西藏高寒河谷沙地植被演替的高光谱遥感识别及恢复潜力评估研究

Estimating the potential vegetation recovery is the prerequisite and basis for ecological restoration of aeolian sandy land in the alpine valley of Tibet. However, the mechanisms of plant community succession and recovery potential are still unclear due to varies types of aeolian sandy land in the alpine valley, which seriously hampered the ecological restoration and the effective controling for the sand disasters. In this study, we will address these gaps to understand mechanisms of plant community succession and comprehensive vegtation recovery potential. For the mechanisms of plant community succession, we will focus on changes of species diversity under different successional stages, spatial pattern of dominant populations and its functional response to spatio-temporal variability of soil moisture. Several case studies will be carried on the alpine vegetation of aeolian sandy land in Tibetan Plateau. To estimate the comprehensive vegetation recovery potential, we will develop indices for different successional stages based on hyperspectral remote-sensing data. We will use the indices to compare vegetation succession process of natural and artificial vegetation recovery. Our methodology involves cutting-edge approaches coupling population point pattern analysis, geostatistics, and hyperspectral remote-sensing, which can also applied to other vegetation conservation and restoration. The results could provide a support for the ecological restoration of aeolian sandy land and security barrier construction around the airports, the railway (roads) and cities on the Tibetan Plateau.

开展植被恢复潜力评估是西藏高寒河谷沙地生态恢复的前提和基础。目前，不同类型沙地的植物群落演替规律、恢复潜力等尚不清楚，严重制约了高寒河谷沙地的生态恢复和河谷风沙灾害的有效防治。为此，本项目拟以高寒河谷沙地植被为研究对象，运用种群点格局分析、地统计学和高光谱遥感等方法，着力于阐明不同植被演替阶段物种多样性变化，以及优势种群空间格局与土壤水分时空异质性的响应关系，建立基于高光谱遥感的用于判别不同植被演替阶段的指标体系和判别标准，进而以自然和人工促进植被条件下植被演替过程为参照，构建高寒沙地植被恢复潜力综合评估模型。研究结果可以服务于西藏高原重要空港、交通要道和城镇周边风沙化土地的生态恢复和安全屏障建设。

开展植被恢复潜力评估是西藏高寒河谷沙地生态恢复的前提和基础。目前，不同类型沙地的植物群落演替规律、恢复潜力等尚不清楚，严重制约了高寒河谷沙地的生态恢复和河谷风沙灾害的有效防治。为此，本项目以西藏高寒河谷沙地植被为研究对象，运用种群点格局分析、地统计学和高光谱遥感等方法，分析了不同植被演替阶段物种多样性变化，阐明了优势种群空间格局与土壤水分时空异质性的响应关系，揭示了主要优势沙生植物种群的高光谱特征以及不同演替阶段的光谱差异性，建立了用于判别不同植被演替阶段的指标体系和判别标准；结合不同类型沙地的植被演替阶段划分和生境特点，采用层次分析法和模糊综合评价方法，通过构建植被恢复潜力评价指标与标准体系，建立了西藏高寒河谷流动沙地植被恢复潜力综合评估模型。结合2008－2014年的植被恢复试验结果，验证与探讨了该模型的评价精度与适用性，气象条件、地形条件和土壤状况决定了生境胁迫条件下植被恢复具备的先天条件，恢复措施则决定了其具备的后天条件；通过强有力的人工促进植被恢复措施可直接提高寒河谷流动沙地植被恢复潜力，亦可间接改变土壤状况，从而提升植被恢复效果。研究结果不仅可服务于西藏雅鲁藏布江流域风沙化土地的生态恢复和安全屏障建设，而且可为青藏高原其它区域和不同气候条件下的沙地生态恢复提供参考依据。