Collaborative Research: The roles of plant roots, mycorrhizal fungi and uptake of deep nitrogen in the permafrost carbon feedback to warming climate

合作研究：植物根、菌根真菌和深层氮吸收在永久冻土碳反馈中对气候变暖的作用

• 批准号: 1504091
• 负责人: Helene Genet
• 金额: $ 34.44万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1504091&HistoricalAwards=false
• 关键词: Collaborative; Research; roles; plant; roots

NontechnicalRelease of carbon frozen in permafrost (frozen ground) has been identified as one of the strongest and most likely positive feedbacks between the biosphere and the warming climate. Permafrost nitrogen release has the potential to stabilize the response of the carbon cycle to climate warming because it is a negative, within-system feedback. It could confer resilience to ecosystem-atmosphere interactions in a warming Arctic. The research under this award will advance understanding of the arctic system by incorporating this feedback into a terrestrial biosphere model used extensively by the community for forecasting arctic environmental change and its links to the Earth system.The collaborative nature of the project will build partnerships between ecosystem ecologists and molecular biologists, creating new knowledge about the role of plant-fungal mutualisms in Earth system feedback cycles. The project will support career development of two female arctic scientists at the postdoctoral or new faculty level. It will contribute to the training of two graduate students in biogeosciences, ecology, and molecular biology, and provide an authentic field or laboratory research experience for about twenty undergraduate students. The project will contribute to broadening participation of under-represented groups in ecological and environmental sciences.TechnicalAbout 1,700 Pg of organic carbon (C) reside in the permafrost soils and sediments of Arctic and Boreal regions. Because this stock is more than twice the size of the atmospheric C pool, there is considerable interest in understanding how the C balance of permafrost ecosystems will respond to observed and predicted climate warming. As permafrost soils thaw, organic matter that has been cryogenically protected for hundreds to thousands of years is exposed to microbial decomposition and released to the atmosphere as greenhouse gases. One key factor that may strongly influence C balance in these ecosystems is the concurrent release of nitrogen (N), the element most likely to limit plant productivity. Release of N at or after thaw could increase plant N availability, stimulate plant C uptake and offset or balance permafrost C emissions. Although scientists acknowledge the key role N is likely to play in the permafrost C feedback to climate, there have been few empirical studies of the factors that control its fate in warming permafrost ecosystems. The objective of this project is to develop a mechanistic understanding of the role of permafrost N in the C balance of Alaskan tundra landscapes underlain by permafrost soils.The project will focus on plant acquisition of permafrost N because in most N-limited terrestrial ecosystems, plant uptake is the dominant fate of N released by microbial processes. Plants depend on fungal partners to access N beyond the reach of roots, so this research will also focus on plant mycorrhizal status and fungal community composition to elucidate the role fungal symbionts play in plant N acquisition. Finally, other fates of permafrost N will be explored, including stasis and loss. Proposed research will explore three general questions: What is the potential for release of plant-available nitrogen from thawing permafrost soil organic matter; what proportion of N released deep in the soil profile, at the base of the active layer, is acquired by mycorrhizae and plants and what are the key biotic and abiotic factors that control acquisition; and how will permafrost thaw and N release affect net ecosystem carbon balance and net biogeochemical radiative forcing from permafrost thaw at local and regional scales?The research approach includes three elements: observations of plants, fungi and soils across a regional survey of upland tundra ecological landscape units on the North Slope of the Brooks Range, Alaska; occupying intensive research sites in cold and warm moist acidic tundra, where measurements of mycorrhizal fungi and plant N acquisition and N loss will be made within long-term warming experiments and well-characterized natural thaw gradients; and modeling and regional integration with a terrestrial biosphere model specifically developed to simulate C and N dynamics in high latitude systems.

永久冻土（冷冻地面）中冷冻的碳的非技术释放已被确定为生物圈和变暖气候之间最强烈，最可能的积极反馈之一。多年冻土氮释放有可能稳定碳循环对气候变暖的反应，因为它是负面的，系统内部的反馈。它可以赋予温暖北极的生态系统 - 大气相互作用的韧性。该奖项下的研究将通过将这些反馈纳入社区广泛用于预测北极环境变化及其与地球系统的联系的陆生生物圈模型来提高对北极系统的理解。该项目的协作性质将建立生态系统生态学家和分子生物学家之间的合作伙伴关系，从而创造了对植物群的新知识之间的伙伴关系。该项目将支持两名女性北极科学家在博士后或新教师层面的职业发展。它将有助于对两名生物科学，生态学和分子生物学的研究生培训，并为大约二十名本科生提供真实的现场或实验室研究经验。该项目将有助于扩大代表性不足的群体在生态和环境科学中的参与。北极和北方地区的冰冻土壤和沉积物中，有1,700 pg有机碳（C）的technicalabout。由于该库存是大气C池大小的两倍以上，因此有很大的兴趣了解，了解多年冻土生态系统的C平衡将如何响应观察到的气候变暖和预测的气候变暖。随着永久冻土融化，在数百到数千年的情况下受到低温保护的有机物暴露于微生物分解，并以温室气体的形式释放到大气中。在这些生态系统中可能强烈影响C平衡的一个关键因素是同时释放氮（N），这是最有可能限制植物生产力的元素。解冻时n的释放可能会增加植物N的可用性，刺激植物C摄取和抵消或平衡多年冻土C的排放。尽管科学家承认N可能在对气候的永久冻土C反馈中可能起着关键作用，但几乎没有关于控制其命运在变暖多年冻土生态系统中的因素的经验研究。该项目的目的是对永久冻土N在Alaskan Tundra景观中的作用的机理理解，该项目将重点放在植物上，因为在大多数N限制的地形生态系统中，植物的植物接收是由Microbobial Processes释放的n占主导地位。植物依靠真菌伴侣来获得n超出根源的范围，因此这项研究还将重点放在植物菌根状态和真菌群落组成上，以阐明真菌共生体在植物N采购中的作用。最后，将探讨其他永久冻土N的命运，包括停滞和损失。拟议的研究将探讨三个一般问题：从解冻多年冻土土壤有机物中释放植物可用氮的潜力是什么？菌根和植物在活性层的基础上释放的n比例在土壤剖面深处，以及控制获取的关键生物和非生物因素是什么？多年冻土和N释放将如何影响净生态系统碳平衡和净生物地球化学辐射性从多年冻结在本地和区域尺度上解冻的强迫？研究方法包括三个要素：对植物，真菌和土壤的观察，对高地tundra tundra sloks slops sloks sloks sloks formant of the and scorment comploctive。在寒冷和温暖的湿酸性苔原中占据密集的研究地点，在长期变暖实验以及表征良好的自然融化梯度中，将对菌根真菌和植物N的获取和N损失进行测量；以及与专门为模拟高纬度系统中的C和N动力学而开发的陆地生物圈模型的建模和区域集成。