高原鼠兔干扰对高寒草甸β多样性的影响

Effects of disturbance by plateau pika on theβdiversity of an alpine meadow

多样性反映生物群落沿某一环境梯度的物种周转速率,该研究尝试采用β多样性揭示植物群落随小型啮齿草食动物干扰梯度变化的生态过程。该研究利用野外随机样地的采集数据,分析了高原鼠兔(Ochotonacurzoniae)不同干扰强度下Whittaker指数的变化特征,并利用群落二元丰富度的方差分解法,确定了单个物种(SCBD)和单个干扰位点(LCBD)对β多样性的贡献。主要结果:随高原鼠兔干扰强度增加,植物群落内物种周转速率呈先增加后降低的趋势;占据位点数居中的物种对区域内的β多样性贡献较大,其中冰草(Agropyroncristatum)、臭蒿(Artemisiahedinii)、小花草玉梅(Anemonerivularisvar.flore-minore)等单个物种对整个区域内β多样性的贡献最为突出;整个区域内干扰位点T0(高原鼠兔干扰强度为0)对区域β多样性贡献值最大,LCBD值和该位点的群落丰富度呈显著负相关关系,但与高原鼠兔干扰强度无显著关联。说明重点保护LCBD值高的干扰位点所在的高寒草甸,以及SCBD值较高的冰草、臭蒿、小花草玉梅,对保护高原鼠兔存在时高寒草甸植物群落多样性具有重要意义。

Aimsβdiversity reflects species turnover rate across environmental gradients,and this study attempts to useβdiversity to reveal relevant ecological processes underlying the changes in plant community composition along a disturbance gradient induced by small burrowing herbivores.Methods This study conducted a field survey at Gangcha County in the Qingzang Plateau to determine the effect of disturbance intensities of plateau pika(Ochotona curzoniae)on theβdiversity of an alpine meadow measured by Whittaker’s index.Then a variance decomposition was used to measure the contribution of individual species to overallβdiversity(SCBD)and single interference sites to overallβdiversity(LCBD)according presenceabsence community matrix.Important findings The turnover rate of species in the plant community first increased and then decreased with the increase of the disturbance intensities induced by plateau pika.Species with intermediate site occupancy had a greater contribution toβdiversity,in which Agropyron cristatum,Artemisia hedinii and Anemone rivular var.flore-minore were the single-species plants that contributed the most to theβdiversity of the study regions.The disturbance plot T0 with the absence of plateau pika had the greatest contribution to theβdiversity of whole study region.LCBD of individual site was negetively related to species richness of that individual site,and had no significant correlation with the disturbed intensity of plateau pika.These results indicate that alpine meadows distributed in high LCBD and Agropyron cristatum,Artemisia hedinii and Anemone rivularis var.flore-minore with high SCBD should be protected to conserve plant diversity when the plateau pikas are present.