The next step: Capitalizing on long-term experimental manipulations to understand and predict arctic terrestrial ecosystem responses to climate warming

毫无疑问，北极最近正在经历快速变暖，这很可能对其生态系统的结构和功能产生重大影响。作为一个陆地生态系统生态学家和地球化学家，我的研究在未来15年的长期目标是大大推进我们的生物学理解加拿大北极苔原生态系统的功能，因此，他们可能会受到气候变化的影响。 在接下来的5年研究期间，我将充分研究我们最近发现的机制和影响，以显着提高我们对北极陆地生态系统功能的生物控制和相互作用的理解。 我的建议描述了多个具体的假设，这些假设集中在我以前的研究中出现的以下三个主要相互关联的目标： 1.研究了中冻土植物生长受氮、磷共同限制的地球化学和生态学意义。 2.预测不仅气候变化，而且驯鹿和其他哺乳动物食草动物的减少对苔原落叶和万年青灌木丰度的可能影响。 3.评价植物、土壤和土壤微生物化学计量差异在理解冻原生态系统对气候变化响应中的地球化学意义。 我的实验室小组将使用我于2004年在加拿大中部低北极地区的达令湖研究基地发起的实验基础设施来测试创新的研究假设。 这些完全复制（n = 5-10）的实验操作包括高和低水平的因子NxP每年增加，夏季塑料温室，雪围栏，驯鹿围栏。此外，我对达令湖景观中所有生境类型的植被变化进行了长期观察研究，在北方魁北克进行了第二次实验施肥研究，在阿拉斯加的图利克和瑞典的阿比斯科正在进行积极的研究合作，我正在领导几项泛北极调查，这些调查基于同事来自52个高纬度苔原站点的树叶和土壤样本。 进行这些调查将提供前沿的HQP培训，如生态化学计量和草食动物-植物-土壤养分相互作用等新兴概念，以及开发和使用新的/最新的技术，如离子交换膜测量植物有效养分在苔原，磷酸盐P 18 Op和15 N同位素分别用于确定P通量和N固定，和土壤酶学。 最终，我希望这项研究将导致适应性的土地管理在北方，以及更大的公众赞赏北极的生态价值，因此作为一个警钟“更有效和可持续的环境政策和做法，为加拿大作为一个整体。

The Arctic is undoubtedly experiencing rapid recent warming that is very likely to substantially affect the structure and functioning of its ecosystems. As a terrestrial ecosystem ecologist and biogeochemist, the long-term goal of my research over the next 15 years is to substantially advance our biological understanding of how Canadian arctic tundra ecosystems function, and therefore how they may be affected by climate change. This next 5 year research period is the time for me to fully investigate the mechanisms and implications of our recent discoveries, so as to significantly improve our understanding of the biological controls and interactions that govern arctic terrestrial ecosystem functioning. My proposal describes multiple specific hypotheses that are centered on the following three major interconnecting objectives which have arisen from my previous research: 1. To determine the biogeochemical and ecological significance of our discovery that mesic tundra plant growth can be co-limited by nitrogen (N) and phosphorus (P). 2. To predict the likely impacts of not just climate change, but also declining caribou and other mammalian herbivory, on tundra deciduous and evergreen shrub abundances. 3. To evaluate the biogeochemical significance of the stoichiometric differences among plants, soils, and soil microbes in understanding tundra ecosystem responses to climate change. My lab group will test innovative research hypotheses using the experimental infrastructure that I initiated at our Daring Lake research site in central low arctic Canada in 2004. These fully replicated (n = 5-10) experimental manipulations include both high and low-level factorial NxP annual additions, summer plastic greenhouses, snowfences, and caribou exclosures. In addition, I have a long-term observational study of vegetation change across the full range of habitat-types in the Daring Lake landscape, a second experimental fertilization research site in Northern Quebec, ongoing active research collaborations at Toolik, Alaska and Abisko, Sweden, and I am leading several pan-Arctic investigations based on colleagues' leaf and soil samples from 52 high latitude tundra sites. Undertaking these investigations will provide cutting-edge HQP training in emerging concepts such as ecological stoichiometry and herbivore-plant-soil nutrient interactions, and in the development and use of novel/recent techniques such as ion exchange membrane for measuring plant available nutrients in tundra, phosphate P 18Op and 15N isotope use for determining P fluxes and N fixation respectively, and soil enzymology. Ultimately, I hope that this research will lead to adaptive land management in the North, as well as greater public appreciation of the ecological value of the Arctic, and therefore serve as a wake-up call' to more effective and sustainable environmental policies and practices for Canada as a whole.