CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, 666303, Yunnan, China.
Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China.
Oecologia. 2020 Aug;193(4):949-957. doi: 10.1007/s00442-020-04729-2. Epub 2020 Aug 26.
Conspecific negative density dependence (CNDD) could be one of the most important local-scale mechanisms shaping plant species coexistence. However, the spatial and temporal changes in the strength CNDD and the implications for the plant diversity remain unknown. We used 10 years of seedling data, in a seasonal tropical rainforest, to discover how CNDD influences tree seedling survival across habitats and seasons. We also evaluated the relation between CNDD and species diversity. We found the strength of CNDD in the valley habitat was significantly stronger than in ridge habitat in rainy season, but not significantly different in dry season. Corresponding to expectations of CNDD as mechanism of diversity maintenance, seedling species diversity was significantly higher in valley habitat than in ridge habitat and significantly correlated with CNDD. Additionally, conspecific and heterospecific seedling neighbour densities positively affected the survival of tree seedlings, but heterospecific adult neighbour density had a weak effect. Our study finds that CNDD varied significantly across habitats and was correlated with local seedling diversity. Our results highlight the importance of CNDD in driving species diversity at the local scale. Recognizing the spatial and temporal variation in the strength of CNDD will aid efforts to model and understand species coexistence.
同种种群负密度制约（CNDD）可能是塑造植物物种共存的最重要的局部机制之一。然而，CNDD 的强度的时空变化及其对植物多样性的影响仍不清楚。我们使用了 10 年的幼苗数据，在季节性热带雨林中，发现 CNDD 如何影响不同生境和季节的树木幼苗的生存。我们还评估了 CNDD 与物种多样性之间的关系。我们发现，在雨季，山谷生境中 CNDD 的强度明显强于山脊生境，但在旱季则没有显著差异。与作为多样性维持机制的 CNDD 的预期相符，山谷生境中的幼苗物种多样性明显高于山脊生境，并且与 CNDD 显著相关。此外，同种和异种种群幼苗邻居密度均对树木幼苗的存活有积极影响，但异种种群成年邻居密度的影响较弱。我们的研究发现，CNDD 在不同生境中存在显著差异，并且与当地幼苗多样性相关。我们的研究结果强调了 CNDD 在驱动局部尺度物种多样性方面的重要性。认识到 CNDD 强度的时空变化将有助于模型和理解物种共存的努力。
