| Wetlands occupy vast areas in boreal regions (above 45oN) and play an important role in the
regional exchanges of carbon dioxide (CO2) and methane (CH4) between land ecosystems
and the atmosphere. We have developed a biogeochemistry model that considers the effects of
thawing permafrost and complex hydrological dynamics on plant photosynthesis, plan
nutrient uptake, and both aerobic and anaerobic decompositions of organic carbon of wetland
ecosystems in this region. The process-based biogeochemistry model was applied to evaluate
how spatial and temporal variations in both CO2 and CH4 have changed in the last century
and will change during this century. Our current estimate of net CH4 emissions from this
region is 67.8±6.2 Tg CH4 yr-1 during the period of 1993-2004. In contrast, we estimate
that the region acts as a net carbon sink of -1.28±0.03 Pg C yr-1 with a persistent wetland
carbon sink from -0.38 to -0.41 Pg C yr-1 and an upland sink from -0.6 to -1.1 Pg C
yr-1. Our analysis indicates that wetlands play a disproportionally important role
in affecting regional greenhouse gas budgets given that they only occupy a small
fraction of the total land area in the region. In addition, this talk will present our
model projections of both CO2 and CH4 dynamics in the region during the 21st
century. More importantly, this talk will make recommendations on data collection
and model improvement based on our decade-long modeling efforts in this region. |