科尔沁沙质草地植物群落的放牧退化及其自然恢复过程

 为了了解不同放牧强度对我国北方沙质草地的影响及其封禁停牧后草地植被的自然恢复过程,我们于1992—2006年在科尔沁沙地开展了草地放牧和封育试验,分析研究了人类放牧活动对草地植被的影响,比较了不同程度退化草地恢复速度及其所受气候变化影响。研究结果表明:①在科尔沁沙地,随着放牧强度的增加,草地植被受放牧影响的程度会加重,但只有持续重牧才会导致植被的严重退化,而且持续重牧对植被盖度、高度和草地生产力的危害程度要大于对物种丰富度和多样性的危害程度;中度放牧可以导致植被盖度、高度、生物量的轻度下降,但对物种丰富度、多样性没有不良影响;对于退化草地而言,持续轻牧可促进植被的有效恢复;②封禁停牧以后,草地原受干扰程度不同,其恢复的相对速度也不同,表现为原草地退化越严重,其恢复速度相对越快,而且是植被高度、盖度、生物量的恢复速度要大于物种丰富度、多样性和频度的恢复速度;③草地植被的恢复演替明显受到气候变化的影响,暖湿气候有利于植被的恢复,暖干气候对于植被的恢复不利。

Changes of Plant Community in Grazing and Restoration Processes n Horqin Sand Land, Inner Mongolia

To understand the effect of different grazing intensities and enclosure on sandy grassland vegetation in north China, a field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that: ①The grazing effect on grassland vegetation tended to increase with increase of grazing intensity, but only the continual overgrazing could resulted in serious degradation of the grassland vegetation, and continual overgrazing had greater effect on the vegetation height, coverage and biomass than on the species richness and diversity; the moderate grazing had not harmful effect on the species richness and diversity though it could result in light decrease of the coverage, height and biomass; continual light grazing could promote the restoration of the original degradation grassland; ②After enclosure to avoid grazing, the restoration of the vegetation had greater differences among original grasslands with different grazing intensity; the relative faster of vegetation restoration, the severe of vegetation degradation, and the ranges of the restoration was greater in the height, coverage and biomass than in the species richness, diversity and frequency; ③The restoration process was significantly affected by the climate changes, and the warm and wetness climate was propitious to the restoration of degradation vegetation, and the warm and drought climate was not favor to the restoration of degradation vegetation.