Our project aims to assess ecosystem effects of reindeer on Kerguelen in order to evaluate different management policies. We will 1) estimate the distribution and habitat use of reindeer on Ile Kerguelen using a combination of faeces counts and helicopter transects, 2) collect simple demographic indices such as calves/females ratio and age of carcasses to compare this predator-free population to e.g. South Georgia, 3) assess if these indices can be validated using marked individuals, 4) estimate plant composition and biomass and relate it to reindeer habitat use and presence of other herbivores using an approach developed in subarctic-alpine ecosystems, 5) establish exclosures in different habitats to assess short-term responses of vegetation to reindeer grazing.