退耕还林树木根系性状对土壤物理特性的影响机制

植物根系调节着土壤生态系统过程，根系通过物理穿插、土壤团聚和分泌物等过程影响土壤结构的形成和稳定性。利用根系可塑性及其与土壤特性相互作用关系可实现生态系统可持续经营。退耕还林的生态效益等备受研究者关注，但仍缺失退耕还林树木根系性状对土壤功能影响的相关知识。本项目以吉林省退耕还林树木根系和土壤物理特性为主要研究对象，采用野外试验、室内分析与模型模拟相结合的手段，通过测定不同树木种类和个体发育阶段的根系形态特征、解剖结构和生理功能，明确树木根系性状的种间和种内变异；结合不同林分土壤物理特性的差异，探明根系性状对土壤团聚体、孔隙分布和持水能力等特性的直接和间接影响；综合树木生长情况、年龄和树种类型等生物因素和土壤微生物群落、物理特性、养分含量等土壤环境条件，构建结构方程模型，揭示退耕还林树木根系性状对土壤物理特性的影响机制。为合理评价退耕还林工程生态服务功能提供理论依据。

Trait-based approaches are being used to interrogate the belowground, in order to predict how changes in vegetation composition influence soil properties and processes, and how shifts in the structure of complex belowground communities impact the functioning of soil. Root traits are the dominant driver of soil functioning, influencing the formation and stability of soil structure through physical interpenetration, soil enmeshment and root exudates. Our study focus on the tree root traits and soil physical properties under the Grain for Green project, which is the conversion from degraded agriculture ecosystem to forest ecosystem in China. In order to analyze the main factors that influence root traits, tree root morphology, structure and physiological traits will be measured based on different species, ontogenetic stage. Soil aggregate, porosity distribution, infiltration rate, soil water storage and other physical properties will be measured, to explore the interaction of root traits and soil function across interspecific and intraspecific variation. At last we investigate the biota and soil condition to reveal the effect mechanism of root traits on soil physical properties under Grain-for-Green project using structural equation model (SEM). We hope to provide the theoretical basis for the rational evaluation of ecological service function of the Grain-for-Green project.