放牧对明油子-扭黄茅灌草丛生物多样性的影响

2005年，在云南元谋干热河谷采用样方调查法及生物多样性分析法研究了放牧干扰对明油子Dodonaea viscosa-扭黄茅Heteropogon contortus灌草丛生物多样性的影响。结果表明，无放牧干扰的明油子-扭黄茅灌草丛植物和节肢动物种类最丰富，节肢动物群落优势度最低，而多样性和均匀度最高，优势种为扁平虹臭蚁Iridomyrmex anceps；曾经过度放牧的明油子-扭黄茅灌草丛植物种类和节肢动物种类最贫乏，灌木-草本层节肢动物多样性最低；长期存在一定放牧干扰的明油子-扭黄茅灌草丛植物种类和节肢动物种类比较丰富，但节肢动物群落优势度最高而均匀度最低；经受或存在放牧干扰的明油子，扭黄茅灌草丛林下以刺吸类昆虫占优势，地表以迈氏小家蚁Monomorium mayri占优势。过度放牧导致明油子-扭黄茅灌草丛种类组成发生变化，生物多样性大大降低，群落趋于不稳定，栖息环境出现退化。放牧干扰对地表节肢动物群落的影响比对灌木-草本层节肢动物群落的影响突出。表6参21

Influence of grazing on diversity of Dodonaea viscosa-Heteropogonetea contortus herb-shrub community

Influence of grazing on biodiversity of Dodonaea viscosa-Heteropogonetea contortus scrub and grass clump in Yuanmou Arid-hot Valley was studied with sample plot investigation and biodiversity analysis.The results showed that the most abundant vegetation species and arthropod species were in the non-disturbed scrub and grass clump.Formica fusca was the dominant species in its arthropod community.And the highest diversity index and the evenness index were found,as well the lowest predominant index.The poorest vegetation species and arthropod species were in the overgrazed scrub and grass clump.The lowest diversity index was found in its arthropod community in the shrub-grass layer.More abundant vegetation species and arthropod species were in the scrub and grass clump with certain long-term grazing.The lowest evenness index and highest predominant index were found in its arthropod community.The piercing-sucking insects were predominant in the shrub-grass layer,and Monomorium mayri was predominant in the litter-layer in the grazed clumps.The species component changed in the overgrazed clump,biodiversity in the ecosystem depressed greatly,the arthropod community was instable,and the habitat degraded.Grazing had more effect on the biodiversity of the litter-layer arthropod communities than that of in the shrub-grass layer.