短期降雨改变对荒漠草原植物群落特征的影响

为了研究长期放牧效应和短期降雨改变对草原生态系统植被特征的影响,以长期控制载畜率(禁牧、轻度放牧、中度放牧、重度放牧)试验为基础,分析模拟不同降雨梯度(减少环境降雨50%、环境降雨、增加环境降雨50%和100%)下植物群落个体数量特征、物种多样性以及地上生物量对水分变化的响应。结果表明:1)长期放牧和短期降雨改变均显著影响群落盖度(P0.05),群落盖度随放牧强度的增加而减少,却随降雨的增加而增大;2)短期降雨改变对物种多样性影响显著(P0.05),中度放牧后在增加环境降雨100%处理下,最多出现22种物种;3)长期放牧和短期降雨改变对地上生物量均有显著影响(P0.05),禁牧样地在环境降雨处理下地上生物量最高,为408.3g·m-2,重度放牧样地在减少环境降雨50%处理下地上生物量最低,为118.2g·m-2。

Effect of short-term rainfall change on plant community characteristics in desert steppe

In order to study the effects of long-term grazing and short-term rainfall variations on vegetation characteristics of a grassland ecosystem,an experiment using different rainfall gradients(50% reduction,am-bient,50% increase,and 100% increase in environmental rainfall)was conducted on the site of a long-term manipulative stocking rate experiment(no grazing,light grazing,moderate grazing,and heavy grazing),and the response(in terms of individual quantities,species diversity and aboveground biomass of the plant commu-nity)to rainfall changes was analyzed.The results showed that:1)variations in long-term grazing and short-term rainfall had significant effects on community coverage(P<0.05)(community coverage decreased with in-creasing grazing intensities but increased with increasing rainfall);2)the rainfall variations had significant effects on species diversity(P<0.05)(there was an increase of 22 species with 100% increase in environmental rainfall under moderate grazing conditions);3)the long-term grazing and short-term rainfall variations had sig-nificant effects on aboveground biomass(P<0.05)(The highest aboveground biomass was 408.3 g·m—2under ambient rainfall under no-grazing conditions,and the lowest aboveground biomass was 118.2 g·m—2with 50%reduction in environmental rainfall in heavy grazing conditions).