木荷次生林种内和种间竞争研究

Study on intraspecific and interspecific competition in Schima superba

基于炎陵县青石冈国有林场的6块木荷次生林标准地调查数据,采用逐步扩大范围的方法确定影响对象木的邻体最佳竞争范围,利用Hegyi简单竞争指数定量分析木荷种内种间竞争强度。结果表明:在木荷群落中对象木的最佳竞争距离为5 m,种内竞争较种间竞争剧烈,随着对象木胸径的不断增大,因为自然演替中的自疏作用产生密度调节,加大了植株间距,竞争强度也随之降低。青冈、马尾松林木数量较多,在群落中占据一定优势,对木荷产生较大竞争压力。竞争强度与对象木胸径服从幂函数关系,并由模型预测可知,木荷胸径大于18 cm时,竞争强度变化很小且维持在较低水平。

Based on the investigation data of 6 secondary forest sample plots of Schima superba in state-owned forest farm of Qingshigang,Yanling County,the optimal competition distance of the objective species was determined by means of gradual area expansion method,in combination with the method of Hegyi＇s competition model for individual tree to quantitatively analyze the intraspecific and interspecific competition intensity in Schima superba.The results indicate that the optimal competition distance of the objective tree in natural Schima superba community was 5 meters.The intensity of intraspecific competition was stronger than that of interspcific competition in Schima superba.Due to the density regulating effect in natural self-thinning process,the intraspecific and interspecific competition intensity of objective species in Schima superba decreased gradually with the increasing of forest tree diameter class and tree distance.A huge number of Cyclobalanopsis glauca and Pinus massoniana,the dominant species in the community,poses great competition pressure on Schima superba.The ratio between the competition intensity and the breadth of the objective species was in agreement with the power function relationship.The results predicted by the model revealed that the competition intensity varied little when the breadth in Schima superba was more than 18 cm.