The effect of vegetation type and snow depth on annual CO2 efflux in a high arctic tundra region
This thesis evaluates the effect of vegetation type and increased snow depth on soil temperature and annual CO2 efflux in an arctic tundra region. Snow fences were set up to manipulate snow accumulation in heath and meadow vegetation on Spitsbergen. Field campaigns lasted from July 2007 - July 2008. CO2 efflux, measured by means of a dark and closed-dynamic soil flux chamber, showed seasonal variation and was lowest in winter time. Soil temperature had a strong influence on efflux year-round, whereas vegetation type was a major driver in the growing season. Temperature based ecosystem respiration models were used to estimate annual efflux to 125 g C m-2 in heath and 162 g C m-2 in meadow sites. CO2 efflux during the 241 days long winter was about 40 g C m-2 in both vegetation types and thus contributed significantly to the annual efflux. Snow fences enhanced snow depth with about 1 m, led to significantly higher soil temperatures and increased winter effluxes with 29-87 %. Increased snow cover resulted in a delayed start of the growing season and led to moister- and for heath sites also cooler- soil conditions in summer. In meadow sites, deeper snow cover had a negative effect on the growth of non-woody plants. The results indicate that changes in winter precipitation can affect the carbon balance of arctic tundra regions by alteration of the soil temperature regime and subsequent enhancement of winter respiration.
ForlagUniversitetet i Tromsø
University of Tromsø
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