LAND: Ecosystem Finnmark (EcoFinn): Ungulate overabundance, trophic cascades and subsidies

We will use the framework of current food web theory for elucidating two likely cascading ecosystem impacts of reindeer overabundance in Finnmark. One cascade we predict to be induced by loss and fragmentation of riparian willow habitats due to reindeer o verbrowsing, which in turn lead to loss of biodiversity and ecosystem functions. The other cascade we predict to be induced by a temporal subsidy of reindeer carrion to generalist predators in winter. This predator subsidy effects, likely to result from reindeer overabundance, we predict to induce a top-down cascade, working though increased generalist predation on vulnerable wildlife as well as a negative feedback on reindeer productivity though calf predation. The two cascades are likely to be coupled and thus need to be studied simultaneously. We will adopt a comprehensive empirical project design consisting of large-scale hypothesis-targeted surveys, combined with in depth observational studies and experiments. The national societal relevance of the project is its contribution in resolving the underlying causes of the current decline of certain alpine/arctic wildlife species in Fennoscandia as well as provide new insight in how reindeer overabundance affect the carnivore guild. In an international co ntext the project may lead to insights which may help counteracting the circumpolar shrub encroachment in alpine and arctic tundra.