Effect of Forest Fire on Fluxes of CH_4 and N_2O in Boreal Forest Soils, Interior Alaska

摘要

Flux measurements at sites of mixed hardwood and black spruce stands from an area (C4) of the Caribou-Poker Creek Research Watershed (CPCRW), interior Alaska, in the summer seasons of 1998, 1999, and 2000 are used to estimate the fluxes of CH_4 and N_2O before and after the forest fire. The FROSTFIRE burning experiment was executed in typical boreal forest from July 8 to 15, 1999. The forest fire significantly decreased soil N_2O emissions, by at most 50 %. On the contrary, CH_4 flux from the soil increased from 7 to 142 %, suggesting that the forest fire plays a role in accelerative thawing of the frozen soil, and subsequently the release of CH_4 from permafrost. Most CH_4 was oxidized in the soil after the fire; however, some was released from the soil when the permafrost maximally thawed at the end of August 1999 and September 2000. Relationships between the fluxes of CH_4 and N_2O and soil temperature before and after the fire showed the exponential correlations, indicating that soil temperature was one of the factors determining the fluxes of non-CO_2 greenhouse gases in boreal forest soils.