人类放牧活动与气候变化对科尔沁沙质草地植物多样性的影响

Effects of human activities and climate changes on plant diversity in Horqin sandy grassland,Inner Mongolia

为了解人类放牧活动和气候变化对我国北方沙质草地植物多样性的影响,笔者于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和降水、气温变化对草地植物多样性的影响。结果表明,1)放牧干扰对草地物种丰富度和多样性有着明显的影响,随着草地放牧干扰强度的增加,草地物种丰富度和植物多样性呈下降趋势,但只有持续重牧才会导致草地物种丰富度和多样性的明显降低;2)放牧干扰对草地不同生活型多样性和不同经济类群多样性的影响有很大差异,表现为随着放牧强度的增加,一年生植物多样性和禾本科植物多样性明显增加,多年生植物及菊科、藜科和杂类草植物多样性明显下降;3)不同放牧强度下的不同生活型多样性和经济类群多样性对气候变化的反应有很大差异,但除了重牧区菊科植物多样性与降水变化、中牧区杂类草植物多样性与气温变化达到显著相关外,其他相关性均未达到显著水平;4)在草地自然恢复演替过程中,暖湿气候有利于草地物种丰富度和多样性的增加,特别是可以明显促进多年生植物以及菊科、豆科植物多样性的增加,而持续暖干气候可以降低草地的物种丰富度和多样性,但对禾本科和藜科植物多样性的不利影响较小。

To help 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 distribution had significant effects on species richness of the grasslands. The richness and diversity decreased with increased grazing intensity, and continuous overgrazing could result in a rapid decrease of the richness and diversity; 2）There were large differences of the grazing effects on grassland plant diversity among different life forms and different economic groups. With an increase of grazing intensity, the annual plant diversity and Gramineae diversity increased while perennial plant diversity and Composite and Chenopodiaceae diversity decreased; 3）Under different grazing intensities, there were large differences in diversity response to climate changes among different life forms and plant families, but the relativity only reached a significant level between Compositae and precipitation in the heavy grazing sites, and between other families＇ diversity and temperature in the moderate grazing site; 4）In the grassland natural restoration succession process, warm and wet weather was favorable to an increase of richness and diversity, especially of perennial plants in the Compositae and Leguminosae. The warming and drying climate will result in a decrease of richness and diversity, but there will be less effect on Gramineae and Chenopodiaceae than on other plants.