Dissertation Research: Controls Over Nitrogen Fixation in a Tropical Rain Forest

特定物种在控制生态系统过程中的作用是我们理解生物多样性如何影响生态系统功能的核心。然而，对热带生态系统中物种和功能之间的联系的理解仍然很差，就像对任何生态系统中微生物的物种-功能关系的理解一样。这笔赠款支持研究树种、树上和树下的自由生活固氮微生物群落以及哥斯达黎加低地热带雨林中自由生活的固氮率之间的联系的实验。初步数据显示，不同树种的相邻树木支持不同的自由生活固氮速率。利用一套互补的基因技术，这项研究将研究微生物群落动态及其与特定冠层树的联系在调节所观察到的固氮率差异方面的作用。热带森林与大气交换的碳、水和能量比任何其他生物群都多，因此在调节全球范围内的环境变化方面发挥着关键作用。随着人类活动继续改变这些森林的物种组成，了解热带系统中高度本土生物多样性的重要性变得越来越迫切。负责这项研究的学生有广泛的外展和培训记录，并将通过将她的研究经验融入以学生为中心的研讨会来继续她与当地高中生和中学生的工作。

The role of particular species in controlling ecosystem processes is central to our perceptions of how biodiversity may influence ecosystem function. Yet, the understanding of links between species and function in tropical ecosystems remains poor, as does the understanding of microbial species-function relationships in any ecosystem. This grant supports experiments that examine the connections between tree species, free-living nitrogen-fixing microbial communities living on and beneath trees, and rates of free-living nitrogen fixation in a lowland tropical rain forest in Costa Rica. Preliminary data show that neighboring trees of different species support distinct rates of free-living nitrogen fixation. Using a suite of complementary genetic techniques, this research will examine the role of microbial community dynamics, and their links to specific canopy trees, in regulating the observed differences in nitrogen fixation rates. Tropical forests exchange more carbon, water, and energy with the atmosphere than any other biome and thus play a critical role in regulating environmental change on a global scale. As human activities continue to alter the species composition of these forests, the need for understanding the importance of high native biodiversity in tropical systems becomes increasingly urgent. The student responsible for this research has an extensive record of outreach and training, and will continue her work with local high-school students and middle-school girls by integrating her research experiences into student-focused workshops.