作 者 ：张忠华,胡刚,倪健*
期 刊 ：生态学报 2010年 30卷 9期 页码：2235~2245
关键词：喀斯特森林；种间分离；Pielou分离指数；生态种组；物种共存；茂兰；
Keywords:Karst forest, interspecific segregation, Pielou’s coefficient of segregation, ecological species groups, species coexistence, Maolan,
摘 要 ：种间分离的研究对于揭示种间相互作用、群落组成与动态具有重要意义。为分析喀斯特原生性森林群落种间的分离特征，进而探讨喀斯特生境上物种的共存机制，以茂兰国家级自然保护区分布的亚热带区域原生性较强的典型常绿阔叶落叶混交林为研究对象，以建立的2块1hm2（100m×100m）样地群落学调查数据为基础，借助ArcGIS软件的空间分析功能，判定每个个体的最近邻体植株的种类与距离。在此基础上，采用N×N 最近邻体列联表及其截表的方法，应用Pielou的分离指数量化了2块样地中各43个树种（多度≥20）的种间分离状况。研究结果表明：两种喀斯特森林群落类型中物种均以随机毗邻种对占优势（P1和P2样地分别为60.91% 和 63.34%），正分离种对次之（分别为38.76%和35.66%），负分离种对极少（分别为033%和1.0%），这种种间分离特征表明种间竞争排除作用减弱，群落已趋于稳定，反映出该森林正处于相对稳定的顶极状态。根据种间分离情况以及物种对环境的适应方式，将两个样地各43个物种分别划分为3个生态种组，各组间物种的生态学特性以及对生境的偏好存在明显差异。种间的分离特征与喀斯特森林高度的生境异质性明显相关，分布在不同生境类型上的物种间大多呈现正分离，而具有相似生境要求或分布广泛的物种间易形成随机毗邻或负分离，这一特征为群落中多物种的稳定共存提供了更大的可能性。因此，以生境的高度分化为基础的种间关系可能是喀斯特森林多物种稳定共存的重要机制之一。
Abstract:The segregation relationship between different species pairs is helpful for revealing the phenomena of species interactions, community structure and dynamics. It can be used to explore the impacts of environmental differences on species distribution. Practically, such study is the scientific fundamental of species conservation and restoration and reconstruction of degraded ecosystems. The Karst forest in Maolan National Natural Reserve of Guizhou Province, southwestern China is a rare, original forest remnant in the mid-subtropics of the world. However, little is known about the interspecific relationship of the species. In order to investigate the interspecific segregation characteristics of the species in karst forest, so as to discuss the mechanism of species coexistence on Karst habitat,We set up two plots of 1hm2 (named P1 and P2, respectively) in two old-growth, evergreen-deciduous broadleaved mixed Karst forests in Maolan National Nature Reserve, Guizhou Province of SW China. All woody species with the diameter at breast height (DBH) ≥1cm were identified and surveyed. The distribution map of 43 tree species with abundance ≥20 individuals from two Karst forest communities were drawn using the Geographical Information System software (ArcGIS). The nearest neighbors of each individual and the distances between every individual-neighbor pair were obtained by using ArcGIS’s extension module. The interspecific segregation in the multi-species community was then analyzed using a sub-table method of a N×N nearest-neighbor contingency table. The Pielou′s coefficient of segregation (S) was adopted to measure the segregated degree between two species. The results show that segregation relations between most of the species are random in two karst forest communities (60.91% and 63.34%, respectively). Some species pairs are positively segregated (38.76% and 3566%, respectively) and a few pairs are negatively segregated (0.33% and 1.0%, respectively). Our results support the Pielou′s opinion that negative segregation is rare in old-growth plant communities. This showed that interspecific competitive exclusion is weakened between the species, and the two forests were at a stable climax stage. According to their adaptability to the environment and relationships between plants and environment, the 43 species from two forest plots were divided into three ecological species groups (ESG). In Plot one, the first ESG includes 17 big tree species such as Cyclobalanopsis glauca, Clausena dunniana, and Engelhardtia roxburghiana, which are light-demanding and drought-tolerant in the first canopy tree layer. The second ESG is 18 tree species in the sub-canopy tree layer including Acer wangchii, Viburnum brachybotryum, and Swida parviflora etc that have less drought-tolerance and some extent shade-tolerance. The ESG 3 has 8 woody species with broad distribution range in mostly the shrub layer. In Plot two the ESG 1 has 13 dominate tree species including Castanopsis carlesii var. spinulosa, Rapanea neriifolia, and Osmanthus fragrans etc in habitat of relatively high soil moisture. 19 tree species such as Distylium myricoides, Lindera communis, and Clausena dunniana occur in the ESG 2. These species grow in relatively dry habitat. The ESG 3 has 12 tree species of sub-canopy layer, occupying broader ecological niche in Plot two. The ecological characteristics and habitat preference of the species in each group showed significant differences. The results also indicated that interspecific segregation is closely related to habitat heterogeneity of karst terrain. Species pairs in different habitats mostly tend to be more positively segregated, but species with similar habitat preference or widely distributed are more likely to be random neighbor or negatively segregated. Therefore, interspecific relationship based on differentiation of habitat may be one of the important mechanisms of species coexistence in species-rich karst forest.
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