Dissertation Research: An Experimental Assessment of Soil Resource Availability and Herbivory in Determining Habitat Specificity in Understory Palms

了解生物多样性是如何维持的是生态学的一个核心问题。一个长期存在的理论是，如果物种对有限资源的需求不同，它们可以共存。对于植物物种来说，土壤资源如水、氮和磷的可用性可能是决定哪些物种在给定地区持续存在的关键。这项研究将研究一组不同的棕榈物种如何在巴拿马的热带山林中共存。将进行一系列的幼苗移植实验，以验证植物在土壤肥力梯度上的表现差异是由于物种间资源分配模式的差异造成的。具体来说，我们预测在最缺乏营养的地方发现的物种会将相对更多的资源分配给根系生物量和抗食草动物防御。这些分配模式应反映从土壤中提取养分的成本增加，以及当养分供应不足时食草动物损害的成本增加。这项研究将成为解释热带树种如何共存的重要假设的首批实验测试之一。此外，拟议的研究将增加关于草食动物压力和地下资源在确定森林下层棕榈树分布方面的相对重要性的新信息，森林下层棕榈树是一组被大量开发用于园艺用途的物种。

Understanding how biodiversity is maintained is a central issue in ecology. One long-standing theory is that species can coexist if they differ in their requirements for limiting resources. For plant species, the availability of soil resources such as water, nitrogen, and phosphorus may be critical in determining which species persist in a given area. This research will examine how a diverse group of palm species can coexist in tropical mountain forest in Panama. A series of seedling transplant experiments will be performed to test the hypothesis that differences in plant performance across a gradient of soil fertility results from differences in resource allocation patterns among species. Specifically, it is predicted that species found on the most nutrient-poor sites will allocate relatively more of their resources to root biomass and to anti-herbivore defenses. These allocation patterns should reflect the increased cost of extracting nutrients from the soil, and increased cost of herbivore damage when nutrients are in short supply. This study will be among the first experimental tests of a prominent hypothesis to explain how tropical tree species coexist. Furthermore, the proposed research will add new information on the relative importance of herbivore pressure and belowground resources in determining the distribution of forest understory palms, a group of species that have been heavily exploited for horticultural use.