The Functional role of Moss in structuring Biotic interactions, and Terrestrialization of Antarctica

尽管条件恶劣，但南极洲有一百多种植物，尽管它们仅限于南极半岛和沿海岛屿上较温和的地区。由于气候变化，南极大陆变得更温暖、更湿润，植物在新暴露的土地上定居，并预计会变得更占优势。然而，对于变暖将如何影响南极的植物群落，或者像南极洲因变暖而出现的那样，一个大陆整体陆地群落的增加将如何进展，人们所知甚少。在与智利生物学家的国际合作中，该项目将通过人为提高植物群落温度的实验，重点了解变暖将如何影响南极植物的繁殖和化学成分。通过了解气候变暖对植物生物学的影响，该项目将解决气候变暖如何影响快速变化的大陆正在进行的植被重建这一关键问题。该项目将通过培养多名研究生和本科生，进一步实现NSF培养新一代科学家的目标。作为这项研究工作的核心部分，研究人员将在智利和美国的机构之间开展研究生培训和合作，包括将智利的学生带到他们在美国的实验室接受新技术培训，并允许美国学生前往智利进行研究合作。气候变化正在改变世界范围内的物种分布，随着温度的持续升高，预计这些变化的物种组合将受到前所未有的大规模影响。苔藓是极地地区的主要植被，但与北极系统相比，我们对南极苔藓在组织群落中的作用知之甚少，对变暖如何影响南极苔藓群落的了解更少。研究人员将使用由他们的智利合作者在乔治国王岛和利文斯顿岛安装了五年的开放式顶部室被动变暖实验，并将集中研究变暖如何影响苔藓植物的生产力、性系统和次级化学物质，以及这些变化如何影响群落过程。一套生态、生理和分子方法将用于研究变暖如何影响特定物种的苔藓功能、群落聚集，并最终影响苔藓介导的南极生态系统工程。该团队将测试三个综合研究假设：1)变暖将改变南极洲苔藓的物种组成、苔藓的性别比例，并对苔藓的生产力和繁殖成功率产生不同的影响；2)变暖将影响苔藓次生化合物的产生，影响南极陆地生物相互作用和生物圈-大气交换的动态；3)变暖将改变苔藓与微生物的相互作用，导致南极洲陆地苔藓食物网和群落动态的改变。这些数据将首次全面测量南极苔藓如何改造其环境，从而推动陆地对变暖的反应。

Despite the harsh conditions, over one hundred plant species occur in Antarctica, although they are restricted to the milder areas on the Antarctic Peninsula and coastal islands. As the Antarctic continent becomes warmer and wetter due to climate change, plants are colonizing newly exposed ground, and are predicted to become more dominant. However, little is known about how warming will affect Antarctic plant communities or how increasing overall terrestrial communities of a continent, as is occurring in Antarctica via warming, will progress. Using experiments to artificially increase temperatures in plant communities in an international collaboration with biologists from Chile, this project will focus on understanding how warming will affect reproduction and chemistry of Antarctic plants. Through understanding the impacts of warming on plant biology, the project will address the critical issue of how a warming climate will impact the on-going re-vegetation of a rapidly changing continent. The project will further the NSF goal of training new generations of scientists by training multiple graduate and undergraduate students. As a central part of this research effort, the investigators will develop graduate student training and collaboration between institutions in Chile and the U.S including bringing students from Chile to be trained in new techniques in their laboratories in the U.S as well as allowing U.S. students to travel to Chile for research collaboration. Climate change is shifting species distributions worldwide, and as temperatures continue to increase an unprecedented large-scale effect on these shifting species assemblages is predicted. Mosses are the dominant vegetation in polar regions but in contrast to Arctic systems, we know relatively little about the role of Antarctic mosses in organizing communities and less still on how warming influences Antarctic moss communities. The investigators will use Open Top Chamber passive warming experiments, which have been installed for five years by their Chilean collaborator on King George and Livingston Islands, and will concentrate on how warming impacts bryophyte productivity, sexual systems, and secondary chemistries, and on how these changes affect community processes. A suite of ecological, physiological, and molecular approaches will be used to examine how warming impacts species-specific moss function, community assembly, and ultimately, the moss-mediated engineering of the Antarctic ecosystem. The team will test three integrated research hypotheses: 1) Warming will alter moss species composition, moss sex ratio, and differentially impact moss productivity and reproductive success in Antarctica; 2) Warming will impact the production of moss secondary compounds, influencing the dynamics of biotic interactions and biosphere-atmosphere exchange in terrestrial Antarctica; and 3) Warming will alter moss-microbe interactions, resulting in alterations to the moss food web and community dynamics in terrestrial Antarctica. These data will be the first comprehensive measures of how Antarctic mosses engineer their environment and thereby drive terrestrial responses to warming.