山西太岳山森林演替过程中建群种的动态特征和种间关系

Dynamic Analysis on Spatial Pattern of Betula platyphylla and Larix principis-rupprechtii in the Succession Process in Taiyue Mountain of Shanxi Province

为解释太岳山白桦(Betula platyphylla)林向华北落叶松(Larix principis-rupprechtii)林演替的生态过程,该研究以不同演替阶段的调查样地数据为基础,通过空间代替时间构建演替的时间序列,即从白桦林演替至白桦+华北落叶松混交林再到华北落叶松林的过程;采用点格局分析法和Monte-Carlo拟合检验对演替过程中白桦和华北落叶松种群的分布格局及其相互关系进行研究。结果表明:(1)山西太岳山白桦种群龄级结构呈"纺锤"型,种群呈衰退的趋势;白桦种群逐渐被华北落叶松(龄级结构呈"金字塔"的增长型)种群所取代。(2)从白桦林演替至华北落叶松林的过程中,白桦种群由集群分布趋向于随机分布,驱动力主要是华北落叶松侵入扩散而形成的种间排斥;华北落叶松集群尺度逐步增大,驱动力主要是种群拓殖和种内竞争。(3)白桦和华北落叶松二者的种间关系,在白桦林阶段无显著相关,在混交林阶段由于排斥呈现显著负相关关系,华北落叶松林阶段二者无明显相关,二者种间关系的变化主要来自于群落剩余资源驱动下的种内种间竞争。

The dynamics characteristics of population patterns in the vegetation succession are rarely explored.Scale,pattern and process of ecological succession are three intertwined concepts in modern ecology.Succession research will inevitably involve scale and pattern analyses.Species spatial patterns and interspecific associations at any scale can be analyzed based on point pattern analysis with spatial mapped points of individuals＇ distribution.Therefore,it is suitable to discuss the relationships between species pattern in the vegetation succession process which have attracted much attention from ecologists.The aim of the present work is to study the spatial pattern formation and relative importance of intra and interspecific competition in dominant tree species of Betula platyphylla and Larix principis-rupprechtii in the vegetation succession process in Taiyue Mountain.The selected forest communities were treated as a time series of successional stages for the traditional space-for-time succession approach by applying the point pattern analy-sis.In the present research,ecological succession of B.platyphyllaand L.principis-rupprechtii in Taiyue Mountain were dynamic characteristics and interspecific relationship.The series reflected the process from B.platyphyllaas the monodominant community to B.platyphyllaand L.principis-rupprechtii as the codominant communities and then to L.principis-rupprechtii as the monodominant community;Point pattern analysis and Monte-Carlo simulation test were used to analyze the spatial pattern of the two dominant species and their interaction relationship.The following conclusions were drawn.（1）The population structure of Taiyue B.platyphylla was spindle type,presenting a de-clining trend.By L.principis-rupprechtii age class structure is gradually replaced＂pyramid＂the growth of the population.（2）During the process from B.platyphyllato L.principis-rupprechtii as the monodominant community reflected,the spatial pattern of B.platyphylla changed from clumped to nearly random distribution,which was mainly caused by the colonization and expansion of L.principis-rupprechtii and the resulted interspecific competition.Besides,the spatial scale of L.principis-rupprechtii community gradually increased,with the species colonization and intraspecific competition as the major cause,which was driven by the intraspecific competition caused by the self-thinning effects and the colonization and expansion of L.principis-rupprechtii and the resulted interspecific competition.（3）In terms of the interspecific competition between the two species（B.platyphyllaand L.principis-rupprechtii）,no obvious relationship was found when B.platyphyllaacted as the monodominant community,significant negative relationship was identified at the co-dominant stage,and no obvious relationship when L.principis-rupprechtii became the dominant species.The change of relationship between the two species was mainly driven by the intraspecific and interspecific competition for residual resources.