云南哀牢山古茶树群落优势树种的种群结构与分布格局

Population Structure and Distribution Pattern of Dominant Tree Species in Ancient Tea Tree Community in Ailao Mountains of Yunnan Province,China

用种群结构、存活曲线、扩散系数、最近邻体指数及Ripley’s K函数等分析了云南哀牢山野生古茶树群落优势树种的种群结构和分布格局。结果表明:1.2 hm2样地内记录到胸径≥1.0 cm的乔木2 894株,隶属于22科38属48种。普洱茶个体数量最多,重要值排名第一,木果石栎重要值排名第二,但具有最大的相对优势度。该群落应为以普洱茶、木果石栎等为优势树种的中山湿性常绿阔叶林类型,目前处于群落演替的顶极阶段。10个优势树种中,木果石栎、红花木莲、腾冲栲3个树种幼苗、幼树较少,大树较多,属衰退型种群,分布格局在大多数尺度下呈随机分布,聚集程度随径级增大而增加。普洱茶、硬斗石栎和针齿铁仔3个树种中树、幼树较多,大树较少,属稳定型种群。红河木姜子、毛尖树、多果新木姜子、西南红山茶4个树种幼苗、幼树多,大树较少,属增长型种群。这7个树种分布格局在多数尺度下呈聚集分布,聚集程度随径级增大而降低。种群结构和分布格局在时间和空间上的变化反映了各树种相互间此消彼长的竞争关系和群落演替趋势。

The size structure,survival curve,dispersion coefficient,index of nearest neighbor and Ripley＇s K function were used to analyze the population structure and distribution pattern of dominant tree species in the ancient tea tree community in Ailao Mountains of Yunnan Province.The results showed that there were 2 894 free-standing individuals with DBH≥1.0 cm recorded in the 1.2 hm2 plot,belonging to 48 species,38 genera and 22 families.Camellia sinensis var.assamica was ranked the first in terms of importance value with the highest abundance and Lithocarpus xylocarpus was ranked the second,although it had the largest relative dominancy.Then the community should be defined as mid-montane humid evergreen broad-leaved forest with Camellia sinensis var.assamica,L.xylocarpus,etc.being the dominant tree species.Now it is in the climax of succession series.Among 10 dominant tree species,L.xylocarpus,Manglietia insignis,Castanopsis wattii were of declining populations since their seedlings and saplings were scarce and the big trees were numerous.These three species tended to be in random distribution at most of scales,but clump intensity increased as population grew.Camellia sinensis var.assamica,Lithocarpus hancei and Myrsine semiserrata were of stable populations since theirs saplings,middle-sized trees were numerous and the big trees were scarce.Litsea honghoensis,Actinodaphne forrestii,Neolitsea polycarpa and Camellia pitardii were of growing populations since their seedlings and saplings were numerous and the big trees were scarce.These seven species tended to be in clumped distribution at most of scales,but clump intensity decreased as population grew.The spatiotemporal variations of population structure and distribution pattern reflected the competition between these species and the trends of succession of community.