Grantee Research Project Results
2002 Progress Report: Effects of Forest Fragmentation on Community Structure and Metapopulation Dynamics of Amphibians
EPA Grant Number: R827642Title: Effects of Forest Fragmentation on Community Structure and Metapopulation Dynamics of Amphibians
Investigators: Johnson, Lucinda , Gross, John , Boone, Randall , Johnson, Catherine
Current Investigators: Johnson, Lucinda , Johnson, Catherine , Boone, Randall , Gross, John , Breneman, Dan , 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 Period Covered by this Report: December 1, 2001 through November 30, 2002
Project Amount: $769,623
RFA: Ecological Indicators (1999) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
The overall objective of this research project is to quantify the effects of forest fragmentation on amphibian community structure and population dynamics in vernal pool ecosystems.
Progress Summary:
Spatial Data. Pertinent digital spatial data for the study region have been acquired or digitized, merged, and archived. Low-level, infrared aerial photos were acquired for the area within 5 km of each wetland cluster, scanned, georeferenced, and used to visually interpret high-resolution land cover mapping within 1 km of each site. This land cover mapping was summarized within concentric buffers ranging from 10 m to 1 km radius from each study site. Landsat 7 satellite scenes were acquired for spring 2000 and fall 1999, to classify upland land cover in the study area.
Field Data. We have completed the final year of field work at 37 study sites (6 wetland clusters in 3 geographically distinct pairs, each with 1 fragmented and 1 unfragmented cluster). Anuran calling surveys were performed and field data (including water quality and macro-invertebrate sampling) were collected during three surveys in 2000-2001, and two surveys in 2002.
Solar Radiation Measurements. Incident radiation was measured in random plots and through the water column in 8 ponds in mid May and 16 ponds in mid June within 3 hours of solar noon. Vertical attenuation profiles of ultraviolet (UV) B, UVA, and photosynthetic active radiation (PAR) were measured in all 37 vernal pools, under the same conditions as the incident radiation measurements in 3 locations per pond. Vertical attenuation coefficients (Kd) were calculated and bulk attenuation coefficients (Ka) were determined for each pond in the laboratory. UVB dose also was measured with polysulfone film UVB dosimeters and with a multiprobe data logger equipped with UVB Minder probes in four ponds.
Macroinvertebrates. Invertebrate samples were returned to the Natural Resources Research Institute (NRRI) laboratory, sorted, and identified. Twenty metrics based on aquatic insect behavior, life stages, and functional characteristics were calculated. Principle Component Analysis and Multivariate Analysis of Variance were used to examine seasonal and treatment interactions. A majority of the variance (50 percent) was explained on the first axis, providing a clear separation between fragmented and unfragmented treatments. The total number of taxa increased slightly between early and late sampling periods for both treatments, but fragmented ponds contained significantly more taxa than unfragmented ponds. Functional attributes such as grazers, gatherers, and scrapers responded in a similar fashion as more of those taxa were recorded in the fragmented ponds.
Amphibians. Pitfall traps and drift fences installed around eight wetlands were checked daily for amphibians from April-August of 2000-2001 and April-June of 2002. Amphibians also were collected via minnow traps, activity traps, or by hand at all other study sites during each of the three seasonal surveys. All captured amphibians were identified and examined for malformations prior to their release; wood frogs (Rana sylvatica) and blue-spotted salamanders (Ambystoma laterale) were weighed, measured, and given a unique mark to allow for individual identification during subsequent recaptures. Approximately 19,800 amphibian specimens (11 species) have been handled during the 3 years of this study. In 2002, 1,300 wood frogs were captured in drift fences, including 777 recaptures from 2000-2001. Approximately 90 percent of the wood frogs recaptured in 2002 were originally marked in 2001; of those, about 40 percent had dispersed from study site ponds as metamorphs in 2001. Although most of the between-year recaptures in both 2001 and 2002 occurred at their original capture location, many individuals were recaptured at different vernal pools. Preliminary analyses of R. sylvatica metamorphs emigrating from the pools indicate a nonrandom directional component from some sites; though the same pattern was not observed in individuals immigrating to ponds in the spring.
Modeling. A vernal-pool hydroperiod model was developed and tested using hydrologic data collected from the field sites with relatively good results. The draft IMOVE amphibian dispersal model also was developed and modified to apply to each of the three general study site locations. This adjustable, correlated random-walk model describes dispersal from vernal pool into upland areas, and movement from uplands to the pools in the spring. The IMOVE model will be tested with empirical data gathered from our field sites, merged with the hydroperiod submodel, and finalized.
Future Activities:
In the coming year, we will quantify landscape structure for the concentric buffers used in the aerial photo-interpretation summaries, as well as for broader spatial extents (1-5 km). These data will be used to quantify relationships among landscape metrics, vernal-pool characteristics, and amphibian community structure, and to assist in the analyses of wood frog and blue-spotted salamander movements within and among years. Modeled amphibian dispersal patterns will be evaluated by comparing drift fence sites R. sylvatica captures predicted by the IMOVE program to actual captures in 2002, and the model then will be generalized to other regions. The results of forest harvest scenarios will be modeled at sites and across the region.
Journal Articles:
No journal articles submitted with this report: View all 9 publications for this projectSupplemental Keywords:
ecological effects, sensitive populations, vulnerability, animal, stressor, indicators, aquatic, conservation, genetics, biology, ecology, monitoring, Midwest, EPA Region 5, wetlands, frogs, salamanders, Rana sylvatila, Pseudacris crucifer, Ambystoma laterale, Ambystoma tigrinum., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Forestry, 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 fragmentationRelevant Websites:
http://www.nrri.umn.edu/cwe/waterresources.htm Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.