典型草原非生长季土壤微生物氮固持对不同功能群植物氮吸收的贡献

项目名称： 典型草原非生长季土壤微生物氮固持对不同功能群植物氮吸收的贡献

项目编号： No.31300440

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 生物科学

项目作者： 马琳娜

作者单位： 中国科学院植物研究所

项目金额： 24万元

中文摘要： 在很多陆地生态系统中，植物的生长受到氮素条件的限制，非生长季土壤氮素的积累量对植物的养分吸收十分关键。基于高纬度地区的研究结果所提出的土壤微生物氮循环季节演替模型认为，秋冬季土壤微生物固持的氮是春季植物生长的主要营养源。然而，该模型在温带草原生态系统中的适用性及非生长季微生物氮固持的机制和主要驱动因素尚未探究；非生长季微生物固持的氮对不同功能群植物氮吸收的贡献仍不确定。本研究以温带典型草原羊草草地为研究对象，采用同位素示踪、磷脂脂肪酸和核酸分析等方法阐明土壤微生物氮循环的季节性格局，揭示非生长季微生物氮固持的机制和主要驱动因素，量化春季氮释放被不同功能群植物所吸收利用的比例，这些研究对于理解和预测植被生产力和植物群落组成变化及其对未来气候变化的响应具有重要的意义，为陆地生态系统氮循环模型提供充足和有力的参数依据。

中文关键词： 非生长季；微生物氮固持；植物功能群；植物生长；典型草原

英文摘要： In most terrestrial ecosystems, plant growth is N-limited. Soil nitrogen (N) accumulation in non-growing season is vital for plant N uptake in early spring. A theory of seasonal succession of N cycles in high-latitude systems: in this concept soil microbes immobilize N in the absence of plant N uptake during autumn and winter, and release N at a time of maximum plant N demand. Such a concept of seasonal succession of N cycles has, to our knowledge, not yet been tested for temperate grasslands and the major driver mechanism to regulate soil microbial N immobilization is uncertainty. To examine these issues, we conducted a field experiment in a temperate steppe of northern China. We used 15N tracer, phospholipid fatty acid and DNA analysis methods to elucidate the pattern of seasonal microbial N cycle, explore major determinants of the pattern of non-growing season microbial N immobilization, and investigate the proportion of nitrogen uptake by different functional groups of plants during the microbial dieback in early spring. These issues will improve our understanding on predictions of plant community composition and ecosystem productivity, and the response of them to the climate change.

英文关键词： Non-growing season；microbial N immobilization；plant functional group；plant growth；typical steppe