Linking Stream Biological Condition with Multiscale Landscape Indices
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Stream studies have tended to focus at individual spatial scales e.g., a single watershed or stream-reach. However, the value of landscape integrity (or condition) information at multiple spatial scales over large areas (e.g., across regions) could allow for a more integrated measure of stream biological condition and better management of these resources. We present a framework and approach that combines instream biological condition data with landscape integrity data at the watershed, catchment, and stream-reach scale in order to inform the spatial scale at which management efforts will most likely succeed. We provide different examples of the framework’s use to demonstrate the flexibility of its application and relevance to management. The examples include Biological Condition Gradient (BCG) and multimetric index (MMI) assessments for fish, macroinvertebrates and diatoms from different regions and states across the U.S. Landscape integrity indicators include the U.S. EPA’s nationally available Index of Watershed Integrity (IWI) and Index of Catchment Integrity (ICI). Scatterplots and a landscape integrity map were used to relate samples of stream condition classes to watershed, catchment and stream-reach scale integrity. Identifying the quadrant in the scatterplot or catchment in the map in which a good or poor condition site is located informs decisions related to targeted management actions, and for informing the spatial extent at which management is applied.