CHANGE IN ARCTIC CO2 FLUX OVER 2 DECADES - EFFECTS OF CLIMATE-CHANGE AT BARROW, ALASKA

A significant difference in net ecosystem carbon balance of wet sedge ecosystems in the Barrow, Alaska region was observed between CO2 flux measurements obtained during the International Biological Program in 1 971 and measurements made during the 1991-1992 growing seasons. Curren tly, high-center polygons are net sources of CO2 to the atmosphere of approximate to 14 gC . m(-2). yr(-1), while low-center polygons are lo sing approximate to 3.6 gC . m(-2). yr(-1), and ice wedge habitats are accumulating 4.0 gC . m(-2). yr(-1). On average, moist meadow habitat s characteristic of the IBP-II site are currently sources of approxima te to 1.3 gC . m(-2). yr(-1) to the atmosphere compared to the reporte d accumulation of approximate to 25 gC . m(-2). yr(-1) determined in 1 971. This difference in ecosystem function over the last two decades m ay be due to the recently reported increase in surface temperatures re sulting in decreases in the soil moisture status. These results point to the importance of long-term research sites and databases for determ ining the potential effects of climate change on ecosystem function.