A Study On The Community Characteristics And Population Pattern Of Quercus Pannosa In Yaoshan,Yunnan

Sclerophyllous broad-leaved evergreen forest is an unique vegetation type in southwest China.Quercus pannosa community in Yaoshan,Yunnan is the most easterly distribution of this vegetation type.We adopted quantitative analysis methods,such as TWINSPAN classification,DCA,CCA,point pattern,and aggregation index,to conduct an inclusive study on its community structure,popualtion pattern,species diversity,and population dynamics of the Quercus pannosa forests.The purpose of this study is to reveal the factors that affect the community structure characteristics,dynamics,and community differentiation.Also we wanted to probe the disturbance impacts on forest dynamics and its community structure,and to understand this ancient relict features of vegetation.The main results are as follows:(1)A total of 64 typical samples were surveyed,and there were 193 species,belonging to 64 families and 125 genera.The dominant species were trees or shrubs.As for single-dominated Quercus pannosa forest,the important value were 0.8577;In shrub community,Quercus pannosa was co-dominated with other species.(2)By TWINSPAN classification,64 sample plots were divided into 4 community groups.There were significant differences in the species richness and diversity among different groups,the community group Ⅳ>the community group Ⅲ>the community group II>the community group I.The differences were related to successional stages,disturbance intensity,and environmental heterogeneity.(3)DCA and CCA indicated community distribution changed with the gradient of disturbance intensity and elevation above sea level.Meanwhile,elevation was the dominant factor that determined the distribution pattern of different Quercus pannosa communities.To some extent,the disturbance affected the succession and secondary characteristics of the communities.(4)Quercus pannosa population pattern was characteristic of aggregation distribution at different altitudinal conditions.Spatial aggregated intensity was positively correlated with the elevation.Also,the spatial pattern was related to the sampling scale.With the increase of the sampling scale,spatial pattern changes from aggregation distribution to random distribution,and the uniform distribution were observed at some scales.(5)Sprouting ability of Quercus pannosa was related to disturbance intensity,specifically,intensively disturbed>continuously disturbed>moderately disturbed>less moderately disturbed>mildly disturbed>undisturbed.The moderate disturbance might promote the ability of individual’s sprouting,but the highly intensive and continuous disturbance would decrease the sprouting ability of the individuals.