DISSERTATION RESEARCH: Is There Evidence Supporting The Existence of Limiting Similarity in Leaf Functional Traits in Temperate and Tropical Forest Tree Communities?

生态学的一个核心问题是生态相似的物种如何能够共存。 换句话说，为什么有些物种在某些生态群落中一起出现，而在另一些生态群落中却没有？ 生态学的经典理论认为，如果物种在功能上过于相似，它们就不能共存。 这一理论和更新的理论可以在植物群落中得到检验。一些生态学家提出，植物群落是通过生境过滤来构建的，即具有相似资源需求的植物将共享相似的生境。 在过去的几年里，一些生态学家甚至提出了中性和生态等效的激进观点--所有的物种，至少在第一个近似值上，从功能的角度来看都是等效的。这项研究将在物种丰富度不同的树木群落中测试这些假设，从温带森林的40种到热带森林的300多种。 这些测试包括测量对光合作用重要的叶片性状的相似程度，以及这些性状在树种内部和树种之间的变异性。 上述三个假设中的每一个都对共同出现的树种之间这些叶性状的相似性和重叠程度有不同的预测。由于光是森林中的主要限制资源之一，因此选择了光合作用中重要的叶片性状，如叶片化学、叶片大小和形状以及叶片密度进行研究。这项研究的更广泛影响包括保护和了解入侵物种的潜在适用性，以及教育和合作机会。

A central question in ecology is how ecologically similar species are able to coexist. In other words, why do some species occur together in some ecological communities, but not others? The classical theory in ecology is that species cannot coexist if they are functionally too similar. This and newer theories can be tested in plant communities. Some ecologists have proposed that plant communities are structured by habitat filtering -the idea that plants with similar resource requirements will share similar habitats. In the last few years, some ecologists have even proposed the radical idea of neutrality and ecological equivalence-all species, at least to a first approximation, are equivalent from a functional perspective. This research will test these hypotheses in tree communities that differ in species richness, ranging from about 40 species in a temperate forest to over 300 in a tropical forest. The tests involve measuring the degree of similarity in leaf traits important to photosynthesis, and the variability of these traits within and among the tree species. Each of the three hypotheses listed above has different predictions for the degree of similarity and overlap to expect in these leaf traits among co-occurring tree species. Because light is one of the primary limiting resources in forests, leaf traits important in photosynthesis, such as leaf chemistry, leaf size and shape, and leaf density, have been chosen for study. Broader impacts of this research include potential applicability to conservation and understanding invasive species, as well as educational and collaborative opportunities.