BE/CBC: Biocomplexity Associated with the Response of Tundra Carbon Balance to Warming and Drying Across Multiple Spatial and Temporal Scales

本研究探讨了北极冻土带生态系统中生物和物理过程如何相互作用来控制碳的吸收、储存和释放，以及这些相互作用的自组织性质如何在多个时空尺度上发生变化。世界上大约25%的土壤有机碳库储存在北纬高纬度地区的永久冻土和北极的季节性解冻土壤中，该地区目前正在经历前所未有的变暖和干燥，以及人类土地利用的巨大变化。了解年度和年际生态系统生产力的变化如何相互作用，并可能抵消北极土壤碳库的平衡和稳定性，对全球气候变化科学至关重要。如果土壤碳以温室气体（即CO2和CH4）的形式净损失到大气中，则温室变暖可能会加剧。这种非线性的、潜在的正反馈反应可能很快导致北极陆地生态系统以一种我们从全新世晚期开始就不知道的方式运作，并对全球产生重大影响。这项研究活动得益于过去三十年来在阿拉斯加北部和其他北极地区开展的国际和国家碳循环研究的基础和财富。该小组将启动一项综合研究，包括一个综合框架，包括多尺度飞机和卫星遥感、微气象、二氧化碳和甲烷通量测量以及350公里的南北样带的水文生态过程模型模拟，该样带横跨北极主要地形和阿拉斯加北部的陆地覆盖单元。研究区域包括许多长期测量站点，这些站点已经存在了5到10年。他们将扩大这些观察，包括广泛的土壤湿度操纵，包括在北极海岸平原阿拉斯加巴罗附近60公顷的冻土带洪水/排水实验。本研究的目的是在多个空间（微生物到景观）和时间（几分钟到几十年）尺度上量化土壤水分与碳吸收、储存和释放之间的联系。只有增加实验操作的空间范围和观测时间序列的持续时间，我们才能更好地理解和预测尺度对北极生态系统内部复杂耦合的影响；也就是说，小尺度过程如何作为高尺度现象的组成部分参与，以及高尺度现象如何约束前低尺度过程。这些知识将提高我们对北极苔原对全球变化的当前行为和潜在反应的理解，从而更好地预测对气候和全球碳循环的反馈。

This research examines how biological and physical processes interact to control carbon uptake, storage and release in Arctic tundra ecosystems and how the self-organizing nature of these interactions varies across multiple spatial and temporal scales. Approximately 25% of the world's soil organic carbon reservoir is stored at high northern latitudes in permafrost and seasonally-thawed soils in the Arctic, a region that is currently undergoing unprecedented warming and drying, as well as dramatic changes in human land use. Understanding how changes in annual and inter-annual ecosystem productivity interact and potentially offset the balance and stability of the Arctic soil carbon reservoir is of utmost importance to global climate change science. If there is a net loss of soil carbon to the atmosphere in the form of greenhouse gases (namely CO2 and CH4), greenhouse warming could be enhanced. This non-linear, potentially positive feedback response could very quickly cause Arctic terrestrial ecosystems to function in a manner not known to us from the late Holocene and with globally significant implications.The activities in this research benefit from a foundation and wealth of international and national carbon cycle research undertaken in northern Alaska and other Arctic regions over the past three decades. The group will initiate a comprehensive study involving an integrated framework of multi-scale aircraft and satellite remote sensing, micrometeorological and CO2 and CH4 flux measurements and hydro-ecological process model simulations over a 350km North-South transect spanning the dominant Arctic topographic and land cover units of northern Alaska. The study region encompasses many long-term measurement sites that have been in place for 5 to 10 years. They will expand these observations to include an extensive soil moisture manipulation involving a 60 hectare tundra flooding/draining experiment near Barrow Alaska on the Arctic Coastal Plain. The objective of this study is to quantify linkages between soil moisture and carbon uptake, storage and release over multiple spatial (microbial to landscape) and temporal (minutes to decades) scales. Only by increasing the spatial extent of our experimental manipulations and the duration of our observational time series can we better understand and predict the effect of scale on the complex coupling within Arctic ecosystems; namely, how small scale processes participate as components of higher scale phenomenon and how higher scale phenomenon constrain the former lower scale processes. This knowledge will improve our understanding of the current behavior and potential response of arctic tundra to global change, resulting in better predictions of feedbacks to climate and the global carbon cycle.