Collaborative Research LTREB: Soil warming and forest ecosystem feedbacks to the climate system

合作研究LTREB：土壤变暖和森林生态系统对气候系统的反馈

• 批准号: 1456610
• 负责人: Serita Frey
• 金额: $ 10.45万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1456610&HistoricalAwards=false
• 关键词: Collaborative; Research; LTREB; Soil; warming

Soils store at least three times more carbon in soil organic matter (SOM) than either the atmosphere or vegetation. The response of SOM to increasing temperature is an important aspect of the interactions between ecosystems and climate. If increasing temperatures cause soil carbon to be transferred to the atmosphere, the result would be a self-reinforcing (positive) feedback to the climate system, with warming leading to more warming. Despite the potential importance of this feedback, there is currently an incomplete understanding of the mechanisms that affect the temperature sensitivity of SOM. This project will continue a long running soil warming experiment at Harvard Forest which is currently in its third decade. The experiments use heated cables to warm the soil in a mature eastern forest. To date, the results of this experiment have shown dynamic responses of SOM to temperature over time. This project will continue to study and monitor long-term soil responses to warming to advance the scientific understanding of how temperature controls decomposition of SOM on a decadal time scale. The results will improve the representation of soil processes in the Earth system models that are used to project future climate.Ongoing field warming experiments in the deciduous forest stands at Harvard Forest have imposed 5oC above ambient soil temperatures at three replicated sites for 8, 11 and 23 years, which now correspond to three distinct phases of CO2 emissions in the longest running experiment. There was an initial increase in soil respiration in response to warming in the first decade, followed by no response, and finally another period of higher soil respiration in the heated plots in the last 8 years. The chronosequence of the three warming experiments offers a unique opportunity to understand how increasing soil temperatures affect soil biogeochemistry, plant-soil interactions, and microbial community composition over time. The research has three major components: 1) continuation of core measurements of carbon and nitrogen stocks and fluxes; 2) short-term temperature manipulations combined with measurements of key indicators of biogeochemical and microbial community changes; and 3) targeted process-level measurements that enhance a mechanistic understanding of soil responses to long-term warming. The project will measure the isotopic composition of carbon and nitrogen, the chemical composition of SOM, and microbial community composition along the chronosequence. The soil warming experiments will continue to operate as an open facility for students and researchers nationwide to study the long-term effects of warming on ecosystem processes.

土壤在土壤有机物（SOM）中的碳储存至少三倍，而不是大气或植被。 SOM对温度升高的反应是生态系统与气候之间相互作用的重要方面。如果温度升高导致土壤碳转移到大气中，则结果将是对气候系统的自我增强（积极）反馈，导致变暖会更加变暖。 尽管这种反馈可能具有重要的重要性，但目前对影响SOM温度敏感性的机制有不完整的理解。该项目将继续在哈佛森林进行长期运行的土壤变暖实验，该实验目前已有第三个十年。 该实验使用加热电缆在成熟的东部森林中加热土壤。 迄今为止，该实验的结果显示了SOM对温度的动态响应。 该项目将继续研究和监测对变暖的长期土壤反应，以提高人们对温度如何在际际时间范围内控制SOM分解的科学理解。结果将改善用于投射未来气候的地球系统模型中土壤过程的表示。哈佛森林的落叶森林林座中的综合田间变暖实验在三个复制的地点上的环境土壤温度高于8、11和23年的环境土壤温度，现在与长期运行的三个不同阶段相对应。 在最初的十年中，土壤呼吸的最初增加，随后没有反应，最后8年中加热地块中较高的土壤呼吸的另一个时期。这三个变暖实验的年代序列提供了一个独特的机会，可以了解土壤温度的升高如何影响土壤生物地球化学，植物土壤相互作用和微生物群落的成分。这项研究具有三个主要组成部分：1）碳和氮库存和通量的核心测量值延续； 2）短期温度操作结合了生物地球化学和微生物群落变化的关键指标的测量； 3）有针对性的过程级测量，以增强对土壤对长期变暖的反应的机械理解。该项目将测量碳和氮的同位素组成，SOM的化学成分以及沿Chronosequence的微生物群落组成。 土壤变暖实验将继续作为全国学生和研究人员的开放设施，以研究变暖对生态系统过程的长期影响。