植物功能性状和微生物特性对草地生态系统土壤氮素内循环的协同调控机制

植物凋落物的输入和微生物的特性对于陆地生态系统土壤氮素内循环的调控作用极为重要，影响生态系统的生产力、稳定性和可持续性。基于功能性状的相关理论，物种被认为是功能性状的集合，物种特性直接作用于生态系统功能（养分循环、生产力等）。因此，本项目拟选择我国北方3种草地类型（草甸草原、典型草原和荒漠草原）的代表性群落作为研究对象，在生长季内定期测定优势物种功能性状、微生物特性、土壤因子以及氮矿化速率等指标，并分析其季节动态和空间格局。采用功能性状的研究方法，利用广义线性模型和结构方程模型分析特征植物（开发种和保守种）性状、微生物特性、环境因子和氮素内循环之间的定量关系，确定植物和微生物对土壤氮素内循环的相对贡献，揭示植物功能性状和微生物特性对氮素内循环的调控机制。研究结果有助于增加对土壤氮同化与氮矿化平衡关系的认识，提高土壤氮固持能力和氮循环效率，对于草地管理和生态系统可持续发展提供实验和理论的支持。

Litter imputs and microbal properties play an important role in the internal nitrogen cycle, and directly affect ecosystem functions. Based on the relevant theories on functional traits, the species was considered as the assemblage of functional traits affecting ecosystem processes and functions (nutrient cycling, productivity etc.). Thus, this project will be performed in three types of grassland (meadow steppe, typical steppe and desert steppe) in North China. In every region, typical plant communities will be selected to measure nitrogen mineralization rate, functional traits of dominant species and microbial properties at four-week intervals during growing season. According to the trait-based approach, generalized linear model and sturctural equation model was used to quantify the relationships of plants (exploitative species and conservative species), microbes, soil and nitrogen cycles, make clear the relative contributions of plant traits and soil microbial properties to internal nitrogen cycle and discover the regulating mechanisms of plant traits and microbial properties in the internal nitrogen cycle. Results and conclusions in this project can increase the knowledge on the balance of nitrogen assimilation and mineralization and enhance nitrogen retention and cycling rate. Under the condition of nitrogen deposition, this will provide experimental and theoretical supports for grassland management and the sustainable development of terrestrial ecosystems.