Studies on the Interspecific Association of Canopy Trees in Davidia involurata Community of Mt.Seven-sister in Western Hubei

Based upon a 2×2 contingency table,a series of techniques including χ² test,association coefficient and Dice index were used to determine the interspecific association in Davidia involurata Community of Mt.Seven-sister.The results were expressed in the forms of semi-matrix and constellation figures,and indicated that the interspecific association was of little significant level,only four pairs of species exhibited significantly positive association.There was a low association degree between most pairs of species;meanwhile few pairs of species were extremely exclusive to each other.Involurata were extremely positively associated with Lithocarpus henryi,Meliosma cuneifolia,Aralia chinensis and Daphniphyllum macropodum,but extremly negatively associated with Padus wilsonii.Davidia involurata,Phoebe sheareri,Camellia caudata,whose importance values ranked first,were slightly associated with each other,and they occupied their own niches respectively,competing slightly for environmental resources.The fact that C.caudata were extremely positively associated with ten species showed its stable place in community and its important role in maintaining the stable structure of Davidia involurata Community.Henryi perhaps was a keystone species,because it was extremely positively associated with the three plants,whose importance values ranked first.Finally,it was proposed how to apply interspecific association more efficiently.