喀斯特地区长期草地利用制度对群落稳定性的影响

草地利用方式和混播组合对群落特性的长期影响不同。利用方式对白三叶（Trifolium repens）盖度没有显著影响,而混播组合与利用方式的交互作用影响显著。白三叶在宿营处理和刈割为主利用下的与鸭茅（Dactylis glomerata）混播中的比例最低,而在刈割利用和宿营处理的多年生黑麦草（Lolium perenne）组合中的盖度最高。混播组合对禾本科组分盖度影响不显著,但利用方式和交互作用有显著的作用,长期放牧绵羊的混播草地多年生黑麦草很少。混播组合对杂草密度、盖度和多样性指数的影响不明显,而利用方式和交互作用显著地影响杂草盖度和多样性指数。放牧草地中的杂草密度高于刈割草地的,其中放牧利用的白三叶/多年生黑麦草草地最高。放牧牛的草地杂草密度较少,而放牧绵羊的草地杂草较多。白三叶、禾本科牧草以及杂草的密度都显著地受混播组合、利用方式及其交互作用的影响,说明密度是一个敏感的指标。

Effects of long-term utilizing systems on community stability of Karst pasture

Long-term utilizing system and composition have different effects on serious community traits of pasture.Utilizing ways have no significant effects on white clover coverage,which were significantly affected by composition and the interaction.White clover was much lower in the mixtures that with cocksfoot than with perennial ryegrass,when under cutting and sheep-panning treat.Grass coverage,the other way round,significantly affected by utilizing ways and the interaction,e.g.,perennial ryegrass is very low under long-term sheep grazing.It is utilizing way and interaction rather than composition strongly affect the coverage and density of weeds and Shannon-Wiener Index.Grazing pasture has more weeds than cuttings,among which,sheep grazing clover/ ryegrass pas-ture is the most.Pasture that under cattle grazing,contains more weeds than those under sheep grazing.Composition,utilizing and the interaction have significant effects on the densities of clover,grasses and weeds,implying that density is a sensitive target.