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A chronosequence study(substituting space for time) was conducted following the retreat of alpine glaciers since the Little Ice Age.The study area is Baishui No.1 Glacier,Mt.Yulong in Lijiang City,Yunnan Province of China.It is the biggest glacier on Yulong Snow Mountain.It has an area of 1.32 km2,the altitude of the equilibrium line is around 4850 m.After the greater advancement of Baishui No.1 Glacier in Little Ice Age,the glacier had began to retreat,and form a large newly-exposed area.This area was divided into five successional seres: SUC1 ≈ 0—9 years;SUC2 ≈ 5—14 years;SUC5 ≈ 200—400 years.They were bounded by dated moraines deposited in 2002,1997,and 17th and 19th centuries.but the age of the two seres(SUC3 and SUC4) is unknow,they were located at an elevation of 4000 m and 3900 m.Then a successional sequence is formed by SUC1 to SUC5.Only a single site was chosen to represent each successional sere.At each sere ten 0.25 m2 quadrats were chosen,we recorded percent cover,height and abundance of each herbaceous species.In SUC4 and SUC5,three 16 m2 and two 100 m2 quadrats were chosen to record height and abundance of bushes and trees respectively. By employing field investigation,factor analysis methods,this study mainly focuses on the communities composition and its number characteristics within different successional times,as well as the variations of vegetation types and the estimation to the age of the terminal moraine in the Little Ice Age.Among the investigated 55 plots,there are 91 types of plants,and about 63 species have been identified from it yet.They belong to 28 families and 46 genera,including arbor,shrub and herb three life forms plants,and most of species are dicotyledon,The number characteristics analysis for different succession stages reveals the communities composition and substitution regulation.Community composition is as follows: In the first successional sere,there are Cerastium caespitosum,Meconopsis horridula and Juncus brachystigma three communities,the dominant species is Cerastium caespitosum;In SUC2,two communities are Polygonum macrophyllum and Carex capilliformis,the former is the dominant;Cerastium caespitosum,Carex capilliformis,Carex crebra and Pedicularis sp.are the main communities in SUC3,and the dominant species is Cerastium caespitosum;Three communities are formed by Carex capilliformis,Carex crebra and Delphinium sp.,and the first one is the dominant in SUC4;Carex crebra,Ligusticum rechingerana and carex kansuensis are the primary communities in the last successional sere.Carex crebra is the dominant species.At the terminal of Baishui No.1 Glacier,the vegetation succession experienced the stages of bare land—herbaceous—shrub—macrophanerophytes.From the perspective of ecological niche,the appearance of this succession process is due to the different ecological niches and their different suitability.The dominant species generally with the wide ecological niche and strong suitability,and can appear in many succession stages.Therefore,the succession toward the orientations of continuing differentiation of ecological niches,and each species try to take advantage of various resources.The species substitution processes often occur under the conditions of intense intraspecies and interspecies crossing competitions.In addition,based on the comprehensively analyses to the geographical characteristics,meteorological features of Mt.Gongga and Mt.Yulong,as well as the vegetation succession process,combing tree-ring materials of Mt.Yulong region,we estimated that the age of terminal moraine is about 170—250 years.