Effects Of Exogenous Nitrogen And Freezing-thawing Cycles On Greenhouse Gas Emissions In Peat Soil

Wetland is one of three ecosystem types in the world. Though its area just occupies 6% of the earth, the carbon storage occupies 30% of global biomes’carbon sink and plays a vital role in biogeochemistry cycles. In nowadays, reinforced intensity of exogenous N enrichment becomes a crucial environment issue around the world and it has great impacts on wetland’s greenhouse gas emission. In order to investigate how different exogenous N enrichment levels affect greenhouse emission during freezing-thawing cycles, we set up an incubation experiment to explore the effects of exogenous N enrichment (high, low and no N added as CK) and freezing-thawing cycles (freeze-thaw, thaw-freeze and constant temperature) on peat soil in Zoige alpine wetland. The results showed that the conductive factor of greenhouse gas emission in wetland peat soil was freezing-thawing cycles, while longer the thawing period, the emission of CO2 and N2O were higher. After freezing period, peat soil transformed the sink of CH4 into the source of CH4. Exogenous N enrichment can also influence the process, the higher level of exogenous N enrichment in peat soil, the more emission of CH4 and N2O; There were significantly interactive effects of exogenous N enrichment and the freezing-thawing cycles on CH^and N2O emission, whereas CO2 emission did not show the interaction; The soil microorganism biomass carbon just had a weak relation with CH4 emission, but there was no significant relation can be found in soil microorganism biomass carbon with CO2 and N2O emission. The soil microorganism biomass nitrogen also had no relation with those three kinds of greenhouse gas emission, either. The microorganism PLFAs in soil can be an indicator for the change of soil CO? emission. The results provide the basis on local pasture management, such as prohibited grazing or rotative grazing, and preserve carbon stock stable, add carbon sink etc. In the future, we should take a long-time observation on the phenomenon in situ, detect total soil microorganism and microbial communities, for providing suitable mechanism on soil greenhouse gas emission.