A HISTORY OF BEAVER ACTIVITY IN THE JORDAN RIVER WATERSHED: SPATIAL DISTRIBUTION, SUCCESSION, AND SEDIMENT

Beavers are exceptional environmental engineers, second only to humans in the modification of their environment. However, their historical response to changing habitat conditions is often difficult to classify due to lack of past spatial and population data. In this study, we demonstrate how combined aerial photo classification, GIS analysis, and in-field ground truthing can be used to model the spatio-temporal rebound of a beaver population previously decimated by the fur trade and habitat destruction in the Jordan River Watershed in northern Michigan. Aerial and high-resolution satellite imagery spanning the period 1938-2011 were digitized and georeferenced to map the fluctuating numbers and distributions of beaver dams in the watershed. By linking these dam counts with statewide beaver harvest estimates, we demonstrate that GIS mapping provides a robust population estimate which can then be spatially analyzed and related to long-term beaver behavioral trends and forest management practices. Additionally, understanding changing spatial sequences of beaver dams is critical for quantifying historical rates of sediment retention at the watershed scale. Overall, this study demonstrates the utility of using a GIS approach to capture the historical spatial and population dynamics of a rebounding beaver population in a post-logging habitat.