喀斯特山地生态系统石漠化过程及其恢复研究综述

喀斯特石漠化一般经历顶极植被-灌草丛-石漠等3个阶段。在这一退化过程中喀斯特石漠化对环境的选择性导致喜Ca、耐旱和岩生性的植物生存，而生物量的移出和耐荫树种消退是退化的关键因素。退化过程中植被、土壤理化性质与环境形成正反馈关系，并具有退化方向上的一致性、退化过程的非同步性和退化速度的非线性等特点。喀斯特植被恢复时，其恢复对策经历了由早期更新对策向中期结构调整对策直至后期结构功能协调完善对策更替。喀斯特生态系统恢复的技术包括自然恢复、人工恢复与复合农林业综合治理技术。喀斯特区域恢复的核心是整体人地系统的生态优化。提出喀斯特生态系统石漠化过程及恢复研究的重点是适应性恢复与适应性管理的基础理论问题。

A REVIEW ON THE STUDIES OF DESERTIFICATION PROCESS AND RESTORATION MECHANISM OF KARST ROCKY ECOSYSTEM

Karst rocky desertification is a process of land degradation in which soil is eroded seriously, bedrock is widely exposed, land productivity declines seriously, and landscape becomes desertificated as a result of intense human disturbance on the fragile environment. Karst rocky desertification generally goes through a process from climax vegetation stage, shrub and grass stage to rocky desert stage. In such degraded process, the key factors are the decrease of vegetation biomass and disappearance of shade-tolerant species. The vegetation degradation is the most important cause and a sign of desertification. During the degradation process, plant-soil and site environment form a positive feedback with the same degradation direction, and the degradation process is characterized by asynchronism and nonlinearity of speed. The strategy for restoration of Karst ecosystem should be changed from sole regeneration in early stage, structure regulation in following period, to structure and function coordination in late stage. Restoration techniques include those of natural restoration, artificial restoration and agroforestry management. The core of restoration should focus on ecological optimization of the whole human-land system in Karst region. It is suggested that adaptive restoration and adaptive management should be emphasized in Karst studies in future.