Biogeochemical controls on the structure and functioning of arctic terrestrial ecosystems

我提出的研究的总体目标是大幅提高我们对北极冻土带生态系统功能的理解。作为一名生态系统生态学家，我研究植物如何与动物、土壤和土壤微生物以及与大气相互作用，这些方式显著影响生物地球化学循环，从而影响生态系统的功能。这一方法的背景是，了解系统的运行情况对于能够预测其对气候变化等扰动的反应是必要的。未来五年，我将有三个主要研究目标： A)确定我们实验室最近的一项研究的范围和生态意义，该研究表明，苔原植物的生长可能受到磷的有效性的限制，也受到氮的限制。这一结果挑战了冻土带植物生长主要受氮素限制的基本假设，并对理解和预测这些生态系统如何应对气候变化具有至关重要的影响，因为这两种元素具有根本不同的生物地球化学循环。 B)进一步发展一个综合的地貌和区域范围的概念框架，以便了解和预测低北极地区灌木生长和扩展增加的模式。 C)描述和比较真菌群落组成的空间格局及其与细菌的分布控制，并更好地了解它们在可能受气候变化影响的关键生物地球化学过程中的相对重要性。 拟议的研究涉及在西北地区进行密集的实验以及区域采样，并将产生重大的新见解，进一步提高我们了解北极陆地生态系统如何运作的能力，并提供大量的尖端科学培训机会。最终，我希望这项研究将导致更好的北方土地管理，以及更多的公众对北极生态价值的认识，从而为加拿大带来更有效的环境政策和实践。

The overall goal of my proposed research is to substantially advance our understanding of how arctic tundra ecosystems function. As an ecosystem ecologist, I study how plants interact with animals, with the soil and soil microbes, as well as with the atmosphere in ways that significantly influence biogeochemical cycling and therefore ecosystem functioning. The context for this approach is that understanding the functioning of the system is necessary to be able to predict its responses to perturbations such as climate change. Over the next five years, I will have 3 main research objectives: a) To determine the extent and ecological significance of our lab's recent study indicating that mesic tundra plant growth may be as limited by the availability of phosphorus, as by nitrogen. This result challenges the fundamental and widespread assumption that tundra plant growth is primarily limited by nitrogen, and has critically important implications to understanding and predicting how these ecosystems may respond to climate change because the two elements have fundamentally different biogeochemical cycles. b) To further develop an integrated landscape and regional-scale conceptual framework with which to understand and predict patterns of increased shrub growth and expansion in the low Arctic. c) To characterize and compare spatial patterns of fungal community composition and controls on their distribution with those of bacteria, and to better understand their relative importance in key biogeochemical processes that will likely be affected by climate change. The proposed studies involve intensive experiments in N.W.T. as well as regional sampling, and will lead to significant new insights that will further improve our ability to understand how arctic terrestrial ecosystems function as well as providing substantial cutting edge scientific training opportunities. Ultimately, I hope that this research will lead to better land management in the North, as well as greater public appreciation of the ecological value of the Arctic, and therefore to more effective environmental policies and practices for Canada.