Grantee Research Project Results
2000 Progress Report: Development and Evaluation of Multi-Scale Mechanistic Indicators of Regional Landscapes
EPA Grant Number: R825870Title: Development and Evaluation of Multi-Scale Mechanistic Indicators of Regional Landscapes
Investigators: Richards, Carl , Host, George E. , Johnson, Lucinda
Institution: University of Minnesota - Duluth
Current Institution: University of Minnesota - Duluth , Natural Resources Research Institute
EPA Project Officer: Packard, Benjamin H
Project Period: December 1, 1997 through November 30, 2000
Project Period Covered by this Report: December 1, 1999 through November 30, 2000
Project Amount: $925,000
RFA: Ecosystem Indicators (1997) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
The objectives of the research project are to: (1) develop predictive models that integrate landscape-scale factors with reach-scale physical and chemical stream attributes to: (a) quantify key compositional and structural attributes of stream biota, and (b) derive ecosystem indicators at multiple spatial scales; (2) evaluate the appropriate scale of terrestrial and aquatic data necessary to resolve regional and local aquatic resource questions and improve our ability to distinguish and quantify natural variation in indicators from that derived from anthropogenic stressors; and (3) assess the extent to which regional and local-scale indices (including standard indices of ecological integrity, e.g., IBI) reflect fundamental ecosystem processes and structural properties of stream habitats and biota.
Progress Summary:
Considerable progress has been made on all aspects of the research. Our progress to date equals or exceeds our expectations for this time period. A summary of the major components of our work efforts follows.
Spatial Databases/GIS. All spatial data for the Indicators Project has been collected and data summarization is approximately 95 percent complete. New landscape metrics (e.g., functional soil variables derived from the STATSGO database and landscape structure derived from FRAGSTATS) have also been calculated for watersheds in both Minnesota and Michigan. The STATSGO-derived metrics allowed us to improve our ability to discern mechanistic relationships between watershed-scale factors and physical, reach-scale factors (also see Analysis/Synthesis below). For example, there is a strong positive relationship between a soil erosion index (K-factor derived from the Universal Soil Loss Equation and included in STATSGO) and % fines in stream reaches. In addition, we find patch density (derived from FRAGSTATS) is a useful surrogate for % row crop agriculture in individual watersheds.
Twelve of the 36 Minnesota watersheds were chosen for high-resolution mapping of riparian areas. Photos for all 12 areas have been scanned, rectified, interpreted, and digitized. Riparian habitats summaries for these areas are nearly complete. Preliminary analyses have found that lower-resolution satellite imagery underestimates the proportion of forest and wetland classes, and overestimates the proportion of agricultural land within 30, 60 and 120 m of the channel compared to the high resolution photos. Using stepwise regression, we have also found that some reach-scale characteristics (e.g., % fines and total nitrogen) were better explained by land-use classes in a 120-m buffer, whereas some biotic metrics (e.g., % macroinvertebrate predators) were best explained by the 10-m buffer.
Physical, Chemical, and Biological Sampling. All field sampling is now complete. We conducted woody debris retention experiments during September 2000 in 11 of 12 streams (one stream was dry) where we have high-resolution land cover data. All physical, chemical, and biological samples have been processed and all data has been entered into computer databases.
Analysis/Synthesis. We are now analyzing all aspects of our data. Our conceptual framework is that reach-scale factors directly affect the macroinvertebrates and fish, and that reach-scale factors reflect the condition of the surrounding watershed; thus factors are arranged hierarchically. Therefore, we are conducting a two-step direct gradient analysis (redundancy analysis) in which we identify: (1) important reach-scale attributes that influence biota, and (2) important watershed attributes that influence the important reach-scale factors. Subsequent analyses (multiple regression) further delineate the relationships between data at specific scales. Some of our preliminary results for macroinvertebrates and fish are as follows.
Macroinvertebrates?Reach-scale characteristics of streams explained similar amounts of variation in macroinvertebrate metrics (52 and 58 percent in MN and MI, respectively). There was some overlap in important reach-scale factors between regions (Table 1), however, both regions had a number of important reach-scale features unique to that region. Factors at the reach scale that were important in both regions include channelization history, bankfull width, and % fines. We hypothesize that differences between regions in underlying geology and land use history are responsible for differences in the relative importance of reach-scale factors. In the second step of this analysis, more variation in reach-scale factors was explained at the watershed scale in streams of MI (58 percent) than in MN (47 percent) (Table 2). This appears to be a function of greater variation in land-use in our study streams in MI than in MN. Results for MI streams agree with our previous work in the region, in which strong hierarchical relationships exist among macroinvertebrates, physical variables at the reach scale, and watershed characteristics. Our comparisons between regions reveal some similarity but considerable heterogeneity in the relative importance of individual factors at multiple spatial scales. Consequently, some indicators are much better for regional use and others may have more utility for cross-regional comparisons.
Fish?Preliminary results for fish metrics in Minnesota streams have also found strong linkages between metrics and reach-scale variables (Table 3). Three reach-scale factors, channelization history, % fines, and maximum temperature, were identified as important for fish metrics and overlapped with important factors for macroinvertebrates in Minnesota. This result suggests similar local factors influence multiple biotic assemblages in our study streams.
Our next task will be to develop multi-scale indicators for macroinvertebrates and fish using the hierarchical relationships described above. Specific hierarchical relationships for each macroinvertebrate and fish metric will be identified using standardized partial regression coefficients calculated from multiple regressions.
We are taking a different analytical approach for our stream nutrient and periphyton data. We hypothesize that both reach- and watershed-scale factors can directly influence nutrient concentrations and periphyton standing crops. As a result we are developing relationships using a one-step direct gradient analysis. Preliminary results for Minnesota streams indicate similar reach-scale factors influence nutrients and periphyton in both summer and spring, whereas watershed-scale factors vary greatly between seasons. Differences at the watershed scale appear to be a result of changes in the timing of anthropogenic activity as well as seasonal precipitation patterns.
An additional objective is to use hydrological modeling to aid in our understanding of how differences in landscape factors in Michigan and Minnesota influence flow regimes and nutrient export, which are key components of ecosystem integrity. Using the model SWAT, the Soil and Water Assessment Tool, we simulated long-term flow regime variability and average yields of water, sediment, and nutrients in all streams. We have conducted considerably more hydrologic analysis of our 72 study watersheds than was originally anticipated due to the need to validate the model runs and due to the importance of modeling for understanding landscape processes. Storm flow sampling was diminished in order to accommodate this effort and due to the less critical nature of storm flow data to our study.
Future Activities:
Spatial Databases/GIS. In the next year, we will continue to analyze our high-resolution riparian data to evaluate the appropriate scale of terrestrial and aquatic data necessary to resolve regional and local aquatic resource questions.
Physical, Chemical, and Biological Sampling. No further sampling is needed.
Analysis/Synthesis. We will continue to focus on the analysis and synthesis of spatial and instream variables. Manuscripts describing hierarchical relationships and indicator development for macroinvertebrates and fish are currently being prepared. An additional manuscript examining the relationship between reach- and watershed-scale factors on nutrient concentrations also will be prepared.
Journal Articles:
No journal articles submitted with this report: View all 38 publications for this projectSupplemental Keywords:
landscape ecology, stream ecology, watersheds, ecological effects, indicators, scaling, integrated assessment, Midwest, EPA Region 5., RFA, Scientific Discipline, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Midwest, Ecology, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Environmental Chemistry, Chemistry, Ecological Effects - Environmental Exposure & Risk, Geology, Ecological Indicators, EPA Region, agriculturally impacted watershed, aquatic ecosystem, nutrient supply, ecological exposure, EMAP, remote sensing, landscape indicator, satellite images, stressors, watersheds, ecosystem integrity, stream ecosystems, regional scale, soil, aquatic ecosystems, water quality, ecosystem stress, multiscale assessment, spatial and temporal patterns, Region 5, land useRelevant Websites:
http://www.nrri.umn.edu/indicators
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.