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

本研究的主题是碳/养分的作用 相互作用对碳循环过程的制约， 陆地生态系统的总体碳预算。 具体 重点是碳/养分相互作用在三个对比 苔原生态系统沿着一个连续体从干燥的高地到潮湿的 阿拉斯加北方的低地。 该研究被放置在 全球变暖的背景下，查看预测的全球 温度升高作为碳/养分实验 生态系统层面的互动。 其中心思想是北极生态系统的初级生产力 是非常营养有限的，因此它的反应能力， 较高的温度受到营养供应的限制。 土壤 另一方面，呼吸更直接地受到低 土壤温度，以及土壤中养分的矿化 有机物 植物碳收益与增加 因此，养分矿化必须与土壤碳平衡 由于土壤呼吸增加而造成的损失。 了解控制 关于生态系统层面的碳平衡，人们需要了解 控制植物碳/养分比和土壤 碳呼吸对氮磷矿化的影响。 提出了一项研究计划，其中包括工艺研究， 全生态系统实验和模拟建模。 的 工艺研究旨在提高对C/N/P的理解 有机物循环中关键点的相互作用 特别注重生态系统的平衡， 土壤呼吸和氮磷矿化。 整个- 生态系统实验的重点是确定相关性 主要有机质C：N：P比值的变化 通量和有机物库。 建模工作是 旨在帮助解释这些相互关联的变化， 生态系统，以确定因果关系，并 阐明对观察到的C：N：P变化范围的限制 比率。

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.