过渡带中岳桦种群生态特征的研究

STUDY ON ECOLOGICAL CHARACTERISTICS OF BETULA ERMANII POPULATION IN ECOTONE

在长白山北坡halt15 2 5m～ 1775m的岳桦云冷杉森林过渡带和 1990m～ 2 170m的岳桦苔原林线过渡带中 ,沿海拔高度 ,采用梯度取样方法 ,进行岳桦种群生态学研究 ,分析了岳桦种群存活曲线、种群分布格局和种群竞争指数 .同时应用分形分析研究了岳桦种群的分形特征 .结果表明 :依据岳桦种群的存活曲线 ,在岳桦云冷杉过渡带中岳桦种群处于由衰退型向稳定型发展的阶段 ,而在岳桦苔原过渡带中则由稳定型向增长型过渡 .从种群分布格局指数分析 ,岳桦在两个过渡带中的分布格局类型都是杂乱无章的 ,而且都偏离随机分布 ,处于由一个生态系统向另一个生态系统转换的相变区 .从竞争指数和盒维数来看 ,在岳桦云冷杉过渡带中 ,这两项指标都是由小到大迅速递增 ,而在岳桦苔原过渡带中情况刚好相反 .图 4参

In the forest ecotone between Betula ermanii forest and Picea-Abies forest from 1 525 m to 1 775 m, and the timberline ecotone between B. ermanii forest and alpine tundra from 1 990 m to 2 170 m on north slope of the Changbai Mountains, using gradient sampling along with elevation, the ecological characteristics of B. ermanii population were studied, and the survival curve, distribution pattern and competition index of B. ermanii population were analyzed. Fractal structure of B. ermanii population was studied also. The results showed that B. ermanii population changed from declining type to stable type in B. ermanii Picea-Abies forest ecotone, and from stable type to increasing type in B. ermanii alpine tundra ecotone according to B. ermanii population survival curve; In the two ecotones, distribution patterns of B. ermanii population were found in disorder, beloning deviated random distribution and were at the phase changing area from one type ecosystem to another based on population pattern index; Competition index and box dimension of B. ermanii population increased rapidly in B. ermanii Picea-Abies forest ecotone, and they decreased quickly in B. ermanii alpine tundra ecotone. Fig 4, Ref 16