氮沉降对森林土壤有机质和凋落物分解的影响及其微生物学机制

氮沉降持续增加背景下土壤C∶N∶P化学计量比和pH环境等的改变及其可能的土壤微生物学机制已经成为陆地生态系统与全球变化研究的新生长点和科学研究前沿.以生态化学计量学和土壤微生物生态学为理论基础,综述了氮沉降对森林土壤有机质和凋落物分解的影响及其微生物学机制的基本理论、最新进展、研究热点与难点,旨在促进全球变化背景下陆地生态系统地下生态学的研究.氮沉降持续增加会导致森林生态系统磷循环加速,导致磷限制.氮沉降不但改变森林土壤有机质和凋落物的C∶N∶P化学计量比和降低土壤pH值,而且改变土壤微生物生物量碳氮磷、细菌、真菌和放线菌的组成以及影响碳氮磷分解的关键酶活性.氮沉降对森林土壤有机质和凋落物分解的影响表现为促进、抑制和无影响,其影响的差异可能来源于微生物效应的不同.叶片在凋落前有显著的氮磷养分回收,但是根无明显的养分回收,造成土壤有机质和凋落物的C∶N∶P化学计量比存在明显差异.基于DNA/RNA等分子生物学方法为土壤微生物生态学研究提供了强有力的手段,将促进氮沉降对森林土壤有机质和凋落物化学计量比改变的微生物学机制研究.

The effect of nitrogen deposition on forest soil organic matter and litter decompostion and the microbial mechanism

The changes of soil C:N:P ratios and pH under nitrogen deposition, its effect on soil organic matter and litter decomposition and the possible soil microbial mechanism are the new position and scientific research front of terrestrial ecosystem and global change. The paper based on ecological stoichiometry and soil microbial ecology, summarized the basic theory, new advances, hot and difficult points of research on the effect of nitrogen deposition on soil organic matter and litter decomposition and the microbial mechanism, to advance the research of terrestrial underground ecology under global change. The continuing increasing nitrogen deposition accelerated the phosphorus cycling of forest ecosystem, caused phosphorus limitation. Nitrogen deposition not only changed soil organic matter and litter C:N:P ratios and decreased soil pH, but also changed soil microbial components of carbon, nitrogen and phosphorus, composition of bacterium, fungus and actinomycetes, the key enzymes for decomposition of carbon, nitrogen and phosphorus. The effects of nitrogen deposition on soil organic matter and litter decomposition have three states: motivation, suppression, no effect, the reasons for the different effect maybe come from different microbial effect. Leaves had obvious resorption of nitrogen and phosphorus, but root had less resorption rate, which caused clearly different C:N:P ratios between soil organic matter. The molecular methods based on DNA/RNA provided advanced tools for soil microbial ecology research,which would promote researches on microbial mechanism of soil organic matter and litter decomposition.