The Effect of Goose Grazing on Decomposition Processes in the Arctic

One of the most important ecosystem processes is decomposition. Decomposition plays a key role in the nutrient cycle, and is one of the main factors limiting plant growth. In addition it can substantially influence species composition. Goose numbers have increased dramatically over the past 50 years mainly due to land use changes and a reduced hunting pressure in their wintering grounds. To understand fully the consequences of these changes, studies on ecosystems processes on the breeding grounds in the high arctic are indispensable. In this project we investigated how geese influence the nitrogen cycle by changing decomposition processes. We took also a closer look at the effects of grazing geese on the microbial communities, paying special attention for those groups involved in the nitrogen cycle. For this study we used 15N labeled litter to study the nitrogen cycle and advanced molecular techniques to look for the microbial communities. We made use of long term exclosures, set up during the FRAGILE project. Since 2003, these exclosures are ungrazed and can be compared with grazed control plots nearby.