing on the national forests in about

1906, stocking rates on the forests have declined overall from highs achieved in

response to increased demand during WWI. Sheep have been gradually

replaced by cattle, though there are a number of viable sheep permits

remaining. Stocking rates have been by reduced by shortening the season of

use, and by the elimination of some permits, as well as by reductions in

numbers.

The present-day linkage between ranching and an ecosystem management

approach that considers the role of public lands in conserving the Sierra
39

ecosystem at a landscape scale is not directly addressed the SNEP report or in

most others for that matter. Considerable acreage in the Sierra foothills is

privately owned by ranchers who to some degree depend on access to public

forage. On the west side of the Sierra, this land is largely foothill oak

woodland, a type described in SNEP as severely threatened by development and

lacking needed protections (Vol II, Chap. 11). In the SNEP document, Duane

states, “...any factor influencing future patterns of human settlement has the

potential to affect...the health and sustainability of Sierra Nevada ecosystems”

(Vol II Chap 11, pg. 310). Ranching is one such factor.

Linkage between ranch foothill woodland ownerships and the use of public

lands by the ranching community is an issue that should not be ignored.

Ranchers own a lot of land, and it is ecologically important (Ewing et al. 1988).

The amount of land in the SNEP study area that is “range,” land used for

grazing, ranges from 4% in Shasta county, to 89% in Inyo County (Vol II, Chap

17, pg. 512). Smethurst (1997) found that in the Central Sierra, private land

used for grazing is second only to land used for timber production. Johnson

(1998) points out that "the future of these (foothill) woodlands lies almost

entirely in the hands of individuals, whose separate, independent decisions about

the disposition and management of their lands will cumulatively determine the

future of California's oak woodlands." Unfortunately, not enough is known

about the basis of rancher decisions and their possible response to various kinds

of ecosystem-wide conservation initiatives.

Overview of the Literature

Grazing in the nineteenth century

Historic writings show that a lack of active ownership and regulation of public domain

lands led to overgrazing in the Sierra as livestock owners competed for available forage in

the latter part of the nineteenth century. Both sheep and cattle are implicated, though

sheep are more mobile and seem to have been the most frequently observed in

contemporaneous accounts, as is well documented in Vol 2 Chapter 1, and Vol 2 Chapter

3 of SNEP. According to most accounts, even the Gold Rush did not lead immediately to

widespread grazing in the Sierra, but the droughts, floods, and over-supply of cattle and

sheep that followed in the 1860’s caused ranchers to drive their stock into the foothills

(Burcham 1982[1957], Burcham 1981, Burcham 1961, Claytor and Beesley 1979,

Edwards 1883, Gomez-Ibanez 1967, LeConte 1875). Competition for level crop lands

gradually limited ranching to the foothills and Sierra thereafter (Burcham 1982[1957]).

One author asserts that livestock began to be driven into the Sierra in 1864, in response to

devastating drought, and that before that time, forage in the Central Valley area was

sufficient (Gomez-Ibanez 1967, pg. 10). He points out that the well-known explorers
40

Henry Brewer and Clarence King first noted the presence of livestock in the Sierra in 1864

(Gomez-Ibanez 1967, pg. 36).

The exact distribution of grazing by cattle and sheep in the Sierra in the nineteenth century

is only known by implication, but it is clear that it was widespread. Burcham

(1982[1957]), a well known historian of California rangelands, describes a large

overstocking of beef cattle in the 1860s, and a number of authors mention that they were

driven into the Sierra due to drought and flood during this period (Burcham 1982[1957],

Burcham 1981, Burcham 1961; Claytor and Beesley 1979, Edwards 1883, LeConte

1875). Dairy cattle were also grazed in the Sierra, and as they must be kept within a

relatively short distance of the milking barn, at least one author states that “Dairy

cattlemen graze their herds entirely within fenced ranges in the higher mountains, always

including as much alpine meadow land as possible” (Sudworth 1900, pg. 511). On the

other hand Sudworth states that those who graze beef cattle claimed to own large tracts of

mountain land, but mostly used unfenced forest land during the summer grazing season

(Sudworth 1900, pg. 511). The regional histories presented in SNEP (Vol III, Chap 22

and Vol 11 Chap 17 pg. 502) mention reports that overstocking with cattle was reported

in early Forest Service documents as a problem in some areas. Farquar (1925, pg. 25)

observed that once transhumance was introduced into the Sierra, “cattle and sheep were to

be found in the most remote mountain meadows and canyon heads.” In his very thorough

and fair-minded report on conditions in the northern Sierra, Leiberg (1902) found cattle

grazing to be more extensive in many basins, particularly on the west slope, than sheep

grazing. He does imply that the steepest, most arid ranges are used primarily by sheep,

but does not make consistent observations about this. Sheep are known to be able to

graze further from water, and to use steep slopes, more easily and willingly than cattle.

In 1900, George Sudworth’s report to the Department of the Interior states “the necessity

for constantly seeking new pasture makes it impossible for sheepmen to maintain

headquarters at one point in the mountain range longer than a week or two at most, but

they graze their flocks over areas within boundaries fixed by common consent, or by

seniority of possession from year to year. The ranges used by sheepmen are usually those

not claimed or used by cattlemen” (Sudworth 1900, pg. 511). He also pointed out that

there was common agreement among sheepmen and cattlemen about which ranges were to

be used by whom. He found that the effects of sheep and cattle grazing were observed

throughout the unprotected forests of the entire region – in this case the Stanislaus and

Lake Tahoe Forest Reserves (pg. 553).

Abusive grazing by sheep is often held up disparagingly as the main cause of grazing

damage in the Sierra in the nineteenth century. A careful examination of anecdotal

accounts reveals that the situation was far more complex, and that it was part of a struggle

for natural resources between those who owned land, and those who did not. Accounts

cited in SNEP (Vol II Chap 3 pg. 41) and other histories indicate that there was pressure

to extend the season of grazing for sheep early (Muir 1911) because of competition for the

first forage, and late (Vankat 1970), because troops protecting reserve areas would leave

in the Fall. There is also ample evidence that the same areas were grazed more than
41

once (Magee, 1885). Beesley states that a common complaint made by nineteenth century

critics of sheepherding was that too many animals were grazing for too long (LeConte

[1875]1930, Edwards 1883) (SNEP, Vol 2, Chap 1, pg. 8). Sudworth comments that he

observed several flocks of sheep in 1900 that were so hungry they ate even pine needles

(Sudworth 1900, pg. 554). He also comments that while in 1900 “cattle grazing is now

carried on over the best range, sheep grazing has, on the whole, obtained over a far more

extensive territory and for a much longer time.” By 1900, according to Sudworth, sheep

had been “nominally excluded” by law from the Stanislaus and Tahoe Forest Reserves, and

from the best rangelands by cattlemen. Gomez-Ibanez makes the point that between 1890

and 1905, “sheepherders suddenly were barred from taking their bands onto most of the

customary grazings in the Sierra Nevada, and this came at a time when they also suffered

from the continuing encroachment of crop agriculture upon their winter ranges” (GomezIbanez 1967, pg. 59). Trespass and overcrowding resulted.

The intensity, timing, and type of grazing in various areas in the Sierra varied. Kinney

(1996) provides accounts that indicate grazing was effectively excluded from National

Parks starting around the turn of the century (Vol II, Chap 3, pg. 42). Vankat and Major

(1978) cite histories and early accounts to claim that sheep grazing was eliminated around

the turn of the century within Sequoia National Park, with cattle grazing allowed only in

certain areas until 1930. Sudworth (1900) states that grazing was eliminated from the

Calaveras big tree grove for 30-40 years prior to his visit in 1900 (pg. 553), and that he

was able to locate several other areas that had been protected for 15-20 years in the area

of his survey. William Russell Dudley, professor of Botany at Stanford University, wrote

after a tour of the Sierra in the late 1890’s, “To pass from the trampled meadows of the

reservation [Sierra Forest Reserve] to the protected meadows of the [Sequoia] National

Park is a lesson in patriotism” (Dudley 1898). Dudley’s observation from 1895 shows that

the army had succeeded in gaining some control over sheep grazing in the National Parks

by the turn of the century. Sudworth’s comments about Calaveras might imply that the

area was only grazed for a few years, if we take his comment, and the suggestion that

grazing did not start in the Sierra until 1864, literally.

Several accounts from this time period are quoted in SNEP (Vol. II, Chap. 3, pg. 42) as

testament to the destruction caused by sheep overgrazing in the late nineteenth century.

Sudworth discusses the differences between the effects of sheep and cattle grazing, saying

that sheep graze more closely, and unlike cattle, will browse conifers, among other things

(1900, pg. 554). Anecdotal accounts, however, are shaped by the tenor of the times.

Examining Dudley’s full report for example, one comes across the following passage:

To him [local farmers] the herder is a foreigner, a non-citizen, a parasite, who intends

eventually to move back to France, Portugal, or Ireland, whence he came, and carry

with him all his gains pilfered through sheep raising on land not his own (Dudley

1898).

Dudley’s concentration on sheep and his earlier reference to patriotism no doubt reflects

to some degree the anti-immigrant sentiments that were widespread in California at the
42

time, as is evidenced by the passage of California’s Chinese Exclusion Act in 1892.

Sheepherders tended to be immigrants. Towards the close of the nineteenth century, they

were commonly of Basque origin (Douglass 1970). Rowley (1985) states that the 1896

National Academy of Science Forest Committee report included the statement that sheep

were often owned by foreigners, "who are temporary residents of this country." Lane

(1974) documents what he terms the “public expression of an anti-Basque ideology”

common to the period. He quotes one of Nevada’s U.S. Senators, Key Pittman, as

providing Congressional testimony that “there is neither reason nor excuse for granting a

bonus to these laborers who are imported from the Pyrenees Mountains between Spain

and France, admitting allegiance to neither one nor the other of those great countries—

men who do not know what a home is, and do not recognize the authority of government;

men of the lowest type and the most inferior intelligence, who rarely seek to become

citizens of the country to which they are imported” (1913 Congressional Record as cited

in Douglass and Bilbao 1975).

Douglass (1970) points out that the “tramp” or “gypsy” sheep bands so bemoaned in

anecdotal accounts arose in large part when immigrant herders began herds of their own

by taking ewes instead of cash for payment, a practice he attributes to the “Basque pattern

of friendship, kinship, and ethnic ties.” He points out that in the 1890’s and up to 1934

many local and state laws were passed making it hard for sheepherders to use the public

domain, including special taxes, cattlemen filing on all the water, and the regulations for

acquiring National Forest permits which he argues were “designed to make the trampband operator move off of lands to which he had as much legal claim as his persecutors”

(emphasis added). The Taylor Grazing Act of 1934 ended the nomadic herders in the

western states, and from the Basque point of view discriminated against Basque enterprise

(Douglass 1970). The Basque presence in Sierra was maintained by those who managed

to acquire base properties (Douglass 1970), required by the Forest Service in order to

obtain most grazing allotments. Forest Service base property requirements preceded the

1934 Taylor Grazing Act (Rowley 1985), which was applied to the remaining public

domain grazing lands.

Early grazing and fire

Knowledge of fire history is important in evaluating the relationship between grazing, fire

frequencies, and vegetation change over time. The more we know about how and why the

vegetation has changed, the better chance we have of predicting the effects of current and

potential management practices.

Dudley (1898) and others comment on evidence of fire in Sequoia groves. Dudley states

that though most of the pines and firs he saw on his 1895 visit to the Sierra bore fire scars,

for some years “no extensive fires had occurred in the region traversed.” Leiberg’s careful

observations lead him to conclude that most of the fires in the Northern Sierra in
43

the year of his visit were associated with sheep camps, but he finds that these are not as

extensive as those he sees evidence of from the past, stating that “it is evident that during

the last decade fires in this region have greatly diminished, and those which have covered

the largest area during this period burned in chaparral” (1902, pg. 41). He suspects early

miners and indigenous people of having set more influential past fires: “the aboriginal

inhabitants undoubtedly started them at periodic intervals to keep down the young growth

and the underbrush. When the miners came, fire followed them” (pg. 40). These

observations lend support to the discussion in Skinner and Chang’s chapter in SNEP about

fire history (Vol II, Chap 38) where by correlating anecdotal accounts and tree ring

studies it is hypothesized that high fire frequencies caused by indigenous burning were

reduced by the destruction of Indian life in the mid-nineteenth century. They argue that

burning by herders in the 1890s was not necessarily more frequent than that originally

carried out by indigenous peoples, but was not as extensive, due to fuel reduction by

grazing (Vol. II, Chap 38, pg. 1058). The statement is made that decreased fuel

continuity reduced the spread of fire, so that in the tree ring fire record many areas show a

reduction in fire during the late 1800s and an increase in tree density (Vankat and Major

1978, Mensing 1992). Sudworth illustrates with pictures the bare forest floor in grazed

and burned areas, comparing them to protected areas with lots of understory shrubs and

tree regeneration (Sudworth 1900). He observes several instances of sheepherders setting

fires accidentally, and to clear brush to improve the forage supply and make herding

easier, noting in one case that 17 fires had been set on the trail of one band of sheep over a

distance of 10 miles (pg. 556). Leiberg (1902) attributes the continued existence of

“grassy fire glades” to burning and grazing, and notes that when protected from grazing

and fire, they rapidly become dense sapling stands (43). Vankat and Major (1978) cite the

Report of the Acting Superintendent of Sequoia National Park, 1897, as stating that the

amount of fires started by sheepherders had been overstated, and that lightning was the

chief cause (Barrett 1935). Heady and Zinke (1978) suggest that indigenous people were

a major factor in preventing tree regeneration during pre-settlement times.

Land tenure

At least one author in SNEP (Vol II. Chap 3, pg. 41), along with other authors too

numerous to cite here but epitomized by Holechek et al. (1998), describe the property

rights regime that led to extensive grazing abuses in the Sierra and elsewhere in the West

in in the 1800s and early 1900s as a “tragedy of the commons.” However, the situation

cannot be characterized as having been a common property regime, at least not by the

currently accepted definitions of such (Bruce 1993). It is instead an example of open

access resources, where no clear ownership is established or enforced (Bruce 1993). Some

resource economists and social scientists would argue that it could not be termed a

commons either, because a commons does not involve unregulated use. All commons

limit use because only community members (not outsiders) have a right to use them

(Bruce 1993). Current widely accepted definitions are:
44

common property resource: A resource managed under a common property

regime. Common property is a commons from which a community can exclude

non-members and over which the community controls use. A commons is land or

another natural resource used simultaneously or serially by the members of a

community (Bruce 1993).

open access resource: A resource to which access is open and uncontrolled (Bruce

1993)

The public domain rangelands were open to all for use, with no set group of owners or

community with rights of use, as in a commons, and no management regime, as in a

common property resource.

The federal government asserted no control over grazing use of most of its lands in the

Sierra until the twentieth century, and took direct action to maintain an open access

regime, according to the accounts presented by all SNEP historians, and others. In much

of the West, when ranchers attempted to exert control over public domain lands by

fencing, for example, fences were removed by the federal government to keep the range

open (Nelson 1995, pgs. 30-32). Yet the land allocation framework set out by the federal

government for the western United States did not provide for private ownership of an

adequate resource base for range livestock production (Nelson 1995). Ranchers came to

depend on public lands to supplement private holdings.

Twentieth century history

Stocking on Sierra rangelands dropped with the establishment of the Forest Reserves and

grazing management policy, and the exclusion of nomadic herds. It is difficult to assess

the appropriateness of early stocking rates set by the government. After the turn of the

century, historians in SNEP (Vol III, Chap 22 pg. 909), (Skinner and Chang, Vol II Chap

38) and elsewhere (Pyne 1982) agree that fire suppression led to an increase in

undergrowth and a gradual reduction in forage production in large areas of the Sierra.

Range productive capacity has been a moving target throughout this century, and

evaluating when AUMs allocated by the agencies and forage production capacity were

brought “into balance” (asserted to be in the 80s or 90s in SNEP Vol III, Chap 22, pg.

910) is difficult to evaluate. Stocking rates were initially set on the basis of “traditional

use” by the permittees, generally local landowners, and it is likely that the “traditional”

stocking rates were optimistic.

Although it is sometimes argued that overstocking on federal lands was stimulated during

both World Wars (SNEP Vol III, Chap 22, pg. 909), a prominent historian of the national

forests, Bill Rowley, asserts that while widespread overstocking occurred in response to

WWI, the Forest Service successfully argued against a similar increase in WWII (Rowley

1985). Forero (1998) conducted a painstaking study of stocking through the twentieth

century on the Shasta-Trinity National Forest. Forero’s (1998) analysis of grazing history

on the Shasta-Trinity National Forest found only a small increase in numbers during
45

WWII, in contrast to a magnitudes greater peak during WWI. Rowley (1985) mentions

that early in the twentieth century there was strong interest in providing allotments to new

landowners, and to distributing grazing permits more equitably among permittees. In

some cases attempts were made to reduce the permits of larger operators and redistribute

them to smaller operators. Reducing permits was extremely difficult, and this created

pressure to maintain high stocking rates to make room for newcomers (Rowley 1985, pg.

94). How much this social agenda affected stocking in the Sierra remains unknown.

Rowley (1985) discusses evidence that the Taylor Grazing Act of 1934, though it did not

apply to National Forests, created a competing range management agency within the

federal government, and caused the Forest Service to at least temporarily loosen grazing

regulation during the mid-thirties.

Reductions in stocking rates, by way of reducing the number of livestock grazing or the

duration of grazing, began fairly early on National Forest lands, and may have varied by

forest. Forero (1998) found that concerns about stocking and season of use appear early in

Forest Service documents for the Shasta-Trinity. The regional post-1905 histories

provided in Chapter 22 of SNEP, do not provide specific detail or sources (Vol. II Chap

22).It cannot be discerned how the stocking rate estimates were determined, whether they

were based on observations or actual data, and whether reductions in season of use were

accounted for.

In the Mammoth-June Lake Ecosystem study grazing history presented in SNEP it is

stated that an aggressive grazing adjustment program began in 1944, and that by 1950,

AUMs had been reduced by over 40% (Vol II, Appendix 50.1, pg. 1311). Data for the

Shasta-Trinity concurs with that reported above for the Mammoth-June Lake study in

SNEP. The sharpest declines in stocking occurred in the 1920s through 1950 (Forero

1998). Forero (1998) shows a very marked peak in the 20s followed by a continual and

relatively steep decline into the 70s, then a slower decline to the present. Permit changes

were evaluated in terms of AUMs, taking into account changes in season of use and in the

geography and extent of permits. This is important, as reductions in grazing during this

time were reductions in duration of use, as much as in absolute numbers (Forero 1998;

SNEP Vol II, Appendix 50.1, pg. 1311). It was found that at various times permits were

lumped together with others, and at other times split into smaller permits, making the

evaluation of this data difficult. Though sheep numbers were higher until about 1950,

cattle AUMs have always been greater than sheep AUMs on the Shasta-Trinity. Duration

of use has also declined over time, reaching a low during the drought of the 70s. These

patterns follow what would be expected based on the work of well known historians of

grazing on the National Forests (Rowley 1985). Data of similar accuracy and

documentation would be desirable for the rest of Sierra.

Methodological problems described by Forero (1998) for the Shasta-Trinity National

Forest may be of relevance to future work on stocking rates in the Sierra. He points out

that “Ranger District Files,” and “Forest Level Files,” (both used as sources in SNEP Vol.

III Chap 22), were often incomplete, had little information about grazing, and
46

differed radically from District to District in quality and amount of information. Allotment

Management Plans tended to be relatively recent, and not contemporaneous accounts.

A summation of the post-1905 history would be that stocking rates have declined overall

from both pre-Forest Service unregulated grazing where large numbers of animals used

the Sierra as an open access resource, and from highs achieved in response to increased

demand during WWI. Sheep have been gradually replaced by cattle, though there are a

number of viable sheep permits remaining. Much of the reduction has been by reducing

the season of use, and by the elimination of some permits.

Current ranching and ecosystem management

The linkage between ranching and an ecosystem management approach that considers the

role of public lands in conserving the Sierra ecosystem at a landscape scale is not directly

addressed the SNEP report or in most others for that matter. Considerable acreage in the

Sierra foothills is privately owned by ranchers who to some degree depend on access to

public forage. On the west side of the Sierra, this land is largely foothill oak woodland, a

type described in SNEP as severely threatened by development and lacking needed

protections (Vol II, Chap. 11). In the SNEP document, Duane states, “...any factor

influencing future patterns of human settlement has the potential to affect...the health and

sustainability of Sierra Nevada ecosystems” (Vol II Chap 11, pg. 310). Ranching is one

such factor.

Ranchers own a lot of land, and it is ecologically important (Ewing et al. 1988). The

amount of land in the SNEP study area that is “range,” land used for grazing, ranges from

4% in Shasta county, to 89% in Inyo County (Vol II, Chap 17, pg. 512). Smethurst

(1997) found that in the Central Sierra, private land used for grazing is second only to

land used for timber production. Johnson (1998) points out that "the future of these

(foothill) woodlands lies almost entirely in the hands of individuals, whose separate,

independent decisions about the disposition and management of their lands will

cumulatively determine the future of California's oak woodlands." Unfortunately, not

enough is known about the basis of rancher decisions and their possible response to

various kinds of ecosystem-wide conservation initiatives. Most simply assume that the

ranching community has no interest in conservation.

Attitudes and values of the ranching community and land use change

In the few studies that have been done in California, ranchers espouse values that rank

environmental amenities highly. A variety of studies have shown that the majority of

ranchers in California oak woodlands enjoy “living near natural beauty” (Huntsinger et al.

1997), and that one reason they keep ranching is because it makes them “feel close to the

earth” (Huntsinger and Hopkinson 1996). Similar results have been found in other studies

in the western U.S. (Smith and Martin 1972). Ranch fundamentalism, an idealization of

the independent ranching lifestyle, and the benefits of ranching to family life, have been

described by economists and others as major factors affecting the decision to ranch despite

low profits from the enterprise (Smith and Martin 1972, Martin and
47

Jefferies 1966, Bartlett et al. 1989). Smith and Martin (1972) found that ranchers in

Arizona resisted selling ranches at market prices far exceeding their value as livestock

operations for reasons that included “love of the land,” and “love of rural values.” A

recent Masters Thesis completed in El Dorado county’s Sierra foothills found that

ranchers continue to ranch in the face of economic hardship and development pressure

because they enjoy the tradition and the way of life and want their children to be able to

ranch if they so choose (Hargrave 1993). Similarly, at least one researcher has described

the ranch as a unit of consumption rather than production (Grisby 1976 & 1980).

Standiford et al. (Vol III Chap 15 pg. 638) assert that “voluntary educational programs

have made dramatic progress in accomplishing sustainable management practices by

ranchers.” Statewide, the percentage of ranchers who believe oaks are being lost in

California, and who do not cut any living oaks, increased dramatically between 1985 and

1992 (Huntsinger et al. 1997). Numerous studies note that social factors, values, and

attitudes, and not just profits strongly affect the decisions of range livestock producers

(Grigsby 1976, Martin and Jefferies 1966, Shanks 1978, Smith and Martin 1972, Bartlett

et al. 1989).

Many foothill woodland ownerships have been in place for a long time. Huntsinger et al.

(1997) found that more than half of ranching families throughout California’s oak

woodlands had owned their land for more than twenty years. Johnson (1998) found that in

El Dorado and Amador foothill woodlands, 32% of active ranching families had owned

their land for more than 100 years; 57% for more than 60 years. In Tulare County,

McClaran and Bartolome (1985) found that 28% of ranches had been owned more than 60

years, and another 31% for more than 31 years. In a study of Central Sierra ranches,

Smethurst (1997) found that ranchers have, over the decades, managed for an open oak

woodland, and have shaped the foothill woodland environment.

A variety of studies have identified distinct ranching cultures around the globe that are

recognized as historically significant (Adams 1967, Douglass and Bilbao 1975, Khazanov

1983, Marshall and Ahlborn 1980, Starrs and Huntsinger 1998, Starrs 1998). A

reluctance to call on outside intervention to resolve disputes or environmental problems

has been described as norms for California ranchers. Instead, western ranching culture has

been found to rely heavily on tradition and customary law (Grigsby 1976, Ellickson 1986

& 1990, Huntsinger and Hopkinson 1996, Huntsinger et al. 1997). Statewide, more than

80% of oak woodland landowners with more than 20 acres agreed that “state regulation

means a loss of liberties and freedom” (Huntsinger et al. 1997). A large majority of

ranchers surveyed in Tehama county, California, reported that livestock trespass problems

should be resolved by contacting the owner or herding the stock back to the owner, rather

than involving any outside enforcement (Huntsinger and Hopkinson 1997).

Ranching as an enterprise to some degree relies on other ranchers and the rural community

for social and economic reasons, for outside jobs, informal labor pools, and support

services (Smith and Martin 1972, Ellickson 1991, Hart 1991). This has been
48

described as the need for a “critical mass” of ranching operations to maintain a viable

community (Huntsinger and Hopkinson 1996, Hart 1991). Estate taxes, conflicts between

multiple heirs, and lucrative purchase offers for land may lead ranchers to sell their land to

developers (Johnson 1998, Smethurst 1997, Hargrave 1993). In her study of ranches in El

Dorado and Amador counties, Johnson points out that "a single ranch-owner's decision

may spell the fate of many thousands of acres. Landowner decisions affect more than their

own property, as nearby properties are also influenced through the fragmentation of land

use, weakening of the agricultural infrastructure, changing land values, and the creation of

new growth nodes in previously undeveloped areas (Johnson 1998, pg. 111). This type of

effect has been noted by a number of researchers into land use change (Berry and Plaut

1978, Hart 1976, 1991). Berry and Plaut (1978) in their review of the land use change

literature are perhaps the most succinct:

At the local level the most remarkable feature of the urbanization process is its great

dispersion over the landscape. Urban development proceeds by scatteration and some

infilling rather than by accretion contiguous to past development.... it is evident that a

relatively small amount of rural land converted to urban uses by this scatteration

process will drastically alter the appearance of the landscape, making formerly rural

areas neither truly rural nor truly urban...From the local perspective, then, it is not

necessarily the volume of farmland or woodland conversion to urban uses that matters,

but rather the dispersal of this development over the landscape. These visual effects are

another of the "costs of sprawl."

The effects of urbanization transcend the conversion of land from rural to urban uses--

they also influence what the farmer does to the land....As this nonfarm population

increases in size it is not surprising that the farmer's political and economic status in his

community becomes relatively diminished and that nonfarm needs become politically

important. ...Among those spillover effects that are political and economic in nature are

1. regulation of routine farming activities to suit urban neighbors; 2. acquisition of

farmland to build roads, reservoirs, and other components of the urban infrastructure; 3.

increase in property taxes and special district assessments to pay for new urban-oriented

services. The increasing density of nonfarm population also may bring new problems

for the farmer, such as damage to crops caused by air pollution, mischievous

destruction of farm equipment or crops; or harassment of farm animals. Because

spillover effects present the farmer with a set of managerial issues and expenses that he

did not have to cope with before, it may become necessary to accommodate regulations

of farming activity, to build new fences to keep children out of the orchards, to work at

community relations explaining to non farmers that farming is a business, and so on.

One would not expect all farmers to be equally able or willing to cope with these

problems. Some farmers complain bitterly and talk about selling out, while others seem

to have sufficiently mastered the art of community relations to continue farming

successfully.

In rapidly developing counties, researchers have found that much ranch land is being held

for development by speculators. McClaran et al. (1985) found that the Williamson Act as
49

an incentive to reduce development was most effective in areas where development

pressure was not yet high. Johnson (1998) found that foothill woodland owned by

investors and developers was 52% at least and could be as high as 62% of the total in El

Dorado and Amador Counties. Another 18% was owned by out of county owners,

resulting in a total of 78% of foothill woodlands in unstable forms of ownership in El

Dorado, and 51% in Amador. About 12% and 19% of the woodlands were owned by

active ranch families, with another 29% in giant trust from a land grant in El Dorado.

Smethurst (1998) concluded that the “Sierra is being transformed to an absentee-owned

landscape, where natural resources such as water, timberland, and recreational assets are

owned by those living outside the region. Residential development has increased, while

ranching, farming, and hardwood rangeland have declined.”

Johnson found that ranching families that want to remain (perhaps those who can cope as

described by Berry and Plaut (1978) above) are often public lands users (pg. 126), and

that all the ranchers she interviewed relied on finding sources of summer forage, and found

that rentable private pasture was in short supply. She concludes that “every rancher who

loses a lease on a high country pasture and seeks rentable pasture near the home ranch is

heightening competition for a commodity already in short supply. These problems could

well encourage ranchers to cut back herd size or just go out of business....Because

livestock returns are such a small percentage of land value, it is unlikely land will be

purchased for new ranches or purchased to be rented out for pasture; thus, development

is the most likely future of land that is abandoned for ranching. In this way Federal land

policies regarding grazing leases in high country locations can easily influence landowner

management decisions on the home ranch miles away” (pgs. 152-3).

Smethurst (1997) argues that as foothill ranchers are linked with the forest economically,

changes in access to resources in the forest will affect the base ranch as well. He

comments that “in an effort to protect public lands from degradation due, allegedly, to

grazing by cattle, proponents of regulations and fee increases have ignored the ecological

links between private ranch lands and national forests. These regulation externalities

could cause a shrinking of wildlife habitat and a corresponding decline in wildlife

populations such as endangered spotted owls. Weakened property rights create

uncertainty among ranchers about their long-term control over and access to forest lands

that they must manage.”

A large majority of ranchers surveyed in Tehama County agreed that “urbanization is a

threat to ranching” (Huntsinger and Hopkinson 1997). Most wanted to see their land

remain used for livestock production in the future. At the same time, they also perceived

local and state land use planning as a threat. Conservation easements have been shown to

be one viable option for maintaining ranching (Wright 1993, 1993b, 1994, & 1997;

Barrett and Livermore 1983) because they can be structured as an integrated incentive that

meets the needs of the larger society, and those of ranchers. Conservation easements can

help ranch estates in two ways: first, by reducing the value of the estate and second, by

generating substantial charitable deductions when given to qualified organizations

(Johnson, 1998, pg. 214). Because ranches in the Sierra often rely on public forage, any

large-scale efforts must be coordinated with the USFS. Trust, built on support for rancher
50

needs and the voluntary nature of participation, is described as one element that can lead

to successful efforts in landscape conservation through easements (Daggett 1996, Hart

1991). Beginning the process before development pressures are high seems likely to

increase success.

Part VI: Social Impacts of Sierra Livestock Grazing on Forest Service

Land

Abstract/summary

Grazing is generally seen as controversial on Forest Service and other public

lands. There is little widely available or published recent work on this topic

specific to the Sierra Nevada. Further study of these topics would be desirable.

There are indications that one fundamental basis for the polarization of views

about the impacts of livestock grazing or about livestock grazing in general is

different perceptions of what “environmental damage” consists of. Studies have

shown that people of differing backgrounds, education, goals for use of public

lands, and places of residence differ in their perceptions of scenic quality and

environmental damage (Sanderson et al. 1986, Richards and Huntsinger 1994,

Huntsinger and Heady 1988, Brunson and Steel 1994).

Both grazing by domestic livestock, and grazing by recreational packstock, can

affect the experience of the recreational visitor.

Overview of the Literature

Impacts of grazing on recreation

Sandersen et al. (1986) found that their respondents in a study of recreationists in Malheur

National Forest of eastern Oregon had a positive attitude toward range management

practices including fencing and grazing overall. Fishermen viewed grazing with the most

disfavor, preferring that it be kept out of riparian areas with fencing if necessary. They

also viewed use of herbicides, and increased access for river recreationists, as problems.

Hunters felt that grazing had little impact on their experience. Campers typically did not

“mind looking at cows from a distance but wouldn’t want to camp with them,” and

preferred that cattle be fenced out of campsites. Those who believed that the primary

purpose of the National Forest was for preservation or recreation were unlikely to view

grazing positively; those who lived in western Oregon or out of state were also more

inclined to object to grazing and fences. Respondents who felt that the National Forests

were for multiple use were highly unlikely to find grazing and fencing objectionable. All

the survey respondents were those that had chosen to continue to recreate in this grazed

area, yet most felt that an intensification of grazing or fencing would negatively effect their

recreational use.

Mitchell et. al. (1996) found that without any cuing, 9% of all visitors surveyed in the Big

Cimarron Watershed of the Uncompahgre National Forest in Colorado listed livestock as

the most important source of interference in their experience. However, when surveyed
51

and given a choice, the number of visitors indicating that range livestock (cattle) added to

their stay (34%), was no different than the number stating a negative relationship (33%).

In this study there was no consistent relationship between attitude toward livestock

presence and home community size, or size of community where the respondent grew up.

Visitors in dispersed campsites tended to be more critical of grazing than those in

developed campgrounds, and visitors from rural areas (25% of the sample) were less likely

to be critical of livestock grazing. Follow-up questions on desired changes in management

found that 10% of visitors wanted cattle removed from the National Forest, while 60%

could think of no needed changes.

Huntsinger and Heady (1988) found that local community members, BLM employees,

grazing permittees, and members of Oregon environmental groups had very different

views of the degree of environmental damage on Malheur County rangelands. Permittees

thought the rangelands were in the best shape, and environmentalists the worst, with local

residents and BLM employees in the middle. Permittees and environmental group

members were also extremely polarized on the issue of whether there was “too much

wilderness” in Malheur (almost all the permittees agreed, almost none of the

environmentalists) or too much grazing (completely the inverse of the other question).

Richards and Huntsinger (1994) found that among BLM employees in the area, length of

service was related to views of grazing, with newer employees having a less favorable

view.

Brunson and Steel (1994) used a nationwide phone survey to discern public attitudes

toward public land management practices, including federal rangeland management. Most

people were neutral on whether or not livestock grazing should be banned on federal lands

(45%), and on whether federal range policy should emphasize livestock grazing (32%).

About 60% agreed that federal range was overgrazed by cattle and sheep, 74% believed

that most wildlife populations were declining on public lands, and only 17% believed that

the extent of overgrazing on federal rangeland had decreased markedly in the last 50

years. Eighty-three percent agreed that a loss of streamside vegetation is a serious range

problem. Respondents felt that “affected local communities” should be given the highest

priority in federal management decisions, followed by national public opinion and then

government natural resource agencies. Environmental groups and affected local industries

were given almost identical rankings below. The authors concluded that the “relatively

large number of noncommital responses” (as many as 45% of the sample), showed that

public attitudes about federal rangelan management are shallow-rooted and vulnerable to

strategies for inducing attitude change. They also conclude that there are “widespread

misconceptions about the overall state of range resources on federal lands”.

Impacts of packstock use

Grazing in the Sierra by packstock has a history longer than that of cattle or sheep grazing

in the Sierra. Packstock were used to bring in supplies to mining camps, but after the

Gold Rush use declined until it began to grow in popularity after WWI (Livermore 1947).
52

Travellers in the nineteenth century sometimes mention a lack of forage for packstock

because of heavy use by cattle and sheep, but establishment of the National Parks, by

excluding grazing, assured forage for packstock (McClaran 1989). At the same time,

limits on hunting in the Parks were seen as a negative for the industry early on (Livermore

1947). By the 1930s recreational pack stock use in the entire Sierra Nevada increased

significantly, and by the 40s there were 60 stations in operation with over 3000 horses and

mules for hire (Livermore 1947). The Sierra Club sponsored their first annual high trip in

1901--250 people spent a month in the backcountry with more than 100 pack and saddle

stock and 15-20 packers. After 42 trips, efforts were made to reduce the impacts by

limiting the trip to 125 people in 1947. The trips were abandoned in 1974 (McClaran

1989).

To some, packstock enhance the pioneering experience of a visit, while others may find

the smell of domestic animals and the sounds of their bells and neighing to be the antithesis

of an experience predicated on escaping the sites and sounds of man (Moore and

McClaran 1991). The sight of grazed vegetation, trampled soil, feces, hitchracks, and

drift fences also influence the visitor's experience. The impact is greatest in camp and trail

settings where backpackers and packstock users are in close proximity. In general, hiker

satisfaction is reduced when they encounter packstock in wilderness (Lucas 1980). The

impact has been found in one study to be greatest where there are little stock (Stankey

1979), indicating that impacts may be worse if packstock use is dispersed away from

traditional areas (McClaran and Cole 1993).

The National Parks have been particularly concerned about the effects of packstock

grazing and trails. There have been over 10,000 recreational pack stock nights per year in

Sequoia and Kings Canyon National Parks since 1977 (McClaran 1989). Forty-three

percent of the trips are from 17 commercial pack stations servicing riding and spot trips,

28% were private groups with own animals, and the rest were park trail crews and

backcountry rangers. However, less than 5% of backcountry users use stock. Overuse by

packstock was acknowledged in 1936 by the National Park Service, and an active

management program that included closure of some meadows and other strategies

characterized as “reactive” by McClaran (1989) began in 1958 (McClaran 1989). A more

proactive approach was initiated with the completion of a comprehensive plan in 1986.

Education of pack operators about minimum impact techniques, the publication of

guidebooks, and user conferences help to minimize impacts (McClaran 1989).

Cole (1989) reviews the literature on recreational pack stock effects. In one study, trails

produced by 1000 horse passes were 2 to 3 times as wide and 1.5 to 7 times as deep as

trails produced by 1000 hiker passes. The bulk density of soils on horse trails increased

1.5 to 2 times as rapidly as on hiker trails. One half the vegetation cover was lost after

1000 hiker passes and 600 horse passes in a grassland and after 300 hiker passes and only

50 horse passes in a forest (Weaver and Dale 1978). Other studies have found that while

hiker use tends to stabilize trail surfaces, horse use loosens the soil, making it more prone

to erosion (Whittaker 1978).

In the Bob Marshall wilderness, Montana, stock sites were 6 times as large as backpacker

sites, with more than 4 times the devegetated area, 11 times as many damaged trees, and
53

25 times as many trees with exposed roots. Stock sites had lost more of their organic

horizons, were more compacted, had slower infiltration rates, and had been more

extensively invaded by exotic plants (Cole 1983). Parties traveling with horses are larger

and stay longer, and are more likely to use a wood fire and to visit during the fall (Lucas,

1985). If stock are dispersed, they are likely to have a greater impact on the ecosystem

(Cole 1989).

Durable sites have been a time-honored approach to limit the extent of packstock effects,

but they can be problematic: Provision of facilities and attempts to confine use are

sometimes considered inconsistent with management goals. This appears to have made

the provision of facilities to reduce packstock impacts unpopular with managers, except in

National Parks (McClaran and Cole 1993). Research in wilderness areas showed that the

impacts of packstock on visitors are usually concentrated at popular places in the

wilderness, often near campsites and along trails in particularly scenic or accessible areas.

For example, in the Eagle Cap Wilderness in Oregon, Cole (1981) estimated that grazing

impacts were confined to less than 2 percent of the wilderness area. Cole concludes that

wilderness-wide application of regulations may not be required, and may unnecessarily

infringe on the visitor’s wilderness experience (Cole 1990).

After a review of the literature and a survey of wilderness managers, McClaran and Cole

(1993) conclude that regulations most limiting visitor freedom and access should be

applied only where necessary, in a site-specific manner. Limits on numbers of animals and

parties and on season of use are the packstock management actions most likely to interfere

with freedom, and they are generally the most specifically applied by management.

Party-size limits may be more important to avoid conflict with backpacking groups. Such

groups particularly dislike encountering large parties with stock (Stankey 1979).

Restricting packstock to existing trails and prohibiting loose herding is important in

preventing the destruction of existing trails, the development of new trails, and in

preventing visitor conflicts caused by runaway animals (Cole 1989). Cole argues that in

addition to knowing more about the ecological effects of grazing, needed areas of research

include more about the effects of differing ways of restraining stock. Hobbles, pickets,

hitchlines, and corrals are all used. More information is also needed about stock and

wildlife interactions and the grazing behavior of stock, and the overall significance of their

impacts.

Part VII: Summary

We have provided a brief glimpse into a large body of the literature relevant to Sierra

Nevada ecosystems and livestock grazing. There is ample evidence to conclude that

grazing as a process is rarely clearly defined, yet needs to be in order to judge ecosystem

response. Abusive grazing is bad and results in unacceptable ecosystem response.

Removal of all grazing results in ecosystem change.

What is missing is a comprehensive synthesis of what we know and don’t know about

different kinds of grazing based on experimental and other kinds of studies. Such a
54

synthesis requires more time and additional expertise. Response will vary by spatial and

temporal scale, and interpretation of effects will vary by area of expertise and values of

individuals.

The social question of whether livestock belong as a use of public lands will not be

answered by science. However, a critical synthesis of the literature provided in this report

and elsewhere will provide the scientific base from which social/political decisions can be

made. Our team, hopefully joined by others, will initiate such a synthesis over the next

year.

Acknowledgments

The Rangeland Science Team thanks UC Berkeley ESPM 268 graduate students, Randall

Jackson, Rich Shefferson, Janice Alexander, Julie Fetherston, Jim Robins, Pete Van

Hoorn, Lisa Mabli, Robin Liffman, and UC Davis students Linda Vance and Betsy Martin

for literature retrieval and review.
55

Cited Literature

Adams, D. C., R.E. Short, M.M. Borman, and M.D. Macneil. 1991. Estimates of fecal

output with an intra-ruminal continuous release marker device. J. Range Manage

44(3): 204-7.

Adams, R. F. 1967. The Cowman and his Philosophy. Austin, TX: Encino Press.

Adams, T. E., P. B. Sands, W. H. Weitkamp, and N. K. McDougald. 1997. Oak seedling

establishment by artificial regeneration on California rangelands. In:N. H. Pillsbury,

J. Verner, and W. D. Tietje (tech. coords.) Proceedings of the symposium on oak

woodlands, ecology, management, and urban interface issues. Albany, CA:

Pacific Southwest Research Station, USDA Forest Service.

———. 1992. Oak seedling establishment on California rangelands. J. of Range Manage.

45: 93-98.

Afzal, M, and W. A. Adams. 1992. Heterogeneity of soil nitrogen in pastures grazed by

cattle. Soil Sci. Soc. of Am. J. 56: 1160-1166.

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Appendix I: Evaluation of SNEP Statements about Livestock

The Sierra Nevada Ecosystem Project (SNEP) was an effort supported by Congress to

conduct an independent science assessment of the conditions and trends in ecosystems and

communities of the Sierra Nevada. The effort was enormous; more than 50 scientists

authored or co-authored articles which pulled together information on the Sierra Nevada

ranging from forest health and productivity to economic impacts of development and

human population growth.

The original RST charter stated that the team would review the existing scientific basis for

management decisions including a review of the SNEP report as it concerned livestock

grazing. The team chose to review the SNEP and SNST reports and collect all statements

made about effects of livestock grazing from the different chapters. A page-by-page

review as well as electronic word-search review resulted in a compilation of 101 quotes.

Team members then traced back the literature foundation for each quote starting with the

literature cited in the quote.

In tracing SNEP cited literature (from a statement) back to the original sources, we found

varying degrees of support for each statement. We have found citations that are valid

interpretations of research work as well as citations that are completely irrelevant to the

statement. We found citations that were based on the author’s conjecture in the discussion

section of a paper (not data), and we found SNEP authors offering opinions with no

citations, and for which we found no experimental basis in the literature available to us. A

key problem with the grazing literature cited in SNEP and SNST is that the authors do not

always differentiate between peer-reviewed original research, non-peer-reviewed

proceedings, editorials, position statements, or informational pamphlets, etc. when

supporting statements.

The appendix is organized by major heading as in our review of the literature. Quotes are

provided (in italics) and referenced to the Chapter and page in the SNEP or SNST

document. Each quote is then followed with an evaluation of the cited literature.

Livestock and Water Resources

Statements concerning links between livestock and specific water resources issues (i.e.

“grazing” impacts on infiltration, stream temperature, stream bank stability, etc.) are found

throughout at least 7 chapters and 3 volumes of the document (Volume 2 Chapters 25, 30,

33, 36, Volume 3 Chapters 5 and 22), and in Appendix I of the SNST Report. Similar

statements are grouped and discussed together as concepts of livestock linkages to

specific water resources issues.

A break down of the ~62 references used in SNEP reveals that 14 (22.6%) are peerreviewed journal articles, 21 (33.9%) are technical reports, 13 (21.0%) are proceedings

papers, 1 (1.6%) is a thesis, 1 (1.6%), 1 is an unpublished report, 1 is a video tape, 2
99

(3.2%) are informational pamphlets, 5 (8.1%) are textbooks, and 4 (6.5%) are other

SNEP Chapters.

The SNST Report Appendix I contains 22 citations in its handling of the subject. Of these

4 (18.2%) are peer-reviewed journal articles, 5 (22.7%) are technical reports, 1 (4.5%) are

proceedings papers, 3 (13.6%) are thesis, 1 (4.5%) are informational pamphlets, and 8

(36.4%) are SNEP Chapters.

SNEP Statements Concerning Upland Soil Cover, Soil Compaction and Infiltration:

1. Overgrazing can also influence soil compaction, erosion, and lowering of water

tables. Volume 1, Chapter 7, Page 115

2. Soil moisture late in the growing season has decreased, and soil bulk density has

increased due to compaction from higher herbivore densities. Volume 1, Chapter 7,

Page 120

3. Gradually during this period (note 1900-1940), cattle began to replace sheep on

many Sierran ranges, resulting in more soil compaction and increased effects on

vegetation in riparian zones (Lux 1995). Volume 2, Chapter 1, Page 14

4. When insufficient vegetation remains after grazing, raindrop impact can change

surface conditions and consequently reduce infiltration and increase runoff (Ellison

1945). Volume 2, Chapter 30, Page 899

5. Soil can become compacted by the repeated pressure of moving animals, especially if

the soil is wet. The combination of soil exposure and compaction can decrease

infiltration and increase surface runoff. If infiltration capacity is severely limited on

a large fraction of a catchment, the extra runoff can quickly enter streams and

generate higher peak flows (e.g. Davis 1977). Volume 2, Chapter 30, Page 899

6. If the animals remain in one place too long, and consume much more than about half

the available forage, vegetative recovery may be impaired and an excessive amount

of bare soil may be expose to erosive rainfall (Fleischner 1994; Committee on

Rangeland Classification 1994). Volume 2, Chapter 30, Page 899

7. Removal of vegetation and compaction of soils by cattle can decrease infiltration and

consequently increase surface runoff and augment local peak flows (Behnke and

Raleigh 1979, Platts 1984). Volume 3, Chapter 5, Page 221

8. Livestock consume plants that hold the streambanks and soil together; mechanically

alter the form, structure, and porosity of soils; and change the composition of the

plant community. Volume 3, Chapter 5, Page 212

9. Since one of the potential primary negative impacts of overgrazing is to alter the

water holding capacity of soils due to soil compaction or lowering of water tables
100

due to stream down-cutting, the relative abundance of grasslike and true grass

species is an important indicator of this change. Volume 3, Chapter 22, Page 923

10. Trampling compaction effects will naturally reverse themselves with natural

freeze/thaw and wetting/drying annual cycles if sites are protected from grazing

period during wet periods for 5-10 years. Tap roots of abundant forbs in overgrazed

meadows will decompose providing routes for improved water infiltration so that it

again reaches subsoil layers. Fibrous rooted grasses will become more deeply rooted

during meadow/riparian restoration stages. Productivity will increase. Temporally

controlled livestock grazing can be a part of this restoration process because grazing

stimulates nutrient availability and plant growth if managed strategically. Volume 3,

Chapter 22, Page 397

11. Trampling reduces soil porosity especially when soils are wet and of high clay

content (D. Zamudio, Toiyabe National Forest, pers comm). Repeatedly trampled

wet or mesic meadows tend to become drier and of lower productivity due to lowered

water infiltration and water holding capacity, and increased runoff. Volume 3,

Chapter 22, Page 936

12. A large literature exists justifying plant community composition and bare soil

exposure changes as indicators of grazing impacts (NRC 1994, Ratliff 1985). We will

not review that literature here except to say that excessive defoliation and trampling,

both temporally and spatially, can selectively reduce growth capacity of individual

plant species thereby reducing their fitness and survival leading to plant community

composition change. Volume 3, Chapter 22, Page 922

13. Heavy grazing usually reduces foliage density and increases bare ground in the

community thereby making sites available to invasion of exotic species if they are

present on a grazing unit. Many of the so-called “increases” on mountain meadow

rangelands are native forbs which can be substantially increased in abundance with

frequent grazing (Ratliff 1985). Volume 3, Chapter 22, Page 936

A review of the Literature Cited in SNEP

Lux (1995) is an appendix in a draft USFS environmental impact statement. This reference

was not evaluated.

The paper (quote 4) by Ellison (1945) reviews the results of several experiments on the

simulated effects of raindrop impacts and overland flow on infiltration capacity and sheet

erosion. None of these studies, or Ellison’s paper, focus on rangeland or grazing. Ellison

does a reasonable job of summarizing the state of the knowledge on the physics of the

raindrop soil surface interface, soil aggregate decomposition, infiltration, and sediment

transport as overland flow in 1945. The case is clearly made that when left bare to rainfall

the soil’s surface is subject to extreme energy which will commence erosion and sediment

transport, as well as to destroy soil surface structure reducing infiltration
101

capacity. Given that it is not the objective of the paper, specific guidelines for the amount

of cover required to protect rangeland soils, or any soils, are not given.

The paper (quote5) by Davis (1977) is in the proceedings of a conference, and does not

appear to be peer-reviewed. The paper seems to focus on southwest riparian habitats. No

original data or research is presented in the paper. Davis does state in several places in his

paper that in his opinion, “Over grazing and the consequent loss of vegetative cover in the

adjacent watersheds is probably the main reason for the frequency of high intensity floods

resulting in drastic changes to the density and composition of riparian bottoms.” Davis

gives no references to support his statements, nor does he analyze any flood data to

support the contention that the frequency of high intensity floods has increased on a

particular southwestern rangeland watersheds, or rangeland watersheds in general.

Fleischner’s paper (1994) is a review article discussing the general ecological impacts of

over-grazing in western North America. While Fleischner does not discuss the 50%

utilization definition for over-grazing as cited, he does give a very concise summary of the

controversy over the definition of the term. He also points out that a large portion of the

literature does not quantify grazing intensity, stocking rate, etc. making it very difficult to

evaluate or interpret the work. In many cases he points out the inconsistent use of relative

terms such as light, moderate or heavy grazing. With regard to bare soil (quote 6),

Fleischner in turn cites Schulz and Leininger (1990), Ohmart and Anderson (1982),

Cooperrider and Hendrix (1937), Davis (1977), Cottam and Evans (1945), Gardner

(1950), Kauffman et al. (1983), and Ellison (1960). Despite his own argument, Fleischner

does not define or describe the “grazing” reported in Schulz and Leininger (1990),

Ohmart and Anderson (1982), or Cooperrider and Hendrixs (1937). He does state that

Cottam and Evans (1945), Gardner (1950), Kauffman et al (1983), and Ellison (1960) are

comparing “heavy grazing” and “overgrazing” to no grazing.

The Committee on Rangeland Classification (1994) does not seem to support the concept

of overgrazing as cited in quote 6. The publication, Rangeland Health: New Methods to

Classify, Inventory, and Monitor Rangelands, represents an effort by a committee

composed of university scientists, federal land management agency staff, environmental

organization representatives and ranchers. The Committee was convened by the Board of

Agricultural of the National Research Council to address the complex issue of “rangeland

health”. The Committee provides a thoughtful discussion of the need to assess range

condition from all perspectives, not just one focused on the condition of the range for

livestock production (such as “take half, leave half). The Committee does discuss at length

the importance of the soil resource to range health, making a strong case that soil erosion

and thus bare soil should be one of the primary indicators of “range health”, and citing

several references in this context. No site specific values for adequate soil cover or

utilization are given, nor would one expect them to be given from such an effort.

The proceedings paper by Behnke and Raleigh (1978, not 1979) is defined by its authors

as “...the perspectives of two fisheries biologists on some of the issues raised at the forum

and suggests some grazing management options to protect riparian/stream ecosystems
102

from excessive grazing damage.” The Behnke and Raleigh’s paper is a proceedings

paper discussing and citing papers from the proceedings of a previous meeting. It is not

clear if either proceedings was subject to peer-review. With specific regard to the

“removal of vegetation” portion of quote 7, Behnke and Raleigh (1978) state “It is

primarily in arid and semi-arid regions that riparian vegetation is susceptible to

overgrazing. Once the vegetation is removed, heavy rains are not absorbed by the soil and

run overland causing erosion. When this occurs the amplitudes of peak runoffs are

tremendously increased.” There is no citation nor original data given in support of this

series of statements. The paper seems to focus on riparian impacts rather than vegetation

removal, increased overland flow, etc. and will be discussed in more detail in a later

section of this report.

The paper by Platts (1984) is a proceedings paper on 7 years of research on the utilization

of 17 riparian areas located in Idaho, Nevada, and Utah under continuous and rest

rotation grazing by sheep and cattle grazing. Although Platts’ initial literature review

generally supports quote 7, the objective, focus and research in the paper is along a

different line and is quite interesting. A major objective of the work is to identify and

document riparian grazing management strategies which do and do not “balance forage

and fish needs.” Platts does identify some important future research needs to allow

identification of riparian compatible grazing management. This paper will be discussed in

a later section of this report.

SNEP Statements Concerning Channel Stability and In-stream Flow Processes:

14. Wet and mesic meadow ecosystems, if overgrazed, show a trend of grass and legume

composition increase at the expense of sedge and rush composition. Volume 1,

Chapter 7, Page 118

15. Overgrazing and livestock concentration in riparian zones have altered stream

morphology and vegetative composition in may areas throughout the Sierra Nevada.

Volume 1, Chapter 7, Page 129

16. Consequently, riparian vegetation is overgrazed, banks are trampled and eroded

back, and bed deposits are disturbed......Degradation of riparian vegetation permits

bank erosion to accelerate under the more frequent peak flows that are caused by the

decrease in infiltration capacity. About half of the channels in the Meiss allotment in

the Upper Truckee River watershed were identified as being in fair or poor condition

as a result of overgrazing (Lake Tahoe Basin Management Unit 1993). Changes in

channel morphology have been related to overgrazing in headwater steams tributary

to the Carson River (Overton et al 1994). Elimination of riparian vegetation by

overgrazing in the broad alluvial valleys of the North Fork Feather River has led to

rapid channel widening and massive sediment loads (Hughes 1934, Soil Conservation

Service 1989). In other areas, such as meadows of the Kern Plateau and San Joaquin

River Basin, downcutting has followed overgrazing (e.g. Hagberg 1995). Volume 2,

Chapter 30, Page 899
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17. Livestock grazing has decreased or eliminated riparian vegetation, broken stream

banks, widened stream bottoms, increased sediment, decreased shade, and increased

water temperature (Platts 1978, California State Lands Commission 1993, Li et al.

1994, Menke et al. 1996). Volume 2, Chapter 35, Page 990

18. From Table 36.3 Volume 2, Chapter 36, Page 1014.

Ecological Consequence Physical Effects References

Livestock trample and

compact banks

Prevent establishment of

vegetation, crush

amphibians

Armour et al. 1991 Chaney

et al. 1990 Jennings 1996

Livestock hooves chisel

banks

Destroy existing vegetation,

destroy undercut banks,

contribute to channel

widening

USDA-FS 1995, Overton et

al. 1994, Kondolf 1994c

Livestock browse seedlings Recruitment of young

woody riparian plants

prevented

Platts 1991

Removal of vegetation, and

compaction in watershed

leads to increased peak

runoff and erosion possible

decreased base flow

Erosion of banks supporting

riparian vegetation

Behnke and Raleigh 1979

Platts 1991, Dudley and

Dietrich 1995

Previously listed factors lead

to incision of channels

especially in meadows

Water table drops,

desiccating wetland species

Odion et al. 1990

Lack of bank vegetation and

undercut banks, channel

widening, and higher water

temperatures

Reduced fish populations

reduced invertebrate

populations

Behnke and Raleigh 1979

Armour et al. 1991 Herbst

and Knapp 1995

19. Grazing throughout a watershed can increase peak runoff and erosion rates, leading

to channel incision (and thus lowered alluvial water tables and desiccation of

riparian plants), bank erosion, and increasing fine sediment content in channels

(Behnke and Raleigh 1979). Volume 2, Chapter 36, Page 1017

20. Grazing by livestock results in the trampling and compaction of riparian areas, the

direct destruction of bank vegetation through the chiseling of banks by hooves, and
104

the elimination of recruitment of young woody riparian plants through browsing

(Armour et al 1991, Platts 1991, Menke et al 1996). Volume 2, Chapter 36, Page

1017

21. The interrelated impacts commonly attributed to overgrazing include:

reduction in vegetative cover

changes in species composition

introduction of exotics

reduction or elimination of regeneration

compaction and cutting of meadow sod

depletion or elimination of deeply rooted vegetation that strengthens banks

loss of litter and soil organic matter

erosion of stream banks, beds, and flood plains

loss of overhanging banks

destabilization of alluvial channels and transformation to wide shallow channels

initiation of gullies and headcuts

channel incision and consequent lowering or water tables

desiccation of meadows

increased water temperature during summer due to reduction of shade

increased freezing in winter from reduction of insulation and snow trapping

efficiency

siltation of stream

bacterial and nutrient pollution

and decline of summer streamflow

(e.g. Platts 1984, Blackburn 1984, Kauffman and Krueger 1984,Skovlin 1984;

Elmore and Beschta 1987, Armour et al. 1991, Platts 1991, Chaney et al. 1993)

Volume 3, Chapter 5, Page 219

22. A recent study of channel characteristics between pairs of currently grazed areas on

National Forests and long-rested areas in National Parks in the Sierra Nevada found

significant differences in bank angle, unstable banks, undercut banks, bed particle

size, and pool frequency (US Forest Service 1995b). Significant differences in

undercut banks and unstable banks were also observed between grazed areas and

adjacent fenced exclosures with a few years of rest. Volume 3, Chapter 5, Page 220
105

23. Broken meadow sod, trampled streambanks, and widened streambeds are commonly

documented in Sierra Nevada meadows under excessive grazing pressure (e.g. Allen

1989, Hagberg 1995, Range Watch 1995). Volume 3, Chapter 5, Page 237

24. Livestock consume plants that hold the streambanks and soil together; mechanically

alter the form, structure, and porosity of soils; and change the composition of the

plant community. Volume 3, Chapter 5, Page 212

25. A recent evaluation of a sample of 24 locations throughout the Sierra Nevada found

13 to be at risk of loss of critical functions and 4 to be not functioning (Menke et al.

1996). Volume 3, Chapter 5, Page 220

A review of the Literature Cited in SNEP

The paper by the Lake Tahoe Basin Management Unit (1993) is an environmental

assessment of a grazing allotment, Hughes (1934) is a USFS progress report, SCS (1989)

is an erosion inventory report, and Hagberg (1995) is a thesis from Humboldt State

University. Given time constraints, these publications were not evaluated.

The paper by Overton et al. (1994) is a U.S. Forest Service Technical Report. The paper

reports the comparison of grazing excluded, horse grazed, cattle grazed, and stock

corridor reaches on Rosgen “C” type reaches of Silver King and Coyote Creek on the

Toiyabe National Forest in California to ungrazed “reference” reaches on Fishhook and

Hell Roaring Creeks in Idaho. Grazing on Silver King and Coyote Creeks is by cattle in a

deferred grazing system, with a 55% use of key forage plants grazing standard. No further

definition of current grazing management is given. The age of all cattle grazing exclosures

is reported as 5 years. Despite the authors assurances that the reaches in Idaho do indeed

represent the “potential” and “future desired potential” of the California creeks, one must

intuitively question this assumption. The streams in Idaho were indeed much different

from those in California, regardless of management.

However, the comparisons between the differently grazed reaches on Silver King and

Coyote Creeks (all within the same watershed, the same ecosystem, and the same State)

are interesting. First, it is extremely important for the reader to note that there is no pretreatment data for this comparison. Thus, any differences or similarities between reaches

may well have existed prior to implementation of the grazing treatments. This has the

potential to mask both positive and negative impacts of all treatments. Second, by the

authors own admission, sample size is quite low (n < 10 transects for the majority of the

means calculated for each reach). Third, the study is reach-based and any cumulative upstream watershed effects could be masking or enhancing “treatment” effect.

Using the Forest Service’s proposed R1/R4 fish habitat inventory procedures the authors

measured the following channel morphological and in-stream sediment parameters for

each habitat type; length, width, depth, maximum depth, surface fines, percent stable

banks, percent under-cut banks. Width/depth ratio, width/maximum-depth ration, residual
106

maximum depth, and residual pool volume were calculated. Habitat types were fast water

(glide, run, riffle) and slow water (meander, pool, bend). For Silver King Creek, the

authors report “little observable differences in means of habitat descriptors for the

different sections (table 3).” Based upon analysis of variance and Tukey’s HSD mean

separation, the authors report “Statistical comparisons of management types revealed few

significant differences; those that were significant did not show a distinct break between

the grazed and rested sections of Silver King Creek (figure 2).” For Coyote Creek, the

authors do report statistically significant differences between grazed and rested stream

sections for most parameters, with the rested streams falling closer to the “desired future

condition” defined by the streams in Idaho. To aid in interpreting this conflicting data, one

would like to know the exact grazing intensity on each of the grazed reaches and the

amount of pre-treatment dissimilarity between comparison reaches. More thought should

have been given to this case study prior to its implementation, the potential of this type of

experiment is high.

Citing a long line of case studies and proceedings papers, the proceedings paper by Platts

(1978) does support the statement as referenced. However, referring to these same

papers, he states “The data and intuitive thinking these authors used to justify their

conclusions lack the statistical strength needed to assign a high degree of validity to their

findings.” In reviewing several of these papers, this becomes obvious to the reader. Platts

goes on to state “However, it would be unreasonable to claim that a direct relationship

between improper livestock grazing of streamsides and aquatic habitat degradation has yet

to be proven.” There was indeed substantial qualitative and observational information to

support this statement, and the author references most of it. Again, the issue lies in

defining “improper” and “proper” grazing. In line with the primary objective of his paper,

Platts goes on to discuss basic statistical considerations which must be addressed when

planning studies to examine livestock-fisheries interactions.

The report by the California State Lands Commission (1993) contains 6 paragraphs on

grazing found on page 334. It presents no original data, nor does it define “grazing” as

overgrazing, current grazing, or past grazing. The report cites the AFS Position Statement

by Armour et al. (1991) and the EPA informational pamphlet by Chaney et al. (1990) in

support of their conclusions.

The paper by Li et al. (1994) is an article in the Transactions of the American Fisheries

Society. This is a somewhat descriptive paper, but provides valid analysis of the specific

hypothesis it set out to test. The authors conduct longitudinal stream surveys examining

the effect of abundance and distribution of riparian canopy, watershed aspect, solar input,

and water temperature on biomass and standing crops of algae, invertebrates, and rainbow

trout. The authors choose a total of five, apparently grazed, creeks on the John Day River

in Oregon. No quantitative description of the grazing management along any of the 5

creeks is given. The creeks had differing abundance of riparian vegetation, the mechanism

causing this was not established experimentally. The authors appear to assume that the

creeks with the lower abundance of riparian vegetation have achieved this state due to

“overgrazing”. It is not clear what assumption the authors assign to explain
107

those streams greater abundance of riparian vegetation. It would be very informative to

know exactly which grazing strategies resulted in abundant riparian vegetation. The

parameter “vegetation use” is measured by the authors. The measurement method is not

defined, nor is “use” linked to grazing strategy. However, the paper did not scientifically

determine what caused the differences in canopy of these streams. It simply documents the

differences in the productivity of these streams. The authors found that watersheds with

greater riparian canopy cover had higher standing crops of rainbow trout, lower daily

maximum temperatures, and perennial flow. The mechanisms for increased perennial flow

are not documented. Watershed aspect was a significant factor affecting trout biomass.

Primary productivity was higher on open streams, but the authors express concern about

maximum daily temperatures.

Menke et al. (1996) is Volume 3 Chapter 22 of SNEP. Menke et al. make at least two

statements regarding grazing impacts on vegetation which would in part support quote 20

above. However, Menke et al. provide no references to support their own statements. This

is an example of the circular references found throughout SNEP.

Armour et al. (1991) is the American Fisheries Society’s Position Statement on The

Effects of Livestock Grazing on Riparian and Stream Ecosystems, published in Fisheries

(quote 20 and 21). Some very interesting statements concerning livestock impacts on

riparian areas as well as potential grazing management solutions to these problems are

made throughout the document. Unfortunately, many of these statements are not

referenced, making it impossible in many cases to separate position from scientific fact. A

total of 29 references are cited in support of this position statement (5 peer-reviewed

journal articles, 9 technical reports, 9 proceedings papers, 3 informational pamphlets, and

1 working paper). Armour et al. do state that “...the immediate effects of over grazing are

loss of stream side vegetation and trampling of stream banks.” They also state “It is our

strong contention that when properly implemented and supervised, grazing could become

an important management tool benefiting fish and riparian habitats.” Specific supporting

citations do not accompany either statement.

The proceedings paper (quote 18 and 19) by Behnke and Raleigh (1978, not 1979) is

defined by its authors as “...the perspectives of two fisheries biologists on some of the

issues raised at the forum and suggests some grazing management options to protect

riparian/stream ecosystems from excessive grazing damage.” The forum referred to was

one held in Denver, CO on November 3-4, 1978. Thus, Behnke and Raleigh’s paper is a

proceedings paper discussing and citing papers from the proceedings of a previous

meeting. It is not clear if either proceedings were subject to peer-review. They cite

Dahlem (1978), Keller et al. (1978), Marcuson (1977), Martin (1978), Storch (1978),

VanVelson (1978), and Winegar (1977) as supporting the following “Typical stream

habitat changes associated with overgrazing....1. Widening and shallowing of the streambed, 2. Gradual stream channel trenching or braiding dependent upon soils and substrate

composition, 3. Silt degradation of spawning and invertebrate food producing areas, 4.

Loss of stream-side and in-stream cover, 5. Increased water temperatures and velocities,
108

6. Decreased terrestrial food inputs, and 7. Reduction of 3 to 4 fold in trout biomass in

grazed versus ungrazed stream sections.”

Dahlem (1978), Keller et al. (1978), Martin (1978), Storch (1978), and VanVelson (1978)

are in the Proceedings of the Forum-Grazing and Riparian/Stream Ecosystems published

by Trout Unlimited, Inc. Marcuson (1977) is a report on a Montana Department of Fish

and Game project, and Winegar (1977) is a paper in the Rangeman’s Journal. All are

reports of case studies where “grazing” was removed from all or some portion of a stream

system. Vegetation and habitat response are monitored within the exclosures and without

for various time periods following fencing. While well-written, the papers do a poor job of

quantifying grazing. The reader gets the sense that the grazing is “over grazing” and is

indeed having a negative impact on the water resources of these particular streams. The

authors also do a fairly poor job of classifying the stream types reported in these case

studies. Given the lack of replication, no statistical analyses are made. However, it is made

fairly clear by the trend data and photographs presented that these streams all responded

positively, in just a few years, to the removal of the apparently “abusive grazing”. Winegar

(1977) gives evidence of enhanced sediment trapping ability in the excluded stream reach.

Together, these case studies make a strong case that abused riparian areas will respond

very rapidly to the removal of the abusive grazing. With increased vegetation, the potential

to provide increased habitat, stream bank stability, and sediment trapping is clear.

Although not mentioned in the SNEP report, Behnke and Raleigh (1978) identify some

management practices they claim protect riparian areas from potential grazing impacts.

Chaney et al. (1990) is an informational pamphlet “aimed at the broad and growing

audience of people interested in improved management of livestock grazing on western

riparian areas and adjacent uplands.” The pamphlet clearly and concisely describes the

potential impacts of “overgrazing” on riparian functions and values. The pamphlet then

illustrates 11 case studies where previously “overgrazed” and degraded riparian areas have

been dramatically improved due to improved grazing management and upland watershed

management (cedar control, road improvements, etc.). Grazing management strategies

described in these case studies include rest-rotation, early season use, permanent stream

fencing with improved upland pasture fencing and water development, 1-3 year rest from

grazing followed by early season grazing, reduction in stocking rate to meet the carrying

capacity of the watershed in conjunction with brush control and re-introduction of fire (no

riparian fencing was used), and changes in season of use dependent upon reproductive

needs of perennial grasses. While the description of overgrazing impacts on riparian areas

presented in Chaney et al. (1990) supports the SNEP statement (quote 18 and 21), the

authors conclude:

1. The case studies demonstrate that the productivity of degraded riparian areas

can be restored, usually with a net gain in livestock forage.

2. These case studies also demonstrate that there is no cookbook of simple,

universal recipes for successful riparian grazing strategies.
109

3. A successful riparian grazing strategy must be custom designed to fit the

specific circumstances.

4. A clearly defined objective or desired future condition for the riparian area is

the foundation of a successful grazing strategy.

5. In order to establish realistic objectives for riparian areas, it is important to

know the vegetation potential for the site under proper grazing management.

The paper by Dudley and Deitrich (1995) is a research completion report to a granting

agency, focusing on a 11 year old livestock exclosure on one-half mile of previously

“heavily” grazed reach of the South Fork Kern River in the Golden Trout Wilderness

Area. Quoting the abstract of this study: “Our objective was to assess the effectiveness of

these cattle grazing exclosures in promoting resource recovery. Toward this objective, we

focused on a cattle exclosure in Templeton Meadow which was installed in 1983. We (1)

resurveyed ten stream cross sections originally measured in 1983 and surveyed and

monumented thirty-seven additional stream cross-sections, (2) conducted infiltration tests

on cattle trails, (3) monitored streambank erosion pins over winter, and (4) measured

nitrogen dynamics in five stream side habitats. We have found little evidence of recovery

inside the cattle exclosure. We were unable to find a difference in stream morphology

attributable to the exclosure...We found no significant difference in bank erosion rates

between locations inside and outside the exclosure. Nor did we find any significant

difference in nitrogen dynamics between locations inside and outside the exclosure.”

Herbst and Knapp (1995) is a paper in Bulletin of the North American Benthological

Society. This paper was not acquired in time to be evaluated in this report, but the title

Biomonitoring of Rangeland Streams under Differing Livestock Grazing Practices looks

interesting and the interested reader should follow up on this paper.

Jennings (1996) is SNEP Volume 2 Chapter 31. Another example of the circular

references found throughout SNEP.

Kondolf (1994) is a profile paper in Environmental Management. The paper seems to be a

mesh of literature review, field monitoring of channel cross sections on grazed and

ungrazed sections of a stream reach conducted during the drought of the mid to late

1980's, and the author’s opinion about making public lands land use decisions in the face

of scientific uncertainty. The paper profiles Cottonwood Creek Watershed in the White

Mountains of California. Cottonwood Creek is home to the federally listed threatened

Paiute cutthroat trout. This evaluation will limit itself to the literature review and field

monitoring component of Kondolf’s paper. In his literature review, Kondolf reiterates the

potential negative effects overgrazing has on watershed scale hydrologic and riparian

habitat parameters, heavily citing Armour et al. (1991) and Chaney et al. (1990). Despite

an increasing population of trout (following chemical eradication of competing nonnatives and hybrids in 1982 and reintroduction of pure-strain Paiutes), with a predictable

die-off between 1988-91 (1260 adults and juveniles in 1988 and 670 in 1991) as a result of

prolonged drought, it has been determined that habitat for the Paiute trout is limited by

excessive amounts of fine sediments in the stream channel. Livestock grazing has been
110

implicated as the cause for these fines. With regard to this, Kondolf states “.....the

relationships between land use and sediment yield have not been conclusively determined,

in large part because there are no historically ungrazed sites to serve as long-term

controls.” Cottonwood Basin is grazed 1 to 2 months in the summer by 200 head of cattle,

and is a popular destination for hikers and fishermen given its natural beauty and access

via a 4 wheel drive road. Evaluating stream cross sections and in-channel sediment

conditions to identify sources of fine sediments, Kondolf states “Because no ungrazed

meadows exist as controls and without major runoff in the basin during the study period, I

could not directly measure the contribution of livestock grazing to sediment yield to the

channel.” Observing greater abundance of riparian vegetation outside livestock exclosures

than within, but no significant differences in channel morphology within and without the

same exclosures Kondolf concludes that channel morphology lags behind vegetative

recovery within the exclosure. He also points out that the channel within the exclosure is

still subject to influence from hydrologic impacts of grazing upstream. No reference or

data is given to support this particular hypothesis. Thus, there is no field data in the paper

by Kondolf (1994) to support the SNEP statement.

Platts (1991) is a chapter titled Livestock Grazing in an American Fisheries Society

Special Publication titled Influences of Forest and Rangeland Management on Salmonid

Fishes and Their Habitats. Reviewing proceedings from forums, seminars, symposia,

workshops, and town hall sessions, Platts concludes:

1. Riparian habitats on grazed lands are degraded.

2. Solutions to land-use problems causing the degradation are not easily found.

3. The problems are most likely to be solved through an interdisciplinary

approach.

4. Enough experience and knowledge exists to begin correcting the problems.

5. More research is needed to develop better understanding and provide

solutions.

Platts provides a thorough review of the body of case study work and observations which

indeed builds the strong case that “overgrazing” can lead to degradation of riparian areas

and stream habitat. Although this body of evidence largely lacks statistical reliability, it

gives scientists a place to focus research. The value of streamside vegetation and habitat

are discussed. Platts evaluates various grazing strategies based upon his personal

observations. Platts rates the various strategies in regard to fisheries compatibility, again

based upon his observations. Ratings range from 1 to 10, 1 having little or no fishery

compatibility and 10 being completely compatible with fishery needs. The strategies are

defined by Platts, and the reader is referred there for details.

Platts (1991) provides no new data in support of the SNEP statement, but does review the

case study literature documenting the negative effects of overgrazing.
111

Odion et al. (1990) is a proceedings paper in a symposium on plant biology of eastern

California. It is not clear if the proceedings are peer-reviewed. The exact objective of this

paper is not clear, no testable research hypothesis is stated. The authors measured

vegetation along transects in Ramshaw and Templeton Meadows in the Golden Trout

Wilderness Area on the South Fork of the Kern River. Transects were evenly split

between grazed areas of the meadows and 2 year old ungrazed areas of the meadow. The

authors define “increasers” as plants which increase with grazing and are “thus not

important components of pristine meadow vegetation”. They define “decreasers” as plants

that decrease with grazing and are “thus important components of pristine meadow

vegetation”. Classification of “increaser” and “decreaser” species was determined from

Ratliff (1985), that is based on Ratliff’s opinion and long field experience. Ratliff (1985)

also cautioned that one should not use his list of increasers and decreasers in other places.

The conclusion, by Odion, that increaser plants have no value for riparian structure and

function is fairly major, and perhaps not well founded. The assumption that the

evolutionary theory developed by Dyksterhuis for grasslands of the Great Plains is

applicable to 8,000+ foot meadows of the Sierra Nevada, is perhaps also not well

founded. Particularly in light of work by Allen (1989) presented below. The authors also

state earlier in their paper that both meadows have been historically grazed by native

herbivores. It not clear how Odion et al. (1990) support the SNEP statement as

referenced. Their survey determined the following:

Site % Decreasers % Increasers

Hydric 64 36

Mesic 34 66

Sagebrush 11 89

Streambanks 19 81

The reference, U.S. Forest Service (1995), is an unpublished report and so was not

reviewed here.

A detailed account of Blackburn’s (1984) review of grazing intensity and upland

hydrologic process is given in this report (page 6).

The reference for Chaney et al. (1993) is essentially the same as Chaney et al. (1990), it is

simply a new version of the same informational pamphlet, focusing even more so on

educating ranchers on the principles of successful riparian grazing strategies.

The paper by Elmore and Beschta (1987) is a discussion paper in Rangelands. The paper

provides no data or supporting references. The objectives of the paper are: 1) to promote

awareness and discussion of riparian issues, 2) to identify the characteristics and benefits

of productive riparian systems, and 3) to encourage managers to reconsider the effects of

traditional grazing and structural channel control measures. The paper provides a good

discussion of the issues it sets out, and does indeed point out the problems of

“overgrazing”. However, the intent of the paper is to foster action by land managers on
112

two fronts: 1) careful consideration of current grazing in light of riparian needs, and 2)

careful consideration of “quick-fix” in stream structures.

The paper by Kauffman and Krueger (1984) is a review (103 papers cited) of the literature

on livestock impacts on riparian ecosystems and the resulting management implications.

The importance of riparian areas to in-stream ecosystems, wildlife and livestock is

discussed. The authors discuss the difficulty in interpreting science from opinion in the

literature being reviewed. Kauffman and Krueger’s review reports on a substantial body

papers which support the SNEP statement above, while at the same time presenting work

finding little or no impacts from grazing. The authors do a very good job of referencing

specific statements, and of reporting grazing management (stocking rate, season of use,

etc) for as many of the studies as possible. Most of the papers cited on the negative

impacts of overgrazing are the same ones cited by Platts (1984), Skovlin (1984), and

Armour et al. (1991). The authors also review livestock impacts on terrestrial wildlife and

riparian vegetation, both of which are discussed elsewhere in this report. Finally, the

review focuses on the successes and failure of numerous case studies and research papers

examining alternative management to restore, enhance and protect riparian areas. The

reader is referred to Kauffman and Krueger for details. Alternative management reported

include exclusion of livestock, alternative grazing strategies, changes in class and /or

number of animals, riparian pastures, in-stream structures, and in-stream structures in

conjunction with modified grazing management. Successes and failures are reported for

almost each management option. The mechanisms for these successes and failures are not

examined in detail.

The paper by Platts (1984) is a proceedings report on 7 years of research on the utilization

of 17 riparian areas located in Idaho, Nevada, and Utah under continuous and rest rotation

grazing by sheep and cattle. Although Platts’ initial literature review generally supports the

statement, the objective, focus and research in the paper is along a different line and is

quite interesting. A major objective of the work is to identify and document riparian

grazing management strategies which “balance forage and fish needs”. Unfortunately, the

author does a poor job in this paper of quantifying the grazing and grazing systems which

were studied. The author gives the reader no definition of “light” or “heavy” grazing, nor

does he provide any pre-treatment data to dispute the fact that the streams were

potentially dissimilar prior to the grazing treatments. Grazing history is stated to be

different for the streams. These are strong confounding factors which could either mask or

enhance treatment effects. Under continuous sheep grazing on Horton Creek in Idaho, he

reports a narrower (4X) and deeper (5X) stream channel, less bank alteration (15X), 7.6X

greater fish density and 10.9X greater fish biomass in the “lightly” grazed compared to the

“heavily” grazed pasture. Under rest-rotation grazing imposed by sheep herding, he

reports 5% utilization on the riparian area and no significant impacts to the stream system.

The comparison of continuous and rest-rotation grazing by cattle reported in this study

must be considered carefully. The rest-rotation treatment was imposed on an area that had

been excluded from grazing for an unspecified time, while the continuous grazing

occurred on a long-term grazed site. Utilization levels in the rest-rotation treatments

ranged from 25-80% while they ranged from 60-100% on the continuous
113

grazed site. This level of utilization likely qualifies as “heavy”. After 2 years of restrotation grazing on the previously ungrazed area, no changes were detectable in any

“water column or stream channel environmental conditions.”. The continuously grazed

pastures were compared to adjacent rested pastures with results similar to those reported

for continuous sheep grazing, but no supporting data was given. Platts points out that

these are preliminary data and as much as an additional 6 years of data are required before

strong conclusions are made.

Skovlin (1984) is titled Impacts of Grazing on Wetlands and Riparian Habitat: A Review

of our Knowledge and is published in National Research Council/National Academy of

Science text on developing strategies for range management. Responses to Skovlin’s

review are provided by Platts and Raleigh in the same text. Skovlin cites at least 167

publications. Skovlin’s review taken together with Platts and Raleigh’s responses capture

much of the case study, observational, opinion, and research-based literature on this issue

in 1984. It is difficult to determine which citations are observation or opinion-based versus

experimental-based. To determine this, that reader must revisit each original paper.

Specific areas covered by Skovlin (1984) include responses of 1) trees, shrubs and

herbaceous plants; 2) water quality, stream bank stability, and features of upland erosion;

and 3) large and small mammals, birds, and invertebrate organisms to livestock grazing are

reviewed. Grazing strategies to improve habitats are proposed. Skovlin states “In

searching the literature for information on riparian habitats, an attempt was made to reach

a comprehensive understanding of the effects of livestock grazing, not only of how grazing

adversely affects habitats, but how grazing management can enhance habitats.” Both

Skovlin’s review and Platts and Raleigh’s comments on it will be discussed further under

Additional Literature. Basically, the review by Skovlin supports the SNEP list above, but

as with many of the other papers referenced here, it contains much additional information.

Allen (1989) is a proceedings paper presented at the California Riparian Systems

Conference. The paper discusses 10 years data from meadows used to evaluate range

condition models for these types of rangeland. The author’s abstract is included: “Grazed

Sierra Nevada stringer meadow systems were sampled on Blodgett Forest Research

Station in northern California between 1977 and 1987 to determine cattle use, and to

examine changes in production and species composition over time. Utilization of meadows

species averaged 61 percent over 10 years, but increased to more than 80 percent

utilization after 1985. Production averaged 2733 kg/ha, but has significantly declined in

recent years. Relative species composition has not changed, nor has total vegetative cover

between 1979 and 1986. Range condition models based on changes in species composition

were not useful for assessing these stringer meadow systems. Managers should instead

base livestock management on stream bank conditions and meadow productivity.” Allen

also reports that application of the traditional range condition model based upon present

composition of decreasers, increasers, and invaders would rate the meadow condition at

both the beginning and end of the trial as fair to poor. Based upon bare ground, the

meadow would be rated in excellent condition. Soil cover criteria (including litter) would

rate the meadow condition as good. Despite these
114

condition scores, Allen reports photographic evidence that indicates broken down stream

banks, widened stream beds, and locally broken meadow sod. This evidence is what leads

the author to conclude “Traditional range condition models are of little value either in

assessing needs for improved management of these riparian systems, or evaluating the

effectiveness of any newly developed practices.”

Note that Allen’s work brings into question the sensitivity of the work conducted by

Odion et al. (1990) on the Golden Trout Wilderness.

Hagberg (1995) is a thesis from Humboldt State University, and was not evaluated due to

time constraints.

Range Watch (1995) is a video tape. It was not evaluated for scientific merit in this

review, so cannot be commented upon.

Menke et al. (1996) is Volume 3 Chapter 22 of SNEP. The statement above (quote 25)

refers to a case study conducted during development of the Chapter to correlate meadow

and riparian condition. In 1995, the authors re-read 24 existing Parker transects on 7

forests. The nearest stream reach was assessed using the USDI-BLM (1998) “Proper

Functioning Condition” assessment method for lotic areas. The 17 parameters in USDIBLM were estimated, as were elevation, width to depth ratio, presence of restoration

project, and “function” and trend as estimated by USDI-BLM (1998). The authors report

that 7 of the stream reaches were fully functioning (29%), 13 were functioning at risk

(54%), and 4 were not functioning (17%). Given that USDI-BLM (1998) is not a tool to

determine cause and effect, grazing could not be identified as the only factor leading to

either functioning or not functioning status.

The SNEP statement (quote 25, Appendix I) does not explore the data from the case

study to its limits. Another interpretation of the date presented in Menke (1996) could be:

1. Twenty of the 24 stream reaches (83%) are currently functioning,

2. Thirteen (54%) of these stream reaches are functioning but at risk,

3. Of the 13 functioning at risk reaches, 6 (46%) are in an upward trend, 4 (31%)

had no apparent trend, and 3 (23%) were in a downward trend,

4. A watershed assessment needs to be conducted on the 3 functioning at

risk/downward trend, the 4 functioning at risk/no apparent trend, and the 4 not

functioning reaches to determine the causes and possible solutions,

5. Long term monitoring on these same 11 reaches needs to be established to

formally document trend.

Digging deeper into the data collected via USDI-BLM (Volume 3, Chapter 22, Page 958,

Table 11) the reader discovers that Menke et al. lump the categories “No” and “N/A”
115

when reporting their results for the 17 parameters assessed under the “Proper Functioning

Condition” method. Under the method presented in USDI-BLM (1998) these categories

have very different meanings. Thus, it is impossible to determine if the stream reach was

“not supporting” of the function or if the function was simply “not applicable” for the

specific reach. Only the positive responses can be interpreted, realizing that a score of “not

supporting” could actually mean “N/A” and visa versa. Examining the data provided

(quote 25) in Table 11 from Menke (1996) one could calculate the following:

1. 54 % of the floodplains are inundated in relatively frequent events.

2. 8% of the reaches have active/stable beaver dams.

3. 67% of the reaches have sinuosity, width/depth ratio, and gradient in balance

with landscape setting.

4. 8% have a widening riparian zone. 8% have a “somewhat” widening riparian

zone.

5. 63% have upland watershed not contributing to riparian degradation.

6. 67% have diverse age structure of vegetation.

7. 88% have a diverse composition of vegetation.

8. 79% have species present which indicate maintenance of riparian soil moisture

characteristics, a 4% “somewhat have species present which indicate

maintenance of riparian soil moisture characteristics.

9. 67% have riparian plants with root mass to old banks.

10. 92% have riparian vegetation exhibiting high vigor.

11. 58 % have adequate cover to protect banks and dissipate energy during high

flows.

12. 25% have plant communities with an adequate supply of coarse and large

woody debris.

13. 54% have floodplain or channel characteristics adequate to dissipate energy.

14. 88% have point bars which are revegetating, and 4% “somewhat” have point

bars which are revegetating.

15. 67% have lateral stream movement associated with natural sinuosity.

15. 79% have vertically stable stream beds.

16. 67% have are in balance with the water and sediment being supplied by the

watershed.

There is a wealth of information in these data that were never addressed within SNEP.

The relatively high values for many of these critical functions paints a bit more positive
116

picture that does either Menke et al. or Kattleman and Embury in SNEP. Obviously, there

is room for improvement in these numbers and the functions they represent.

SNEP Statements Related to Pathogens and Nutrients

26. Congregation of cattle in and around streams provides a direct pathway for nutrients

and pathogens to degrade water quality (Springer and Gifford 1980, Kunkle 1970).

Volume 2, Chapter 30, Page 900

27. Cattle grazing in backcountry areas provides a source of Giardia cysts (Suk et al.

1985). Volume 2, Chapter 30, Page 900

A review of the Literature Cited in SNEP

Springer and Gifford (1980) is a proceedings paper reviewing unconfined grazing and

bacterial water pollution. The paper focuses on indicator bacteria such as total coliforms

(TC), fecal coliforms (FC), and fecal streptoccocci (FS) as indicators of pollution from

grazing animals. The authors report on several studies attempting to determine

“background” indicator counts from ungrazed watersheds. Bacterial indicators are present

in waters from ungrazed watersheds, indicating wildlife can be a significant source. The

literature clearly shows a relationship between coliform counts, streamflow, and turbidity.

This indicates that bacterial indicators are “flushed” from the watershed both within

season and within storm. This pattern was evident in both grazed and ungrazed

watersheds. Many of the studies cited indicate an higher in bacterial indicators in streams

draining grazed than ungrazed pastures/watersheds. The review also discusses the

temporal and spatial of livestock manure deposition on watersheds, as well as bacteria

survivability.

Kunkle et al. (1970) was not evaluated in this report.

Suk et al. (1985) is a proceedings paper reporting surveys for Giardia in the Sierra

Nevada. From the author’s abstract: “ Cysts of Giardia sp. were detected in 27 of 78

water samples collected at remote streams in California’s Sierra Nevada range. The data

suggest that intensity of human recreational use may play a significant role and/or be a

useful indicator in the contamination of surface water with Giardia. Cysts of Giardia spp.

were detected in 26 of 309 fecal samples collected from cattle grazing in back-country

areas in the Sierra Nevada.”

SNEP Statements Concerning Water Temperature

28. Removal of riparian vegetation and channel widening by grazing expose the stream

to much more sunlight. Therefore stream temperatures in summer may be several

degrees higher than if shade remained. These artificial changes in temperature

impact aquatic organisms that rely on a more natural temperature regime. Volume 2,

Chapter 30, Page 900
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29. Livestock grazing has decreased or eliminated riparian vegetation, broken stream

banks, widened stream bottoms, increased sediment, decreased shade, and increased

water temperature (Platts 1978, California State Lands Commission 1993, Li et al

1994, Menke et al 1996). Volume 2, Chapter 35, Page 990

30. From Table 36.3 Volume 2, Chapter 36, Page 1014.

Ecological Consequence Physical Effects References

Lack of bank vegetation and

undercut banks, channel

widening, and higher water

temperatures

Reduced fish populations

reduced invertebrate

populations

Behnke and Raleigh 1979

Armour et al. 1991 Herbst

and Knapp 1995

A review of the Literature Cited in SNEP

These references are reviewed in the Stream Channel Stability and In-stream Flow

Processes.

Livestock and Plant Resources

SNEP Statements Concerning Meadow and Riparian Resources

31. Livestock consume plants that hold the streambanks and soil together; mechanically

alter the form, structure, and porosity of soils; and change the composition of the

plant community (Volume 3, Chapter 5, page 212)

32. Heavy grazing usually reduces foliage density and increases bare ground in the

community thereby making sites available to invasion of exotic species if they are

present on a grazing unit. Many of the so-called “increasers” on mountain meadow

rangelands are native forbs which can be substantially increased in abundance with

frequent grazing (Ratliff 1985) Volume 3, Chapter 22, page 936).

33. Ratliff (1985) has compiled an extensive list of species responses to grazing in

Sierran meadows. (Volume 3, Chapter 22, page 936)

34. Some observers attribute the reduction of native perennials and their replacement by

more aggressive annual species in upper elevation grassy hillsides and higher

elevation meadow systems to this unregulated sheep grazing (Muir 1894, Douglass

and Bilbao 1975, Rowley 1985, Beesley 1985) (Volume 2, Chapter 1, page 7).

35. Wet and mesic meadow ecosystems, if overgrazed, show a trend of grass and legume

composition increase at the expense of sedge and rush composition. (Volume 1,

Chapter 7, page 118).
118

36. Overgrazing and livestock concentration in riparian zones have altered stream

morphology and vegetative composition in many areas of the Sierra Nevada (Volume

1, Chapter 7, page 129).

37. Livestock grazing has been implicated in plant compositional and structural changes

in foothill community types, meadows, and riparian systems, and grazing is the

primary factor affecting the viability of native Sierran land bird populations (Volume

1, Chapter 5, page 74).

38. Moderate grazing usually increases native plant species’ diversity in wet and mesic

meadow, but can suppress diversity in dry meadows (Ratliff 1985). Particularly in

grasslike plant (Carex spp. especially) dominated wet parts of meadows, livestock

grazing can reduce dominance and litter accumulations and allow more species to

inhabit a site. These species are usually native. (Volume 3, Chapter 22, page 936)

39. ...wet meadows converted to dry terraces above an incised stream as a result of

overgrazing may not recover even over a century without active restoration work.

Riparian vegetation tends to become reestablished within a few years after chronic

disturbance is eliminated, but readjustment of channel morphology to a natural shape

may require decades. Although disturbances such as a single timber harvest or a fire

may have severe short-term effects, natural recovery from them generally occurs at a

much faster rate than recovery from chronic disturbances. (Volume 1, Chapter 7,

page 130).

40. Overgrazing and livestock concentration in riparian zones have altered stream

morphology and vegetative composition in many areas throughout the Sierra Nevada.

(Volume 1, Chapter 7, page 129).

41. Overgrazing has altered riparian communities throughout much of the Sierra

Nevada.(Volume 3, Chapter 5, page 203).

42. Riparian areas often suffer from overgrazing because their vegetation tends to be

grazed more heavily than upland vegetation because of consumption preference and

availability of water and shade. (Volume3, Chapter 5, page 220).

43. A prime problem with respect to grazing is that areas degraded in past decades have

never had a chance to recover, even though grazing intensity may have greatly

diminished. Such areas have to be rested for a t least a few years if recovery is to

begin. (Volume 3, Chapter 5, page 241).

44. Riparian vegetation degraded by overgrazing generally recovers within a decade

once grazing pressure is removed (e.g. Platts and Nelson 1985, Chaney et al. 1993,

Nelson et al. 1994). (Volume 3, Chapter 5, page 221).
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A review of the Literature Cited in SNEP

Ratliff (1985) is frequently cited in SNEP. It is a compendium of research and experience

in Sierran mountain meadows over the career of the author. The publication presents a

classification of meadow types, meadow productivity values, management problems and

meadow condition and trend. It describes the diversity of meadows across gradients of

elevation, moisture, and hydrologic condition. The statement (quote 32) that increasers on

mountain meadow rangelands are native forbs which can be substantially increased in

abundance as attributed to Ratliff (1985) was not found although this statement certainly

follows the Range Condition Model. It is true that Ratliff (1985) has compiled an

extensive list of species responses to grazing but response to grazing is not based on

experimental evidence. Rather the list is his own observations along with information

gleaned from Dayton 1960, Hayes and Garrison 1960, Hermann 1966, 1970, 1975,

Hitchcock 1950, Munz and Keck 1959, USDA Forest Service 1937, Weeden 1981.

The idea of native perennial displacement by exotic annuals is highly controversial (See

Foothill Oak Woodland, this report, page 61). There is little evidence that the California

grassland was dominantly native perennials (Hamilton 1997).. Muir (1894) and Douglass

and Bilbao (1975) are non-scientific narratives. Rowley (1985) is a review of Forest

Service grazing history. We did not find Beesley (1985).

Platts and Nelson (1985) is a Rangelands article that does not mention recovery rates.

Instead they compared 3 grazing systems and found that streamsides were more heavily

utilized than the uplands. They also found streamside zones were not heavily used early in

the season, but received greater use later in the season. Chaney et al. (1993) is a non-peer

reviewed report at the Information Center Inc. in Eagle, ID. Nelson et al. (1994) is in the

Ecological Support Team Workshop Proceedings for the California Spotted Owl

Environmental Impact Statement, on file at the USFS Pacific Southwest Station, San

Francisco. The workshop proceedings report the opinions of group of scientists and

professionals and do not address recovery rates.

SNEP Statements Concerning Blue oak

45. Allen-Diaz and Bartolome (1992) looked at blue oak seedling establishment and

mortality with the treatments of grazing and prescribed burning in coastal areas of

hardwood rangelands. Neither of these treatments significantly affected oak seedling

density nor the probability of mortality when compared to unburned and ungrazed

areas, suggesting that seedling establishment is compatible with grazing and fire.

Volume 3, Chapter 15, page 660.

46. Perhaps the importance of fire on oak regeneration is explained by the enhanced

postfire oak sprout growth documented by Bartolome and McClaran (1989). They

concluded that in areas of moderate grazing with fire intervals around 7 years,

seedlings taking up to 18 to 20 years to exceed the browse line (around 5 feet) would

survive to become saplings and persist in the stand. In heavily grazed areas, only

those trees that exceeded the browse line in 10 to 13 years would be recruited.

Volume 3, Chapter 15, page 660.
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47. For the blue oak, livestock grazing has been proposed for the cause for their increase

in density. Livestock grazing removes herbaceous competition for blue oak seedlings

and decreased fuel levels, so fires are less intense and thus less detrimental (Vankat

and Major, 1978). Volume 2, Chapter 39, page 1083

48. When grazing pressures and plant competition are minimal (along roadsides beyond

pastures) or where micro-habitat is favorable, pioneer establishment of blue oaks in

open sites can occur. Volume 3, Chapter 15, page 655.

49. From the period 1932 to 1992, the canopy density and basal area of blue oak

woodlands at the stand level has increased under typical livestock grazing practices,

and fire exclusion policies (Holzman, 1993). Volume 3, Chapter 15, page 649

A review of the Literature Cited in SNEP

Allen-Diaz and Bartolome (1992) found no significant difference among the grazing and

prescribed burning treatments on seedling establishment and mortality.

McClaran and Bartolome (1989) did document enhanced postfire oak sprout growth,

supporting their hypothesis that fire stimulated sprouting is beneficial to blue oak

recruitment. The statement about time requirements to exceed the browse line should be

taken in the context they present it: “Recognizing the absence of replicated observations

and our inability to measure variables such as fire season and intensity effects on postfire

sprouting, we offer the following interpretation. With heavier livestock browsing

pressure, only plants that surpass the browse line in approximately 10-13 years will be

recruited. This applies to both postfire sprouts and true seedlings. However, under

lighter browsing pressure, nonfire-related seedling will be recruited even in surpassing the

browse line requires approximately 18-20 years.”

Long term changes in blue oak stands was investigated in 4 biogeographical regions by resampling plots established in the 1930s (Holzman, 1993). The results were a significant

increase in the mean total basal area of blue oaks. This was attributed to the growth of

trees existing in the 30s, as well as the introduction of new trees (average of 3 trees per .2

acre plot) into the stand. These results were consistent across grazed and ungrazed plots

(54% and 46% of the sample plots, respectively). These results stand in contrast to a

model predicting widespread lack of blue oak recruitment developed by Swiecki et al

(1997b).

The statement (quote 47) attributed to Vankat and Major (1978) is contained in a review

article without stated references for support. The statement used is an adaptation of

“Thus, we hypothesize that intense livestock grazing in the nineteenth century initiated the

density increase by removing herbaceous competition for Q. douglasii seedlings and

decreasing fuel levels, so that fires were less intense.” The other statement (quote 48),

that without grazing pressure or plant competition establishment of blue oaks in open sites

can occur, is true and supported by research (Adams et al, 1992; Adams et al, 1997;
121

McCreary and Tecklin, 1997 ). However, it implies that with grazing and competition

establishment of blue oak is not possible, which is not supported by research (see

following).

SNEP Statements Concerning Oak Woodland Vegetation Community Change

50. With the introduction of domestic livestock and exotic annuals during the Spanish

mission days, hardwood rangeland ecosystems have changed dramatically. The

herbaceous layer changed from a perennial layer to an annual layer (Crampton,

1974). Fire intervals have increased dramatically and fire intensity has also

increased (McClaran and Bartolome, 1989). The overstory layer, if not converted to

another land use, has generally increased (Holzman and Allen, 1991). Soil moisture

late in the growing season has decreased, and bulk density has increased due to

compaction from higher herbivore densities (Gordon et al, 1989). Riparian zones are

now less dense and diverse (Tietje et al, 1991). Volume 3, Chapter 15, page 650

51. The combination of poor grazing practices and extended periods of drought

contributed to the conversion of Sierra foothills from perennial to annual grasslands.

Volume 1, Chapter 7, page 114

52. Perennial grasses were dominant in the grassland communities, although exotic

annuals had begun their invasion even before the arrival of the first missions in 1769.

Volume 2, Chapter 3, page 42

53. It is thought that the native grasses were replaced by grazing-tolerant non-native

annual grasses (Mack, 1989) Volume 2, Chapter 47, page 1206

54. Impacts of overgrazing are considered on second to dams and river regulation as

causing degradation of riparian areas in the Sierra Nevada foothills (Nelson et al,

1994). Volume 3, Chapter 5, page 218

A review of the Literature Cited in SNEP

McClaran and Bartolome (1989) concluded that “between 1848 and 1948, fires were three

times more frequent than between 1681 and 1848. The limitations of fire scar evidence

should be considered before concluding the ignitions were more frequent after AngloAmerican settlement. Ignitions before Anglo-American settlement may have been very

frequent and therefore of such low intensity that scarring was not likely, an trees harboring

older fire scars may be dead or rare.” They concluded that fire frequency increased on one

of their two sites after 1948. They did not relate this phenomena to livestock grazing, but

did note that the site with the increased fire frequency also had “traditionally less livestock

grazing” than the site where they could not conclude that fire frequencies had increased.

The statement that the overstory layer, if not converted to another use, has generally

increased is supported by Holzman and Allen (1991), and further substantiated by
122

Holzman (1993). Long term changes in blue oak stands were investigated in 4

biogeographical regions by re-sampling plots established in the 1930’s. The results were a

significant increase in the mean total basal area of blue oaks. This was attributed to the

growth of trees existing in the 30’s, as well as the introduction of new trees (average of 3

trees per .2 acre plot) into the stand. These results were consistent across grazed and

ungrazed plots (54% and 46% of the sample plots, respectively)

Gordon et al (1989) conducted a trial examining the effects of 2 annual species (Bromus

diandrus and Erodium botrys) on soil water potential and blue oak seedling growth and

water relations. They found higher soils water potentials, greater dry weights, and longer

growing seasons for oak seedlings with Erodium competition and the control container

(no competing plants) than in those with Bromus competition. They suggested that the

competition for soil water with annual species contributes to blue oak seedling mortality.

They found that soil water depletion occurred most rapidly in the high density Bromus

planting, with the low density Bromus planting reaching a similar water potential soon

afterwards. Erodium plantings had significantly greater soil water potential throughout

the summer growing period than in the Bromus plantings, and there was no observed

change in soils water potential when oaks were planted alone. However, there was no

investigation into the effect of compaction from higher herbivore densities on soil moisture

late in the growing season, nor on bulk density.

The statement (quote 50) that riparian areas are now less dense and diverse, attributed to

Tietje et al (1991) is a misquote. While the authors did refer to differences in species

diversity of two riparian communities at different locations, they did make any claims

about prior riparian communities. We did not find other supporting research literature,

either general or specifically in regards to livestock grazing.

Mack (1989) in a review article that addresses changes in the Central Valley states that

“the huge numbers of cattle and sheep recorded for the Central Valley from the mid-19th

century onward testify to the tremendous grazing and trampling these animals must have

exerted on the communities dominated by caespitose grasses,” citing Burcham

(1982[1957]) as the source. (See following for additional discussion)

The statement (quote 54) about the impact of overgrazing on riparian areas in the Sierra

Nevada foothills by Nelson et al (1994) appears in a non-peer reviewed document without

any supporting documentation. The statement occurs in one of two paragraphs (pages 5

and 12) which summarize the authors opinion of livestock grazing impacts in riparian

areas. We found no other literature to support this statement.

Livestock and Wildlife Resources

SNEP Statements Concerning Amphibians

55. “There are waters where native amphibians are still surviving. In the foothills, these

tend to be small streams that have a dense riparian canopy, that are free of
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introduced species, and that have not been disturbed by grazing and other impacts.”

Volume 1, Chapter 7, Page 128

56. “The causes of frog and toad population declines are not wholly understood and

differ depending on latitude, altitude, and species. Low elevation species, such as

foothill yellow-legged frog (Rana boylii) and the California red-legged frog (R.

aurora draytonii) have been most impacted by alteration of streams and wetland

habitats as a result of grazing, mining, reservoir construction, and urbanization.”

Volume 2, Chapter 31, Page 939; SNST, Page 39

57. “Grazing has been implicated as a major factor affecting the habitat of the leopard

frog and the recent drought has exacerbated already tenuous conditions (Jennings

and Hayes 1994).” (SNST, Page 39)

58. “Specific examples of factors contributing to this degradation [note: of riparian

habitat for amphibians] are livestock grazing, road building, reservoir construction,

and recreation (Jennings and Hayes 1994). The most obvious reasons for the demise

of native amphibians due to these factors are: (1) increased dehydration and

increased predation due to loss of vegetative cover; (2) changes in the structure and

composition of the flora (thus affecting important food resources); and (3) the

crushing or removal of small or cryptic individuals due to trampling, vehicles, or the

results of human activity. Specific examples include (1) increased dehydration rates

for slender salamanders in habitats where the riparian cover was removed (see Ray

1958); (2) the loss of riparian willow (Salix spp), which resulted in increased

predation on California red-legged frogs by raccoons (Procyon lotor) (Miller 1994);

(3) the loss of important food resources that are critical for the growth and survival

of juvenile frogs and toads, due to the removal of vegetation upon which

invertebrates feed (Jennings and Hayes 1994); and (4) the crushing of individuals by

livestock grazing in alpine meadows, which resulted in trampled larval and juvenile

Yosemite toads (D. Martin, Maring, Canorus, Ltd., letter to the author, May 12,

1991), or by motorcycle use in riparian zones, which crushed juvenile and adult

foothill yellow-legged frogs and garter snakes (personal observations by the author

[M. R. Jennings] 1986-90).” Volume 2, Chapter 31, Page 939

59. “The more open vegetation resulting from grazing may expose amphibians to

predation and desiccation. Direct trampling by livestock may be an important cause

of amphibian mortality.” Volume 3, Chapter 5, Page 220

A review of the Literature Cited in SNEP

Literature other than SNEP documents referenced by the above quotes include Ray

(1958), Jennings and Hayes (1994), and Miller (1994). Ray (1958) showed

experimentally that slender salamanders in captivity could be killed by dehydration in a

desiccation chamber. Nevertheless, the SNEP author is simply speculating that removal of

riparian vegetation could result in mortality of salamanders. Jenning and Hayes (1994)
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produced a major review of all amphibians and reptiles suspected of warranting “special

concern” by the California Department of Fish and Game because they were rare,

threatened or likely to become so. This report is important, and likely the best information

available to that date, but it is not a refereed publication in the traditional sense. Miller

(1994) refers to a document placed into the Congressional Record by Congressman Miller

proposing to list the California red-legged frog as endangered. There is no reference in

Miller (1994) to support the statement that raccoons may prey on red-legged frogs.

SNEP Statements Concerning Birds

The following statements from SNEP and the USFS Science Team Review indicate some

of the issues and concerns regarding the influences of the livestock industry on native birds

in the Sierra Nevada. Some statements are located under the headings for highlighted

species.

60. “Livestock grazing has been implicated in plant compositional and structural

changes in foothill community types, meadows and riparian systems, and grazing is

the primary negative factor affecting the viability of native Sierran bird

populations.” Volume 1, Chapter 5, Page 74

61. “The extinction of least Bell's vireo in the Sierra appears most likely related to nest

parasitism by brown-headed cowbirds, although destruction of willow-dominated

riparian corridors, which were fragmented by grazing, greatly reduced its habitat.

Volume 1, Chapter 5, Page 79

62. “Among the potential risks faced by Sierran land birds, grazing and its secondary

effects appear to be the single most significant negative factor. Montane meadows

and montane riparian habitats are extremely important for Sierran birds; by

midsummer, montane meadows may be the single most critical Sierran habitat

requirement for may species that do not use this habitat during the actual breeding

season. Grazing catalyzes changes in meadow plant species and cover, with

cascading effects on birds. Changes in herbaceous and shrubby growth in meadows

potentially alter the levels of prey insects, change use patterns by predatory birds,

alter nest-building opportunities, and change the water relations of meadows, which

sometimes leads ultimately to loss of meadow area.” Volume 1, Chapter 5, Page 82

63. “Grazing has also been implicated in the decline of great gray owls outside of

Yosemite National Park; great gray owls do not forage in grazed meadows, perhaps

because grazed meadows are attractive to great horned owls which exclude them

(Gaines 1988), or because of changes in prey populations.” Volume 2, Chapter 25,

Page 717

64. “The major deleterious effects of grazing on montane meadows are decrease in the

density and height of herbaceous growth in the meadow. Many of the landbird

species utilizing these meadows depend upon insects that either live on the
125

herbaceous growth or depend upon the primary productivity of the herbaceous

growth for sustenance. (The dense concentrations of aphids on lupines and corn

lilies in these meadows is one example.) A decrease in the quantity of this

herbaceous growth will result in a decrease in the food sources of landbirds that use

the meadow.” Volume 2, Chapter 25, Page 717

All the above statements are undocumented except for the reference to Gaines (1988).

This is the earlier version of a bird guide to the Yosemite area that was revised in 1992.

The later edition also contains Gaines’ comments regarding great gray owls’ preference

for ungrazed areas inside Yosemite. These comments fall under the category of

speculation from observations. Great gray owls do forage outside Yosemite Park (R.H.

Barrett, personal observation).

We found comparative (e.g. Dobkin et al. 1998) but no experimental scientific reports on

the response of bird species to livestock grazing (Appendix 2). Some bird species respond

positively to livestock grazing while others respond negatively. Great gray owls (Strix

nebulosa) are rare in the Sierra Nevada, and may well prefer ungrazed meadows for

feeding, but this is undocumented in peer-reviewed scientific literature. The least Bell’s

vireo (Vireo bellii pusillus) has been extirpated from the Sierra Nevada, and livestock

grazing has been hypothesized to be a factor at least indirectly in the opinion of one author

(Goldwasser et al. 1980).

The following sections consider two bird species for which more than speculation or

expert opinion is available regarding their response to livestock grazing.

Willow flycatcher

65. “Grazing of Sierran habitats, particularly mountain meadow and montane riparian

habitats, may constitute a significant threat to Sierran landbirds. Grazing of

montane meadows has been implicated as a major cause of the drastic decline of

willow flycatchers; Gaines (1988) claims that willow flycatchers do not nest in

willows whose lowermost foliage has been denuded by livestock.” Volume 2, Chapter

25, Page 717

66. “Overgrazing of meadows has been suggested as a major cause of the decline of

Willow Flycatchers (Ohmart 1994). Cattle can directly disturb Willow Flycatchers

and other birds nesting in montane meadows by knocking over nests in willows or

crushing eggs on the ground (Sanders and Flett 1989).” Volume 3, Chapter 5, Page

208

67. “Declines [note: in willow flycatcher] are believed to be related to direct

degradation of nesting and foraging habitat from livestock grazing in meadows and

loss of riparian habitat (Serena 1982, Harris et al. 1987, Harris et al. 1988).”

(SNST Page 42)
126

Four out of the five citations in the above quotes deal with willow flycatchers in the Sierra

Nevada (Serena 1982, Harris et al. 1987, Harris et al. 1988, Gaines 1988, Sanders and

Flett 1989) and are discussed below. Ohmart (1994) is a comprehensive (57 citations)

review paper on the impacts of livestock grazing on birds focusing primarily on

southwestern riparian habitats. Ohmart (1996) is a more comprehensive work (237

references) covering all wildlife in which he reviewed Taylor’s work (Taylor 1986, Taylor

and Littlefield 1986) on willow flycatchers in Oregon (see below). Ohmart (1996) and

Skovlin (1984) are the only two comprehensive reviews of the links between wildlife and

livestock in western riparian habitats.

Brown-headed cowbird

68. “The most serious effects [note: of non-native species] have been produced by the

brown-headed cowbird, which was self-introduced early in the century. The spread of

this nest-parasitizing bird in the Sierra (and the West in general) has mirrored the

spread of farmland, livestock grazing, clearcut logging, and suburban development.

Cowbirds are directly implicated in or directly charged with the decline of several

songbirds in the Sierra Nevada, especially the willow flycatcher, least Bell's vireo,

yellow warbler, chipping sparrow, and song sparrow.” Volume 1, Chapter 5, Page

80

69. “Preferred foraging areas for cowbirds in the Sierra include heavily grazed

meadows, recent clear-cuts (especially those that are grazed), open forest with short

grass understory, pack stations and stables, picnic areas and campgrounds, lawns

and golf courses, and residential areas with bird feeders.” Volume 1, Chapter 5,

Page 80

70. “Grazing may increase nest parasitism by non-native cowbirds, although grazing

itself is not as important to the spread of cowbirds as are agricultural practices and

feedlot distribution in the regions adjacent to the Sierra. Local cowbird-control

programs related to grazing practices and aimed at certain critical meadows and

riparian habitats may be necessary to protect remnant populations of some rare

Sierran birds and already show promise where they have been tried. In recent

decades cowbird populations on the Sierran transects have been declining, perhaps

from reductions in grazing and logging disturbances where those transects occur.”

Volume 1, Chapter 5, Page 82

71. “The most serious effects [note: of alien species] have been produced by the

brown-headed cowbird. The spread of this brood parasite in the Sierra Nevada (and

the west in general) has mirrored farming, livestock grazing, clear-cut logging, and

suburban development (Gaines 1977, Rothstein et al. 1980, Verner and Ritter 1983,

Airola 1986, Coker and Capen 1995). Preferred foraging habitats in the Sierra

include heavily grazed meadows, recent clear-cuts, especially those that are grazed,

open forest with short grass understory, pack stations and stables, picnic areas and

campgrounds, lawns and golf courses, and residential areas with bird feeders.
127

Closed-canopy and multi-layered forests, forests with shrub understory, tall-grass

meadows, and clear-cuts after shrubs and trees are established do not provide

cowbird foraging habitat (Laymon 1995).” Volume 2, Chapter 25, Page 713

72. “And finally, the grazing of montane meadows promotes contact between cowbirds

(which are attracted to grazing livestock) and a high density of nearby nests of many

host species, including both those that nest in the meadow itself and those that nest,

often in higher than average numbers, in the adjacent forest.” Volume 2, Chapter 25,

Page 718

73. “The amount of grazing in the Sierra, at least at mid- and higher elevations, has been

decreasing in recent years. Perhaps related to this, BBS indicates cowbird

populations seem to be decreasing as well (DeSante 1995). However, at the present

time grazing and its secondary effects may well be the single most significant

negative factor in the maintenance of native Sierran landbird populations.” Volume

2, Chapter 25, Page 718

74. “In all cases, grazing tends to decrease the amount of herbaceous plant growth

present in the forest, woodland, and brushland habitats, thereby negatively affecting

the food resources of many granivorous and some insectivorous [bird] species, and

tends to increase the contact between cowbirds and their host species. Volume 2,

Chapter 25, Page 718

75. “Cowbird invasion into the mountains is favored by livestock grazing, clear-cutting,

and disturbances such as pack stations, picnic areas, and campgrounds (Rothstein et

al. 1980, Verner and Ritter 1983).”(SNST Page 42)

A review of the Literature Cited in SNEP

Of the seven citations in the above quotes, six are observational or comparative field

studies in the Sierra Nevada (Gaines 1977, Rothstein et al. 1980, Verner and Ritter 1983,

Airola 1986, DeSante 1995, Laymon 1995). Gaines (1977) and DeSante (1995) are nonrefereed documents, but they contain large amounts of personal observation by these

expert ornithologists. Coker and Capen (1995) is a peer-reviewed study of the cowbird

habitat preferences in Vermont.

Historic and Current Ranching Use

76. “Livestock were introduced into the Sierra in the mid-1700s following settlement by

the Spanish” (Vol. 3, Chap 22, pg. 909). We found no evidence to support this

statement.

77. “Grazing was perhaps the most ubiquitous impact, as cattle and sheep were driven

virtually everywhere in the Sierra Nevada that forage was available” (see Menke et al

1996; Kinney 1996) (Vol II, Chap 30, pg. 866; Vol III, Chap 5 pg. 215)
128

78. “Grazing by sheep and cattle is widely believed to have been virtually ubiquitous

throughout the Sierra Nevada before 1930” (Vankat and Major 1978; McKelvy and

Johnston 1992; Kinney 1996)... (Vol III Chap 5 pg. 218)

79. “Virtually all the Sierra Nevada has been grazed at some time (Kinney 1996, Menke

et al 1996)”

80. “Grazing by livestock was virtually ubiquitous in the Sierra Nevada from the

nineteenth century through 1930 (Vankat and Major 1978, McKelvy and Johnston

1992, Kinney 1996) (Vol II Chap 36 pg. 1017-8)”

The exact distribution of historic grazing in the Sierra has not been evaluated in any

comprehensive sense, but it is often stated as “ubiquitous” in SNEP. A review of these

comments reveals that they lack full documentation. This reviewer did not find these

claims made by Kinney 1996, particularly with reference to cattle. Though Menke found

accounts of heavy grazing in each of the regions he examined, he does not make the claim

that the livestock “grazed everywhere that forage was available,” and quotes Kinney for

information about pre-1900 grazing. Kinney documents that there were high numbers of

sheep and cattle in California, and numerous compelling anecdotal accounts of

overgrazing, but also does not attempt to argue that grazing took place “everywhere that

forage was available.” Vankat and Major (1978) cite histories and early accounts to

claim that “cattle were widespread,” but restrict their claims that livestock grazing was

“ubiquitous” to Sequoia National Park. They also state that sheep grazing was

eliminated around the turn of the century within the Park, with cattle grazing allowed

only in certain areas until 1930. McKelvy and Johnston (1992) is part of an apparently

unpublished report on the spotted owl and was not reviewed. The significance here is

that it may be possible to find areas of the Sierra that are so difficult of access that they

have not been grazed, and that the amount, timing, and type of grazing that has taken

place in various areas may vary. Further discussion of distribution of historic grazing can

be found within this text.

81. “Most cattle, especially those associated with dairying, were kept on lower elevation,

higher quality, and often fenced ranges. Sheep grazed on all other

rangelands”(Sudworth, 1900; Leiberg, 1902) (Vol II Chap 1 pg. 8)

Review of Leiberg and Sudworth does not find support for this attribution. Only on the

east-side basin of Long Valley do sheep seem to be more extensive than cattle according

to Leiberg. Near Truckee only does he describe a pattern where cattle use the “levels”

and sheep the slopes and summit – but even the “levels” in the Truckee area are at a high

elevation. In west slope basins the following is more typical: “...all through portions of

the high regions are cattle and sheep” (pg.69, and “...cattle roam throughout the region,

sheep are confined chiefly to the eastern and more mountainous tracts” (pg. 98).

However, it is probably not fair to generalize from Leiberg’s observations too much; his

objective was not after all to fully describe the range of either cattle or sheep in the

Sierra.
129

82. As it related to livestock, fire had its greatest effect from 1880 to 1910 when

sheepherders apparently set large brush fires every fall as they left the public lands

(Vol. III Chap 22, pg. 909).

83. Again, the sheepherders’ fires impacted the foothills more than grazing (Vol. III,

Chap 22, pg. 915).

84. This greater impact (of sheep grazing) was mainly due to the higher numbers of

sheep over a longer summer season and to the sheepherder’s burning practices,

which were evidently more frequent and extensive than those of Native Californians

(Vol II, Chap 3, pg. 40).

The statements are not attributed to any source, and do not seem to be supported by the

review of historical literature within this document.

85. While no records were kept...the largest percentage of the most destructive fires in

the mountains of California were caused by sheepmen during the 30 years preceding

the establishment of the National Forest (Fire History--Sheepman Fires by Thomas

West 1932) (Vol III, Chap 22, pg. 915)

86. “The historical accounts...seem to agree that sheep grazing, as conducted during this

period, affected rangeland condition more than cattle grazing” (Vol 2 Chap 3 pg.

40).

A full citation for the attribution is not provided for this statement, and it was not found

in the UC Berkeley libraries or database.

87. “Under a system of common ownership of a resource, with no regulation of individual

use, the so-called “tragedy of the commons” occurs. In economic terms, the common

property resource, here the public rangelands, are overused, because no individual

user has any incentive to conserve or steward the resource; any reduction in his use is

quickly captured by other users (Howe 1979). Sierra Nevada grazing in the late

1800s is a classic example of this type of market failure...” (Vol II. Chap 3, pg. 41)

(emphasis added).

Public domain rangelands do not fit well-accepted definitions of the term common

property resource (Bruce, 1993), as elaborated in the review.

88. “Due to the suppression of fire from 1920-present, these areas closed in with brush

or denser forests thus becoming uneconomical and unproductive for livestock

forage. Since wildfires still occur, transitory range continues to be created, but at a

much more limited scale, never attaining the size of the areas opened to grazing as

in the past” (Vol III, Chap 22, pg. 909).

This statement is unattributed and contradicts evidence presented elsewhere in SNEP,

which argue that increases in shrub and woodland density were well underway by 1900

(Skinner and Chang).
130

89. “During the World Wars I and II increased livestock use occurred on National

Forests and other public lands throughout the West, often without regard to

appropriate stocking rates, thus causing overuse from 1914-1920 and again from

1939-1946” (Vol III, Chap 22, pg. 909).

No source is given for this assertion. A prominent historian of the national forests, Bill

Rowley, asserts that while widespread overstocking occurred in response to WWI, the

Forest Service successfully argued against a similar increase in WWII (Rowley, 1985).

90. “Until the 1934 Taylor Grazing Act very little attention was given to grazing carrying

capacity limits [on the Modoc National Forest]” (Vol III, Chap 22, pg. 910).

91. “During this period [1908-1946] grazing was allowed in the high Sierra on National

Forest land, but only by local ranchers holding “base property” according to the

Taylor Grazing Act” (Vol III, Chap 22, pg. 910).

Assertions are made about the Taylor Grazing Act’s influence on Forest Service practice

in SNEP, but no citations are given, and they seem derive from a mistaken idea that the

Act applied to Forest Service lands.

Rangeland History

Many documents cited in the SNEP history (Vol. II Chap 22) are undated, and it cannot

be determined if they are primary data or a rehash of anecdotal accounts. The term

“uneconomical” is used frequently with reference to why permits were discontinued or

ranches closed down, but is never really explained or defined. It cannot be discerned how

the stocking rate estimates were determined, whether based on observations or actual

data, and whether reductions in season of use were accounted for. It is important to

know if stocking was evaluated in terms of AUMs or just livestock numbers, but this is

not made clear.

Reviewing grazing records for the Mammoth area, the authors reported in SNEP that

92. “...this reduction was achieved not so much by a reduction in actual animal

numbers, but by a reduction in the number of days animals were allowed on a given

range” (Vol II, Appendix 50.1, pg. 1311.)

 This concurs with results for the Shasta-Trinity National Forest (Forero, 1998).

Analysis of demographic and land use trends in the Sierra leads Duane to the following

conclusions:

93. “The rapid population growth being experienced in some rural areas has the

potential to transform radically the physical and the social environments of those

regions, including significant fragmentation of habitat and the likely loss of native

biological diversity” (Vol II Chap 11, pg. 246).
131

94. “Existing institutional arrangements for land use and environmental planning in the

Sierra Nevada appear inadequate for managing rapid population growth and the

land conversion process associated with human settlement” (Vol II Chap 11, pg.

236).

95. “Innovative growth management strategies to coordinate and consolidate

development across these parcels may...be...necessary if the impacts of future

population growth are to be mitigated” (Vol II Chap 11, pg. 236).

In the Chapter “Range Assessment” (Vol III Chap 22), Menke adds:

96. “... housing development continues to reduce the contribution of oak trees to foothill

ecosystem function” (Vol II, Chap 22, pg. 905).

This supports efforts in the review to look at grazing in its ecosystem context.

97. “The increased values associated with the amenity benefits of open space lands are

not easily captured by landowners” (Vol II, Chap 11, pg. 279), and,

98. “Agriculturists beyond the range of speculative development are ...likely to support

such efforts (preservation of agricultural lands), for they yield marginal benefits at

very low opportunity cost. large landowners within the range of speculative

development are likely to oppose such preservation efforts despite a long family

history in agriculture and/or natural resources and a commitment to agricultural

preservation. Their children often do not want to continue in this difficult line of

work...”(Vol II, Chap 11, pg. 279).

No citations or research results were provided to support these statements.
132

Appendix II: Supplement to Part IV: Livestock and Wildlife

The following table lists approximately 115 citations about livestock and various species

of wildlife. The articles range from opinion pieces in SNEP chapters or journals to

experimental studies. Only 9 of the articles provide an estimate of livestock grazing

intensity in the paper. Fourteen citations are about experiments with 10 of these papers

citing negative effects on bighorn sheep, small mammals or deer; 3 papers are reviews of

experiments and 1 paper reported no effect. Of the ~115 citations, ~24 took place in the

Sierra Nevada.

The table is organized by taxa. For each paper, a relevant quote about livestock and

wildlife is listed to provide a context for our evaluation of whether the article provides an

opinion, a comparative study, or an experiment. If the quote is from SNEP, the V

(volume): C (chapter): and P (page) is provided.

Although a totally comprehensive review of literature available on livestock and wildlife

was not possible in the time frame for this study, this table does point out the need for

more Sierra Nevada based experimental research on wildlife. It also points out the need

for a comprehensive synthesis of existing experimental and “gray” literature for the Sierra

Nevada.
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

amphibians Other Ray 1958 N/A

"Various species of amphibians show a range of 

water loss tolerance of from 7 to almost 50% in 

terms of the percentage of their total weight lost 

during desiccation."

amphibians Sierra cattle Year Jennings and Hayes 1994 negative "

amphibians Sierra cattle Summer Graber 1996 3:5:220 negative

"The more open vegetation resulting from grazing 

may expose amphibians to predation and 

dessication. Direct trampling by livestock may be 

an important cause of amphibian mortality."

amphibians Sierra cattle Year Jennings 1996 2:31:939a negative

"...factors contributing to this degradation [of riparian habita

for amphibians] are livestock grazing, road building, 

reservoir construction and recreation."

amphibians Sierra cattle Year Jennings 1996 2:31:939b negative

"The most obvious reasons for the demise of native 

amphibians...are (1) increased dehydration and increased pr

vegetative cover; (2) changes in the...flora, and (3) 

the crushing or removal of...individuals..."

amphibians Sierra cattle Year Jennings 1996 2:31:939c negative

"...examples include...increased dehydration rates 

for slender salamanders in habitats where riparian 

cover was removed."

amphibians Sierra cattle Year Jennings 1996 2:31:939d negative

"...examples include...the loss of riparian willow which resu

amphibians Sierra cattle Year Jennings 1996 2:31:939e negative

"...examples include...the crushing of individuals by livesto

grazing in alpine meadows, which resulted in 

trampled larval and juvenile Yosemite toads..."

amphibians Sierra cattle Year SNEP 1996 1:8:128 negative

"In the foothills, [native amphibians are still 

surviving in] small streams that have a dense 

riparian canopy, that are free of introduced species, 

and that have not been disturbed by grazing..."

bighorn Other cattle Summer Bissonette and Steinkamp 1966 negative

"The core areas used by bighorn and distances to 

escape terrain generally decreased as cattle moved 

closer to sheep. Likewise, sheep moved from cattle 

as cattle approached them."

bighorn Other sheep Year Foreyt and Jessup 1982 negative

"...acute fibrinopurulent bronchopneumonia resulted in high 

Washington. Circumstantial evidence indicated that 

the apparently healthy domestic sheep transmitted 

pathogenic bacteria to the bighorns..."

bighorn Sierra sheep Year Jessup 1985 negative

-bighorn sheep populations can be devastated by 

pneumonia contracted from domestic sheepbighorn Other sheep Year Coggins 1988 negative

"...two-thirds of 100 bighorn 

sheep...died...circumstantial evidence linked the 

die-off to contact with domestic sheep."

bighorn Other sheep Year Onderka and Wishart 1988 negative

-contact between bighorn and clinically normal 

domestic sheep caused fatal pneumonia in Rocky 

Mountain bighornbighorn Other sheep Year Weaver and Clark 1988 negative

"The death of >50 bighorn sheep was probably 

caused by 1 stray domestic ewe that introduced a 

severely pathogenic strain of bacterial pneumonia 

[to the Warner Mountains].

bighorn Other sheep Year Foreyt 1989 negative

-confirmed that clinically normal domestic sheep 

carried bacterium responsible for dieoff of bighornbighorn Bleich et al. 1990

"...[in 1989] California bighorn [numbered] 300 in 

the Sierra Nevada..."

Prepared by Reginald H. Barrett 133
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

bighorn Other sheep Year Foreyt 1990 negative

"...domestic sheep and bighorn sheep should be 

separ4ated or bighorns may die from pneumonia."

bighorn Other sheep Year Jaworski et al. 1993 N/A

"...ribotyping...procedures have the discriminatory capabilit

monitor the transmission of specific strains of 

bacteria within and between animal populations."

bighorn Other sheep Year Foreyt 1994 negative

"...all bighorn sheep died from acute 

bronchopneumonia after contact with dometic sheep 

and mouflon sheep."

bighorn Other sheep Year Foreyt et al. 1994 negative

"...a relatively nonpathogenic and common isolate of 

healthy domestic sheep was lethal in bighorn sheep 

under experimental conditions."

bighorn Other sheep Summer Pybus et al. 1994 N/A

"...there is ample evidence that some bighorn sheep populat

declined subsequent to introduction of domestic 

sheep onto traditional bighorn ranges."

bighorn Other none Year Fitzsimmons et al. 1995 N/A

"By the end of year eight, more heterozygous rams 

had 13% higher horn volumes than less 

heterozygous rams."

bighorn Other none Year Ramey 1995 N/A

"Significant differences in mtDNA haplotype 

distributions over short distances and high values of 

Nst on a local scale appear to be a result of the 

tendency of female mountain sheep to disperse less 

frequently and over shorter distances than males."

bighorn Sierra none Year Wehausen 1996 N/A

"Mountain lions effectivelyhalted a previously 

successful restoration program for bighorn sheep in 

the Sierra Nevada and reversed the overall 

population trend."

birds Other cattle Year Wiens 1973 negative

"Local plot-to-plot differences, associated with 

grazing intensity, were considerably more important 

than the regional differences [in bird community 

composition]."

birds Other Year Desante and George 1994 negative

"...75 native landbird species decreased...destruction of ripa

grasslands, shooting, overgrazing, logging..., and 

cowbird parasitism where the major factors 

responsible..."

birds Other cattle Year Johnson and Jehl 1994 negative

"The later activity [livestock grazing] continues to 

be the most pervasive current threat to [western] 

riparian habitats and their avifauna."

birds Other none Johnson and Jehl 1994 N/A

"Without trustworthy temporal baselines, it is 

premature to invoke processes responsible for 

patterns of abundance...causation remains as elusive 

as ever."

birds Sierra cattle Summer Graber 1996 2:25:717 negative

"Grazing of Sierran habitats, particularly mountain 

meadow and montane riparian habitats, may 

constitute a significant threat to Sierran landbirds."

birds Sierra cattle Summer Graber 1996 2:25:718 negative

"...grazing tends to decrease the amount of herbaceous plant 

woodland, and brushland habitsts, thereby 

negatively affecing the food resources of many 

granivorous and some insectivorous [birds]..."

birds Sierra cattle Summer SNEP 1996 1:5:79 negative

"...grazing is the primary negative factor affecting 

the viability of native Sierran bird populations."

Prepared by Reginald H. Barrett 134
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

birds Sierra cattle Summer SNEP 1996 1:5:82 negative

"Among the potential risks facd by Sierran land 

birds, grazing and its secondary effects appear to be 

the single most significant negative factor."

birds Sierra cattle Summer SNEP 1996 2:25:717 negative

"Grazing of Sierran habitats, particularly mountain 

meadow and montane riparian habitats, may 

constitute a significant threat to Sierran landbirds."

birds Sierra cattle Year Verner et al. 1997 no effect

"Overall, results of this study do not show that 

grazinghas led to the loss of any bird species that 

regularly nests in this foothill oak-pine woodland."

birds Other cattle Year Dobkin et al. 1998 negative

"Avian species richness and relative abundances 

were greater on [plolts ungrazed for 30 years]...[ungrazed] p

were dominated by wetland and riparian birds 

[versus upland birds]."

bobwhite Other cattle Year Kiel 1976 negative

"The establishment of large blocks of solid stands of 

buffelgrass, coastal bermudagrass, and bluestem [for 

cattle] is not favorable for bobwhite quail."

bobwhite Other cattle Year Hammerquist-Wilson and Crawford 1981 no effect

Found no significant differences in relative 

abundance of bobwhite among three different 

grazing systems on the Welder Wildlife Refuge.

bobwhite Other cattle Year Murray 1958 negative

"The [bobwhite] population varied directly with the 

acreage in cultivation and inversely with the acreage 

grazed [bobwhite declined when grazing 

intensified]."

cowbird Sierra horse Summer Rothstein et al. 1980 negative

"Cowbirds apparently exploit horse corrals and other 

human developments for group foraging during 

midday, scattering by evening or early morning to 

dispersed breeding sites."

cowbird Sierra horse Summer Verner and Ritter 1983 negative

"Cowbirds strongly prefer meadow edges as 

breeding habitats...cowbird abundance declined rapidly with 

from...pack stations...abundance of warbling vireos 

was negatively correlated with that of cowbirds."

cowbird Sierra horse Summer Rothstein et al. 1984 negative

"[cowbirds] spent mornings in host-rich habitats 

such as forests and then commuted 2.1-6.7 km to 

one or more prime feeding sites such as horse 

corrals and bird feeders..."

cowbird Sierra cattle Summer Airola 1986 negative

"Parasitism was strongly associated with habitat 

disturbance... Hosts that prefer riparian habitats are 

most likely to decline due to cowbird parasitism."

cowbird Other Beezley and Rieger 1987

-removal of cowbirds by trapping resulted in 

increased least Bell's vireo numberscowbird Sierra sheep Summer Flett and Sanders 1987 negative

"...sheep were always accompanied by flocks of 5-50 brown

cowbirds that foraged in the immediate vicinity of 

the flock..."

cowbird Other Laymon 1987 N/A

-concluded from model that cowbird parasitism over 

48% would lead to least Bell's vireo extinction in 

short timecowbird Sedgwick and Knopf 1988 N/A

"...at least 11/15 pairs (73.3%) [of willow 

flycatchers in Colorado] were parasitized [by 

cowbirds]."

cowbird Sierra Harris 1991 N/A

-13 of 19 willow flycatcher nests (68%) on 7 of 8 

territories (88%) were parasitized by cowbirds; a 

percentage sufficient to cause decline in hostPrepared by Reginald H. Barrett 135
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

cowbird Sierra horse Summer Gaines 1992 negative

"Brown-headed cowbirds dine at stables, 

campgrounds,, picnic areas and meadows, but 

search forests and thickets for foster parents to raise 

their young. Every horse corral and stable supports 

a summer flock."

cowbird Sierra horse Summer Rothstein 1994 negative

"Habitat restoration, not cowbird control, holds the 

most promise for the long-term management of 

these hosts [least Bell's vireo; willow flycatcher]."

cowbird Other cattle Summer Coker and Capen 1995 negative

"The model that best predicted patches used by 

cowbirds [used] area of the patch, distance to closest 

chronic disturbance patch, and number of livestock 

areas within 7 km of the patch."

cowbird Sierra cattle Summer Graber 1996 2:25:713 negative

"The most serious effects [of alien species] have 

been produced by the brown-headed cowbird. The 

spread of this brood parasite in the Sierra Nevada...has mirr

farming, livestock grazing, clear-cut logging and 

suburban development."

cowbird Sierra cattle Summer Graber 1996 2:25:718 negative

"...grazing of montane meadows promotes contact between 

attracted to grazing livestock) and a high density of 

nearby nests of many host species..."

cowbird Sierra cattle Summer SNEP 1996 1:5:80a negative

"Cowbirds are directly implicated in or directly 

charged with the decline of several songbirds in the 

Sierra Navada..."

cowbird Sierra cattle Summer SNEP 1996 1:5:80b negative

"Preferred foraging areas for cowbirds in the Sierra 

include heavily grazed meadows, recent clearcuts 

(especially those that are grazed), ...pack stations 

cowbird Sierra cattle Summer SNEP 1996 1:5:82a negative

"Nest parasitism by non-native cowbirds may be 

increased by grazing, although grazing itself is not 

as important to the spread of sowbirds as are 

agricultural practices and feedlot distribution in the 

regions adjacent to the Sierra."

cowbird Sierra cattle Summer SNEP 1996 1:5:82b negative

"In recent decades cowbird populations on the 

Sierran transets have been declining, perhaps from 

reductions in grazing and logging disturbances 

where those transects occur."

cowbird Sierra cattle Year Verner et al. 1997 negative

"It is almost certainly true that the number of 

cowbirds in these woodlands is highter with cattle 

present than would be the case without them."

cowbird Other cattle Year Ortega 1998 p269 negative

"Minimizing interspersion of cowbird feeding areas 

is an important step in conservation efforts 

(Thopmson 1994)"

cowbird Sierra cattle Summer STR 1998 p42 negative

"Cowbird invasion into the mountains is favored by 

livestock grazing, clear-cutting, and disturbances 

such as pack stations, picnic areas and 

campgrounds."

deer Other sheep Summer Jensen et al. 1972 positive

"Sheep grazing on winter ranges is compatible with 

big game [deer] use in this type of forage mix 

[northern Utah] provided it is restricted to the early 

gowing season [May-June] before bitterbrush twigs 

are growing rapidly."

deer Other cattle Summer Anderson et al. 1975 no effect

A rotational grazing system improved an 

southeastern Oregon winter range for elk but had no 

effect on mule deer.

Prepared by Reginald H. Barrett 136
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

deer Other cattle Year Reardon et al. 1978 negative

"White-tailed deer definitely preferred a rangeland 

grazed under a system which included a systematic 

rotational deferment, and the more frequent the 

deferment the higher the preference."

deer Other sheep Summer Smith et al. 1979 positive

"...quality of deer [winter] diets [in northern Utah] was not 

detrimentally affected where sheep had grazed 

[moderately] during the preceding spring..."

deer Other cattle Year Bryant et al. 1981 positive

"The Merrill 4-pasture grazing system appeared to 

increase the availabilty and use by deer of grass 

regrowth."

deer Other cattle Year Holechek 1982 positive

"Heaving grazing by livestock between 1880 and 

1930 resulted in a large scale increase in several 

shurbs and trees...[beneficial to mule deer in the 

Intermountain West]."

deer Other cattle Year Urness 1982 positive

Bitterbrush for deer can be stimulated by heavy 

grazing of grasses by livestock, especially horses, in 

spring and early summer.

deer Other cattle Year Warren and Krysl 1983 negative

"...livestock grazing must be controlled to maintain a high le

of nutritional status in the econimically important 

white-tailed deer of central Texas."

deer Other cattle Year Bowyer and Bleich 1984 negative

"...found significantly fewer...deer...in meadows where cat

occurred than in similar areas where cattle were 

prohibited."

deer Sierra cattle Summer Kie et al. 1987 negative

Increasing cattle stocking intensity decreased deer 

hiding cover.

deer Other cattle Year Urness 1990 positive

"...reduction or outright removal of livestock set in train a re

condition [more grass less browse] and decreased 

deer carrying capacity along the Wasatch Front."

deer Sierra cattle <1.5AUM/ha Summer Kie et al. 1991 negative

"Deer spent more time feeding and less time resting 

with increased cattle stocking rates." "Time spent 

feeding by deer was negatively correlated with 

standing crop of herbaceous forage..."

deer Sierra cattle <1.5AUM/ha Summer Loft et al. 1991 negative

"In the absence of grazing, meadow-riparian habitat 

comprised a greater proportion of deer home 

ranges..." "Within home ranges, deer preferred 

meadow-riparian habitat..."

deer Sierra cattle <1.5AUM/ha Summer Loomis et al. 1991 negative

"The incremental benefits of deer hunting gained 

under the 2-years-of, 1-year-on grazing system is 

greater than the lost net economic value of the 

forage to the rancher..."

deer Sierra cattle <1.5AUM/ha Summer Loft et al. 1993 negative

"Deer home ranges increased in area as cattle 

grazing level increased." "...deer and cattle were attracted to 

distributed meadow-riparian and aspen habitats 

where herbaceous forage was most available..."

deer Other cattle Year Bernardo et al. 1994 negative

"...net returns are maximized from cattle grazing without co

habitat. Low to moderate deer and quail habitat 

ratings are associated with this plan."

deer Sierra cattle <1.5AUM/ha Summer Kie 1996 negative

-increased cattle grazing increased doe foraging time 

beyond the preferred crepuscular activity periodducks Other cattle Year Gjersing 1975 negative

"[Duck] pair populations generally increased in 

pastures excluded from cattle grazing the previous 

year and decreased in pastures grazed in the fall of 

the previous year."

Prepared by Reginald H. Barrett 137
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

frogs Sierra Moyle 1973 negative

"The disappearance of R. aurora from the region, 

and the continuing reduction in range of R. boylii , is 

attributed to habitat alteration coupled with 

predation and competition from R. catesbeiana ."

frogs Sierra none 0 Bradford et al. 1993 N/A

"...[The mountain yellow-legged frog] was eliminated by int

this century in many of the lakes and streams in 

Sequoia and Kings Canyon National Parks..."

frogs Sierra none 0 Fellers and Drost 1993 N/A

"The almost complete disappearance of Rana 

cascadae from the Lassen National Park area does 

not appear to be caused by any single factor."

frogs Sierra none 0 Sherman and Morton 1993 N/A

frogs Sierra none 0 Bradford et al. 1994 N/A

"...survey...failed to reveal significant differences in water 

chemistry parameters between sites with and sites 

without each of the three [frog] species."

frogs Other Miller 1994 negative "

frogs Sierra none 0 Drost and Fellers 1996 N/A

frogs Sierra cattle Year STR 1998 p39a negative

"Low elevation [frogs] have been most impacted by 

alteration of streams and wetland habitats as a result 

of grazing, mining, reservoir construction and 

urbanization."

frogs Sierra cattle Year STR 1998 p39b negative

"Grazing has been implicated as a major factor 

affecting the habitat of the leopard frog..."

great gray owl Sierra cattle Summer Gaines 1992 negative

"...great gray owls rarely forage in grazed meadows; for this 

reason they rarely stray outside the [Yosemite] park 

boundaries."

great gray owl Sierra cattle Summer Graber 1996 2:25:717 negative

"...great gray owls do not forage in grazed meadows, perhap

because grazed meadows are attractive to great 

horned owls which exclude them."

jack rabbit Other cattle Year Taylor et al. 1935 positive

"A preference [by jack rabbits] was found for areas 

on which livestock grazing had reduced the 

vegetative stand, provided a moderate forage supply 

was still available."

least Bell's vireo Sierra cattle Year Goldwasser et al. 1980 negative

"Populations of least Bell's vireo have declined 

substantially throughout Califonria."

least Bell's vireo Sierra cattle Summer SNEP 1996 1:5:74 negative

"...extinction of least Bell's vireo in the Sierra appears most 

cowbirds, although destruction of willow-dominated 

riparian corridors, which were fragmented by 

grazing, greatly reduced its habitat."

lizards Other sheep Year Bury and Busack 1974 negative

Found an inverse relationship between sheep 

grazing in the Mohave Desert and lizard population 

lizards Other cattle Year Jones 1981 negative

"Lizard populations sampled on heavily grazed...communiti

lower relative abundance and species diversity 

indices than those of similar, lightly grazed sites."

N/A Other cattle 1.5ha/AUM Fall Kauffman et al. 1983 N/A

"...erosion related to livestock grazing and trampling was en

to create significantly greater annual streambank 

losses when compared to ungrazed areas."

N/A Other cattle 1.5ha/AUM Fall Kauffman et al. 1983 N/A

"Shrub use was generally light except on willow...on gravel 

bars...[where] succession appeared to be retarded by livesto

grazing."

pheasant Other cattle Year Koerth et al. 1983 negative

"...there is no reason for concern that short duration grazing 

with cattle will increase trampling loss of ground 

nests over continuous grazing."

Prepared by Reginald H. Barrett 138
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

prairie chicken Other cattle Year Jackson and DeArment 1963 negative

"Changing land-use practices are responsible for 

keeping lesser prairie chickens at low population 

levels in the Texas Panhandle. The more important 

of these are overgrazing of cattle range..."

small mammals Other cattle Year Grant et al. 1982 negative

Biomass of small mammals was lower at grazed 

sites than ungrazed sites in three of four grassland 

types.

small mammals Other cattle Year Hanley and Page 1982 variable

"Microtine rodents were consistently found in lower 

abundance in livestock-grazed than -ungrazed 

comunities. Other species...appeared to act as 

"decreasers" in zeric haitats and "increasers" in 

mesic habitats."

small mammals Other cattle 2.0ha/AUM Fall Kauffman and Krueger 1984 negative

"Livestock grazing and the subsequent removal of 

forage...cause[d] significant short-term decreases in 

small mammal composition and densities."

small mammals Other cattle Year Hayward et al. 1997 negative

"...small mammals were 50% more abundant on plots 

from which livestock were excluded [for 10 years]."

small mammals Other cattle Year Uresk et al. 1982 positive

"Blacktail prairie dogs were more abundant in areas 

of southwestern South Dakota heavily grazed by 

cattle than in areas were cattle were excluded."

snake Sierra none Jennings et al. 1992 N/A

"Reasons for the declines of B. canorus and R. 

muscosa are not clear...[but] T. elegans should not be drama

declines of Bc and Rm because it appears more 

strongly associated with P. regilla than these 

species..."

turkey Other cattle Year Baker 1978 negative

"...these findings emphasize the benefits of rotational grazin

success. [Turkey nest] survival rate was 

significantly higher in the pasture deferred longer."

waterfowl Kantrud 1990 positive

"Nearly all previous studies indicate that reductions 

in height and density of tall, emergent hydrophytes 

by fire and grazing (unless very intensive) generally 

benefit breeding waterfowl."

waterfowl Other cattle Summer Sedivec et al. 1990 positive

"Nesting success [of prairie ducks] on nongrazed 

prairie was consistently lower than the [short 

duration] grazing treatments."

waterfowl Payne 1992 p289a positive

"The purpose of livestock grazing as an aquatic and 

semiaquatic habitat modification technique is to 

open up dense patches of cover to improve 

composition so that diving ducks and other 

waterbirds can penetrate it for nesting."

waterfowl Payne 1992 p289b positive

"Trampling and smashing of vegetation and 

moderate grazing are recommended for marsh edges 

with solid stands of tall, rank vegetation such as 

cattail, pharagmites, bulrush, cordgrasses, and 

willows..."

waterfowl Payne 1992 p289c

"Ideally, cattle should be used for 2 to 3 months in 

late winter and early spring...Cattle should be 

excluded from ...marshes during [nesting] July, 

August, and September."

waterfowl Payne 1992 p294 negative

"Grazing generally impacts nesting waterfowl 

negatively...As a general rule, use by cattle and ducks is com

[winter] grazing removes only one-half the average 

amount of the primary forage plants produced 

annually."

Prepared by Reginald H. Barrett 139
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

wildlife Other cattle Year Storer 1932 negative

"Grazing is, and has been, practiced in all suitable 

areas of the state [California] from the earliest times 

[and has had a major impact on wildlife]. 

wildlife Other cattle Year Carothers 1977 negative

"...the most insidious threat to the riparian habitat 

[for wildlife] today is domestic livestock grazing."

wildlife Holechek et al. 1982 positive

"Specialized grazing systems show potential for 

amelioration of negative impacts of livestock 

grazing on wildlife habitat."

wildlife Other cattle Heady 1985 negative

"The long-used management ofone kind of animal 

[cattle] and the existence of others [wildlife] will 

continue to be practiced in most situations."

wildlife Anderson et al. 1990 positive

"Livestock and wildlife can be compatible on the 

same range provided that management of each is 

coordinated with the objectives for the area, 

phenology and physiology of key forage species, and 

ecological capability of the resources."

wildlife Guthery et al. 1990 positive

"[Short duration grazing] could be used in 

management of wildlife species inhibited by ground 

cover that is too tall and dense."

wildlife Kie and Loft 1990 positive

"Livestock can open up dense stands of shrub 

vegetation such as willow thickets and improve 

access for several species of wildlife through 

trampling and browsing."

wildlife Kie 1991 variable

"Livestock grazing affects different species of 

wildlife in different ways, and the effects depend on 

how those livestock are managed."

wildlife Payne 1992 p290a

"Riparian habitat is probably the single most 

important, least abundant, and most abused plant 

community for wildlife..."

wildlife Payne 1992 p290b positive

"...cattle can improve structural diversity by creating tunnels 

through the [dense riparian] brush...But mostly, 

riparian habitat should be fenced and ungrazed."

wildlife Payne 1992 p290c

"...the four-pasture rest-rotation system seems best in the So

single grazing strategy for riparian areas functions 

well under all situations...[provides 13 guidelines]"

wildlife Kie et al. 1994 p663a

"Management of public rangelands in the United 

Sates is constrained by both federal and state laws, 

and those laws require managers to address the 

impact of livestock grazing on all wildlife."

wildlife Kie et al. 1994 p663b

"...impacts of livestock grazing can vary widely from one ec

vegetatiion conditions also can be extreme. 

Therefore, much of the existing literature may seem 

contradictory."

wildlife Kie et al. 1994 p664

"...the range condition terms excellent, good, fair, and poor 

differ greatly among species...the terms excellent, good, fair

seral..."

Prepared by Reginald H. Barrett 140
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

wildlife Kie et al. 1994 p665a negative

"Heavy livestock grazing has been detrimental to 

many wildlife species in western North America...Where su

adverse impacts occur, elimination of livestock can 

improve habitat conditions..."

wildlife Kie et al. 1994 p665b positive

"When properly managed, livestock grazing can be 

used to improve habitat for wildlife species 

dependdent on early-seral stage plant communities."

wildlife Kie et al. 1994 p665c

"The relationship between grazing and wildlife 

habitat is complex."

wildlife Kie et al. 1994 p666

"Livestock management practices that can affect 

wildlife habitats and populations include livestock 

numbers, timing and duration of grazing, animal 

distribution, livestock types, and specialized grazing 

system. These practices can be modified to reduce 

or eliimiate adverse effects on wildlife, and 

sometimes to enhance wildlife habitats..."

wildlife Kie et al. 1994 p667a

"Livestock effects on wildlife become more 

pronounced with increasing stocking rates, and the 

relationship is often nonlinear..."

wildlife Kie et al. 1994 p667b

"...a range manager's traditional definition of proper grazing 

livestock forage and preventing soil erosion. 

Optimal livestock densities for wildlife may occur at 

different, and often lower, stocking rates."

wildlife Kie et al. 1994 p670

"[among all grazing systems] Rest-rotation grazing 

may have the most potential to provide benefits to 

wildlife [e.g. graze 2 out of 3 years]."

wildlife Kie et al. 1994 p671a

"Using livestock to maintain a plant community in 

an early seal stage often will benefit those wildlife 

species dependent on such habitat, while at the same 

time adversely affect species associated with climax 

communities."

wildlife Kie et al. 1994 p671b negative

"Maximizing benefits to wildlife from prescribed 

grazing almost always will involve reducing 

livestock numbers and shortening grazing seasons 

compared to management plans designed to 

maximize livestock production."

wildlife Kie et al. 1994 p617c

"...managers should avoid generalizations and evaluate the r

habitats independently for each species [of wildlife], 

grazing plan, and management situation."

wildlife Kie et al. 1994 p617d

"Wildlife use riparian zones disproportionately more 

than any other habitat type."

wildlife Kie et al. 1994 p671e

"Little information is avaiilable on wildlife/riparian 

interactions. In general, this resuits in wildlife 

management considerations being excluded from 

land use plans."

wildlife Kie et al. 1994 p673a

"Management of riparian areas needs to be 

considered for two locations: (1) onsite or within the 

riparian zone, and (2) offsite or outside the riparian 

zone, which accounts for all adjacent uplands that 

exert influence over the watershed."

Prepared by Reginald H. Barrett 141
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

wildlife Kie et al. 1994 p673b negative

"Livestock grazing is perhaps the greatest biological 

threat to riparian habitats in the West, given that 

about 91% of the total rangeland is grazed..."

wildlife Kie et al. 1994 p673c

"Isolated case studies have demonstrated that 

revised grazing management improved conditions, 

but the condition of riparian habitats [in the West] 

continues to decline..."

wildlife Kie et al. 1994 p673d

"...riparian areas are as badly deteriorated today as at any ot

reason may be because the number of cattle on 

western rangelands has steadily increased since 

1875."

wildlife Kie et al. 1994 p674a

"Riparian vegetation usually improves from grazing 

relief within 4-6 years, depending on severity of 

use...Areas with severe overuse require greater 

periods of time (>15 years)..."

wildlife Kie et al. 1994 p674b

"...riparian vegetation should be managed as the 

most sensitive and most productive North American 

wildlife habitat."

wildlife Kie et al. 1994 p674c

"The best management strategy for sustaining 

rangeland riparian areas is one that (1) maintains the 

productivity of the vegetation...(2) maintains the integrity of 

and (3) recognizes that several factors interact to 

maintain a dynamic equilibrium..."

wildlife Other cattle Year Moore and Terry 1979 positive

"Short periods of intensive grazing followed by long 

rest periods show potential for improving wildlife 

habitat [in Florida].

willow flycatcher Sierra cattle Summer Serena 1982 negative

"Willow flycatchers were...absent from 

otherwise...suitable areas where the lower branches 

of willows had been stripped of leaves and twigs or 

were missing entirely due to livestock."

willow flycatcher Sierra cattle Summer Stafford and Valentine 1985 negative

"Results to date suggest that willow flycatcher 

production may not be affected by cowbird 

parasitism, but may be by the acitivities of range 

cattle."

willow flycatcher Other cattle <1.7AUM/ha Year Taylor 1986 negative

-passerine species richness, including willow 

flycatchers, increased as shrub volume increased 

and grazing decreasedwillow flycatcher Other cattle Year Taylor and Littlefield 1986 negative

"...willow flycatchers were found in high numbers only on 

transects undisturbed or rarely used by cattle and 

with high shrub volume."

willow flycatcher Sierra cattle Summer Flett and Sanders 1987 negative

"...the placement of [willow flycatcher] nests in willow clum

potentially vulnerable...because they were built near 

the edge...and low enough to be knocked over by 

cattle."

willow flycatcher Sierra cattle Summer Harris et al. 1987 negative

"The Kern River [willow flycatcher] population 

appears to have increased steadily...and evenly over 

the area [since grazing was eliminated]..."

willow flycatcher Sierra cattle Year Unitt 1987 negative

"The available evidence indicates that the [willow 

flycatcher] has declined precipitously and...is now 

rarer than many other birds formally designated as 

endangered."

willow flycatcher Sierra cattle Summer Harris et al. 1988 negative

"The Kern River [willow flycatcher] population 

appears to have increased steadily...and evenly over 

the area [since grazing was eliminated]..."

Prepared by Reginald H. Barrett 142
Appendix 2: Wildlife literature reviewed in this study (including literature cited in SNEP SNST reports. The SNEP quotes are also referenced by V (volume):C (chapter), P (page).

Wildlife Location Livestock Intensity Season Authors Date SNEP-V:C:P Opinion Comparison Experiment Quote from this reference

willow flycatcher Sierra cattle Summer Valentine et al. 1988 negative

"From 1983 through 1986, four of 20 studied nests 

were destroyed by livestock prior to the young 

fledging. During 1987 no nests were upset by cattle 

[with reduced cattle stocking]."

willow flycatcher Sierra cattle Summer Sanders and Flett 1989 negative

"Cattle can disturb willow flycatchers and other 

birds nesting in montane meadows by knocking 

over nests in willows or crushing eggs on the 

willow flycatcher Sierra cattle Summer Gaines 1992 negative

"In the Sierra...grazing may be the major factor 

[limiting willow flycatcher populations]."

willow flycatcher Other cattle Year Ohmart 1994 negative

"The resiliency of riparian habitats is remarkable 

after only eight years of cattle exclusion...in experience the 

healing process is extended at least three of four 

times what it would be with total exclusion."

willow flycatcher Sierra cattle Summer Rothstein 1994 negative

"...breeding meadows are grazed by livestock which can kno

[willow flycatcher] nests and consume the lower 

foliage of willows."

willow flycatcher Sierra cattle Summer Graber 1996 2:25:717 negative

"Declines [in the willow flycatcher] are believed to 

be related to direct degradation of nesting and 

foraging habitat from livestock grazing in 

willow flycatcher Sierra cattle Summer Kattelmann and Embury 1996 3:5:208 negative

"Overgrazing of meadows has been suggested as a 

major cause of the decline of willow flycatchers."

willow flycatcher Sierra cattle Summer SNEP 1996 3:6:208 negative

"Cattle can disturb willow flycatchers and other 

birds nesting in montane meadows by knocking 

over nests in willows or crushing eggs on the 

willow flycatcher Sierra cattle Summer STR 1998 p42 negative

"Declines [in the willow flycatcher] are believed to 

be related to direct degradation of nesting and 

foraging habitat from livestock grazing in meadows 

and loss of riparian habitat."

Prepared by Reginald H. Barrett 143