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森林生态系统凋落物被微生物分解的过程影响整个土壤碳库的碳来源及稳定性,在氮沉降全球化的趋势下因试验树种、试验方法、试验时间等不同因素导致森林地上凋落物分解产生了促进、抑制和无影响等3种响应。氮沉降对凋落物分解的影响主要通过3种机制实现:1不同浓度的氮沉降对凋落物中纤维素和木质素分解的影响不一致,原因可能是外加低浓度氮时,与之相关的真菌和细菌的生物量、活性会升高,高氮时则反之;也有部分研究表明氮沉降一般促进含木质素少抑制含木质素较多的凋落物的分解;2氮沉降对微生物产生的胞外酶活性影响也不一致,所以微生物酶对凋落物分解速率影响不同;3通过对微生物的生物量、多样性、群落组成以及生态化学计量比等的影响,氮沉降也会影响凋落物分解木质素、纤维素等化学物质的过程。
The process of microbial litter decomposition in forest ecosystem affected the carbon source and stability of the whole soil carbon pool. Under the trend of globalization of nitrogen deposition, litter decomposition in forest litter resulted from different factors such as test species, test methods and test time Promote, inhibit and no effect of three kinds of response. The effects of nitrogen deposition on litter decomposition are mainly achieved through three mechanisms: 1 The effects of nitrogen deposition at different concentrations on the litter decomposition of cellulose and lignin are inconsistent, probably due to the effects of low concentration of nitrogen and related fungi and Bacterial biomass, activity will increase, while the high-nitrogen is the opposite; some studies have shown that nitrogen deposition generally promote less lignin containing more lignin inhibition litter decomposition; 2 nitrogen deposition of microbial extracellular enzyme The effect of microbial enzymes on litter decomposition rate is different; 3 Nitrogen deposition also affects the litter decomposition of lignin through the influence of microbial biomass, diversity, community composition and ecological stoichiometry, Prime chemical and other processes.