COLLABORATIVE RESEARCH: Dynamics of plant-soil feedbacks in changing environments

人类活动增加了世界各地的氮(N)有效性。氮的增加通常会导致陆地生态系统中植物生产力的提高。大量的工作也表明，人为的氮素增加会导致植物物种丰富度的降低。植物多样性的减少通常归因于植物资源的竞争，但其他机制也可能导致受精区植物物种的损失。这项研究的目标是将“看不见的大多数”--地下微生物相互作用--纳入理解N的增加如何改变地上植物群落结构。与简单的植物资源竞争相比，植物与微生物(如土壤寄生虫、共生体、分解者)的相互作用可能是植物多样性因氮肥增加而下降的更重要的决定因素。利用长期施肥小区的微生物调查、组织培养实验和湿润草甸苔原和其他草地系统的田间操作，以前关于N增加导致多样性损失的假设将扩展到包括地下微生物相互作用。此外，这项研究还将通过网上虚拟实地考察、分发给高中教室的实际微生物活动套装以及对妇女、特别是西班牙裔妇女和科学家的培训，促进教学、培训和对与生物多样性和环境变化有关的问题的理解。最终，地下微生物相互作用的纳入将提高对环境变化因素(如氮沉积)如何影响陆地生物多样性的预测能力。

Human activities have increased nitrogen (N) availability throughout the world. Nitrogen enrichment commonly results in increased plant productivity in terrestrial ecosystems. A large amount of work also indicates that anthropogenic nitrogen enrichment can lead to reduced plant species richness. Reductions in plant diversity have most commonly been attributed to plant resource competition, but other mechanisms may contribute to the observed loss of plant species in fertilized plots. The goal of this research is to include the 'unseen majority' - belowground microbial interactions - in understanding how N enrichment alters plant community structure aboveground. Plant interactions with microbes (e.g., soil parasites, symbionts, decomposers) could be an even more important determinant of plant diversity decline in response to N enrichment than simple plant resource competition. Utilizing microbial surveys of long-term fertilization plots, tissue culture experiments, and field manipulations in the moist meadow tundra and other grassland systems, previous hypotheses of diversity loss with N enrichment will be extended to include belowground microbial interactions. In addition, this research will promote the teaching, training and understanding of issues related to biodiversity and environmental change through virtual field trips accessible on the web, hands-on microbial activity sets distributed to high school classrooms, and the training of women, particular Hispanic women, scientists. Ultimately, the inclusion of belowground microbial interactions will improve predictive abilities regarding how environmental change factors such as N deposition may affect terrestrial biodiversity.