A multiscale landscape approach for prioritizing river and stream protection and restoration actions

River and stream conservation programs have historically focused on a single spatial scale, e.g., a watershed or stream site. Recently, the use of landscape information (e.g., land use, and land cover) at multiple spatial scales and over large spatial extents has highlighted the importance of incorporating a landscape perspective into stream protection and restoration activities. Previously, we developed a novel framework that links information about watershed-, catchment-, and reach-scale integrity with stream biological condition using scatterplots and a landscape integrity map. Here we examined an application of this approach for streams in urban and other settings in King County, Washington State, United States, where we related stream macroinvertebrate condition to two indices of landscape integrity, the USEPA's nationally available Index of Watershed Integrity (IWI) and Index of Catchment Integrity (ICI). We generated a scatterplot of IWI vs. ICI for sample sites, where points represented site macroinvertebrate condition from poor to good. The same data were also visualized as a landscape integrity map that displayed catchments of King County according to the level of watershed and catchment integrity (high or low IWI/ICI). Over three quarters of poor condition sites were unexpectedly associated with high integrity watersheds and catchments (i.e., underperforming sites), which suggested that either one or both national indicators was insufficient for this area or that sites underperformed because of local-scale factors. In response, we used a catchment-scale indicator related to forest condition (PctForestCat) after examining several GIS-based dispersal indicators from the National Hydrography Dataset, and other candidates from the USEPA’s StreamCat dataset. We then compared the results of the scatterplots and maps based on the current and original analyses and found that many of the sites previously classified as underperforming now performed as expected: i.e., they were poor condition sites in poor condition catchments. This analysis demonstrates how results based on a national dataset can be improved by developing an alternative that represents regionally-important stressors. The methods used to develop an effective landscape indicator based on StreamCat datasets, and the utility of the multiscale approach, could provide important tools for prioritizing, optimizing, and communicating stream conservation actions.

Impact/Purpose

Incorporating information on landscape condition (or integrity) across multiple spatial scales and over large spatial extents (e.g., across regions) in biological assessments may allow for a more integrated measure of stream biological condition and better management of these resources. However, streams are often assessed and managed at a single spatial scale (e.g., a watershed or stream-reach) without a larger regional multiscale context. ORISE post-doctoral associate Luisa Riato, and CPHEA/PESD researchers Scott Leibowitz, Marc Weber, and Ryan Hill previously developed a conceptual framework that relates stream condition to multiscale landscape integrity data at different spatial scales: watershed, catchment and stream-reach scale. They recently related the USEPA's nationally available Index of Watershed Integrity (IWI) and Index of Catchment Integrity (ICI) to stream macroinvertebrate condition data collected across the Puget Lowland, including King County, Washington, through the use of a multiscale scatterplot and landscape integrity map. Over three quarters of poor condition sites were unexpectedly associated with high integrity watersheds and catchments (i.e., underperforming sites), which suggested that either one or both national indicators was insufficient for explaining degraded biological conditions in this area or that the sites underperformed because of local-scale factors. In the current effort, the authors addressed this problem by developing an alternative landscape indicator for the region based on the USEPA’s StreamCat dataset, which successfully reduced the number of underperforming sites. In so doing, the authors demonstrated how to replace a default national indicator with a more effective landscape indicator and to develop a tool for better management of streams. The methods used to develop an effective landscape indicator based on StreamCat datasets, and the utility of the multiscale approach, could provide important tools for prioritizing, optimizing, and communicating stream conservation actions. This work comes under SSWR 1.3.2, “Synthesis of approaches to biological condition assessment”. Contact Luisa Riato, ORISE Post-Doctoral Fellow, CPHEA/PESD; (541) 754-4702; riato.luisa@epa.gov 

Citation

Riato, L., S. Leibowitz, M. Weber, AND R. Hill. A multiscale landscape approach for prioritizing river and stream protection and restoration actions. ESA Journals, 14(1):e4350, (2023). [DOI: 10.1002/ecs2.4350]

DOI: A multiscale landscape approach for prioritizing river and stream protection and restoration actions