Permafrost thaw as a framework for understanding plant-microbial interactions and terrestrial feedbacks to climate

永久冻土融化作为理解植物-微生物相互作用和陆地对气候的反馈的框架

• 批准号: RGPIN-2015-03781
• 负责人: Turetsky, Merritt
• 金额: $ 2.91万
• 依托单位: University of Guelph
• 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=687939
• 关键词: Permafrost; thaw; framework; understanding; plant

Half of Canadian land sits on permafrost, a layer of frozen soil, water, and rock.  We are a permafrost nation.  Northern Canada is also one of the most rapidly warming regions on Earth, and the stable frozen ground that has fundamentally shaped ecosystems, infrastructure, and resources across the north is thawing at unprecedented rates. Thawing permafrost provides new sources of energy for microbes, which in turn release carbon dioxide and methane to the atmosphere that contribute further to the greenhouse effect.  Known as the "permafrost carbon feedback", this cycle is one of the most likely positive feedbacks from land to the atmosphere with warming. However, the fate of permafrost carbon release as greenhouse gases depends on several key factors, including 1) whether thawing soils become flooded, which could reduce the activity of microbes, 2) whether thawing permafrost creates nutrient-rich conditions, which could stimulate microbial activity, and 3) whether increases in plant growth in response to thaw can help to offset permafrost carbon release. To address these issues, the proposed research will develop a mechanistic understanding of how plants and microbes compete for nutrients under aerobic and anaerobic thaw trajectories in the Northwest Territories and Alaska, two regions where permafrost is experiencing widespread thaw. The research will measure changes in nitrogen and phosphorus availability with permafrost thaw, and the consequences of soil nutrient enrichment on plant and microbial processes. Experimental studies that examine plant and microbial processes in real time will be complemented by a gradient approach, where a space-for-time substitution will be used to examine consequences of thaw on time-scales of 100s to 1000s of years. This research will inform science-based evidence promoting effective environmental regulation, land and water management, and resource development in the face of a warming climate and dynamic permafrost conditions throughout the North.**

加拿大一半的土地位于永久冻土层上，这是一层冻土、水和岩石。加拿大北部是一个永久冻土国家，也是地球上变暖最快的地区之一，稳定的冻土从根本上塑造了生态系统。北部地区的基础设施和资源正在以前所未有的速度融化，永久冻土层的融化为微生物提供了新的能源，而微生物又将二氧化碳和甲烷释放到大气中，进一步加剧了温室效应。这种循环被称为“永久冻土碳反馈”，是随着变暖从土地到大气的最可能的正反馈之一。然而，永久冻土碳作为温室气体释放的命运取决于几个关键因素，包括1）土壤是否融化。被淹没，这可能会减少微生物的活动，2）永久冻土的融化是否会创造营养丰富的条件，从而刺激微生物活动，以及3）是否会增加植物生长以响应为了解决这些问题，拟议的研究将深入了解西北地区和阿拉斯加这两个永久冻土地区广泛存在的有氧和厌氧解冻轨迹下植物和微生物如何争夺养分。该研究将测量永久冻土融化时氮和磷有效性的变化，以及土壤养分富集对植物和微生物过程的影响。实时检查植物和微生物过程的实验研究将得到梯度方法的补充，其中将使用空间替代时间来检查解冻在数百年至数千年的时间尺度上的后果。这项研究将提供信息。面对整个北方气候变暖和动态的永久冻土条件，基于科学的证据促进有效的环境监管、土地和水管理以及资源开发。**