Grantee Research Project Results
2001 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, 2000 through September 30, 2001
Project Amount: $677,351
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems
Objective:
Identifying landscape indicators 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. However, 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. This study addresses two 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 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 change.
Progress Summary:
The third year of this project included completion of the third season of field work, continuing data analyses, and completion of manuscripts based on analysis of historical aerial photography for the study area. One postdoctoral research associate (Dr. James Miller) continued working on the project, and two postdoctoral associates (Drs. Hojeong Kang and Matthias Burgi) moved on to new positions. Two more graduate students completed their theses (Dixon, 2001; West, 2001), and an undergraduate student (Rebecca Nowak) completed her senior honors thesis. Additional undergraduates (Leah Bowe, Jennifer Follstad, Aaron Thiel) have continued mentored research in conjunction with this project. We also completed a synthetic paper (Miller, et al., submitted) that examines the approaches used for extrapolation of ecological data across scales and to new locations. This provided us with a firm foundation for the extrapolations that we will conduct during the coming year. Thus far, our research has led to 32 presentations at national meetings, 5 theses/dissertations, and 9 manuscripts submitted. We anticipate producing at least 8 additional manuscripts based on this research. Some key results from this year's work are summarized below.
Floodplain land use and land cover have been analyzed since the 1930s along nine 12-20 km reaches of the Wisconsin River by digitally classifying 200 historical aerial photos corrected against modern orthophotographs. We focused on a conspicuous aspect of change-forest patch connectivity-which can lead to fragmentation and loss of wildlife habitat, and influence soil biogeochemical processes (Freeman, et al., submitted). Floodplain deciduous forest cover increased up to 51 percent (although the number of patches has dropped) in almost every reach, even along the riverbank and near rapidly developing areas. Forest cover was more predominant along the river's edge, although gaps in the buffer have increased in half of the reaches since the 1930s. In some reaches, wetlands have increased in patch extent or number, suggesting an ongoing recovery due to the abandonment of marginal agricultural areas. Connectivity trends suggest that, although forest cover has increased, patches have become less blocky and more dissected along their edges. Using scenarios based on realistic forest management agendas, we explored how various conservation options might affect the connectivity of these Wisconsin River floodplain landscapes. We found that converting similar amounts of land cover using very different management options can produce similar increases in forest cover and connectivity metrics, depending on the initial distribution of the landscape patches. Such scenarios may be useful to future floodplain management work, particularly because conservation organizations are interested in applying landscape ecological concepts (Freeman and Ray, 2000).
Field sampling extended from late May through July 2001. Vegetation and soil properties were sampled within the three new study reaches in preparation for testing predictions based on the first 2 years of field study. Private landowners and state and nongovernmental 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 quadrants. 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 now are in progress. Birds were re-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 to avoid any observer-related biases. All data have been entered and proofread, and we now are beginning analysis of the 3-year data set.
Analyses of the 1999-2000 vegetation data are well 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 0 to 2. Forest vegetation varied with flooding and past land cover, but the current landscape pattern explained little variation. Tree species occurrence varied geographically and was strongly influenced by flooding indicators (e.g., Quercus velutina occurred at higher elevations and distances farther from the river, whereas Acer saccharinum occurred at lower elevations and closer to the river). If a tree species was present, its abundance was related to historic land use. Invasive shrubs were more likely to occur at drier locations, and abundance was greater in sites that were nonforest in the 1930s. Floodplain forest is extensive and well connected along much of the Wisconsin River, and forest structure and composition varies with past land use and flooding rather than with contemporary landscape structure (Turner, et al., in preparation).
Analyses of our 1999-2000 bird data have focused on the effects of landscape context of forest patches and prior land uses (Miller, et al., in preparation). Although the overall size of the floodplain, and the amount of land under cultivation differed among reaches, the forested portion was consistently 40-60 percent. Overall, typical measures of habitat fragmentation explained a relatively small portion of the variation in the structure and composition of the bird communities studied. Landscape measures accounted for a relatively small amount of the variation in species richness and overall abundance. Although measures of habitat fragmentation have accounted for a large amount of the variation in habitat use by forest interior birds in other landscape contexts, this was not the case along the Wisconsin River. These results may reflect the fact that riparian forests still occupy a relatively large portion of the floodplain and also tend to be naturally fragmented. Distance from the confluence with the Mississippi River showed a strong negative correlation with species richness and abundance for several avian guilds, particularly woodpeckers, suggesting that forests along the Mississippi may serve as a population source for some species.
Analyses of 1999 and 2000 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 (Stanley, et al., in preparation). Soil moisture was strongly related to measured rates of denitrification. Importantly, significant effects of tree species composition on biogeochemical cycling were observed. Many large river floodplain ecosystems have undergone pronounced changes in forest species composition in the past 50 to 100 years. In midwestern systems such as the Wisconsin River, floodplain forest changes have been driven by declines in relative abundances of oaks and basswood, and increases in ashes, elms, and silver maples. We assessed potential effects of these tree species shifts on soil biogeochemistry by comparing litter inputs, and chemical and microbial attributes of soils adjacent to five tree species that have experienced long-term shifts in relative abundance: silver maple (Acer saccharinum), swamp white oak (Quercus bicolor), basswood (Tilia americana), green ash (Fraxinus pennsylvanica), and American elm (Ulmus americana). Silver maples produced the greatest amount of litter (184 g m-2) over a year. Microbial activity and organic matter content (15 percent) in surrounding soils were significantly greater for silver maples than for other trees. This implies that an increase in maple has potentially modified biogeochemical processes and soil C cycle.
Future Activities:
During the coming year, we will complete and submit manuscripts based on the 1999-2000 field data obtained in six river reaches (bird censuses, vegetation sampling, denitrification, and soil microbial activity) in relation to landscape indicators; analyze data from 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).
Journal Articles on this Report : 9 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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Burgi M, Turner MG. Factors and processes shaping land cover and land cover changes along the Wisconsin River. Ecosystems 2002;5(2):184-201. |
R826600 (2001) R826600 (Final) |
Exit Exit |
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Dixon MD, Turner MG, Jin C. Riparian tree seedling distribution on Wisconsin River sandbars: controls at different spatial scales. Ecological Monographs 2002;72(4):465-485. |
R826600 (2001) R826600 (Final) |
Exit |
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Freeman RE, Ray RO. Landscape ecology practice by small scale river conservation groups. Landscape and Urban Planning 2001;56(3-4):171-184. |
R826600 (2001) R826600 (Final) |
Exit Exit Exit |
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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) |
Exit Exit |
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Gergel SE. Assessing cumulative impacts of levees and dams on floodplain ponds: a neutral-terrain model approach. Ecological Applications 2002;12(6):1740-1754. |
R826600 (2001) R826600 (Final) |
Exit |
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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) |
Exit |
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Gergel SE, Miller JR, Stanley EH, Melack JM, Turner MG. Indicators of human impacts to river-floodplain systems: the importance of landscape context. Freshwater Biology. |
R826600 (2001) |
not available |
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Kang H, Stanley EH, Park S-S. A sensitive method for the measurement of ammonium in soil extract and water. Communications in Soil Science and Plant Analysis 2003;34(15-16):2193-2201. |
R826600 (2001) R826600 (Final) |
Exit Exit |
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Miller JR, Turner MG, Smithwick EAH, Dent CL, Stanley EH. Spatial extrapolation: the science of predicting ecological patterns and processes. BioScience 2004;54(4):310-320. |
R826600 (2001) R826600 (Final) |
Exit Exit |
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 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.