2002 Progress Report: Development And Testing Of A Multi-Resource Landscape-Scale Ecological Indicator: Forest Fragmentation, Structure, and Distribution Relative to Topography

EPA Grant Number: R826598
Title: Development And Testing Of A Multi-Resource Landscape-Scale Ecological Indicator: Forest Fragmentation, Structure, and Distribution Relative to Topography
Investigators: Seagle, Steven W. , Townsend, Philip A.
Institution: University of Maryland Center for Environmental Science
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through September 30, 2003
Project Period Covered by this Report: October 1, 2002 through September 30, 2003
Project Amount: $683,374
RFA: Ecological Indicators (1998) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems


The objective of this research project is to develop topographic predictors of avian habitat quality in multiple-use landscapes of the Mid-Atlantic Highlands, and to test whether water quality covaries with avian habitat quality because of a mutual dependence on land use and topography. If this correlation exits, then it should be feasible to develop indicators that simultaneously reflect both resources using only widely available databases of topography (digital elevation models) and land use. Additional goals are to: (1) statistically characterize the linkages among topography, forest productivity, avian food resources, and avian reproductive success (which is the ultimate measure of habitat quality); (2) apply synthetic aperture radar-remote sensing to integrate forest structural diversity with avian diversity and productivity; (3) test locally (western Maryland) derived relationships between topography and forest productivity across a broader regional area; and (4) apply our topography and avian productivity models to a statistically random sample of points across the Mid-Atlantic Highlands and compare results with an avian community index that reflects landscape condition.

Progress Summary:

During this reporting period, our work focused on several tasks: (1) revising and testing the robustness of our forest productivity index; (2) collecting field data to test the regional validity of our topography-forest productivity relationships; (3) finalizing land-use classifications and rectifying land use with watersheds for which we have water-quality variables; and (4) processing of synthetic aperture radar images for extraction of variables to predict forest-physical structure. Each of these topics is addressed separately.

Forest Productivity Calculations. During the previous reporting period, we found that forest songbird reproduction is significantly correlated with topographic variation in forest productivity. Site index proved to be a reliable index of forest productivity across the range of site conditions that we measured in the Ridge-and-Valley and Appalachian Plateau physiographic provinces. We knew from previous literature surveys that there were multiple equations for calculating site index. Discussion of our results with various individuals made it clear that our choice of site index calculations would be highly scrutinized in manuscripts submitted for publication. Thus, we recalculated the site index for our field data using additional methods. Statistical comparisons of forest-site quality were improved through the use of a concordance correlation coefficient that quantified the reproducibility of four different site index equations in predicting site index for mature oak forests in western Maryland. The results identified those published tree age-height relationships that produced site index estimates most consistent with independent topographic equations for site index in the same region. Correlations among site index values produced by different equations indicate that our site index values are quite robust. The data also indicate that our age-height relationships tend to underestimate site quality in mature second-growth oak stands. However, this bias is consistent across physiographic provinces and study sites. These efforts have produced specific values of site index that will be standardized among the publications resulting from our work.

Regional Validity of Forest Productivity Estimates From Topography. To establish the statistical relationships among topography, forest productivity, and avian productivity, intensive field studies were needed. Significant statistical relationships were found that predict forest and bird productivity, but we also found that these statistical relationships were stronger for study sites in the Ridge-and-Valley province. We interpret this result as a function of the generally lower rainfall in the Ridge-and-Valley compared to the Appalachian Plateau. Nonetheless, our objective of extrapolating results from our intensive study sites over larger regions is dependent on these statistical relationships being valid at larger spatial scales. Consequently, during the current reporting period, we collected field measurements (topographic position, geographic coordinates, tree height, tree age, etc.) that will allow us to calculate forest productivity (site index) for 20 locations distributed across the Ridge-and-Valley province (both north and south of our centrally located study sites). Tree cores to determine tree age were returned to the Appalachian Laboratory, mounted, and sanded, and tree age was calculated. We are in the process of deriving topographic predictor variables for these locations. The regional efficacy of our statistical model will be tested by using the model derived from our study sites to predict the site index of the distant sites. We will correlate model estimates of the site index with site index values calculated from field data.

Watershed Land Use. One objective of this research project continues to be the identification of relationships among watershed nutrient export, the extent of forest cover, and the spatial distribution of forest cover. Previously, we reclassified land use in Landsat images for most of the Chesapeake Bay Watershed. During the current reporting period, these images were "pieced together" to provide coverage compatible with boundaries for those watersheds for which we have water quality data. We then used those watershed boundaries to overlay with land-use images and with digital-elevation models. The resulting spatial database is being used to generate a series of variables that describe watershed structure and land-use composition. These variables then will be correlated with water quality for the watersheds.

Forest Physical Structure. Based on field data that we have collected during the course of this project, we previously developed a geometric model of forest-vertical structure. This model holds promise for spatially characterizing forest structure that can be correlated with forest invertebrate biomass, avian diversity, and avian reproductive success. Our objective is to use the model to help predict these variables across the Mid-Atlantic Highlands. During this reporting period, we focused on deriving data from synthetic aperture radar (SAR) images, of the Mid-Atlantic Highlands. That portion of the SAR data corresponding to our field study sites in western Maryland will be correlated with the empirical representation of forest structure from our geometric model. Once tested, this correlation will be used to predict forest structure across the larger region covered by the SAR images. To extract characteristics from the SAR images, we have ortho-rectified all 17 images using both digital election models and U.S. Geological Survey (USGS) topographic base maps. The rectified images were calibrated to resolve backscatter (i.e., the signal received by the SAR satellite after emitted radar waves interact with forest structure). To better resolve backscatter, especially for areas with topographic variation, we calculated the angle of incidence between the satellite and earth's surface and are factoring that angle into backscatter calculations. Backscatter data were first extracted for the 180 field plots in our intensive study areas in western Maryland. During ortho-rectification and calibration, it was found that about 25 percent of our SAR images were significantly distorted. Although time consuming, this distortion was corrected and data extraction from all SAR images is now complete. SAR data currently are being statistically related to the geometric variables of forest-canopy structure derived from our field data.

Future Activities:

In the coming year, we will focus on: (1) completing our analysis of watershed water quality as a function of forest land use and topographic pattern of land use; (2) comparing watershed water quality with avian habitat quality to test our hypothesis that these resources correspond in space; (3) creating regional maps of avian habitat quality; (4) developing spatial concepts of avian habitat quality based on both habitat productivity and habitat structure; and (5) attempting a comparison of avian habitat quality predicted from our site index models with an independent measure of habitat condition based on bird-community composition. Obviously, we will be following the review and revision process of currently submitted manuscripts carefully during the next funding period. In addition, we anticipate submitting further manuscripts related to the foci noted above. We also will work with researchers at Penn State University to apply our avian habitat quality indices to field sites located across the Mid-Atlantic Highlands.

Journal Articles on this Report : 3 Displayed | Download in RIS Format

Other project views: All 38 publications 7 publications in selected types All 7 journal articles
Type Citation Project Document Sources
Journal Article Seagle SW, Sturtevant BR. Forest productivity predicts invertebrate biomass and ovenbird (Seiurus aurocapillus) reproduction in Appalachian landscapes. Ecology 2005;86(6):1531-1539. R826598 (2002)
R826598 (Final)
  • Abstract: ESA
  • Journal Article Sturtevant BR, Seagle SW. Comparing estimates of forest site quality in old second-growth oak forests. Forest Ecology and Management 2004;191(1-3):311-328. R826598 (2002)
    R826598 (Final)
  • Full-text: Science Direct
  • Abstract: Science Direct
  • Other: Science Direct
  • Journal Article Sturtevant BR, Seagle SW. Food availability for forest interior songbirds in the central Appalachians: the role of topography. Landscape Ecology. R826598 (2001)
    R826598 (2002)
    not available

    Supplemental Keywords:

    water, watersheds, land, animal, ecosystem, indicators, scaling, terrestrial, aquatic, habitat, biology, ecology, hydrology, Environmental Monitoring and Assessment Program, EMAP, surveys, Landsat, remote sensing, Chesapeake Bay, EPA Region 3, Maryland, MD, Mid-Atlantic Highlands, forest interior, fragmentation, topography, digital elevation models, synthetic aperture radar, invertebrate., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Ecology, Water & Watershed, Ecosystem/Assessment/Indicators, Ecosystem Protection, Forestry, Ecological Effects - Environmental Exposure & Risk, Mid-Atlantic, Ecological Risk Assessment, Biology, Geology, EPA Region, Watersheds, Ecological Indicators, risk assessment, remote sensing, landscape indicator, multi-level indicators, stream ecosystems, Region 3, bird habitat, ecosystem indicators, estuarine ecosystems, gypsy moth, Mid-Atlantic Highlands, terrestrial, aquatic ecosystems, water quality, stress responses, defoliation, land use

    Progress and Final Reports:

    Original Abstract
  • 1999
  • 2000 Progress Report
  • 2001 Progress Report
  • Final Report