广西桂林漓江河岸带植被配置类型与退化机制研究

Spatial Patterns of Riparian Vegetations and its Optimization in Lijiang River: an Intensive Tourism Karsts River in the southern subtropical China

河岸带植被结构与组成等配置状况直接影响其稳定河岸、净化水质、生物多样性、生物栖息地以及旅游景观等重要功能。查明漓江河岸带主要植被配置类型及其各自退化表现、原因与恢复途径,是开展河岸带退化植被恢复的基础与前提。该研究通过野外实地调查与测量,对漓江桂林-阳朔河段51个河岸带断面的地形、土壤、植被等进行了系统调查,分析了河岸带植被退化的主要表现、主导干扰因素,并通过流域与河岸带尺度综合的角度,提出了漓江河岸带植被恢复的思路。从岸坡地形与植被组合出发,按照自然、近自然、人工等干扰程度,广西漓江河岸带可划分为江心洲宽滩地疏林灌草自然型、丘陵陡坡林灌草自然型、平原农田缓坡灌草近自然型、平原滩地林草近自然型、聚落阶地疏灌林草人工-自然混合型、城镇岸坡林草人工型等6种典型植被配置模式。漓江河岸带植被退化主要表现为多样性差、景观破碎、生态功能弱,而城镇、交通、旅游等不合理开发建设是主导性的干扰因素。从生态稳定和景观美观的角度,提出了漓江河岸带植被恢复与优化的思路,以期为广西漓江河岸带生态修复提供科学依据。

Riparian vegetations have multi-functions including sediment removal and erosion control. They can filter agricultural contaminants, and provide habitat for high numbers of species and improve the landscape quality. Lijang River is a world famous tourism river for its typical Karst landscape. In recent decades, riparian vegetation of Lijiang shows a degradation trend due to suffering intensive tourism activities. In order to provide some useful information for the degraded riparian restoration, we investigated the spatial patterns and composition of riparian vegetation and highlighted the behaviors of deteriorated riparian and its driving factors of Lijiang River through the typical crosswise sections synthetically surveyed at 51 sites in topography, soil, vegetation, and disturbances. Considering the combinations of topography- vegetation and the disturbed degrees suffering from human activities, spatial patterns of riparian vegetations of Lijiang River could be classed into sixes typical classes. The main performances of the degraded riparian vegetation included low species diversity, landscape fragmentation, ecosystem service function decrease and scenic landscape degenerate. The main disturbances to riparian vegetation contained urbanization, traffic construction, tourism exploitation, etc. We also have provided some proposals on riparian vegetation restoration in ecological healthy and scenic landscape beautify. The results could not only enhance the understanding of riparian vegetation degradation, but also provide some useful suggestions to ecological restoration in Lijiang River.