Tundra ecosystem responses to 30 years of experimental and observed changes in climate

苔原生态系统对 30 年实验和观测气候变化的反应

• 批准号: RGPIN-2019-05267
• 负责人: Henry, Gregory
• 金额: $ 2.91万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688139
• 关键词: Tundra; ecosystem; responses; 30; years

Tundra ecosystems have shown strong responses to recent changes in climate. Coordinated distributed experiments such as the International Tundra Experiment (ITEX) have provided critical knowledge on how these systems respond to experimental and observed changes in climate and the response variation across the tundra biome. I established the first set of ITEX studies in 1992 in seven different tundra communities at a High Arctic site on Ellesmere Island and continue to maintain the experiments. Each site has a warming treatment of transparent open-top chambers (OTCs), and in single sites warming is combined with nutrient addition and snow manipulation. Over the next 5 years, I will bring the experiments to an end and use this unique opportunity to measure the response of tundra systems to the termination of the experiments. Graduate students and postdocs will conduct field studies and use the extensive data base from the 30+ years of research at the site to answer questions linking plant traits to community and ecosystem change, to test the ability of tundra plants to adapt to a warming climate and the determine if the long-term manipulations have fundamentally altered the tundra systems.***Plants in the warmed plots have consistently shown advanced phenology and increased growth and reproductive effort and success, especially those that flower early. In addition, the composition and abundance has shifted with increased cover of a few dominant species but also greater diversity. However, we have yet to link the responsiveness of the traits to the changes in biodiversity in the plots, and this will lead to better predictions of vegetation change. Students will explore these links using trait data from all of the species measured. These trait-based studies will provide one of the first assessments of temporal variability in plant traits.***The warmed plots have been 1-3ºC above the ambient summer temperature for 30 years, and the ambient temperature has also increased by 2ºC since 1992. Students will help determine the trajectory of the differences between experimental and control plots continue after the treatments are removed. In the second year of the study, 50 % of the OTCs will be removed and responses followed over the next three years to examine the “relaxation” of the system to ambient conditions. Responses will be measured at the plant level (e.g., phenology, reproductive effort and success, and photosynthesis); the community level, including changes in composition and abundance; and the ecosystem level, including measurements of nutrient availability and uptake, net ecosystem exchange of CO2, and spectral characteristics of the plots. In the fifth year of the proposed study, we will conduct destructive harvests in the plots to determine changes in above and below-ground biomass (NPP) and plant traits. The bitter sweet end to these experiments will provide continued critical knowledge of tundra ecosystems as they continue to change.

苔原生态系统对最近的气候变化表现出强烈的反应。协调的分布式实验，如国际苔原实验（ITEX）提供了关键的知识，这些系统如何应对实验和观察到的气候变化和整个苔原生物群落的反应变化。我在1992年建立了第一套ITEX研究，在七个不同的苔原社区在高北极地区的埃尔斯米尔岛，并继续保持实验。每个地点都有一个透明的开顶室（OTCs）的升温处理，在单个地点，升温与营养添加和雪处理相结合。在接下来的5年里，我将结束实验，并利用这个独特的机会来测量冻土系统对实验结束的反应。研究生和博士后将进行实地研究，并使用该网站30多年研究的广泛数据库来回答将植物性状与社区和生态系统变化联系起来的问题，以测试苔原植物适应气候变暖的能力，并确定长期操作是否从根本上改变了苔原系统。温暖地块中的植物一直表现出先进的物候和增加的生长和繁殖努力和成功，特别是那些开花早。此外，随着少数优势物种覆盖率的增加，物种的组成和丰度也发生了变化，但多样性也有所增加。然而，我们还没有将这些特征的反应与地块中生物多样性的变化联系起来，这将有助于更好地预测植被变化。学生们将使用所有测量物种的性状数据来探索这些联系。这些基于性状的研究将提供对植物性状时间变异性的首批评估之一。30年来，变暖的地块一直比夏季环境温度高1-3ºC，自1992年以来，环境温度也增加了2ºC。 学生将帮助确定实验和控制地块之间的差异的轨迹继续治疗后被删除。在研究的第二年，50%的OTC将被拆除，并在未来三年内跟踪响应，以检查系统对环境条件的“放松”。响应将在工厂层面进行测量（例如，物候学、繁殖努力和成功以及光合作用）;群落水平，包括组成和丰度的变化;生态系统水平，包括养分可用性和吸收的测量、CO2的净生态系统交换以及地块的光谱特征。在拟议研究的第五年，我们将在地块中进行破坏性收获，以确定地上和地下生物量（NPP）和植物性状的变化。这些实验的苦乐参半的结局将为冻土带生态系统的持续变化提供持续的关键知识。