Urban Stream Corridors and Forest Patches – The Connections: A Case Study of Bloomington, IN

Abstract

Streams and forests are connected ecosystems, but few studies have looked at the connectivity between streams and forests in urban environments. City-made decisions affect connections between streams and forests by isolating both streams and forests. Streams are often channelized or buried to reduce flooding and increase potential developable areas. Forests become fragmented and are removed unless they are protected by public ownership, private ownership, or mixed governance arrangements. Historical choices in land usage affect the sites and sizes of current urban streams, forests, and development. This affects the distribution of impervious surfaces, a ubiquitous urban land cover type, which separates streams from forests. Despite these barriers to stream/forest interactions, cities can experience stream/forest connectivity. Seven Bloomington watersheds are ranked on their proportions of buried streams, channelized streams, forested hydrology, forested streams, urban forest patch cover, and impervious surface cover, along with historical presence of urbanization. Several watersheds demonstrate stream/forest connectivity, with five of these watersheds containing 50% or greater forested stream segments. Bloomington canopy cover reduces stormwater runoff by approximately 127 kiloliters per year. These forested areas reduce flooding, reduce nutrient loading, and reduce stream conditions associated with urban stream syndrome. Streams provide incentive for forest protection, aesthetic value, and recreational value. Understanding urban stream/forest connectivity can improve green infrastructure design and green space design, which improves urban resilience and better connects residents to the environment.