人类活动与气候变化对科尔沁沙质草地植被的影响

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和气候变化对草地植被的影响。研究结果表明：①人类放牧活动对沙质草地植被具有显著影响，其中轻度放牧可使原退化草地植被盖度、高度、物种丰富度和多样性明显提高，中度放牧下虽然草地植被盖度和高度有所下降，但对物种丰富度和多样性无不良影响，持续过度放牧可以导致草地植被迅速破坏；②围栏封育可以促进退化草地植被盖度、高度、物种丰富度和植物多样性得到较快恢复，其恢复速度是草层高度＞植被盖度＞物种丰富度＞多样性；③暖湿气候有利于草地维持较高的植被盖度、高度、物种丰富度和多样性，而持续干旱会导致相应指标的明显下降，多雨时期气温变化对植被的影响较大，干旱时期降水变化对植被的作用较强。

Effects of Human Activity and Climate Changes on Vegetation in Horqin Sandy Grassland, Inner Mongolia

To understand the effects of human activities and climate changes 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: (1) the grazing had significant effects on grassland vegetation, in that the continual overgrazing could result in severe degradation of the vegetation, the light grazing was favorable to restoration of the height, coverage, richness and diversity, and the moderate grazing didn't induce decrease of the richness and diversity thought it also resulted in decrease of the height and coverage; (2) The enclosure could promote increase of the height, coverage, richness and diversity, the increased speed was the height ＞ the coverage ＞the richness ＞the diversity; (3) the warm and wetness climate was favorable to maintain higher the height, coverage, richness and diversity in the sandy grassland, and the warm and dry climate could resulted in significant decrease of the height, coverage, richness and diversity; and the effects of the temperature on the vegetation was greater in the rainy period and the effects of the rainfall on the vegetation was greater in the drought period.