RAPID: Collaborative Research: Do negative plant-soil feedbacks outweigh positive ectomycorrhizal mutualisms in dipterocarp rainforest?

高树种多样性是南美洲、非洲和东南亚热带雨林的一个特征。然而，对于生态学家来说，仍然很难解释为什么如此多的物种在使用相同的少量资源（光、水、营养）的情况下，差异如此之大，却能共存。理论上，只有少数占主导地位的竞争者会持续存在。解释这一难题的一个假设是，土壤真菌导致幼苗在树木生长时死亡，从而阻止任何一种物种变得比其他物种更常见。目前对这一课题的研究是有希望的，但主要有两个缺点。首先，尽管世界各地的土壤真菌存在根本差异，但它在很大程度上仅限于中美洲和南美洲的热带雨林。其次，它没有考虑到一些土壤真菌对幼苗有利，而不是有害。在这个项目中，研究人员将利用马来西亚婆罗洲罕见的大规模播种事件来建立实验，以测试在这个生态未被开发的世界部分积极的植物-真菌相互作用的假设。这项工作具有巨大的潜力，可以为形成热带雨林惊人多样性的生态过程提供新的见解。除了提高我们对维持热带生物多样性的生态认识外，通过这项研究获得的见解将有助于保护东南亚极度濒危的雨林生态系统。尽管这些热带雨林拥有全球生物多样性的主要部分，并在全球生物圈的功能中发挥着关键作用，但该地区的森林砍伐速度却令人担忧。通过研究影响幼苗招募的因素，本研究将为成功造林和恢复退化森林提供重要的知识。此外，这项研究还将揭示这些热带雨林中鲜为人知且可能面临风险的生物多样性微生物层面。最后，这项工作将为美国大学的研究生提供宝贵的培训，使他们能够在一个非常复杂的生态系统中工作，并提高美国参与这些生态系统的能力。

High tree species diversity is a characteristic feature of rainforests in South America, Africa and Southeast Asia. However, it continues to be difficult for ecologists to explain how such a large number of species can be different enough to coexist when they all use the same small set of resources (light, water, nutrients). Theoretically, only a few dominant competitors should persist. One hypothesis explaining this conundrum is that soil fungi cause seedlings to die as tree populations grow, thus preventing any one species from becoming much more common than any other species. Current research on this topic is promising but has two primary shortcomings. First, it has largely been limited to Central and South American rainforests, despite fundamental differences in soil fungi around the world. Second, it has not considered that some soil fungi benefit, not harm, seedlings. In this project, investigators will take advantage of a rare mass seeding event in Malaysian Borneo to establish experiments that will test hypotheses about positive plant-fungal interactions in this ecologically under-explored part of the world. The work has great potential to lead to new insights into the ecological processes that shape the astounding diversity of tropical rain forests. In addition to improving our ecological understanding of the maintenance of tropical biodiversity, the insights gained through this research will help conserve the critically endangered rainforest ecosystems of Southeast Asia. Although these rainforests harbor a major share of global biodiversity and play a critical role in the function of the global biosphere, the region is experiencing alarming rates of deforestation. By studying the factors that impact seedling recruitment, this research will provide important knowledge required for successful reforestation and restoration of degraded forests. In addition, the study will shed light on the little known and potentially at risk microbial dimensions of biodiversity in these rainforests. Finally, this work will provide invaluable training for graduate students at US universities to work in a very complex ecosystem and increase US capacity to engage in these ecosystems.