Because of the"foehn effect",deeply incised gorges of major rivers in the Hengduan Mountains(commonly called dry valleys)have semiarid or arid climate.Harsh environment and difficult access have so far obstructed the systematic inventory and documentation of the flora of these dry valleys.This is particularly problematic for efforts towards the conservation of endemic and valuable plant species.Therefore,102 shrub-meadow community survey plots were set up along four dry valleys in Ganzi prefecture,located in the eastern Hengduan Mountains,China.The compositions,richness,diversity of these communities were calculated and assessed using sample plot survey and phytosociological approach.Overall,244 plant species were recorded,consisting of subtropical(48.77％)and temperate(38.83％)species,47.13％of which were endemic to southwest China.Obvious differences in species composition and structure along the altitude gradient were observed.The variations of richness,diversity,and evenness followed a bimodal-hump shaped pattern with increasing altitude,with peak occurring at mid-level altitude(3501-4000 m)and valley occurring at 2501-3000 m altitude.The regions at 2501-3000 m altitudes were more sensitive to global climate change and biological interference,and were found to have the highest protection value.The impacts of altitude gradients and climatic parameters on the features of this shrub-meadow community were also evaluated using principal component and multiple linear stepwise regression analysis methods.Altitude and temperature-related variables were the most important drivers of both species richness and cover.Species α-diversity here only depended on the precipitation frequency.This founding could help to understand the impact of the very harsh environment and altitude gradient on plant-plant interactions in a variety of natural systems.

ZONG Hua;SUN Jia-rui;ZHOU Lu;BAO Fang;ZHENG Xian-zhu

Department of Landscape,College of Architecture,Southwest Jiaotong University,Chengdu 11756,China;China Railway Eryuan Engineering Group Co.LTD,Chengdu 610031,China

山地科学学报（英文版）

[1]ZONG Hua;SUN Jia-rui;ZHOU Lu;BAO Fang;ZHENG Xian-zhu-.Effect of altitude and climatic parameters on shrub-meadow community composition and diversity in the dry valley region of the eastern Hengduan Mountains,China)[J].山地科学学报（英文版）,2022(04):1139-1155

foehn,gorges,Harsh,phytosociological

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