Degradation Features of Alpine and Subalpine Meadows under Grazing Pressure in Mt.Wutai
ZHANG Yi-ping~1,JIANG Yuan~1,LIU Quan-ru~2,TAO Yan~1,WANG Geng-rui~1(1.Beijing Area Major Laboratory of Protection and Utilization of Traditional Chinese Medicine,Beijing 100875,China;2.College of Life Sciences,Beijing Normal University,Beijing 100875,China)
Wutai Mountain,a high and isolated alpine environment in Shanxi Province in northern China,has numerous subalpine and alpine meadows around its peaks.The alpine meadow zone with diverse meadows has large areas of high-quality grasses suitable for cattle grazing.However,over-grazing in recent years has exerted heavy pressure on the meadow vegetation,leading to serious deterioration in species composition and dominant species succession.This paper,through quantitative analyses of field survey data,describes the grazing impacts on alpine meadow communities and shows the features of degraded meadows under grazing influences,with the goal of improving both the utilization and conservation of the meadow resources.Based on data from 85 quadrats obtained from field investigations using a radial transect,we assessed the degree of degradation of the alpine and subalpine meadow communities under grazing pressure in Wutai Mountain by applying Canonical Correspondence Analysis(CCA).Comprehensively considering changes in community structure and the corresponding features in environmental conditions by CCA,degradation of the meadow vegetation could be classified into 5 groups: conventional interference,light degradation,medium degradation,heavy degradation and extreme degradation.The results of analysis showed that,along with the aggravating degradation,environmental factors such as animal dung quantity and soil compaction significantly increased,while soil depth decreased.This was especially true for the extreme degradation group.Quantitative features of communities such as coverage,aboveground biomass,species richness and diversity were reduced,whereas the percentage of annual and biannual plants in species composition increased.The dominant species of Kobresia myosuroides,K.pusilla and Thalictrum alpinum under conventional interference were replaced by species of K.myosuroides and K.pusilla(in subalpine meadow) and Polygonum viviparum, K.pygmaea,and Deschampsia caespitosa(in alpine meadow) under light degradation,and by K.pusillas under medium degradation.Under heavy and extreme degradation,Potentilla anserine and Plantago depressa became the dominant plants in most communities.The results also showed that cattle grazing severely influenced community diversity,suggesting that it was the main driving force causing meadow ecosystem degradation.To limit further degradation and promote the restoration of meadow resources in Wutai Mountain,we suggest that effective measures for meadow protection should be taken,such as a periodic grazing ban,fencing in severely degraded meadows,and artificial planting of indigenous grass plants.
【CateGory Index】： S812
【CateGory Index】： S812