Key Laboratory for Forest Resources &Ecosystem Processes of Beijing, Beijing Forestry University, No. 35 Qinghua East Road, Haidian District, Beijing 100083, China.
Faculty of Forestry and Forest Ecology, Georg-August-University Göttingen, Büsgenweg 5, D-37077 Göttingen, Germany.
Sci Rep. 2016 Sep 8;6:32844. doi: 10.1038/srep32844.
Negative density dependence may cause reduced clustering among individuals of the same species, and evidence is accumulating that conspecific density-dependent self-thinning is an important mechanism regulating the spatial structure of plant populations. This study evaluates that specific density dependence in three very large observational studies representing three successional stages in a temperate forest in northeastern China. The methods include standard spatial point pattern analysis and a heterogeneous Poisson process as the null model to eliminate the effects of habitat heterogeneity. The results show that most of the species exhibit conspecific density-dependent self-thinning. In the early successional stage 11 of the 16 species, in the intermediate successional stage 18 of the 21 species and in the old growth stage all 21 species exhibited density dependence after removing the effects of habitat heterogeneity. The prevalence of density dependence thus varies among the three successional stages and exhibits an increase with increasing successional stage. The proportion of species showing density dependence varied depending on whether habitat heterogeneity was removed or not. Furthermore, the strength of density dependence is closely related with species abundance. Abundant species with high conspecific aggregation tend to exhibit greater density dependence than rare species.
负密度依赖性可能导致同种个体之间的聚集减少，越来越多的证据表明，同物种密度依赖自疏是调节植物种群空间结构的重要机制。本研究通过在中国东北地区的一个温带森林中代表三个演替阶段的三个非常大的观测研究，评估了特定的密度依赖性。方法包括标准的空间点格局分析和异质泊松过程作为零模型，以消除栖息地异质性的影响。结果表明，大多数物种表现出同物种密度依赖自疏。在早期演替阶段，16 个物种中有 11 个，在中期演替阶段，21 个物种中有 18 个，在老龄阶段，所有 21 个物种在去除栖息地异质性的影响后都表现出密度依赖性。因此，密度依赖性的普遍性在三个演替阶段之间有所不同，并随着演替阶段的增加而增加。表现出密度依赖性的物种比例取决于是否去除了栖息地异质性。此外，密度依赖性的强度与物种丰度密切相关。具有高同种聚集的丰富物种往往比稀有物种表现出更大的密度依赖性。
