草地利用方式对草甸草原植被空间异质性的影响

Effects of different grassland use modes on spatial heterogeneity of vegetation in meadow steppe

研究不同利用方式下植物群落中物种的分布特征,有助于解释植物在不同利用方式干扰下的演替规律。本研究以内蒙古呼伦贝尔草甸草原为研究对象,通过野外调查,基于幂函数法则,探讨围封、放牧和刈割利用方式下草地植被物种分布状况和群落整体空间分布的变化。结果表明:在放牧和刈割利用及围封下,草甸草原植被物种分布规律符合幂函数法则;与围封相比,放牧增加了群落整体的空间分布异质性,而刈割则降低了这种变化,刈割和放牧草地物种异质性指数高于群落整体异质性指数的物种增多;物种出现频率发生变化,如对糙隐子草(Cleistogenes squarrosa)种群而言,围封地中糙隐子草的出现频率为0.010,刈割和放牧增加了糙隐子草的出现频率(0.151和0.521),刈割和放牧降低了狭叶青蒿(Artemisia dacunculus)的出现频率(0.132和0.028)。

Understanding the spatial distribution of species in plant communities is important for explaining community succession under different use modes. Here,we investigated the spatial distribution of species and communities under three different use modes( grazing,mowing,and fence) in Hulun Buir meadow grassland in Inner Mongolia by using exponential function based on field survey data. The results showed that the patterns of species distribution well fitted the law of exponential function under all modes. Compared with control,grazing increased and mowing reduced community spatial heterogeneity. The number of species with higher species heterogeneity index than the community heterogeneity index increased under mowing and grazing. Mowing and grazing increased or decreased species frequency. For example,the frequency of Cleistogenes squarrosa was 0.010 in exclosure,0.151 in mowing and 0.521 in grazing. The frequency of Artemisia dacunculu was 0.755 in exclosure,0.132 in mowing and 0.028 in grazing.