Dissertation Research The Role of Ectomycorrhizal Associations in Tropical Monodominance

虽然热带雨林的特点是树种的高度多样性，但Dicymbe corymbosa树形成了纯粹的林分，排除了大量其他热带雨林树木。提出的研究探索了一种可能性，即特定的根栖真菌使Dicymbe corymbosa能够排除其他树木，从而导致这种雨林树木形成纯粹的树木。在这些树与真菌的合作关系中，树木向真菌提供光合作用产生的碳，作为交换，真菌从土壤中向树木提供有限的营养。我们提出，通过这些植物-真菌伙伴关系介导的积极相互作用，以及伙伴真菌和分解凋落叶的微生物之间同时发生的消极相互作用，维持了在更大的树木多样性群落中存在的树木的单优势。为了验证这一假设，我们将在圭亚那地盾的一个自然形成的单优势森林中整合实地研究和实验研究。这项研究将大大提高我们对热带雨林中植物-真菌相互作用的有限理解，将从分子到生态系统的过程整合到一个尚未在优势热带树种中进行测试的概念框架中。这项研究还将有助于培训圭亚那大学的本科生，并将雇用来自土著帕塔莫纳部落的实地助理，这是圭亚那内陆的一个美洲印第安人群体，那里的工作机会很少。

Although tropical rain forests are characterized by a high diversity of tree species, the tree Dicymbe corymbosa forms pure stands that exclude a wide array of other rainforest trees. The proposed research explores the possibility that particular root-inhabiting fungi enable Dicymbe corymbosa to exclude other trees, which leads to the formation of pure stands by this rainforest tree. In these tree-fungal partnerships, trees give fungi carbon they produce from photosynthesis, and in exchange the fungi give the trees limiting nutrients from the soil. We propose that positive interactions mediated through these plant-fungal partnerships, with concurrent negative interactions between the partner fungi and the microorganisms that decompose leaf litter, maintain monodominance of a tree that exists within a larger community of high tree diversity. To test this hypothesis, we will integrate both field and experimental studies in a naturally occurring monodominant forest in the Guiana Shield. This research will significantly enhance our limited understanding of plant-fungal interactions in tropical rainforests, integrating processes from molecules to ecosystems in a conceptual framework that has not yet been tested for dominant, tropical tree species. This research will also contribute to the training of undergraduate students from the University of Guyana, and will employ field assistants from the indigenous Patamona tribe, an Amerindian group in the interior of Guyana, where job opportunities are scarce.