LTER: MCM6 - The Roles of Legacy and Ecological Connectivity in a Polar Desert Ecosystem

McMurdo Dry Valleys LTER旨在了解生态连通性的时间变化如何与现有景观遗产相互作用，从而改变这一极端极地沙漠生态系统的结构和功能。这项研究具有广泛的意义，因为它将帮助我们了解自然生态系统如何应对持续的人为全球变化。与此同时，该项目还具有重要的教育和推广功能，为来自不同背景的学生和艺术家提供身临其境的研究和教育体验，并有助于确保极地生态系统科学和管理领域多样化和训练有素的下一代领导者。最终，这个项目的结果将帮助我们更好地了解和准备气候变化的影响，并发展远远超出南极生态系统的科学见解。麦克默多干谷（mdv）在南极洲最大的无冰地区构成了一个极端的极地沙漠生态系统。这个生态系统中的生物通常都很小。细菌、微型无脊椎动物、蓝藻垫和浮游植物可以在溪流、土壤、冰川和冰雪覆盖的湖泊中找到。这些生物已经适应了寒冷和干旱的环境，除了在南方的夏季，当生态系统被液态水连接时，寒冷和干旱的环境一直存在于湖泊之外。在夏季，当气温上升到冰点以上时，土壤变暖，冰川融水通过溪流流入湖泊的开放护城河。大部分生物活动都发生在夏季。整个冬季，或极夜（6个月的黑暗），冰川、溪流和土壤生物群在充足的光、热和液态水返回之前都是不活跃的，而湖泊群落全年都保持活跃。在过去的30年里，MDVs受到了降温、热浪、洪水、湖泊水位上升以及永久冻土和湖泊冰融化的干扰。考虑到对这种物理驱动因素变化的明确生态响应，以及预测进一步变暖和更多降水的气候模型，MDV生态系统处于当前极端寒冷和干燥条件与不确定未来之间的阈值。该项目旨在确定过去事件和条件的遗产与当前物理和生物相互作用形成当前生态系统的重要性。将测试四个假设，涉及1)特定生物的状态是否指示生态系统稳定性，2)过去事件的遗产与当前生态系统弹性（对大变化的抵抗力）之间的关系，3)在生态系统高度连通性和活动之间的物质携带有助于维持生态系统稳定性，以及4)干扰的变化影响生态系统如何在年度极夜（即延长的黑暗和寒冷时期）中持续存在。在McMurdo LTER项目（MCM6）的这一次迭代中，项目团队将在一个受强物理驱动因素（地质遗迹、极端季节性和当代气候变化）和微生物驱动的系统中测试生态连通性和稳定性理论。由于微生物调节着世界上大多数关键的生物地球化学功能，这些见解将远远超出极地生态系统，并将为理解和期望自然和管理生态系统如何应对持续的人为全球变化提供信息。MCM6建立在以前在南极洲和LTER网络内进行的基础研究的基础上，以考虑连通性的时间方面及其与生态系统稳定性的关系。该项目将研究生态连通性的时间变化如何与现有景观的遗产相互作用，这些遗产已经定义了数千年来的栖息地和生物地球化学循环。项目团队假设MDV生态系统的结构和功能取决于遗产和当代生态连通性的频率、持续时间和规模。这一假设将通过新的和持续的监测、实验和长期数据集分析来检验：1)哨兵分类群所反映的这些生态系统的稳定性；2)生态遗产与生态系统恢复力之间的关系；3)低连通性时期物质携带对维持生物活动和群落稳定的重要性；4)扰动动力学的变化如何在极夜破坏生态循环。将利用已收集的新的长期数据集在实地和建模活动中对这些假设进行检验。实地活动产生的新数据集将通过广为人知的在线数据库（MCM、LTER和EDI）免费提供。项目团队还制定了六个南极核心理念，涵盖了从数据素养到极地食物网的主题，并在整个教育和推广活动中形成了一致的线索。在过去成功的基础上，将与科学团队内的教师和艺术家建立合作关系，他们将努力开发具有直接经验和艺术表达的科学内容的教育模块。本科生指导工作将通过MCM REU学生的新数据密集型科学培训计划纳入计算方法。该项目还将为科罗拉多大学博尔德分校的社区大学生建立南极研究体验，为来自不同背景的社区大学学生提供身临其境的教育和研究体验。MCM LTER将继续其培训和指导学生，博士后和早期职业科学家的使命，作为极地生态系统科学和管理的下一代领导者。历史上代表性不足的参与将在项目的各个层面得到扩大。为了协助这些工作，该项目成立了教育与推广委员会和多样性、公平和包容委员会，通过MCM6的各个方面来领导、协调、支持和整合这些活动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical AbstractThe McMurdo Dry Valleys LTER seeks to understand how changes in the temporal variability of ecological connectivity interact with existing landscape legacies to alter the structure and functioning of this extreme polar desert ecosystem. This research has broad implications, as it will help us to understand how natural ecosystems respond to ongoing anthropogenic global change. At the same time, this project also serves an important educational and outreach function, providing immersive research and educational experiences to students and artists from diverse backgrounds, and helping to ensure a diverse and well-trained next generation of leaders in polar ecosystem science and stewardship. Ultimately, the results of this project will help us to better understand and prepare for the effects of climate change and develop scientific insights that are relevant far beyond Antarctic ecosystems. The McMurdo Dry Valleys (MDVs) make up an extreme polar desert ecosystem in the largest ice-free region of Antarctica. The organisms in this ecosystem are generally small. Bacteria, microinvertebrates, cyanobacterial mats, and phytoplankton can be found across the streams, soils, glaciers, and ice-covered lakes. These organisms have adapted to the cold and arid conditions that prevail outside of lakes for all but a brief period in the austral summer when the ecosystem is connected by liquid water. In the summer when air temperatures rise barely above freezing, soils warm and glacial meltwater flows through streams into the open moats of lakes. Most biological activity across the landscape occurs in summer. Through the winter, or polar night (6 months of darkness), glaciers, streams, and soil biota are inactive until sufficient light, heat, and liquid water return, while lake communities remain active all year. Over the past 30 years, the MDVs have been disturbed by cooling, heatwaves, floods, rising lake levels, as well as permafrost and lake ice thaw. Considering the clear ecological responses to this variation in physical drivers, and climate models predicting further warming and more precipitation, the MDV ecosystem sits at a threshold between the current extreme cold and dry conditions and an uncertain future. This project seeks to determine how important the legacy of past events and conditions versus current physical and biological interactions shape the current ecosystem. Four hypotheses will be tested, related to 1) whether the status of specific organisms are indicative ecosystem stability, 2) the relationship between legacies of past events to current ecosystem resilience (resistance to big changes), 3) carryover of materials between times of high ecosystem connectivity and activity help to maintain ecosystem stability, and 4) changes in disturbances affect how this ecosystem persists through the annual polar night (i.e., extended period of dark and cold). Technical AbstractIn this iteration of the McMurdo LTER project (MCM6), the project team will test ecological connectivity and stability theory in a system subject to strong physical drivers (geological legacies, extreme seasonality, and contemporary climate change) and driven by microbial organisms. Since microorganisms regulate most of the world’s critical biogeochemical functions, these insights will be relevant far beyond polar ecosystems and will inform understanding and expectations of how natural and managed ecosystems respond to ongoing anthropogenic global change. MCM6 builds on previous foundational research, both in Antarctica and within the LTER network, to consider the temporal aspects of connectivity and how it relates to ecosystem stability. The project will examine how changes in the temporal variability of ecological connectivity interact with the legacies of the existing landscape that have defined habitats and biogeochemical cycling for millennia. The project team hypothesizes that the structure and functioning of the MDV ecosystem is dependent upon legacies and the contemporary frequency, duration, and magnitude of ecological connectivity. This hypothesis will be tested with new and continuing monitoring, experiments, and analyses of long-term datasets to examine: 1) the stability of these ecosystems as reflected by sentinel taxa, 2) the relationship between ecological legacies and ecosystem resilience, 3) the importance of material carryover during periods of low connectivity to maintaining biological activity and community stability, and 4) how changes in disturbance dynamics disrupt ecological cycles through the polar night. Tests of these hypotheses will occur in field and modeling activities using new and long-term datasets already collected. New datasets resulting from field activities will be made freely available via widely-known online databases (MCM LTER and EDI). The project team has also developed six Antarctic Core Ideas that encompass themes from data literacy to polar food webs and form a consistent thread across the education and outreach activities. Building on past success, collaborations will be established with teachers and artists embedded within the science teams, who will work to develop educational modules with science content informed by direct experience and artistic expression. Undergraduate mentoring efforts will incorporate computational methods through a new data-intensive scientific training program for MCM REU students. The project will also establish an Antarctic Research Experience for Community College Students at CU Boulder, to provide an immersive educational and research experience for students from diverse backgrounds in community colleges. MCM LTER will continue its mission of training and mentoring students, postdocs, and early career scientists as the next generation of leaders in polar ecosystem science and stewardship. Historically underrepresented participation will be expanded at each level of the project. To aid in these efforts, the project has established Education & Outreach and Diversity, Equity, and Inclusion committees to lead, coordinate, support, and integrate these activities through all aspects of MCM6.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.