青秀山风景区优势种大叶栎种内与种间的竞争关系

Intraspecific and interspecific competition of dominant tree Castanopsis fissa in Qingxiushan Scenic Spot, Guangxi, southern China

树木之间的竞争关系是塑造森林结构和动态的关键因素。采用Hegyi单木竞争指数,定量分析了青秀山次生林优势种大叶栎Castanopsis fi ssa种内与种间的竞争关系。结果表明:1)大叶栎种内竞争强度随着胸径的增大而逐渐减小,这与种内的密度制约性的自疏效应有关。2)大叶栎与乔木上层建群种马尾松Pinus massoniana的竞争最为强烈,其次为大叶栎、稠木Lithocarpus glabra、阴香Cinnamomum burmannii等树种。大叶栎种间竞争较种内竞争更为剧烈,竞争的结果可能会导致马尾松种群逐渐退出群落。3)大叶栎种内以及与整个林分的竞争强度与对象木胸径之间近似服从幂函数关系,而大叶栎与伴生树种的竞争强度与其胸径间近似服从对数函数关系,竞争强度和对象木胸径间呈显著的负相关关系。大叶栎种内和种间的竞争强度随大叶栎树龄的增大而减小,当其胸径超过30 cm后,种内和种间竞争强度的变化很小。

Competitive relation between forest trees is a key factor in shaping forest structure and dynamics evolution. By using Hegyi single-tree competition index model, the intraspecific and interspecific competition intensity of Castanopsis fissa in Qingxiushan Scenic Spot Guangxi, southern China were quantitatively analyzed. The results show that （1） the intensity of intraspecific competition in C. fissa stand decreased gradually with increasing tree diameter class, this was related to self-thinning effect of intraspecific density-conditionality. （2） The intense completion occurred between C. fissa and Pinus massoniana, followed by tree species C. fissa, Lithocarpus glabra, Cinnamomum burmannii, et al; this resulted that the interspecific competition was more intensive than the intraspecific competition in C. fissa, and the P.. massoniana population may gradually decline in community. （3） The relationships of the DBH （diameter at breast height） of objective trees and the competition intensity between competitive trees and objective trees in the whole forest and C. fissa population nearly conformed to power function relations, while that between other competitive trees and the objective C. fissa tree conformed to logarithm function; the DBH of the objective tree was significantly negative correlation with competition intensity. The results show that the larger the DBH of the objective trees, the smaller the competition intensity of the C.fissa population, and when the DBH of C.fissa reached 30 cm, the change in competition intensity was very small.