Using Multitemporal Imagery to Improve Mapping and Inventory of Forested Roads in Michigan’s Upper Peninsula

Abstract

Although a road network provides transportation for people and goods, several negative ecological impacts stem from a road network. Significant effects of concern for rural roads include an increase in the number of road–stream crossings, which can potentially cause fish passage problems, in-stream habitat impacts, increased stream sedimentation, and an increase in potentially affected wetlands through hydrologic alteration. Although several studies have examined and quantified the effects that roads have on terrestrial and aquatic ecosystems, many studies may have been made on the basis of incomplete road network data sets. An updated and improved road network data set is needed before researchers can draw inferences that quantify the total ecological impact that a road network has on an ecosystem. The purpose of this work was to develop an updated and improved regional road network data layer through interpretation of existing multitemporal aerial imagery, with the resulting geographic information system layer being applied in ecological analyses and planning. Results from two watersheds in Michigan’s Upper Peninsula indicated that each watershed experienced an approximate increase of 200% in total road mileage when compared with the results from the original road network data set. Individual hydrological unit code level-12 subwatersheds within each watershed experienced an increase ranging from 16% to 2,700%. The number of road–stream crossings for each watershed also increased by at least 100%. The updated road network data set also reported the location and total area of wetlands that have potential hydrological impacts, ranging from 70,000 ha to 121,000 ha for each watershed.