The spatial patterns and properties of beaver ponds change abruptly during population expansion, and there are scale- dependent pathways of pond establishment and abandonment. Thus, ecosystem properties of beaver ponds are not randomly distributed across the landscape nor do they change randomly through time. This research project suggests the following hypothesis: Ecosystem dynamics in valleys occupied by beaver are determined by 1) the geomorphology, hydrologic regimes, and carbon and nutrient pools antecedent to pond establishment, 2) changes in food supply in uplands as beaver forage, and 3) changes in the hydrologic regimes and nutrient cycles during pond creation and abandonment. The relative importance of each of theses factors changes during beaver population cycles, resulting in multiple successional pathways and multiple stable states across the landscape. This project will test this hypothesis at landscape and ecosystem scales by: 1) analyses of spatial patterns of ponds and adjacent riparian forests using a 65 year sequence of air photos, geographic information systems, geostatistics, and percolation theory: 2) manipulating nutrient availabilities in mixed species communities in the field and manipulating nutrients, water, and litter in monoculture mesocosms; and 3) constructing a scale- dependent model of the dynamics of boreal landscapes influenced by beaver.
