荒漠草原灌丛引入过程土壤水分响应及生态阈值

For accelerating the vegetation recovery in desert grassland in Ningxia area, the introduced xeric shrubs restoration has been a common rebuilding model in this area. However, with the cover of the shrubs increasing, the contradiction between plant utilization and soil available water is more obvious, which leads to the competition for recourses between the native herbs and the introduced shrub, and then the native herbs is degrading. To identify the ecological restoration threshold and avoid the xeric shrub encroachment, these methods, such as field observation, statistics analysis of data and model simulation will be used to study the ecological response and threshold to soil moisture of desert grassland with introduced shrub recovery in Ningxia eastern area. Based on the field data of soil properties, floristic composition and structure, community transpiration, soil seed banks and soil microbial mineralization, the spatial distribution of soil moisture, biotic response and utilization of soil moisture of desert grassland with introduced shrub restoration will be studied, and furthermore the threshold and capacity of soil moisture will be evaluated. This research aims at understanding in floristic composition characteristics and soil water resource utilization in the ecological process of the introduced shrub recovery model, and revealing the potential ecological problems of the restored desert grassland in Ningxia，and finally providing the scientific theoretical basis for desert grassland restoration and sustainable utilization.

为加快宁夏荒漠草原植被恢复,人工旱生灌木成为普遍恢复模式，但随盖度增加，植被与土水矛盾日益显现，为避免荒漠草原大量灌丛化，保证荒漠草原生态系统向着稳定平衡方向发展，本项目拟开展荒漠草原人工灌丛恢复过程中土壤水分生态环境响应及阈值研究，该研究利用野外观测、控制实验、数理统计及模型模拟等方法，在对不同演替阶段群落的土壤特性(土水）、植被群落特征、土壤种子库、土壤微生物矿化及蒸发蒸腾数据观测和分析的基础上，开展荒漠草原人工灌丛恢复过程中土壤水分生态环境响应机理、土壤水分阈值效应及植被承载研究，旨在了解该地区草原-退化-恢复过程中群落特征及水土资源利用规律，寻找存在于人工植被与草本稳定的土壤水分生态阈值，以期揭示荒漠草原存在主要及潜在生态问题，为荒漠草原恢复和可持续利用提供科学理论依据。

本研究以生态系统稳态转变理论和灌丛入侵过程理论为基础，通过野外调查和控制试验设置、地理信息系统和高通量测序方法的应用及土壤碳氮水为主的多因子基础数据集的构建，开展了宁夏东部荒漠草原地区灌丛引入过程中植被、土壤特性及微生物响应特征研究，揭示了植被、土壤碳氮及微生物要素在灌丛化过程中形成的正反馈过程，并确定出该地区荒漠草原土壤水分、生物量阈值分别为8.11%~14.19%和0.06 kg·m-2~0.07 kg·m-2，同时也定量化灌丛化过程中的两种优势植物柠条锦鸡儿和蒙古冰草萌发及定植时平均土壤水分阈值分别为5.58%~6.63%、6.21%~6.98%和6.94%~12.86%、7.14%~13.69%。该研究结果旨在为半干旱荒漠草原生态系统的可持续性管理提供科学依据和数据支撑。