The Storage Characteristics And Stability Of Soil Organic Carbon In Hummock Carex Dominated Peatland

Peatland contain approximately 15%-30% SOC pool of terrestrial soil carbon pool,it is an important SOC pool in terrestrial.Because of the large flux,even a small change in respiration rate would have profound impact on the atmospheric CO₂ concentration.It is common to see cylindrical and hemispherical tussocks in sedge dominated peatland.That form a unique microtopgraphy ravine peatland in China’s northeast.The raise of tussock on the surface lead to the different of the soil moister and temperature.And the differences would influence the SOC storage characteristics and the SOC stability.Meanwhile,the tussocks consist of remains of plants,so it may be the significant SOC pool.In this study,the method of plot survey in the wild combined the soil test and soil incubation in the laboratory to estimate the storage of SOC in Dongming in Changbai mountain,to study the feature of soil labile carbon and to probe the feature of carbon mineralization and the influence factors in the hummock-microtopography peatland.The main conclusion as following:In the reference site,there are 2.26 tussocks per m2,the coverage of tussocks is 30%.The tussock SOC content is 456.84 g/kg,more than 2-3 times in tussock deep and tussock interspace.However,the bulk density of tussock is significantly lower than tussock deep and tussock interspace.The SOC density of tussock deep is 66.65 kg C/m3,it is more than 0.3 times in tussock soil and 0.8 times in tussock interspace.By calculating,the storage of SOC in the hummock-microtopofraphy is31.92 kg C/m2,the storage of tussock and tussock deep is 4.66 kg C/m2 and 11.75 kg C/m2 respectively.Accounting for 51.41% of total storage..If to neglecte the storage of tussock and tussock deep,the storage of hummock-microtopography will be lose more than 30%.Hence,the high carbon of tussock and tussock deep is unignorable in estimate soil carbon storage of herbaceous-peatland.In the study area,the labile organic carbon（EOC,MBC,DOC）content of tussock is the largest.It demonstrate that the soil of tussock is more activity and unstable.The labile organic carbon content of tussock deep and tussock interspace are decrease with the deepness of soil deepen.It demonstrate that the surface soil of tussock deep and tussock interspace are more activity than the deeper soil.The larger labile organic carbon storage of tussock and the surface soil of tussock deep and tussock interspace would decompose more easily in the global climate change and peatland degradation.Therefore exacerbate the global warming.According to the correlation analysis,the soil labile organic carbon is increase with the soil organic carbon increase,and demonstrate that the soil organic carbon would influence the soil labile organic carbon.Hydrothermal condition and site influence CO₂ flue apparently.In the all gradients of temperature,the CO₂ emission rate of tussock is more 0.5-2 times than tussock deep and tussock interspace,it demonstrate that in the same hydrothermal condition,the tussock contribute more CO₂ to global warming.The increase of ambient temperature would cause the more CO₂ emit from the carex-peatland.the Q10 of the study peatland is 1.5-1.7,it is smaller than the average of global soil Q10.It demonstrate that the carex-peatland is less sensitive than other ecosystems.The most suitable soil moisture of carbon mineralization of soil in the tussock,tussock deep and tussock interspace are 100%WHC、100%WHC、60%WHC respectively.And the soil in the tussock and tussock interspace more sensitive to the change of soil moisture.In the 30%WHC and 60%WHC soil moisture condition,the soil of all the site is the CH₄ sinks,and the methane oxidation of tussock and tussock deep is more.In the 100%WHC and 150%WHC soil moisture condition,the soil of all the site is the sources of CH₄,and the methane flue of tussock is the most.It demonstrate that the moister is the key influence factor for soil oxidized or emit methane,and the soil of tussock and tussock deep contribute more influence to atmosphere.With the soil moister increase,the rate of increase of tussock soil and tussock deep soil is more than tussock interspace.hence,the tussock response to soil moister stronger.With the soil temperature increase,the methane oxidation of tussock soil and tussock deep soil is decrease,it demonstrate the increase of temperature is adverse to the oxidation of methane.