Microbial Community Diversity Of Carbon Sequestration And Its Influencing Factors In The Tibetan Alpine Meadows

Meadow grassland in the alpine region of the Tibetan Plateau is the highest and most unique grassland ecosystem in the world.It is an important carbon pool in the region and is sensitive to climate change caused by excessive greenhouse gas emissions.The biogeochemical cycle of soil carbon is particularly important in the ecosystem material cycle.Soil microbes are the driving force and important carrier of ecosystem function and biochemical cycle.In order to understand the response of soil carbon cycle to environmental change in Tibetan Plateau,it is necessary to study the structure and diversity of carbon-fixing microbial community in soil and its influencing factors.In this paper,the meadow soils in southeastern Tibet were selected on the horizontal and vertical scales.The high-throughput sequencing technology in metagenomics technology was used to explore soil carbon sequestration microbial communities at two different gradient levels.The trend of structure is analyzed,and the relationship between soil carbon sequestration microbial community structure and environmental factors is analyzed.The main conclusions obtained are as follows:In the precipitation gradient zone,the soil organic carbon content decreased with the decrease of annual precipitation,the correlation between them was significant.The microbial species richness is high in the west of the study area,and the distribution of soil species in the west is more uniform.The difference in carbon-fixing microbial community diversity between different sites was significantly greater than the difference within the group,showing a distinct geographical distribution pattern;Proteobacteria was dominant in the composition of carbon-fixing microbial communities,and the dominant species included Alkalispirillum and Sulfurifustis.The main influencing factors controlling soil carbon sequestration microbial diversity are annual average precipitation,soil moisture content,vegetation coverage,average temperature and pH value,among which pH value is negatively correlated with other environmental factors;The average annual precipitation is positively correlated with other environmental factors except particle size and pH.Annual average precipitation is the main factor affecting soil carbon sequestration microbial diversity.On the elevation gradient: the soil organic carbon content decreases with altitude first,and the overall trend is high in the east and low in the west.The species richness and evenness of the samples on the east slope were better.The dispersion of the west slope group was serious,and the difference between the east and west slope groups was significant.The composition of the carbon-fixing microbial community,Nitrosomonadales,Rhodobacterales,etc.,is dominant in the eastern slope,the west slope is similar to the east slope,and the abundance of the Chromatiales is prominent.The advantage of relatively high abundance is the genus Cupriavidus,Rhodobacter and the like.The most important factors influencing the soil carbon sequestration microbial diversity are altitude,followed by coverage,soil moisture,soil organic carbon,and sand grain size.Most of the environmental factors are positively correlated,and the altitude change is the most important factor affecting the soil carbon sequestration microbial diversity in the Mila Mountains.