Plant Community Classification And Environmental Interpretation Of Alpine Meadows In Mt.Jade Dragon

Mt.Jade Dragon,located in the core belt of Hengduan Mountains,with the most abundant alpine plant species,could be a typical area of vertical distribution of alpine mountain community in northwestern Yunnan,of great significance to the study and conservation of vegetation landscape and geographical environment.In order to make an intensive study about the relationship between the distribution of plant community and the environmental factors,we selected the plant community in Mt.Jade Dragon Meadows as the research object and obtained the data of the meadows plant community and the environmental data from 3000 m to 4000 m with the method of field survey.Firstly,the methods of quantitative ecology,including Multiple Regression Tree(MRT)and Two-way Indicator Species Analysis(TWINSPAN),were used to classify the communities in the aspect of formation and the pattern of association.Then,we discuss the relationship between plant communities and environmental factors in the approach of Canonical Correspondence Analysis(CCA).The interpretation of the distribution pattern of the formations mainly selected the environmental factors,which determine the material and energy redistribution pattern of mountain material,such as elevation,slope,slope,aspect and so on.As for the association,selected the habitat factors that directly determine the plant growth and distribution of heat,water,soil conditions and other habitat characteristics,including soil wetness index(WET),soil organic matter content(SOC),soil pH(SPH),soil pH(SPH),total soil nitrogen(TSN),solar radiation(SUN),etc.The main results are summarized as follows:(1)The classification of the formation of communities and the pattern of association of the meadows communities of Mt.Jade Dragon Meadows by MRT shows the result,.different types of plant community in different standard were controlled by different environmental factors.The formation of communities was determined by the elevation,slope and aspect.And the elevation is the main factor.The associations standard can be divided by the habitat conditions such as heat,soil nutrient and soil moisture and other habitat conditions.And what decide the result of classification are solar radiation(SUN),soil organic material(SOC)and pH(SPH).Finally,all the meadow samples were divided into four formations,nine associations.(2)Naming the results of the community division of the MRT,use the dominant species and indicator species.If a specie has a high indication in a community and a low indication in other communities,the indicator specie is not only represent the characteristics of the environment,but also the difference among the communities.(3)Based on the important value(IV)of meadow plants,TWINSPAN divided into four formations and eight associations.Its name has quoted the idea of the "Chinese vegetation",naming the communities with the dominant specie.Comparing the result of MRT with TWINSPAN,the coincidence probability of them is 90.6%,very high,however,the result of MRT might be more objective,considering the analysis of environmental factors.(4)The relationship between the distribution pattern of meadows communities and environmental factors shows the fact that,at the level of formations,elevation is the main factor affecting the distribution pattern of meadows communities,and at the level of associations,the sun radiation(SUN),soil organic matter(SOC),total soluble nitrogen(TSN)and soil wetness(WET)determine the distribution pattern of clusters together.It shows that the elevation is the most important factor restricting the distribution of meadows communities in Mt.Jade Dragon at the landscape scale.However,at the habit scale,the determining factors changed into heat,nutrient and water condition.The study put forward the suggestion of meadow protection:it could be more accurate to reveal the ecological relationships between the vegetation and plant community,and between plants and the environment by the method of MRT,with an elementary and theoretical significance for the rational utilization of mountain meadow and the protection of biodiversity.The thermal conditions,obtained by the corresponding model analysis,are the main environmental factors affecting the vegetation distribution in the Mt.Jade Dragon,therefore,more attention should be paid to the species with preference for heat in the plant conservation.The changes of soil pH values is related to the degradation of meadows vegetation.In the conservation of meadows vegetation,the interference caused by human activities should be reduced.