Grantee Research Project Results
2001 Progress Report: Hierarchical Physical Classification of Western Streams: Predicting Biological Condition in Terms of Key Environmental Processes Bridging Local to Ecoregional Scales
EPA Grant Number: R828636Title: Hierarchical Physical Classification of Western Streams: Predicting Biological Condition in Terms of Key Environmental Processes Bridging Local to Ecoregional Scales
Investigators: Bledsoe, Brian P. , Wohl, Ellen E. , Poff, N. LeRoy
Institution: Colorado State University
EPA Project Officer: Packard, Benjamin H
Project Period: January 15, 2001 through January 14, 2004 (Extended to January 14, 2005)
Project Period Covered by this Report: January 15, 2001 through January 14, 2002
Project Amount: $788,144
RFA: Development of National Aquatic Ecosystem Classifications and Reference Conditions (2000) RFA Text | Recipients Lists
Research Category: Water , Aquatic Ecosystems
Objective:
Existing physical classifications for streams do not explicitly include considerations of how primary environmental drivers--such as flow regime, geophysical setting, intermediate-scale geomorphic processes, and anthropogenic impacts-- interact and vary in importance across spatial scales in controlling stream environments and shaping biotic communities. We are developing a hierarchical classification framework for stream environments in the western United States that identifies the relative importance of key environmental constraints or filters operating across multiple spatial scales. This a priori classification integrates hydrologic regime, geologic context, and critical geomorphic processes with reach classification. Given the current emphasis on ecoregional and local scales in biomonitoring protocols, this approach will provide essential information on how environmental factors measured at intermediate scales (watershed, valley bottom/geomorphic process domain, and reach) can be used to understand and predict biotic condition at individual sites distributed across the landscape. Specific objectives of the research are to:
- Develop an exhaustive, multi-scaled physical habitat classification of western U.S. streams, to derive predictive statistical models relating biotic condition to multi-scaled environmental variables.
- Demonstrate the explanatory power and flexibility of the classification within and across diverse western U.S. ecoregions.
- Explicitly assess how well a classification that includes intermediate scale processes (at the valley bottom/process domain scale) can predict biotic condition at localities without requiring extensive local (reach scale) habitat data.
- Develop a systematic approach for objectively identifying and stratifying reference sites.
Progress Summary:
We are utilizing Regional Environmental Monitoring and Assessment Program (R-EMAP) data on first through fourth order streams from six ecoregions in Colorado, Oregon, and Washington. We also are utilizing new data as available from the EMAP Western Pilot Study to link a multi-scale physical classification with expectations of taxa distribution and categorical abundance in western U.S. streams and rivers. Prior to analyzing physical-biological linkages, we developed the first iteration of a hierarchical classification framework for stream environments in the western United States. This a priori classification integrates hydrologic regime, geologic context, and critical geomorphic processes with reach classification.
At the watershed scale, we have completed an inventory of landscape metrics reported in the scientific literature and in use by state and federal agencies. As a result of this inventory, and through the development of new metrics primarily associated with flow regime and topographically and proximity-weighted disturbance, we have developed an extensive set of watershed analysis programs for use with ARC/INFO and Arcview. By combining these landscape metrics with the R-EMAP and EMAP site data, we have developed a comprehensive matrix of physical descriptors at the watershed and reach scales. To verify and extend our description of the valley and reach scales, we have conducted revisits of 45 R-EMAP sites in the southern Rockies to assess the accuracy of our valley scale descriptors and Rosgen and Montgomery & Buffington stream type assignments based on data from the original site visits. The geomorphic and lithotopographic types associated with the sites in CO, OR, and WA are being further verified through field reconnaissance during summer 2002.
We have developed new indices of substrate stability that include a dynamic flow regime component and a technique for scaling stream slope using energy concepts to reduce the number of associations between flow energy and bed material. Work in progress suggests that Hack's relationship can be used to explain differences in slope between streams of varying size that have similar channel morphology by scaling slope to some power of drainage area. The aim of this work is principally to determine: (1) whether watershed scale variables can be utilized to predict reach scale channel features of ecological interest, (2) if Hack's law can specifically be employed to predict a range of substrate sizes or a dominant channel morphology through the use of watershed scale variables, and (3) if the size (scale) of the watershed plays an important role in fluvial classification systems.
We also are developing watershed-scale hydrologic classifications. We have compiled and organized streamflow data from gauges proximate to the CO, OR, and WA R-EMAP sites and are utilizing these data in conjunction with climatologic, topographic, geologic, and other information to develop regression relationships for regionalizing hydrologic characteristics. These models are being used in conjunction with TOPMODEL to characterize ecologically relevant characteristics of the flow regime for each of the CO, OR, and WA sites. This work also involves an analysis of the redundancy and transferability of hydrologic indices to identify a minimum set of salient descriptors needed for characterizing flow regimes.
The benthic macroinvertebrate data have been checked for taxonomic consistency and a suite of functional traits have been assigned to the taxa. These traits include non-taxonomic categories such as functional feeding groups, environmental tolerance, life history traits, and others (e.g., mobility, desiccation resistance, resistance to crushing) for which metrics have been partially developed. This functional characterization allows hypothesized mechanistic relationships between environmental drivers and biotic organization to be examined across geographically dispersed sites.
We have held meetings with other STAR grant recipients at Utah State University (An Empirical Evaluation of the Performance of Different Approaches to Classifying Reference Conditions in Streams, Principal Investigator: C.P. Hawkins) and Colorado State University (Space-Time Aquatic Resources Modeling and Analysis Program, Co-Principal Investigators: J.A. Hoeting, N.S. Urquhart, D.M. Theobald) to explore synergistic collaborations. These meetings have resulted in agreements and strategies for data sharing and continuing communication that will substantially increase the benefits of these complimentary projects.
Future Activities:
The a priori physical classification and the suite of metrics describing the physiochemical environment at multiple scales across OR, WA, and CO R-EMAP and EMAP sites will be further refined prior to testing with biological data in the second year of the project. Once a comprehensive matrix of hydrogeomorphic descriptors at the watershed, process domain/ valley, and reach scales is developed, we will use statistical analyses (multiple regression, CCA, CDA, Stochastic CART analysis, and other approaches) to elucidate the key physical controls on biological communities. Lastly, we will apply the classification in collaboration with the state of Montana to stratify diverse stream environments and systematically identify probable reference sites using multi-scale physical and chemical information. We then will examine the predictive utility of the classification by comparing the ecological health of these reference sites versus sites selected using less systematic methods. This application will assist in further generalization of the classification, improving user-friendliness, and demonstrating practical applications.
This research will provide a better basic understanding of how scaled environmental factors constrain the performance and distribution of stream biota in western U.S. streams. Such understanding has direct benefits in: (1) determining the right scales for classification, (2) assessing the relative benefits of different levels of physical description in explaining biological variation, and (3) identifying reference sites in a defensible and objective manner. By examining how much additional variation in community organization is explained by characterizing environmental filters at scales other than ecoregions and local habitat, this work provides essential information for weighing the costs and benefits associated with different levels of spatial resolution in monitoring. Thus, it directly supports the EMAP initiative.
Because the selection of stream reference sites currently is performed on a somewhat ad hoc basis, a comprehensive, multi-scale physical classification provides a stronger scientific basis for systematically identifying candidate reference sites within appropriate strata. Our work will test the efficacy of using coarser scale physical and chemical information (at the valley bottom/ process domain and watershed scales) to make a priori predictions of where minimally impacted sites are likely to occur. Our plans for working directly with water quality managers in testing and applying the classification will serve to further generalize and refine the classification, improve user-friendliness, and provide case studies in reference development. Furthermore, we will use EMAP data from the Western Pilot Study to test the classification within and outside the ecoregions used for calibration. This will define the extent to which the physical classification may be extrapolated without loss of significant explanatory power.
Journal Articles:
No journal articles submitted with this report: View all 11 publications for this projectSupplemental Keywords:
scaling, aquatic, indicators, EPA Region 8, EPA Region 9, EPA Region 10, CO, WA, OR, RFA, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Aquatic Ecosystems & Estuarine Research, State, Aquatic Ecosystem, Ecological Risk Assessment, Ecology and Ecosystems, biocriteria, EMAP, streams, Oregon, multiple spatial scales, ecoregional scale, Washington (WA), hierarchical physical classification, water quality, biological indicators, ecological classification, predicting biological condition, Colorado (CO)Relevant Websites:
http://www.engr.colostate.edu/~bbledsoe Exit
http://lamar.colostate.edu/~poff/home.html Exit
http://www.cnr.colostate.edu/ER/fac-staff/home/ellenw.html 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.