A prominent tree species coexistence mechanism suggests host-specific natural enemies inhibit seedling recruitment at high conspecific density (negative conspecific density dependence). Natural-enemy-mediated conspecific density dependence affects numerous tree populations, but its strength varies substantially among species. Understanding how conspecific density dependence varies with species' traits and influences the dynamics of whole communities remains a challenge. Using a three-year manipulative community-scale experiment in a temperate forest, we show that plant-associated fungi, and to a lesser extent insect herbivores, reduce seedling recruitment and survival at high adult conspecific density. Plant-associated fungi are primarily responsible for reducing seedling recruitment near conspecific adults in ectomycorrhizal and shade-tolerant species. Insects, in contrast, primarily inhibit seedling recruitment of shade-intolerant species near conspecific adults. Our results suggest that natural enemies drive conspecific density dependence in this temperate forest and that which natural enemies are responsible depends on the mycorrhizal association and shade tolerance of tree species.

中文翻译：

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树木的性状影响在温带森林中哪些天敌会推动Janzen-Connell效应。

突出的树种共存机制表明，宿主特异性天敌以高的同种密度（负的同种密度依赖性）抑制幼苗的募集。天然敌人介导的同种密度依赖性影响许多树木种群，但其强度在物种之间有很大差异。了解具体的密度依赖性如何随物种的特性变化并影响整个社区的动态仍然是一个挑战。使用在温带森林中进行的为期三年的操纵性社区规模实验，我们表明，与植物相关的真菌和较小程度的昆虫食草动物会降低成虫高成虫密度下的幼苗募集和存活。与植物相关的真菌主要负责减少外生菌根和耐荫物种中同种成虫附近的幼苗募集。相比之下，昆虫主要抑制同种成虫附近不耐荫的物种的幼苗募集。我们的结果表明，天敌在该温带森林中驱动特定的密度依赖性，而天敌负责的则取决于树种的菌根结合和遮荫能力。