Grantee Research Project Results
2000 Progress Report: Ecological Indicators for Large River-Floodplain Landscapes
EPA Grant Number: R826600Title: Ecological Indicators for Large River-Floodplain Landscapes
Investigators: Turner, Monica G. , Stanley, Emily H.
Institution: University of Wisconsin - Madison
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through September 30, 2001 (Extended to September 30, 2002)
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $677,351
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems
Objective:
Identifying landscape indicators that are well correlated with specific aspects of ecological function is a crucial research need requiring an integrated approach that combines landscape monitoring with field studies. Large river-floodplain systems are among the most diverse and dynamic landscapes, providing many important societal values, but relatively little effort has been devoted to development and testing of landscape indicators for these systems. We are developing and testing ecological indicators (population, community, ecosystem and landscape) for large river-floodplain landscapes along reaches of the Wisconsin River. We are addressing two main questions:
1. Which landscape metrics are most useful for monitoring population, community and ecosystem processes in large river-floodplain landscapes? Spatially extensive field sampling is being combined with landscape analysis in six reaches of the Wisconsin River sampling to quantify the ability of landscape indicators to predict ecological variables over broad scales. Landscape indicators will be evaluated by their utility for detecting changes in the structure and function of the Wisconsin River floodplain landscape resulting from modification of the natural flow regime, historical land use, and current land-use patterns.
2. What are the constraints on extrapolating relationships between landscape metrics and ecological processes in large river-floodplain landscapes? We will use field data, landscape analysis and simulation modeling to evaluate the constraints on spatial and temporal extrapolation of landscape indicators by: (1) predicting and testing population, community and ecosystem indicators for the Wisconsin River floodplain landscape based on landscape indicators in new study landscapes; (2) determining whether there are thresholds in landscape pattern beyond which ecological processes change qualitatively; and (3) assessing the sensitivity of ecological indicators to landscape changes.
Progress Summary:
The second year of this project included completion of the second season of field work, the analysis of historical aerial photography, and the compilation of spatial data bases. Data from the first field season were analyzed, and the second field season data were entered into the computer. Two postdoctoral research associates (Drs. James Miller and Hojeong Kang) continued working on the project along with four graduate students (Mark Dixon, Sarah Gergel, Ross Freeman, and Jonathon West), and a Swiss postdoctoral fellow (Dr. Matthias Burgi) collaborated with us for one year. Two graduate students completed their theses (Freeman, 2000; Gergel, 2000). An undergraduate student (Rebecca Nowak) conducted field work for her senior Honors Thesis, which will be completed in May 2001, and several undergraduates (Leah Bowe, Jennifer Follstad, and Aaron Thiel) have conducted mentored research in conjunction with this project.
Floodplain land use and land cover were analyzed since the 1930s along nine 12-20 km reaches of the Wisconsin River by analyzing and digitally classifying 200 historical aerial photos corrected against modern orthophotographs. Results showed that floodplain deciduous forest cover increased in almost every reach up to 51 percent while the number of forest patches declined, indicating an increase in the amount and connectivity of forest. The number of gaps in forest cover have increased in half the reaches since the 1930s, but an increase in wetlands suggests restoration of natural habitat as agriculture declined.
Field sampling extended from late May through late-July 2000. A total of 190 new plots were sampled within the six study reaches based on extending coverage to adequately sample a range of patch sizes and past land uses. Private landowners and state and non-governmental organizations were contacted to secure permission for field sampling. Precise locations of each plot were obtained using a global positioning system (gps). Vegetation was sampled within a 10 x 20 m plot in which each tree was identified to species and its diameter-at-breast-height recorded. All shrubs and saplings were identified to species and censused, and overall canopy cover and shrub cover were estimated for each plot. Seedling abundance, slope position, herbaceous cover, and leaf litter were recorded within each of three randomly located 1-m2 quadrats. Within three additional 100-cm2 randomly located quadrants, litter accumulation was assessed by collecting surface organic matter, and three soil cores were obtained to estimate potential denitrification rates and characterize soil conditions. Data entry and initial analyses are now in progress.
Birds were censused at each of the 220 plots established in 1999 and a subset of the 2000 plots using 8-minute point counts, during which all birds seen and heard were noted. Each transect was visited twice, with the second round commencing only after all transects had been censused once. For each transect, the first of the two censuses began at dawn and the second census began at approximately 0900 hours; a different observer conducted each of the two censuses on a transect in order to avoid any observer-related biases. All data have been entered and proofed, and we are now beginning analysis of the 2-year data set.
Analyses of the 1999-2000 vegetation data are underway. To examine forest community composition, relative importance values were computed for each tree species on each sampling plot. Relative importance value is the sum of the relative density and basal area for each species on a plot and ranges from zero to two. Initial analyses suggest geographic variation in forest community composition and significant effects of flooding frequency and historical land use. The relative importance values of flood-tolerant species (e.g., Acer saccharinum, Fraxinus pennsylvanica) were significantly higher in locations that were unleveed or between the river and a levee compared to locations upland of levees. Flood-intolerant species (e.g., Quercus velutina, Q. ellipsoidalis), in contrast, were more abundant in areas upland of levees. The abundance of seedlings of pioneer tree species (Acer saccharinum, Betula nigra, Populus deltoides, and Salix spp.) along sand bar substrates varied with physical characteristics at local (quadrat) and landscape (sandbar, channel, and river cross section) on the distribution of pioneer tree seedlings. In addition, the timing and magnitude of river flows influenced the composition and abundance of pioneer tree seedlings.
Analyses of 1999 denitrification, soil microbial activity and soil organic matter indicate several interesting trends. Denitrification rates, litter, and organic matter were significantly higher in sections of the floodplain that were unleveed or between levees and the river, compared to locations that were upland of levees. Soil moisture was strongly related to measured rates of denitrification. Measurements of soil microbial activity under different canopy tree species (Acer saccharinum, Tilia americana, and Quercus bicolor) demonstrated higher activities under Acer saccharinum which were associated with higher concentrations of dissolved organic carbon in leaf litter leachate. Thus, our data suggest that changes in species composition in floodplain forest may produce changes in biogeochemical cycling. Microbial processes play a pivotal role in determining the ecological integrity of floodplain ecosystems and these results suggest that changes in land use pattern, construction or removal of levees, or changes in dominant tree species all play a role in affecting these processes.
Analyses of our 1999 bird data have thus far focused on the effects of landscape context of forest patches and prior land uses. Statistical models explained 25-55 percent of overall species richness and habitat occupancy by migrant species, forest interior species, and birds that nest high in the forest canopy. Of particular note was the significance of variables describing historical land cover in nearly every model that we tested. Thus, our analyses suggest that land-use legacies appear to influence habitat use by birds today. Land use in and near the floodplain has occurred in a non-random fashion, and our results suggested that historical land use patterns may produce long-lasting ecological effects. We suspect that the historical variables we examined are proxies for fine-scale features of the vegetation today, and we are testing this assumption presently using detailed information on vegetation structure and composition collected at the sampling points. Landscape metrics explain only part of the variation in habitat use by forest birds along the Wisconsin River.
Postdoctoral researcher Dr. Matthias Burgi examined historical changes in
land use and vegetation in our study areas with independent funding through a
fellowship from the Swiss National Science Foundation. Results from the
interpretation of a variety of historical data sources reveal a general shift
from agricultural land to forest in the floodplain. Land-use changes from 1938
to 1992 were explained by both abiotic and socioeconomic variables, and the
inclusion of socioeconomic variables always improved model performance. Initial
comparisons of relative abundance of tree species in the floodplain between the
mid 1800s, as recorded by the General Land Office Survey, and our 1999-2000 data
reveal an decrease in the relative abundance of oaks and an increase in maples,
ashes, and poplars. A historical perspective will prove invaluable in gaining a
better understanding of the factors underlying current ecological patterns in
floodplain forests.
Future Activities:
During the coming year, we will complete analyses of the1999-2000 field data obtained in six river reaches (bird censuses, vegetation sampling, denitrification, and soil microbial activity) in relation to landscape indicators and submit several empirical manuscripts on our findings; conduct the third season of field sampling in which we test our ability to predict ecological patterns and processes in new locations (three test reaches) based on empirical data from other locations (the six study reaches); and continue developing the models and analyses required to address the questions associated with extrapolating relationships between landscape metrics and ecological processes. In addition, personnel associated with the project will be giving presentations on this research at several national and international meetings (U.S. Chapter of the International Association for Landscape Ecology, Ecological Society of America, North American Benthological Society, and American Society for Limnology and Oceanography). We also anticipate completion of two more graduate student theses and an undergraduate honors thesis during the coming year.Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 58 publications | 16 publications in selected types | All 16 journal articles |
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Type | Citation | ||
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Freeman RE, Stanley EH, Turner MG. Analysis and conservation implications of landscape change in the Wisconsin River floodplain, USA. Ecological Applications 2003;13(2):416-431. |
R826600 (1999) R826600 (2000) R826600 (2001) R826600 (Final) |
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Gergel SE, Dixon MD, Turner MG. Consequences of human-altered floods: levees, floods, and floodplain forests along the Wisconsin River. Ecological Applications 2002;12(6):1755-1770. |
R826600 (1999) R826600 (2000) R826600 (2001) R826600 (Final) |
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Supplemental Keywords:
water, watersheds, soil, land, ecosystem, indicators, ecological effects, regionalization, scaling, habitat, ecology, remote sensing, Midwest., RFA, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, State, Ecological Effects - Environmental Exposure & Risk, Ecology and Ecosystems, Ecological Risk Assessment, Ecological Indicators, ecological exposure, landscapes, anthropogenic stresses, habitat, remote sensing, landscape indicator, Midwestern U.S., large river floodplain landscapes, Wisconsin (WI)Relevant Websites:
http://ravel.zoology.wisc.edu/
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.