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

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.

尽管环境严苛，南极洲境内仍分布有逾百种植物，但这些植物仅局限于南极半岛及沿海岛屿的温和区域。随着气候变化导致南极大陆逐渐暖湿化，植物正逐步定植于新近裸露的土地，且预计其优势度将进一步提升。然而，目前学界对气候变暖如何影响南极植物群落，以及变暖驱动下的南极陆地群落整体扩张将如何演进，仍知之甚少。本项目联合智利生物学家开展国际合作，通过人工升温实验操控南极植物群落的温度环境，旨在解析气候变暖对南极植物繁殖与化学特性的影响。通过厘清变暖对植物生物学特性的作用机制，本项目将回应一个核心科学问题：气候变暖将如何影响这片快速变化大陆上正在进行的植被重建过程。本项目将通过培养多名硕士研究生与本科生，助力美国国家科学基金会（National Science Foundation, NSF）达成培养新一代科研人才的目标。作为本研究工作的核心环节，项目团队将推动智利与美国高校间的研究生培养合作机制建设：一方面邀请智利学生赴美，在美方实验室学习前沿实验技术；另一方面支持美国学生赴智利开展合作研究。气候变化正在重塑全球物种分布格局，随着气温持续上升，预计将对这些动态变化的物种集合产生前所未有的大规模影响。苔藓是极地地区的优势植被，但与北极生态系统不同的是，学界对南极苔藓在群落构建中的作用认知有限，对于气候变暖如何影响南极苔藓群落的了解则更为匮乏。项目团队将采用智利合作方已在乔治王岛与利文斯顿岛搭建五年的开顶式气室（Open Top Chamber, OTC）被动升温实验装置，重点研究气候变暖对苔藓植物生产力、性别系统以及次生代谢的影响，同时解析这些变化如何作用于群落过程。研究团队将综合运用生态学、生理学与分子生物学手段，探究气候变暖对不同苔藓物种功能、群落组装的影响，最终揭示苔藓驱动的南极生态系统构建过程。本次研究将验证三项整合性科学假说：1）气候变暖将改变南极苔藓的物种组成与性别比例，并对不同苔藓的生产力及繁殖成功率产生差异化影响；2）气候变暖将影响苔藓次生代谢产物的合成，进而调控南极陆地生态系统中的生物相互作用动态与生物圈-大气气体交换过程；3）气候变暖将改变苔藓与微生物的互作关系，最终引发南极陆地苔藓食物网与群落动态发生改变。本研究产生的数据将是全球首次全面解析南极苔藓如何构建其生存环境，并由此驱动陆地生态系统响应气候变暖的系统性研究成果。