Combined Use of 15N Natural Abundances and Tracers to Elucidate Above- and Belowground C and N Cycle Linkages during Forest Succession

结合使用 15N 自然丰度和示踪剂来阐明森林演替过程中的地上和地下 C 和 N 循环联系

• 批准号: 0947329
• 负责人: Knute Nadelhoffer
• 金额: $ 30万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0947329&HistoricalAwards=false
• 关键词: Combined; Use; 15N; Natural; Abundances

Re-growing forests across the North Temperate Zone presently remove about 15% of fossil fuel carbon dioxide (CO2) emissions. It is unclear, however, how long and to what extent these forests will continue to sequester CO2 and thereby offset a major fraction of human-derived CO2 emissions. Recent measurements suggest that, in contrast to the long-held idea that ecosystem CO2 uptake declines to zero over time, forests can continue storing carbon for centuries after establishment. For this to occur, nitrogen cycling patterns and rates must change as tree species composition of the forest shifts during succession. How this occurs is not well understood, however, so this project will investigate mechanisms by which nitrogen cycling influences carbon uptake. The research will be conducted using novel, multi-scale, stable nitrogen isotope approaches in a large-scale, bold, experimental forest setting in northern Michigan where losses of maturing, early successional tree species are being accelerated by stem girdling. Carbon uptake by the experimental forest is being compared to a nearby non-manipulated forest under separate funding. The NSF-supported research here focuses on nitrogen exchanges between late-successional tree species, their fungal symbionts and soils as they control forest carbon balances. Results will provide a more complete understanding of controls on forest growth across successional stages and will improve predictions of temperate forest CO2 uptake and carbon balances. The study will serve as a resource for 'Kindergarten-to-Gray' environmental education and insights derived from this research will inform decisions of policymakers and resource managers regarding forest carbon sequestration and provision of ecosystem services.

北温带地区的森林再生目前消除了约15%的化石燃料二氧化碳（CO2）排放。 然而，目前尚不清楚这些森林将在多长时间内以及在多大程度上继续封存二氧化碳，从而抵消大部分人类产生的二氧化碳排放。 最近的测量结果表明，与生态系统二氧化碳吸收量随着时间的推移下降至零的长期观点相反，森林可以在建立后继续储存碳几个世纪。 要做到这一点，氮循环模式和速率必须改变的树种组成的森林转移在演替过程中。然而，这是如何发生的还没有很好的理解，因此本项目将研究氮循环影响碳吸收的机制。这项研究将在密歇根州北方的一个大规模的，大胆的，实验性的森林环境中使用新的，多尺度的，稳定的氮同位素方法进行，其中成熟的，早期演替树种的损失正在加速干环剥。实验森林的碳吸收量正在与附近的未受操纵的森林进行比较。NSF支持的研究集中在后期演替树种，真菌共生体和土壤之间的氮交换，因为它们控制着森林碳平衡。 结果将提供一个更完整的了解控制森林生长的演替阶段，并将改善温带森林二氧化碳吸收和碳平衡的预测。这项研究将作为“从森林到灰色”环境教育的资源，从这项研究中得出的见解将为政策制定者和资源管理者关于森林碳固存和提供生态系统服务的决定提供信息。