青藏高原东缘高寒草甸土壤氮矿化和硝化速率驱动因子研究

Global climate is warming. The rates of soil nutrient cycling and conversion will accelerate. At present, the function of soil nitrogen mineralization and nitrification are increasingly valued in meadow soil fertility maintain and vegetation restoration, and become a hot research topic. This study main research in alpine meadow, using an in situ resin core incubation contrast to indoor alternate leaching aerobic incubation to study the soil nitrogen transformation rates under three different habitats (north slope, south slope and flat land) of alpine meadow on the eastern of the Tibetan plateau. Analysis of nitrogen mineralization and nitration rates relate to the above ground vegetation, soil physical and chemical properties, the content of soil microbial carbon and nitrogen, and local environmental conditions of soil temperature and humidity. To explore the effect factors and mechanisms of soil nitrogen transformation in different alpine meadow, it is provide theoretical basis for degraded meadow community restoration and nitrogen cycle with global changing. And it is great significance that to fully understand the relationship between grassland ecosystem degradation mechanism and the global climate change.

随着全球气候变暖，土壤养分循环和转化速率相应加快。当前，土壤氮矿化和硝化在高寒草甸土壤肥力保持、植被恢复过程中的作用正日益受到重视，并成为一个研究热点。本项目以青藏高原东缘高寒草甸为研究对象，拟采用原位树脂芯与室内间歇通气淋洗培养相结合的方法来研究青藏高原东缘高寒草甸三种生境（阴坡、阳坡和滩地）下土壤氮转化速率；通过室内外通气培养比较分析氮矿化、硝化速率与地上植被、土壤理化性质、土壤微生物碳、氮量及环境因子（温度与湿度）的关系，揭示青藏高原东缘高寒草甸在不同生境下土壤氮素转化的关键因子和作用机制，为全球气候变化退化草甸群落的恢复及氮素循环提供理论依据，而且对全面理解草地生态系统退化机理与全球气候变化的关系具有重大意义。

通过不同海拔和坡向（阴坡、阳坡和滩地）来代替土壤温度梯度和水分梯度，分析高寒草甸土壤氮的转化速率，同时测定土壤理化指标和地上植被功能群特征，旨在研究不同空间和生境对土壤氮转化的主要因子。对2016-2018三年自然群落数据的重复测量方差分析表明，高寒草甸土壤氮氨化速率和硝化速率均受海拔、年际、年纪与海拔交互和海拔、坡向、年际三者交互的影响。原位培养实验表明海拔和坡向能通过改变土壤温度和水分而直接的影响土壤理化属性，最终间接作用于土壤氮素转化效率。综合地上群落特征、功能群性状与地下土壤理化性质分析，高寒草甸土壤氮素在空间和生境的氨化和硝化速率不再是水分和温度决定的，氨化速率在地下主要受铵态氮与土壤全氮比和地上群落的杂草氮含量的影响，氮素硝化速率主要由地下土壤硝态氮和铵态氮各占土壤总氮的比例以及地上杂草功能群中全氮和全磷含量决定。表明氮素转化过程由地上群落优势种来主导无论是随年际、空间还是生境的改变。这一结果与高寒草甸群落功能类群中杂草所占比例较高的结果一致。本研究将为退化草地在全球气候变化下的养分循环提供理论参考。.已接收待发表SCI论文1篇，出版生态系统生态学1部，培养在读研究生8名，协助培养毕业研究生1名。后续成果还在审稿和陆续投稿中。