生态化学计量对揭示生态系统各组分之间的元素循环规律及其相互关系具有重要意义。干旱沙区固沙植被建立后，植被结构与组成、土壤理化性质、生物多样性等都发生了一系列的演变。然而，还有一些科学问题仍不清楚，如土壤微生物功能群结构和酶活性如何响应植被和土壤的这些变化？其C:N:P生态化学计量特征呈现什么样的变化规律？土壤微生物功能群和酶活性的计量特征与植被和土壤C:N:P存在怎样的内在联系？解答这些科学问题是认知固沙植被演替规律、揭示沙区植物与土壤关系的关键和基础。本项目将利用沙坡头站不同年代建植的固沙植被演替序列，以天然植被和流动沙丘为对照，采用野外调查、底物添加试验和室内分析等手段，以土壤微生物功能群和酶活性生态化学计量为核心内容，研究植被、土壤微生物功能群、土壤酶活性和土壤的C:N:P特征，阐明固沙植被-土壤之间C:N:P计量转换的土壤微生物和酶学调控机理，为科学地管理固沙植被提供理论依据。

Ecological stoichiometry poses a great significance to reveal the rules of elements cycling and their relationships among ecosystem components. Since establishment of the sand-fixed revegetation in the arid desert, a series of evolutions in structure and composition of revegetation, soil physicochemical properties, and biodiversity, etc. occurred. However, some scientific questions are unclear to date. How are soil microbial functional structures and enzymatic activities responded to such variations in revegetation and soil? And what rules can be found about their C:N:P ecological stoichiometric properties? How about the correlations of C:N:P ecological stoichiometry among soil microbial functional community, enzymatic activity, soil and vegetation. Answers to these questions are the theoretical basis to reveal the rules of sand-fixed revegetation succession and the relationships between plants and soil in desert. Using the chronosequence of sand-fixed revegetations established in different years at Shapotou Station and taken the near natural vegetation and move sand dunes as the controls, this project will combine methods of field survey, substrate addition test and lab analysis to focus on variations in soil microbial functional communities and enzymatic activities, and to study the C:N:P ecological stoichiometric properties of soil microbial functional community, soil enzymatic activity, soil and vegetation. The purposes are to illuminate the microbial and enzymatic mechanisms of controlling the transition of C:N:P stoichiometry from vegetation to soil, and to offer the theoretical basis for management of sand-fixed revegetations scientifically.