Landscape Influences on Stream Habitats and Biological Assemblages

<em>Abstract.</em>—–Describing the unique spatial context of any river unit requires integrating catchment and local valley characters. We believe that adding hydrologic regime and key fish species to standard geomorphic variables improves the delineation and characterization of river valley segments as ecological units. Valley segments constrain habitat units, and several segments together can encompass home ranges of mobile fishes. Segments can be accurately defined and characterized using maps and then analyzed across large geographic areas, making them practical for statewide planning and management. By incorporating prior knowledge from modeling landscape–river relationships, we interpreted multiple landscape maps to delineate and assign initial attributes to river valley segments. The resulting classification system provides a new, ecologically informed view of Michigan’s rivers that has helped managers better perceive and consider environmental patterns that constrain habitat and biological variation within and among individual rivers. It is being used throughout Michigan and regionally as a framework for fisheries and water management, conservation planning, and education.