祁连山青海云杉种群种内竞争分析

On the Intraspecific Competition of Picea crassifolia Population in the Qilian Mountains

采用逐步扩大范围的方法和改进的单木竞争指数模型对祁连山亚高寒山区青海云杉(Picea crassifolia)林内设置的1 hm2样地内的青海云杉种内竞争状况进行了分析.结果表明:①在青海云杉种群中,随着样圆半径的增加,竞争强度逐渐减弱,青海云杉个体的竞争影响样圆半径为6m。②青海云杉种内竞争强度随着对象木胸径的增加,竞争强度不断减小,在径级为5～10cm、25～30cm时,竞争强度随径级的增加急剧减小,并在径级25～30 cm形成明显拐点。随着径级的继续增大,青海云杉受到的竞争压力变化较为平缓,竞争主要发生在径级小于25～30cm植株上。③青海云杉种内竞争强度和对象木胸径大小服从乘幂函数,并达到显著水平。实验数据表明,该模型能很好的用于青海云杉种群种内竞争强度的预测。

In this study, a 1 hm^2 sample plot of Picea crassifolia forest was delimited to analyze the intraspecific competition of Picea crassifolia population in the subalpine zone of the Qilian Mountains using the method of gradually expanding the scope and Duan Renyan＇s improved individual tree competition index model. The results were as follows ： （ 1 ） In the Picea crassifolia population, the competition intensity decreased gradually with the increase of circularity radius, and the circularity radius affecting the competition of Picea crassifolia trees was 6 m; （2） The competition intensity of Picea crassifolia decreased with the increase of diameter at breast height （ DBH）, especially it decreased sharply in the DBH ranges of 5 - 10 cm and 25 - 30 cm, and the inflection point occurred at DBH range of 25 - 30 cm. With the increase of DBH, the competitive pressure of Picea crassifolia changed gently, and the competition occurred mainly in DBH range less than 25 - 30 cm ; （3） The intraspecific competition and diameter of Picea crassifolia trees followed a power function of CI = AD-B, and the level was significant. The experimental data showed that the model could be used to predict the intraspecific competition of Picea crassifolia population well. The analyzed results could provide a theoretical basis and reference for tending and managing Picea crassifolia forests in the Qilian Mountains