Emissions of CH_4 and N_2O from Island Forested Swamp in Da Hinggan Mountains

Emissions of CH4 and N2O in swamps especially at high latitudes are significant to evaluate greenhouse gases emissions at the northern latitudes. During the growing season of2011, using a static opaque chamber-GC technique, we researched CH4 and N2O emission fluxes in two typical island-forested swamps(Betula platyphylla-Carex schmidtii swamp and Larix gmelinii- Carex schmidtii swamp) in Da Hinggan Mountains of China, analyzed the seasonal characteristics of CH4 and N2O fluxes, and investigated the influences from temperature and water master factors to the emission fluxes. The results showed that: CH4 was in weak absorption during growing season in both B. platyphylla-C. schmidtii swamp and Larix gmelinii-Carex schmidtii swamp except that CH4 fluxes had emission peaks in spring; while N2 O emission peaks appeared in early summer and spring in two swamps. The average emission fluxes were-60.61,-93.21 μg·m-2·h-1and 82.92, 45.06 μg· m-2·h-1respectively. CH4 and N2O emission fluxes during growing season in L. gmelinii-C. schmidtii swamp were in negative correlation with 10-40 cm and 15-40 cm soil temperatures respectively; while CH4 and N2 O emission fluxes during growing season in B. platyphylla-C. schmidtii swamp were only in negative correlation with 40 cm soil temperature. Neither two types of swamp and soil water ratio had approached strong correlations. CH4 and N2O emission fluxes during growing season were-2.21,-2.74 kg·hm-2and 2.74, 0.93 kg·hm-2respectively in B. platyphylla-C. schmidtii swamp and L. gmelinii-C. schmidtii swamp, which became the sinks of CH4 weak absorption and the sources of N2 O weak emission.