Study On The Effects Of Grazing On Methane Production And Oxidation Protential And Methanotrophs Of Xilin River Riparian Wetland

Riparian wetland is an important source of methane emission in the atmosphere,and also the main place of carbon fixation.Methane oxidation can effectively reduce methane emissions.In recent years,grazing has degraded the ecological functions of riparian in grassland areas and affected the global carbon cycle process.Therefore,it is of great significance to study the methane production and oxidation characteristics of riparian wetland under the background of global warming.In this study,the wetland ecosystem of Xilin River riparian,a typical inland river in grassland area,was selected as the research object.By compared the differences of soil bacterial community structure between grazing and fencing wetlands,it was found that grazing disturbance had a significant impact on the abundance of some methanotrophs.Based on this,the change of methane production and oxidation potential in soil vertical profile 0-100 cm was studied,and the community structure and pmo A functional gene abundance of methanotrophs were determined by molecular technology.By analyzed the effects of aboveground plant biomass,soil physical and chemical properties and soil depth changes on them,the methane production and oxidation potential after grazing disturbance and the change characteristics and driving factors of methanotrophs in soil vertical profile of riparian wetland were discussed.The main research results were as follows:(1)Methane production potential was positively correlated with soil moisture,total carbon,total nitrogen and total organic carbon content,and negatively correlated with p H(p<0.05);methane oxidation potential was positively correlated with sand proportion,and negatively correlated with soil moisture content and SO₄^2-and Fe content(p<0.05).Methane production and oxidation potential had a very significant positive correlation,both of which first increased and then decreased with the change of depth,and the depth of soil layer has a significant effect on both(p<0.05);(2)After grazing disturbance,the soil moisture,total carbon,total nitrogen and total organic carbon content at 0-20 cm increased,and the soil particle size decreased,which promoted the methane production potential of soil at 0-20 cm and inhibited the methane oxidation potential of soil.At the depth of 20-100 cm,the opposite was true;(3)Generally speaking,the study area was dominated by type II methanotrophs,and the relative abundance of Methylocystis was the highest.Soil p H,total organic carbon and Fe content were the main driving factors affecting the community structure of methanotrophs in wetland;(4)Grazing disturbance and soil depth significantly affected the richness of methanotrophs(p<0.05).After grazing disturbance,the abundance of methanotrophs decreased significantly at 0-10 cm(p<0.001)and increased significantly at 20-70cm(p<0.01).There was a significant positive correlation between the abundance of methanotrophs and methane oxidation potential(p<0.05);(5)Soil moisture content was the main driving factor affecting the methane oxidation capacity,which can directly affect the methane oxidation potential,and can also indirectly affect the methane oxidation potential by directly affecting plant factors,other physical and chemical factors and the abundance of methanotrophs.This study provides new evidence for methane production and oxidation potential and changes of methanotrophs community under vertical profile after grazing disturbance,and it is of great significance to carry out in-depth research on the impact of human activities on the mechanism of wetland methane production and oxidation.