Global Change and the Carbon Balance of Arctic Ecosystems: The Importance of Carbon/Nutrient Interactions

全球变化和北极生态系统的碳平衡：碳/养分相互作用的重要性

• 批准号: 9019055
• 负责人: Gaius Shaver
• 金额: $ 81.68万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-11-01 至 1996-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9019055&HistoricalAwards=false
• 关键词: Global; Change; Carbon; Balance; Arctic

The Subject of this research is the role of carbon/nutrient interactions as constraints on carbon cycling processes and overall carbon budgets of terrestrial ecosystems. The specific focus is on carbon/nutrient interactions in three contrasting tundra ecosystems along a continuum from dry uplands to wet lowlands in northern Alaska. The research is placed in the context of global warming, viewing the predicted global temperature increase as an experiment in carbon/nutrient interactions at the ecosystem level. The central idea is that primary production of arctic ecosystem is strongly nutrient-limited, and thus its ability to respond to higher temperatures is constrained by nutrient supply. Soil respiration, on the other hand, is more directly limited by low soil temperature, as is the mineralization of nutrients in soil organic matter. Plant carbon gains associated with increased nutrient mineralization must thus be balanced against soil carbon losses due to increased soil respiration. To understand controls on carbon balance at the ecosystem level, one needs to understand controls on plant carbon/nutrient ratios and the ratio of soil carbon respiration to N and P mineralization. A program of research is proposed that includes process studies, whole- ecosystem experiments, and simulation modeling. The process studies are designed to improve understanding of C/N/P interactions at key points in the cycle of organic matter in terrestrial ecosystems, with a particular focus on the balance of soil respiration and N and P mineralization. The whole- ecosystem experiments are focused on determining correlations between changes in the C:N:P ratios of the major organic matter fluxes and organic matter pools. The modeling efforts are designed to help explain these correlated changes in whole ecosystems, to identify cause-effect relationships, and to clarify constraints on the observed range of variation in C:N:P ratios.

本研究的主题是碳/养分相互作用作为碳循环过程和陆地生态系统总体碳预算的约束的作用。 具体重点是阿拉斯加北部从干燥高地到潮湿低地的三个截然不同的苔原生态系统中的碳/养分相互作用。 该研究置于全球变暖的背景下，将预测的全球气温上升视为生态系统层面碳/养分相互作用的实验。 其中心思想是，北极生态系统的初级生产受到养分的严重限制，因此其对较高温度的反应能力受到养分供应的限制。 另一方面，土壤呼吸更直接地受到低土壤温度的限制，土壤有机质中养分的矿化也是如此。 因此，与养分矿化增加相关的植物碳增益必须与由于土壤呼吸增加而导致的土壤碳损失相平衡。 要了解生态系统层面碳平衡的控制，需要了解植物碳/养分比率以及土壤碳呼吸与氮和磷矿化的比率的控制。 提出了一个研究计划，包括过程研究、全生态系统实验和模拟建模。 该过程研究旨在提高对陆地生态系统有机质循环关键点的 C/N/P 相互作用的理解，特别关注土壤呼吸和氮磷矿化的平衡。 全生态系统实验的重点是确定主要有机物通量和有机物库的 C:N:P 比率变化之间的相关性。 建模工作旨在帮助解释整个生态系统中的这些相关变化，识别因果关系，并澄清对观察到的 C:N:P 比率变化范围的限制。