Effects of Forest Fragmentation on Community Structure and Metapopulation Dynamics of Amphibians

EPA Grant Number: R827642
Title: Effects of Forest Fragmentation on Community Structure and Metapopulation Dynamics of Amphibians
Investigators: Johnson, Lucinda , Boone, Randall , Gross, John , Johnson, Catherine
Current Investigators: Johnson, Lucinda , Boone, Randall , Breneman, Dan , Gross, John , Johnson, Catherine , Olker, Jennifer H.
Institution: University of Minnesota - Duluth , Colorado State University
EPA Project Officer: Packard, Benjamin H
Project Period: December 1, 1999 through November 30, 2002
Project Amount: $769,623
RFA: Ecological Indicators (1999) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems

Description:

The objectives of this study are to:

  1. Quantify the manner and extent to which forest fragmentation influences amphibian community structure of vernal pool ecosystems;
  2. Assess the extent to which regional and local-scale indices reflect fundamental structural properties of vernal pool habitats and biotic communities and, conversely, the extent to which indices of biotic integrity (e.g., amphibian community structure) reflect local and landscape properties;
  3. Develop predictive models which integrate landscape-scale factors with pond-scale attributes to: i) quantify key compositional and structural attributes of the amphibian community, and ii) derive ecosystem indicators at multiple spatial scales; and
  4. Develop predictive models to quantify the extent to which forest fragmentation influences the metapopulation dynamics of woodland amphibians and predict the consequences of landscape change on these metapopulations.
Estimated Improvement in Risk Assessment or Risk Management: The study will provide information on the levels of connectivity necessary to ensure the persistence of diverse amphibian communities in forested landscapes. The research will elucidate the mechanisms by which fragmentation may directly and indirectly effect the composition and structure of amphibian communities, the dynamics of metapopulations, and regional persistence of amphibian populations. Demographic and community-level data collected as part of the research also can be used to assess the power of ongoing monitoring studies to detect long-term population trends. Models developed as part of this research will provide a valuable tool for scientists, regulators, and land managers to use in assessing the potential effects of differing forestry practices or other land use activities that could result in fragmentation of existing forest resources.

Approach:

Recent evidence of declines and an increased rate of malformations in amphibian populations has prompted much interest and research into the potential anthropogenic stressors associated with these occurrences. Results of some of this research indicate that fragmentation may have a significant effect on the metapopulation dynamics of amphibian communities, which could result in declines and regional extinctions of populations. Forest fragmentation results in changes to forest landscapes and habitats that may have both direct and indirect effects on local and regional amphibian communities (e.g., direct habitat loss, disruption of dispersal corridors, altered habitat structure, and microclimate changes). We hypothesize that forest fragmentation can be directly related to changes in landscape structure and local habitats (e.g., vernal pools) that have a quantifiable effect on the integrity of amphibian communities. We will quantify landscape and local habitat and biotic community variables to examine effects of forest fragmentation on pond-breeding woodland amphibians at three spatial scales: the landscape scale, the local or "pondscape" scale (including ponds and surrounding terrestrial habitat), and the aquatic pond habitat. Relationships among these hierarchically-nested scales will be quantified using an integrated series of empirical models. This approach of identifying relationships across scales, and integrating them into a modeling framework will allow the development of multi-scale ecological indicators of the effect of forest fragmentation on vernal pool ecosystems and on regional amphibian communities. We hypothesize that indices of community diversity and structure and amphibian species traits can be used to assess effects of forest fragmentation on vernal pool systems and regional amphibian communities. Metapopulation models will be developed to assess the effects of fragmentation on local and regional populations, and elucidate the mechanisms by which forest fragmentation may influence the composition and persistence of vernal pool communities.

Expected Results:

The proposed research will develop, evaluate, and integrate indicators across multiple spatial scales, using a multi-tiered sampling and modeling strategy. We will integrate data collected at landscape scales via satellite imagery, and local scales via high resolution imagery and field sampling. Indicators of critical landscape features will have direct, mechanistic linkages to key process and structural attributes associated with amphibian community integrity. This study should identify principle factors affecting amphibian community structure and metapopulations in forested habitats in the northern Great Lake's region. Results of this research will enhance our ability to quantify the effects of landscape fragmentation on vernal pool communities, and to assess the consequences of forest fragmentation on regional amphibian populations and their habitats. It is likely stressors associated with increased fragmentation (e.g., decreased canopy cover, altered hydrological patterns, and increased isolation of habitat patches, increased UV radiation) will result in changes in the species composition and relative abundances of amphibian communities. Thus, woodland amphibians should provide robust ecosystem indicators of the effects of forest fragmentation that can be applied across geographic regions. Using spatial and demographic data gathered as part of this study, we will develop a predictive metapopulation model to elucidate the mechanisms by which landscape fragmentation affects regional population dynamics. This model will provide a valuable tool for assessing the potential impacts of forest fragmentation on amphibian communities. While model development will be based on data collected from forest habitats, the processes identified could be extended to the effects of fragmentation in other ecosystems and landscapes. By clarifying the relationship between landscape patterns, local habitat parameters, and metapopulation dynamics, this study will identify potential long-term threats to the integrity and persistence of amphibian populations.

Publications and Presentations:

Publications have been submitted on this project: View all 6 publications for this project

Supplemental Keywords:

wetlands, frogs, salamanders, Rana sylvatica, Pseudacris crucifer, Ambystoma laterale, Ambystoma tigrinum., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecology, exploratory research environmental biology, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Forestry, Ecological Effects - Environmental Exposure & Risk, Environmental Monitoring, Ecological Risk Assessment, Agronomy, Ecological Indicators, risk assessment, ecological exposure, anthropogenic stresses, wetlands, algae, aquatic biota , landscape indicator, UV effects, frogs, vernal pool ecosystems, amphibian, multiple spatial scales, ecosystem indicators, regional scale, multiscale assessment, forest fragmentation

Relevant Websites:

http://www.nrri.umn.edu/cwe/waterresources.htm

Progress and Final Reports:

  • 2000 Progress Report
  • 2001 Progress Report
  • Final Report