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对生物多样性如何影响生态系统功能的看法的核心。然而，对热带生态系统中物种与功能之间联系的理解仍然很差，对任何生态系统中微生物物种与功能关系的理解也是如此。这项资助支持的实验，研究树种之间的联系，自由生活的固氮微生物群落生活在树上和树下，并在哥斯达黎加的低地热带雨林的自由生活固氮率。初步数据表明，不同物种的相邻树木支持不同的自由生活固氮率。 使用一套互补的遗传技术，本研究将研究微生物群落动态的作用，以及它们与特定冠层树木的联系，在调节所观察到的固氮率差异。热带森林与大气交换的碳、水和能量比任何其他生物群落都多，因此在调节全球范围的环境变化方面发挥着关键作用。随着人类活动不断改变这些森林的物种组成，了解热带系统中高度本地生物多样性的重要性的必要性变得越来越紧迫。负责这项研究的学生有广泛的推广和培训记录，并将继续她的工作与当地高中生和中学女生通过整合她的研究经验到学生为重点的研讨会。

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.