B31C-0556
Carbon and nutrient responses to fire and climate warming in Alaskan arctic tundra
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Yueyang Jiang1,2, Edward B Rastetter2, Gaius R Shaver3, Adrian V Rocha4, Bonnie Kwiatkowski2, Andrea Pearce5, Qianlai Zhuang6 and Umakant Mishra7, (1)Oregon State University, Forest Ecosystems and Society, Corvallis, OR, United States, (2)Marine Biological Laboratory, Woods Hole, MA, United States, (3)Marine Bio Lab, Woods Hole, MA, United States, (4)University of Notre Dame, Notre Dame, IN, United States, (5)University of Vermont, Burlington, VT, United States, (6)Purdue University, West Lafayette, IN, United States, (7)Argonne National Laboratory, Environmental Science, Argonne, IL, United States
Abstract:
Fire frequency has dramatically increased in the tundra of northern Alaska, which has major implications for the carbon budget of the region and the functioning of these ecosystems that support important wildlife species. We applied the Multiple Element Limitation (MEL) model to investigate both the short- and long-term post-fire succession of plant and soil carbon, nitrogen, and phosphorus fluxes and stocks along a burn severity gradient in the 2007 Anaktuvuk River Fire scar in northern Alaska. We compared the patterns of biomass and soil carbon, nitrogen and phosphorus recoveries with different burn severities and warming intensities. Modeling results indicated that the early regrowth of post-fire tundra vegetation was limited primarily by its canopy photosynthetic potential, rather than nutrient availability. The long-term recovery of C balance from fire disturbance is mainly determined by the internal redistribution of nutrients among ecosystem components, rather than the supply of nutrients from external sources (e.g., nitrogen deposition and fixation, phosphorus weathering). Soil organic matter is the principal source of plant-available nutrients and determines the spatial variation of vegetation biomass across the North Slope of Alaska. Across the North Slope of Alaska, we examined the effects of changes in N and P cycles on tundra C budgets under climate warming. Our results indicate that the ongoing climate warming in Arctic enhances mineralization and leads to a net transfer of nutrient from soil organic matter to vegetation, thereby stimulating tundra plant growth and increased C sequestration in the tundra ecosystems.
