A well-known example is conspecific negative density dependence (CNDD) — the concept that the local abundance of a species negatively affects the establishment and performance of neighbouring seedlings of the same species. A study published in Nature (L. Hülsmann et al. Nature 627, 564–571; 2024), and discussed in Nature Plants (J. A. LaManna. Nat. Plants 10, 701–702; 2024), demonstrates the importance of CNDD in stabilizing population abundances in rare tropical tree species. But whether the influence of CNDD persists once a tree has died had not yet been considered. Mapping species abundance, mortality events and recruitment of more than 37,000 trees over a 10-year period, Daniel Johnson and colleagues at the University of Florida sought to answer this question in an article published in Ecology Letters.

Once a tree dies, the canopy opens, which leaves a gap for other individuals to exploit light and nutrient resources. For conspecific individuals this may be particularly advantageous, by releasing them from the CNDD constraints imposed by living trees of the same species. However, the analysis from Johnson et al. revealed the opposite to be true: when a neighbouring conspecific tree dies, that individual continues to exert a negative effect on the survival of the remaining living trees.

一个著名的例子是同种负密度依赖性（CNDD）——一个物种的局部丰度会对同一物种的邻近幼苗的建立和表现产生负面影响的概念。发表在Nature上的一项研究（L. Hülsmann et al. Nature 627 , 564–571; 2024）并在Nature Plants上进行了讨论（JA LaManna. Nat. Plants 10 , 701–702; 2024），证明了 CNDD 在稳定植物生长方面的重要性。稀有热带树种的种群丰富度。但尚未考虑到一旦树木死亡，CNDD 的影响是否仍然存在。佛罗里达大学的 Daniel Johnson 及其同事在 10 年间绘制了物种丰富度、死亡事件和 37,000 多棵树的补充情况，试图在《生态快报》上发表的一篇文章中回答这个问题。

一旦一棵树死亡，树冠就会打开，这为其他个体利用光和营养资源留下了空隙。对于同种个体来说，这可能特别有利，因为可以将他们从同一物种的活树施加的 CNDD 限制中释放出来。然而，约翰逊等人的分析。事实恰恰相反：当邻近的同种树死亡时，该个体会继续对剩余活树的生存产生负面影响。