Study on Carbon and Nitrogen Cycles Driven by Microorganisms in Grassland Ecosystem of Qinghai-Tibet Plateau

1.Study the soil CO2 flux in Qinghai-Tibet Plateau. Metagenomic sequencing technology was used to analyze the variation characteristics of soil microbial functional gene abundance and microbial community structure and composition. We expect to get the explanation of microbial functional genes for the difference of soil CO2 emission between two alpine grasslands. It is proposed for the first time that microbial intracellular biochemical processes have important effects on soil CO2 emissions from grassland ecosystems. 2. To study the differences in the decomposition potential of plant- and microbial-derived carbon on the Qinghai-Tibet Plateau and to determine the trends of microbial carbohydrate enzyme genes between alpine grasslands and meadows ; explore the main factors affecting the abundance of microbial carbohydrate enzyme genes. 3. To study the seasonal variation of microbial community composition on the Qinghai-Tibetan Plateau ; describe the biological functions of unique genes carried by abundant species in controlling CH4 emission rate changes ; reveal how the expression of unique genes carried by abundance species is affected by environmental factors. 4. To study unique and shared species in different grassland ecosystems on the Qinghai-Tibetan Plateau and their effects on N2O emissions ; the genes ( e.g., nirK, nirS, norB ) carried by unique and shared species were analyzed to better elucidate the microbial mechanism behind N2O emissions ; exploring the effects of environmental factors ( e.g., pH, SON, SOC ) on unique species and shared species provides a theoretical basis for elucidating the impact of N2O emissions in alpine grasslands.