Cannon Patrick G, O'Brien Michael J, Yusah Kalsum M, Edwards David P, Freckleton Robert P
Department of Animal and Plant Sciences The University of Sheffield Sheffield UK.
Área de Biodiversidad y Conservación Universidad Rey Juan Carlos Móstoles Spain.
Ecol Evol. 2020 Oct 25;10(23):13154-13164. doi: 10.1002/ece3.6906. eCollection 2020 Dec.
Fungal pathogens are implicated in driving tropical plant diversity by facilitating strong, negative density-dependent mortality of conspecific seedlings (C-NDD). Assessment of the role of fungal pathogens in mediating coexistence derives from relatively few tree species and predominantly the Neotropics, limiting our understanding of their role in maintaining hyper-diversity in many tropical forests. A key question is whether fungal pathogen-mediated C-NDD seedling mortality is ubiquitous across diverse plant communities. Using a manipulative shadehouse experiment, we tested the role of fungal pathogens in mediating C-NDD seedling mortality of eight mast fruiting Bornean trees, typical of the species-rich forests of South East Asia. We demonstrate species-specific responses of seedlings to fungicide and density treatments, generating weak negative density-dependent mortality. Overall seedling mortality was low and likely insufficient to promote overall community diversity. Although conducted in the same way as previous studies, we find little evidence that fungal pathogens play a substantial role in determining patterns of seedling mortality in a SE Asian mast fruiting forest, questioning our understanding of how Janzen-Connell mechanisms structure the plant communities of this globally important forest type.
真菌病原体通过促进同种幼苗的强烈负密度依赖死亡率（C-NDD），被认为在推动热带植物多样性方面发挥作用。对真菌病原体在介导共存中作用的评估来自相对较少的树种，且主要是新热带地区的树种，这限制了我们对它们在许多热带森林中维持高度多样性作用的理解。一个关键问题是，真菌病原体介导的C-NDD幼苗死亡率在不同植物群落中是否普遍存在。通过一项可控的温室实验，我们测试了真菌病原体在介导8种婆罗洲具大种子结果习性树木的C-NDD幼苗死亡率中的作用，这些树种是东南亚物种丰富森林的典型代表。我们证明了幼苗对杀菌剂和密度处理的物种特异性反应，产生了微弱的负密度依赖死亡率。总体幼苗死亡率较低，可能不足以促进整个群落的多样性。尽管我们的实验方式与之前的研究相同，但我们几乎没有发现证据表明真菌病原体在决定东南亚具大种子结果习性森林中幼苗死亡率模式方面发挥重要作用，这对我们关于詹曾-康奈尔机制如何构建这种全球重要森林类型的植物群落的理解提出了质疑。
