United States Office of Research and EPA/600/R-00/059

Enivronmental Protection Development September 2000

Agency Washington, DC 20460 www.epa.gov/ncerqa

Proceedings

2000 STAR Regional Scale Analysis

and Assessment Progress

Review Workshop

September 18-19, 2000

Las Vegas, Nevada

NATIONAL CENTER FOR ENVIRONMENTAL RESEARCH
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research iii

Table of Contents

Introduction ................................................................. v

Section 1. Projects Initiated With Fiscal Year 1997 Support

Assessment of Forest Disturbance in the Mid-Atlantic Region: A Multiscale 

Linkage Between Terrestrial and Aquatic Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Keith N. Eshleman, Robert H. Gardner, Louis F. Pitelka, Steven W. Seagle, 

Philip A. Townsend, William S. Currie, James N. Galloway, 

James R. Webb, Alan T. Herlihy

Section 2. Projects Initiated With Fiscal Year 1998 Support

Multilevel Statistical Modeling for Generalizing From Case Studies .............................. 7

Richard A. Berk, Jan de Leeuw, Richard Ambrose, Cindy Lin

Regional Scale Impacts of Phase I of the Clean Air Act Amendments: The Relation 

Between Emissions and Concentrations, Both Wet and Dry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Gene E. Likens, Tom Butler

Regional Analysis of Variation in Adirondack Lake Ecosystems: Landscape Scale 

Determinants of Dissolved Organic Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Michael L. Pace, Charles D. Canham, Michael Papaik

Methodologies for Extrapolating From Local to Regional Ecosystem Scales: Scaling Functions 

and Thresholds in Animal Responses to Landscape Pattern and Land Use . . . . . . . . . . . . . . . . . . . 10

John A. Wiens, Beatrice Van Horne

Section 3. Projects Initiated With Fiscal Year 1999 Support

Application of Remotely Sensed Data to Regional Analysis and Assessment 

of Stream Temperature in the Pacific Northwest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Stephen Burges

Effects of N Deposition on Gaseous N Loss From Temperate Forest Ecosystems . . . . . . . . . . . . . . . . . . . . 17

Peter M. Groffman, Louis V. Verchot, Christopher Potter, 

Mary Beth Adams, Ivan Fernandez, Lindsey Rustad

Regional Analysis of Net Ecosystem Productivity of Pacific Northwest Forests: Scaling Methods,

Validation, and Results Across Major Forest Types and Age Classes . . . . . . . . . . . . . . . . . . . . . . 19

Beverly E. Law, D. Turner, C. Daly, M.E. Harmon, S. Acker, 

W. Cohen, M. Unsworth

Multiscale Effects of Forest Fragmentation and Landscape 

Context on Population Health of Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Thomas E. Martin, R.L. Redmond, M.M. Hart, M.E. Clark
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

iv The Office of Research and Development’s National Center for Environmental Research

Table of Contents (continued)

Regional Ecological Resource Assessment of the Rio Grande Riparian Corridor: A Multidisciplinary 

Approach To Understanding Anthropogenic Effects on Riparian 

Communities in Semi-Arid Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Jay Raney, Melba Crawford, Frank Judd, Gene Paull, Robert Lonard, 

Amy Neuenschwander, Thomas Tremblay, William White

A Hierarchical Patch Dynamics Approach to Regional Modeling and Scaling . . . . . . . . . . . . . . . . . . . . . . . 23

Jianguo Wu

Index of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research v

Introduction

The mission of the United States Environmental Protection Agency (EPA) is to protect public health and

safeguard and improve the natural environment—the air, water, and land upon which life depends. Achievement of

this mission requires the application of sound science to the assessment of environmental problems and to the evaluation

of possible solutions. The National Center for Environmental Research (NCER) at EPA is committed to providing

the best products in high-priority areas of scientific research through significant support for long-term research.

The Office of Research and Development’s (ORD) Environmental Monitoring and Assessment Program

(EMAP) identifies integrating information across multiple scales as one of its largest challenges. This approach is

based on The Committee on Environment and Natural Resource’s (CENR) publication entitled Integrating the Nation’s

Environmental Monitoring and Research Networks and Programs, A Proposed Framework.

In support of this identified research need, NCER issued a Request for Applications (RFA) on Regional Scale

Analysis and Assessment in 1997. It was followed up with subsequent RFAs in 1998 and 1999. The purpose of these

solicitations was to support research that would lead to the development and demonstration of approaches to link sitespecific information with regional survey data and remote sensing imagery for conducting regional-level ecological

assessments. A total of 11 grants have been funded under this program. This research represents part of the extramural component of ORD’s Environmental Monitoring and Assessment Program (EMAP). You may find extensive

information about the EMAP Program at http://www.epa.gov/EMAP.

Annual program reviews such as this allow investigators to interact with one another and discuss progress and

findings with EPA and other interested parties. If you have any questions regarding the program, please contact the

Program Manager, Barbara Levinson, by telephone at 202-564-6911, or by e-mail at levinson.barbara@epa.gov.
Section 1.

Projects Initiated With Fiscal Year 1997 Support
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 3

Assessment of Forest Disturbance in the Mid-Atlantic Region: 

A Multiscale Linkage Between Terrestrial and Aquatic Ecosystems

Keith N. Eshleman 1, Robert H. Gardner 1, Louis F. Pitelka 1, Steven W. Seagle 1, Philip A. Townsend 1, 

William S. Currie 1, James N. Galloway 2, James R. Webb 2, and Alan T. Herlihy 3

1

University of Maryland Center for Environmental Science, Appalachian Laboratory, Frostburg, MD; 2Department

of Environmental Sciences, University of Virginia, Charlottesville, VA; 3

Department of Fisheries and Wildlife,

Oregon State University, Corvallis, OR 

The objective of this project is to develop, test,

validate, and demonstrate an analytical framework for

assessing regional-scale forest disturbance in the MidAtlantic region by establishing a multiscale linkage between forest disturbance and forest nitrogen export to

surface waters. It is hypothesized that excessive nitrogen

(N) leakage (export) from forested watersheds is a potentially useful, integrative “indicator” of a negative change

in forest function that occurs in synchrony with changes

in forest structure and species composition. This research project focuses on forest disturbance associated

with historical defoliations by the gypsy moth larva at

spatial scales ranging from small watersheds to the entire

region. 

The technical approach for establishing a multiscale linkage between forest disturbance (i.e., gypsy

moth defoliation) and N leakage to surface waters has

made use of extensive forest, forest disturbance, and

water quality data collected for the Mid-Atlantic region

at all spatial scales (intensive watershed sites, subregional survey, regional survey, and remotely sensed data).

These data were supplemented with on-the-ground measurements of forest species composition for a selected

sample of watersheds for which N export had been previously monitored.

In early 2000, an analysis was completed of

regional-scale forest disturbance and associated dissolved

N export from Shenandoah National Park (SNP), Virginia—a large contiguous area of forested land within the

Chesapeake Bay Watershed. Long-term watershed research conducted in SNP indicates that annual export of

dissolved N from forested watersheds to surface waters

increases dramatically in response to vegetation disturbances. These results suggest that a parsimonious, empirical unit N export response function (UNERF) model

can explain large percentages of the temporal variation in

annual N export from a group of small gaged forested

watersheds in the years following disturbance. The empirical UNERF modeling approach is completely analogous to the unit hydrograph technique for describing

storm runoff, with the model representing annual N export as a linear deterministic process both in space and

time. 

The purposes of this analysis were to: (1) test the

applicability of the UNERF model using quarterly

streamwater nitrate data from a group of ungaged watersheds in SNP; (2) demonstrate a park-wide application of

a regional UNERF model that references the geographic

distributions of bedrock geology and the timing of gypsy

moth defoliation over the entire SNP area; and (3) visualize the temporal and spatial patterns in vegetation disturbance and annual dissolved N export through the use

of PC-based animation software.

The results of this analysis showed that: (1) forested ecosystems within SNP normally retain a very high

percentage of atmospherically deposited N, but forest

disturbances such as insect defoliation can dramatically

alter the input/output balance; (2) annual nitrogen export

from SNP forests began increasing in 1987 from a baseline rate of about 0.1 kg/ha, peaked in 1992 at an average rate of 1.68 kg/ha (more than a 1,500% increase),

and has since been steadily declining (see Figure 1);

(3) natural biogeochemical processes need to be considered in modeling N export dynamics of forests; and

(4) linear systems models can apparently provide parsimonious approximations of ecosystem complexity that

are useful for purposes of regionalization.

In the final year of the research project, this type

of integrative analysis will be extended to other forested

watersheds in the Chesapeake Bay Watershed. The focus

will be on first through third order drainages in the MidAtlantic Highlands Area (MAHA) that comprise a target

subpopulation of the EMAP surface water survey in the

eastern United States. In completing this analysis, historical remote-sensing data (AVHRR) will be used as a

means of better characterizing the spatial and temporal

variations in forest defoliation within the region during

the last 15 years.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

4 The Office of Research and Development’s National Center for Environmental Research

Figure 1. Modeled SNP-wide N export to surface waters and heavy gypsy moth defoliation during the period 1980-1999.
Section 2.

Projects Initiated With Fiscal Year 1998 Support 
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 7

Multilevel Statistical Modeling 

for Generalizing From Case Studies

Richard Berk, Jan de Leeuw, Richard Ambrose, Cindy Lin

Institute of the Environment, University of California at Los Angeles, Los Angeles, CA

Case studies, the foundation of environmental reearch, are too often faced with a very difficult “so

what?” criticism. Just because certain findings apply to

a given study site does not necessarily mean that they

apply to any others. Yet, the goal of such research commonly is to arrive at broadly relevant conclusions. 

In this research project, a generalization of multilevel statistical modeling is employed to consider the degree to which credible conclusions across a set of case

study sites can be drawn. Multilevel modeling within a

regression analysis framework allows for the explicit

consideration of how statistical summaries vary systematically over a set of sites. As a result, the degree to

which findings can be applied beyond a single site is addressed directly. 

The contribution of this research project is to provide a generalization of multilevel modeling and the necessary software, so that the generalized linear model can

be worked with, including such features as spatial and

temporal dependence, inherently nonlinear relationships,

and latent variables. For example, outcomes can be categorical, and sites closer to one another in space may be

treated systematically as more alike. The emphasis in

this research project is on technique, with the data used

as an illustration. The data come from a Regional Environmental and Monitoring Assessment Program (REMAP) project, U.S. Environmental Protection Agency

Region 9, undertaken in conjunction with the Environmental Science and Engineering Program at the University of California at Los Angeles. The research involves

a spatially intensive stream bioassessment monitoring

study for Calleguas Creek Watershed, Ventura County,

CA. 

This project includes sampling of riparian habitat

and streams for two seasons between 1999 and 2000.

Data are collected at 70 sites. Field assessment in the

watershed includes water quality, physical habitat assessments (e.g., measures and/or visual estimates of channel

cross-sectional dimensions, substrate, fish cover, bank

characteristics, and riparian vegetation structure), and

benthic and fish community sampling. The project seeks

to assess the current ecological condition of coastal

Southern California streams and examine impacts of land

use on water quality and aquatic ecosystem integrity. 
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

8 The Office of Research and Development’s National Center for Environmental Research

Regional Scale Impacts of Phase I of the Clean Air Act Amendments: 

The Relation Between Emissions and Concentrations, Both Wet and Dry

Gene E. Likens and Tom Butler

Institute of Ecosystem Studies, Millbrook, NY

A comparison of data records in the 1990s both

before (1991–94) and after (1995–97) implementation of

Phase I of the Clean Air Act Amendments (CAAA) of

1990 for seven regions of the eastern United States

shows a significant reduction in SO2 emissions for most

states, except for Texas, North Carolina, Illinois,

Florida, and Alabama. However, of the major NOX

emitting states, only two eastern states (New York and

Pennsylvania) show significant declines in NOX.

A pattern of large declines in SO2 emissions

(>20%) after CAAA implementation, and large declines

in precipitation concentrations of SO4

= and H+, as well

as air concentrations of SO2 and SO4

= (components of

dry deposition) exists for most regions of the eastern

United States. The regions examined include: Northern

New England and the Adirondack Mountains (NE); New

York, excluding the Adirondack Mountains (NY); Pennsylvania, northern West Virginia and eastern Ohio

(PA); Delaware, Maryland, and eastern Virginia (M-A);

Ohio, eastern Indiana, and northern Kentucky (OH);

Illinois and western Indiana (IL); and the southern Appalachian Mountains and surrounding area (SA). In most

cases, the emission/concentration relations are close to

1:1 (a near equal percent decline in concentrations for a

given percent decline in emissions) when the source region based on 15-hour air mass back trajectories is used

for the New England region, and source regions based on

9-hour back trajectories are used for the other eastern

regions. 

The southern Appalachian Mountain region is an

acid-sensitive area receiving high levels of acidic deposition that has not seen an appreciable improvement in

precipitation acidity. This area also has had the least improvement in wet and dry sulfur concentrations of the

areas examined (see Table 1). Precipitation base cations

(Ca++ and Mg++) show a pattern of increasing or level

concentrations when comparing 1990–1994 to 1995–1998

data for six of the seven regions that were examined.

Ammonium concentrations generally have changed less

than 10 percent, except for the Illinois region and the

southern Appalachian Mountain region, both of which

increased more than 15 percent. 

A future focus of this work will include an evaluation of how changing emission levels will affect New

England waters, using the Hubbard Brook Experimental

Forest as a test case.

Table 1. Changes in emissions of: (a) NOX, (b) SO2, and (c) combined emissions from source regions based on 9-hour back trajectories (except for NE, which is based on 15-hour back trajectories), expressed as percentagess; and changes, also expressed as percentages, in: (d) precipitation SO4

= concentrations, (e) SO2 and particulate SO4= air concentrations (sources of dry S deposition), and (f) precipitation acidity (H+ concentrations) for the study regions. The years 1991–1994 (pre-CAAA implementation) are compared with 1995–1997 (post-CAAA implementation). The percentage change in parentheses for NE and under 

(b) represent changes in emissions when the Province of Ontario is included as part of the source region.

EMISSIONS CONCENTRATIONS

91-94

vs.

95-97

(a)

NOx

% change

(b)

SO2

% change

(c)

2S+N (moles) 

% change

(d)

SO4

= wet

% change

(e)

S dry

% change

(f)

H+ wet

% change

 NE -10 -20 (-19) -17 -25 -29 -14

 NY -12 -24 (-22) -20 -24 -23 -22

 PA -7 -23 -18 -21 -21 -17

 M-A -3 -22 -15 -24 -18 -19

 OH +2 -23 -16 -18 -23 -16

 IL +2 -20 -13 -12 -20 -17

 SA +5 -19 -11 -6 -10 <-1
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 9

Regional Analysis of Variation in Adirondack Lake 

Ecosystems: Landscape Scale Determinants of Dissolved Organic Carbon

Michael L. Pace, Charles D. Canham, and Michael Papaik

Institute of Ecosystem Studies, Millbrook, NY

Lakes represent a critical ecological and economic

resource. The consequences of many types of air and

water pollution have been manifested and best understood in the study of lakes, especially at regional scales,

as for example in studies of the consequences of eutrophication and acidification. 

The goal of this research project is to develop an

approach to assessing variation in lake-watershed interactions at a regional scale. Specifically, it is sought to

predict variation in lake ecosystem properties as a function of landscape characteristics, especially in relation to

landscape and within lake processes that determine variation in lake dissolved organic carbon (DOC). 

Lake DOC is an important measure of overall lake

conditions and is one of the primary features that varies

among lakes in landscapes where lakes are not heavily

impacted by nutrient loading. The focus of this study is

on the Adirondack Park of New York State. This region

represents one of the largest areas of wilderness and

minimally developed land in the United States east of the

Mississippi River. Because of extensive prior studies,

there are large numbers of data sets on the watersheds

and lakes of the Adirondacks. 

From this information, data on the water chemistry

and complementary watershed data have been assembled

for more than 600 lakes in the Oswegatchie Black and

Upper Hudson Watersheds of the Park. This data set is

a representative sample of the larger number of lakes in

the region. Data layers allow for visualization of the elevation contours (from a new digital elevation map with

10 m resolution); all standing water bodies; uplands in

five categories of land use; wetlands in eight categories

derived from a more extensive classification of wetland

type; the extent of wetlands that fringe lakes at 50 m,

100 m, and 200 m intervals; streams; watershed boundaries; roads; and developed areas. A complete chemistry

data set for the study lakes has been assembled from

earlier water quality studies conducted by the Adirondack

Lake Survey. A series of watershed statistics have been

added to this data set using Geographic Information System (GIS) analysis.

Two analytical projects currently are underway.

The first is a multivariate statistical analysis of watershed

and lake characteristics with a goal of empirically evaluating controls on the variation in DOC observed among

lakes at a regional scale. 

The second analysis is the development of a maximum likelihood mass balance model for lake DOC.

This model will describe the inputs, outputs, and withinsystem processing of DOC in lakes. A key feature of

this model is the spatial analysis of inputs of DOC along

flow paths to a lake from various landscape source areas.

Flowpath data sets have been developed in the initial GIS

analysis of the watersheds to parameterize these input

functions. A simulated annealing algorithm will be used

to iteratively solve the basic model equation describing

inputs, processing, and outputs. This approach will

solve simultaneously for the parameter values that maximize the likelihood of the data set where mean lake

DOC is predicted. 
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

10 The Office of Research and Development’s National Center for Environmental Research

Methodologies for Extrapolating From Local 

to Regional Ecosystem Scales: Scaling Functions and

Thresholds in Animal Responses to Landscape Pattern and Land Use

John A. Wiens and Beatrice Van Horne 

Colorado State University, Fort Collins, CO

The objective of this research project is to develop

and test new concepts and methods for evaluating how

the structure and configuration of landscapes change with

changes in spatial scale, and how these changes in landscape scale relate to the scales at which various groups of

plants and animals respond to the environment, which

ultimately affects their distribution and abundance. 

Specifically, the aims of this project are to: (1) develop ways of modeling how the scaling of species’

responses to environmental variation is coupled to scaledependent changes in landscape composition and structure; (2) develop protocols for determining the scales at

which the responses of species and communities are

likely to exhibit thresholds, based on functional properties of the species; and (3) develop mathematical scaling

functions that can be coupled with Geographic Information Systems (GISs) to make use of remote sensing.

The overall goal is to derive scaling functions and GISbased spatial models that can be used to assess how information gathered at fine scales in intensive studies can

be extrapolated to the broad scales of ecological monitoring and environmental risk assessment.

There are three phases to this research. The first

phase is using existing data sets (faunal surveys, GIS layers, remote sensing) to explore how to link the spatial

structure of landscapes with the distribution of organisms

over multiple scales, and to determine the most appropriate statistical approaches to such scaling relationships.

The second phase is gathering information on the spatial

configuration of landscapes and the distribution of key

groups of organisms (vascular plants, beetles, butterflies,

and birds) at five study sites located on a broad-scale gradient from the shortgrass steppe to the tallgrass prairie

(see Figure 1). This series spans a gradient of increasing precipitation, productivity, and land-use intensity,

and will provide the foundation for detailed multiscale

analyses. The third phase is using the data to derive and

test mathematical, GIS, and spatial models that relate

changes in species occurrences, functional group composition, and biodiversity at multiple scales to the scaling

properties of landscapes. 

Data sets have been used for grasshopper distributions in eastern Wyoming and bird and vegetation

distributions in Idaho shrub steppe to explore several approaches to the analysis of spatially referenced data.

These studies have evaluated: (1) the differences between using land-cover classification data and quantified

or ordinal data in multivariate ordinations in GIS-based

analyses of the environmental correlations of animal

distributions; and (2) ways of determining the contributions of geographical distance to assessments of community-environment relationships. The studies in phases

two and three are just beginning.

These studies show that multivariate ordinations

may reveal features of environmental associations of

organisms that are not apparent when using classified

(categorical) data, and that geostatistical modeling can

considerably improve the explanatory power of causal

models of variations in community composition.

Detailed information on the spatial properties of

landscapes and organism distributions at scales from

1 m2 to tens of km2 will be gathered through field sampling in June-September 2000. Analysis of these samples will be conducted during the following 8 months,

along with generation of data sets derived from onground surveys, published literature, and remote sensing

to develop accompanying GIS layers. Combined with

the results of the ongoing examination of the properties

of various statistical approaches to spatial pattern and

scaling, these will form the foundation for the initial

stages of model development. The resulting models will

be tested using field data gathered in summer 2001,

followed by another phase of sample analysis and model

refinement.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 11

Figure 1. The Western Great Plains, showing the region encompassed by the scaling transect. LTER = long-term ecological research site. 

SGS = shortgrass steppe.
Section 3.

Projects Initiated With Fiscal Year 1999 Support 
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 15

Application of Remotely Sensed Data to Regional Analysis

and Assessment of Stream Temperature in the Pacific Northwest

Stephen Burges

Department of Civil and Environmental Engineering, University of Washington, Seattle, WA

The characteristics of water vary throughout a

stream network, presenting a major obstacle to regional

water quality assessments. Figure 1 illustrates the variation in stream temperature observed on a single day in

one stream network (covering approximately 100 km2

) in

western Washington State. The goal of this project is to

develop efficient methods for regional assessments of

stream temperature using remotely sensed thermal infrared (TIR) images of stream corridors to augment instream temperature monitoring. The TIR images are obtained from the ASTER camera mounted on the Terra

Satellite that was launched on December 18, 1999, as

well as from a forward-looking TIR radiometer mounted

on an aircraft.

The research is focused on water temperature to

illustrate and explore methods of water quality assessment because water temperature is biologically important, it is affected by anthropogenic activities, and the

kinetic temperature of visible surfaces can be measured

over large areas using aircraft- and satellite-based instruments. A hierarchical approach is used in which temperature monitoring techniques are adapted to address the

different issues faced in different parts of a stream

network. The range is from large streams that are clearly visible from both remote platforms, but may not be

thoroughly mixed, to small streams that constitute only

a portion of any “pixel” in a remotely sensed image from

the Terra Satellite.

Although the specific methods for monitoring

stream temperature vary depending on location in a

stream network, this approach takes advantage of the

synergy between remotely-based and in-stream instruments as illustrated by four examples. First, remotely

based instruments identify strong longitudinal (downstream) temperature gradients and the appropriate location and “density” of in-stream monitoring stations.

Second, in-stream measurements quantify the spatial

temperature structure of streams that is represented by

single values (i.e., pixels) in remote images. Third, instream instruments provide a continuous time-series of

temperature for periods when remotely sensed images

are not available. Fourth, remotely based measurements

facilitate interpolation of water temperatures between instream measurements.

Existing water quality monitoring programs provide

a spatially limited view of conditions in stream networks.

Synoptic surveys, such as those illustrated in Figure 1,

expand the purview of a water quality monitoring program, but many gaps in the coverage remain. The target

is to produce stream temperature maps that fill in the

gaps and provide a more complete picture of water

quality in the region.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

16 The Office of Research and Development’s National Center for Environmental Research

Figure 1. Mid-day stream temperatures (C) on August 19, 1998, throughout the Soos Creek Network, King County, WA.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 17

Effects of N Deposition on Gaseous 

N Loss From Temperate Forest Ecosystems

Peter M. Groffman 1, Louis V. Verchot 1*, Christopher Potter 2, Mary Beth Adams 3, Ivan Fernandez 4, 

and Lindsey Rustad 5

1

Institute of Ecosystem Studies, Millbrook, NY; 2NASA-Ames Research Center, Moffett Field, CA; 3USDA Forest

Service, Timber and Watershed Laboratory, Parsons, WV; 4

University of Maine, Orono, ME; 5USDA Forest

Service, Northeastern Research Station, Pownal, ME (*Now at the International Centre for Research in

Agroforestry, Nairobi, Kenya) 

Although much effort has gone into determining the

fate of atmospheric N in temperate forest ecosystems,

many uncertainties remain as to just where N is stored

and what processes and pathways influence N retention

and/or loss. One of the largest areas of uncertainty is

gaseous loss. This flux may be large and may be very

sensitive to N deposition. 

The specific objectives of this research project are

to: (1) determine the importance of gaseous loss of N

from temperate forest ecosystems; (2) determine the impacts of N deposition on gaseous loss of N from these

ecosystems; (3) test a mechanistic model that relates N

gas emissions to N availability and soil moisture content;

and (4) develop a new and more mechanistic version of

the daily NASA-CASA ecosystem model for N gas emissions that can be applied at the regional level using

satellite remote sensing and other spatial data sets in a

Geographic Information System (GIS) format. This new

simulation model will be used to assess trends in N

cycling over gradients of N deposition in the northeast

United States and to project changes in N gas fluxes with

changing air pollution.

Gas fluxes (NO, N2O, N2) will be sampled on a

monthly basis at five sites along an N deposition gradient

in the northeast United States: Fernow Experimental

Forest, WV; Catskills State Forest, NY; Hubbard Brook

Experimental Forest, NH; Harvard Forest, MA; and

Bear Brook Watershed, ME. Several additional measurements of factors known to control flux rates (e.g., N

pool sizes and turnover rates, denitrification rates, soil

temperature, soil pH, and soil moisture) will be made.

Samples will be taken in both N fertilized and unfertilized plots at each location. These data then will be used

to develop a new and more mechanistic version of the

daily NASA-CASA ecosystem model for N gas emissions that can be applied across a 10-state region (ME,

NH, VT, MA, RI, CT, NY, NJ, PA, and WV) using

satellite remote sensing and other spatial data sets in a

GIS format. This new simulation model will be used to

assess trends in N cycling over gradients of N deposition

in the northeast United States and to project changes in

N gas fluxes with changing air pollution.

Field measurements for this project have not begun

yet; however, one of the first tasks has been to establish

experimental designs to capture the main factors influencing N gas fluxes at the different sites (e.g., topographic position, N availability, species composition).

Preliminary data from one of the sites, the Hubbard

Brook Experimental Forest, suggest that tree species

composition may be a strong controller/indicator of N

gas fluxes at these sites (see Figure 1).

One of the least well-understood facets of the complex N cycle is loss of N in gaseous forms from the soil.

Quantifying this flux is important from the perspective of

understanding the fate of N deposited on these ecosystems from the atmosphere and for determining the

source strength of northeastern forests in regional and

global budgets of NO (an ozone precursor) and N2O (a

greenhouse gas). The modeling effort will permit placing constraints on the regional contribution of the soil

source of N gases and make projections of the impact of

increasing N saturation on the regional atmospheric

budget of these gases. Regional quantification of gaseous N loss and improved understanding of the spatial

variability of this process will be important for development of critical load tolerances for N deposition.

Sites currently are being established, instruments

are being purchased and set up, and field and laboratory

protocols are being finalized. Flux measurements should

begin by early June 2000.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

18 The Office of Research and Development’s National Center for Environmental Research

0

10

20

30

40

50

0 5 10 15 20 25 30 35

Time (days)

N O evolution (ng N g 2 -1 d-1)

Maple

Birch

**

*

*

*

*

Figure 1. N2O production in soils from sugar maple and yellow birch stands at the Hubbard Brook Experimental Forest, NH. Soils were 

incubated in the laboratory for 33 days. All differences between points were statistically significant at p < 0.05.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 19

Regional Analysis of Net Ecosystem 

Productivity of Pacific Northwest Forests: Scaling Methods, 

Validation, and Results Across Major Forest Types and Age Classes

Beverly E. Law, D. Turner, C. Daly, M.E. Harmon, S. Acker, W. Cohen, M. Unsworth 

Departments of Forest Science, Geosciences and Atmospheric Sciences, Oregon State University, Corvallis, OR

This project started on July 1, 2000. The objectives are to: (1) develop and test a regional scale approach that combines modeling, data from remote

sensing, sample surveys, and intensive research sites to

better estimate variation in the carbon balance of forest

ecosystems in the Pacific Northwest; and (2) apply this

strategy to investigate how processes controlling variation in net ecosystem productivity are influenced by

forest development, disturbances, and contrasting climatic conditions.

Net ecosystem productivity (NEP) is a critical characteristic of terrestrial ecosystem response to environment. Processes controlling NEP operate on a variety of

temporal and spatial scales and are influenced by plant

physiology, forest age or developmental stage, climate,

and disturbance. This project will simulate productivity

and NEP in Oregon and Washington using a combination

of remote sensing, survey data, process-level measurements in different age classes of forests, and process

models. Model outputs will be tested using detailed ecosystem studies at intensive sites, more basic ecological

measurements at other existing intensive sites, and survey data from Forest Health Monitoring (FHM) and

Forest Inventory and Analysis (FIA) plots. 

For each 30 x 30 m unit of ground, forest productivity will be predicted and evaluated for an east-west

longitudinal swath along a steep climatic gradient

through central Oregon from the coast to the semi-arid

east side of the Cascade Mountains, and a north-south

latitudinal swath from the southern Oregon border to

southern Washington. BIOME-BGC, a physiologically

based process model, will generate current NEP, productivity, and “carbon stress index” estimates for the region

for a mean climate year, 1999, and 2000. STANDCARB, an ecosystem process model, will be used to estimate current carbon pools by accounting for long-term

trends in NEP. BIOME-BGC will be initialized using

remote sensing (Thematic Mapper) estimates of forest

cover type, age class and the amount of leaf area present

for photosynthesis, and soil survey data. The model will

be driven by spatially distributed climate data based on

interpolations of weather station data by climate models.

Remotely sensed variables will be validated with data

from intensive sites and the survey sites, and new measurements in underrepresented forests. 

Model predictions of carbon budget components

will be validated with flux data, other intensive site data,

and survey data. Sensitivity of NEP to forest type, developmental stage, disturbance, and interannual variability in climate will be evaluated. A practical approach for

linking remote sensing, sample surveys, and intensive

site data via modeling at the regional scale will be demonstrated.

The data acquisition phase will start soon, so there

are no findings to report as of yet. In the first year of

this project, existing data will be assembled, remote sensing imagery will be acquired, and the spatially derived

climate data sets will be produced. Working with statisticians, a sample design for the field measurements will

be developed. The field season will begin in June 2001.

Modeling activities will include testing the models with

existing site data across the region.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

20 The Office of Research and Development’s National Center for Environmental Research

Multiscale Effects of Forest Fragmentation and 

Landscape Context on Population Health of Birds

Thomas E. Martin, R.L. Redmond, M.M. Hart, and M.E. Clark 

Montana Cooperative Wildlife Research Unit, The University of Montana, Missoula, MT

Data from intensive studies of avian demography at

replicated sites and multiple spatial scales within and

among geographic regions will be used to assess the effects of spatial scale and landscape context on major factors (nest predation and Brown-headed Cowbird parasitism) that influence the health of bird populations. 

Results from this work will provide new and more

general insight into the influence of spatial scale on fragmentation and landscape context in relation to nest predation and cowbird parasitism in birds. Moreover, results of this work then can be applied to land cover data

across North America and across time to examine and

predict the potential demographic consequences of future

land-use changes on bird populations. 

A Geographic Information System (GIS) will be

used to characterize landscapes, particularly in terms of

forest fragmentation, at roughly 30 sites across the

United States using bird demographic data compiled for

the Breeding BIology Research and Monitoring Database

(BBIRD) program. At these sites and the more than 250

plots within them, data on nesting success have been

collected from more than 30,000 nests of more than 200

species of birds. 

The BBIRD and GIS data will be used to examine:

(1) the spatial scales that influence demographic processes (i.e., predation and parasitism) within and among

geographic regions; (2) the role of cover type (e.g., forest, agriculture, human habitations, etc.) in the landscape

(landscape context) on predation and parasitism relationships; and (3) predation and parasitism relationships with

landscape characteristics among regions. 

The information on predation and parasitism relationships obtained from these three sets of analyses will

be used to: (1) develop predictive models of bird demographic responses to forest fragmentation throughout

North America; (2) examine the demographic consequences among functional groups (i.e., nest types, habitat

requirements) to determine variation in population sensitivity and identify high-risk species and species groups;

and (3) model these demographic relationships in terms

of population sustainability to attempt to identify landscape conditions that support source (self-sustaining)

populations. 

At this time, efforts are focused on building the

necessary GIS databases for characterizing landscapes.

GIS data are being compiled on a site-by-site basis; each

site’s landscape is defined by a circle with a 100 km

radius centered on that site. The National Land Cover

Data set (NLCD) provides a consistent layer for the conterminous United States at a spatial resolution of 30 m.

Other GIS layers include digital elevation data, hydrography, roads, and the locations of the BBIRD sites.

Once the databases are assembled, predation and parasitism will be examined, then modeling can begin.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 21

Regional Ecological Resource Assessment of the Rio Grande 

Riparian Corridor: A Multidisciplinary Approach To Understanding 

Anthropogenic Effects on Riparian Communities in Semi-Arid Environments

Jay Raney 1, Melba Crawford 2, Frank Judd 3, Gene Paull 4, Robert Lonard 3, Amy Neuenschwander 2, 

Thomas Tremblay 1, and William White 1

1

Bureau of Economic Geology and 2Center for Space Research, The University of Texas at Austin, Austin, TX; 3

The University of Texas–Pan American, Edinburg, TX; 4The University of Texas at Brownsville, Brownsville, TX

Riparian ecosystems of the southwestern United

States are characterized by high species diversity and are

among the most productive ecosystems of North America. The rapid decline of riparian ecosystems throughout

the United States has made riparian conservation a focal

issue for the public, federal and state governments, and

private organizations. 

Among the objectives of this 3-year multidisciplinary study of the riparian corridor are to: (1) acquire and

analyze high-resolution remotely sensed data from multiple sensors; (2) integrate existing and new field data

and remotely sensed data into a Geographic Information

System (GIS); (3) ascertain whether the native communities are maintaining themselves and identify the

topographic, edaphic, and other ecological factors that

perpetuate these communities; (4) interpret spatial variations in riparian habitats, including comparisons of the

north and south banks of the Rio Grande; (5) analyze

temporal changes at specific locations; and (6) develop

a foundation for future analysis of riparian floodplain

communities by linking local and remotely sensed regional data using GIS. 

The study area includes the lower reach of the Rio

Grande from Falcon Dam to the mouth of the river (see

Figure 1). Detailed, local-scale, ecological transects of

dominant riparian vegetation will be correlated with

high-resolution videography and multispectral data to

delineate the spatial extent of the riparian community.

This correlation will provide ground truth for the classification output from high-resolution (4–7 m) hyperspectral and airborne synthetic aperture radar (SAR)

data. Classification output from high-resolution data will

in turn provide the class mixtures for medium-resolution

(20–30 m) LandsatTM and SPOT multispectral data that

cover the entire study area, on both sides of the Rio

Grande. Data on geology, soils, land use, water quality

and hydrology, and topography from Topographic Synthetic Aperture Radar (TOPSAR), as well as airborne

laser altimetry data acquired for the study, will be investigated as additional inputs to the classification process and will be used to help explain temporal and spatial

changes in ecological resources indicated in the remotely

sensed data. GIS-based spatial models and statistical

modeling results will be used to predict the expected

future effects of landscape change on plant distribution,

biodiversity, and functional organization at multiple

scales of resolution. The developed methodologies will

help to guide future assessments of riparian regions.

Only very preliminary analyses of data have been

completed as of April 2000. Initial integration of data

into a GIS and preliminary analysis reveal the utility of

certain data sets. For example, U.S. soil maps include

parameters such as conductivity or soil salinity, which

allow construction of specific GIS layers that can be used

to examine relationships with riparian vegetation. One

difficulty has been correlating Mexican soil maps with

U.S. soil maps because of differences in scale and terminology. Preliminary analysis of two airborne hyperspectral data-imaging systems, which have similar spatial

resolution but different spectral coverage, shows that

riparian vegetation composition is better defined by the

sensor that includes longer wavelength infrared bands.

The next steps are to continue acquiring needed

data, classifying remotely sensed data, ground truthing,

and to begin preliminary analysis and testing of the methodology.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

22 The Office of Research and Development’s National Center for Environmental Research

Figure 1. Map of Lower Rio Grande valley showing approximate location of existing ecological transects and example of riparian vegetation

in the Santa Ana National Wildlife Refuge. 
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 23

A Hierarchical Patch Dynamics 

Approach to Regional Modeling and Scaling

Jianguo Wu

Department of Life Sciences, Arizona State University West, Phoenix, AZ

Scaling is imperative for understanding and predicting broad-scale dynamics based on fine-scale observations. To scale up or down, it is necessary to construct multiscale models or to link individual models at

different scales, which together capture the spatial heterogeneity of pattern and process. Hence, to develop

cross-scale models, there are both theoretical and technical challenges. 

To meet these challenges, a hierarchical patch dynamics modeling (HPDM) approach is proposed (see

Figure 1). HPDM involves three basic steps. First,

based on empirical data, the patch hierarchies relevant to

the phenomena and objectives of study using the principles of loose vertical and horizontal coupling and neardecomposability need to be identified. The second step

is to develop and validate unit hierarchical models in

which the next higher level provides boundary conditions and other constraints, while dynamics at the next

lower level are described mechanistically. The third step

is to link unit hierarchical models across scales through

an input-output chain. 

The HPDM approach will be discussed and illustrated through an example of modeling the pattern and

process of urbanization in the Phoenix metropolitan area.

Figure 1. Hierarchical scaling or extrapolating information along a hierarchical scaling ladder. Scaling up or down is implemented by

changing model grain size, extent, or both across successive domains of scale.
2000 STAR Regional Scale Analysis and Assessment Progress Review Workshop

The Office of Research and Development’s National Center for Environmental Research 25

Index of Authors

Berk, R.A., 7

Burges, S., 15

Eshleman, K.N., 3

Groffman, P.M., 17

Law, B.E., 19

Likens, G.E., 8

Martin, T.E., 20

Pace, M.L., 9

Raney, J., 21

Wiens, J.A., 10

Wu, J., 23
United States

Environmental Protection Agency(8701R)Washington, DC 20460Official BusinessPenalty for Private Use$300