【摘要】 采用样方法对东祁连山地区不同退化程度高寒草甸植物群落进行了调查,对群落结构、物种组成和群落生产力进行了分析,并运用α多样性、β多样性等指标研究了其物种多样性变化。结果表明,1)研究样地内共有植物种13科27属40多种,从未退化-轻度退化-中度退化-重度退化-极度退化,不同退化演替阶段的优势种分别为线叶嵩草+禾草、线叶嵩草+珠芽蓼、珠芽蓼+线叶嵩草、珠芽蓼+杂类草、平车前+杂类草。2)随退化程度的加剧,草地总盖度降低,优良牧草生物量减少,而毒杂草的比例逐渐上升,草地质量下降;地上、地下生物量均明显降低,地上生物量远低于地下生物量,分布在各层的植物根量越来越少,地下根系具有浅层化特点。3)高寒草甸植物群落α多样性指数基本上与均匀度、丰富度指数呈正相关,与生态优势度指数呈负相关;群落的物种丰富度在中度退化阶段最高,但多样性指数和均匀度指数在重度退化阶段最高,群落多样性更多地受均匀度的影响。4)随退化程度的加剧,样方内微生境或资源异质性减小,样方间异质性增大,从而导致β多样性增加;各草地植物群落物种替代速率由大到小的顺序为重度退化-极度退化>未退化-轻度退化>中度退化-重度退化>轻度退化-中度退化。更多还原

【Abstract】 The community structure and productivity,plant composition and diversity of alpine meadow under different degrees of degradation,including non-degradation(ND),light-degradation(LD),moderate-degradation(MD),heavy-degradation(HD) and over-degradation(OD),were studied.Results indicated that: 1) There were more than 40 plant species,in 13 families and 27 genus.The dominant species in different degradation stages from ND to OD were Kobresia capillifolia+Poaceae,K.capillifolia+Polygonum viviparum,P.viviparum+K.capillifolia,P.viviparum+forbs,Plantago depressa+forbs.2) With increasing degradation,the vegetation coverage,biomass of high quality forages,total aboveground/underground biomass and root weight in different soil layers and grassland quality decreased,while the root system distribution became shallower.However,the proportion of toxic plant and forbs in community increased.3) The α index showed positive correlative relationships with evenness and richness and a negative relationship with dominance.The richness of communities was highest in MD,but the diversity index and evenness index were the highest in HD.The evenness had more impact on the diversity index.4) The difference of microhabitat or heterogeneity within sampling sites decreased along with degradation,but it increased among sampling sites,and this resulted in an increase of the β index.The order of plant species replacement rate was: HD-OD>ND-LD>MD-HD>LD-MD.更多还原