Thinking Big: Linking Rivers to Landscapes

Exploring relationships between landscape characteristics and rivers is an emerging field of study, bolstered by the proliferation of satellite data, advances in statistical analysis, and increased emphasis on largescale monitoring. Climate patterns and landscape features such as road networks, underlying geology, and human developments determine the characteristics of the rivers flowing through them. A multiagency team of scientists developed novel modeling methods to link these landscape features to instream habitat and to abundance of coho salmon in Oregon coastal streams. This is the first comprehensive analysis of landscape-scale data collected as part of the state’s Oregon Plan for Salmon and Watersheds. The research team found that watershed characteristics and human activities far from the river’s edge influence the distribution and habitats of coho salmon. Although large-scale landscape characteristics can predict stream reaches that might support greater numbers of coho salmon, smaller scale features and random chance also play a role in whether coho spawn in a particular stream and in a particular year. The team developed new models that successfully predicted the distribution of instream habitat features. Volume of instream wood and pool frequency were the features most influenced by human activities. Studying these relationships can help guide large-scale monitoring and management of aquatic resources.