人为干扰与喀斯特森林群落退化及评价研究

导致贵州喀斯特森林发生退化的原因是火烧、开垦、放牧和樵采。选用群落高度、显著度、萌生株比例、生物量和耐荫树种比例5个指标对群落退化进行定量评价。结果表明，退化群落可分为A－F6个退化等级。在受自然力作用和人为干扰不明显时，顶极群落发生正常的波动（A）。在干扰力的作用大于波动的振幅时，顶极群落发生明显退化（B－F），群落退化度逐渐增大。群落退化等级与退化群落自然恢复的演替阶段基本一致，生物量的移出和耐荫树种消退是退化的关键因素，火烧、放牧、开垦干扰群落主要分布于退化等级C－F中，樵采干扰群落多发生于B－C中。4种干扰对退化群落萌生株数影响较大，受火烧、樵采开扰群落多，而受开垦、放牧干扰群落较少。各干扰群落退化度从小至大排序为樵采干扰群落、开垦干扰群落、放牧干扰群落、火烧干扰群落。

Evaluation on degradation of Karst forest community and human disturbance

Fire, reclamation, herd, and cut led to degradation of Karst forest in Guizhou Province. Five indexes as height, dominance, percentage of asexual individual, biomass, and percentage of shade-tolerant for evaluating community degradation were selected. Degraded communities were divided into six degraded grades (A-F). Community structure and function fluctuated normally in climax (A) under nature force or light human disturbance. While effect of disturbance was preponderated over the range of community fluctuation, climax community degraded evidently, and degraded degree of communities increased gradually. Degraded grades of communities were consistent to succession stages of degraded community. In degraded process, the key factor was decrease of biomass and shade-tolerant species. Degraded communities due to fire, herd, and reclamation were distributed in grades C-F, and degraded community due to cut was in grades B-C. Amount of asexual individual was influenced by disturbance type, and the amount in degraded communities due to fire and cut was more than that due to reclamation and herd. Degraded degree of different disturbed community was in order of cut community < cleared community < herded community < fired community.