Collaborative Research: Experimental Studies of Ecosystem Responses to Elevated CO2: Interactions with Nitrogen, Water, and Species Characteristics

菲尔德，查平和穆尼博士将进行综合研究， 加州一年生草地对资源变化响应 平衡，重点是控制反应的因素， 生态系统的二氧化碳浓度升高。 他们的研究涉及协调 实证和建模程序来测试一系列假设， 潜在地解释了 地上和地下生产的系统水平行为， 分解和养分循环，以应对改变 资源 系统级影响的概念模型 CO2浓度升高基于两种机制假设 的系统级响应和直接效应的位点。 首先，他们假设二氧化碳浓度升高可能会产生新的 资源平衡，但植物生长的反应可以是 从其他变化的反应中理解和预测， 资源平衡，改变碳的可用性，相对 其他资源。 其次，他们假设系统级 对CO2浓度升高的反应主要是通过直接 对植物的影响 本研究计划由五个部分组成：1）研究 自然生态系统对开顶大气CO2浓度升高的响应 钱伯斯 2)一个关于生态系统对一系列 改变，包括CO2升高，改变营养和水分 可用性和改变物种组成，使用人工 微生态系统在开顶的房间里。 3)一项关于控制 分解和养分循环与实验室，现场和 微生态系统实验使用植物凋落物从其他 实验以及同位素示踪剂。 4)的探索 资源对植物生长、分配和组织化学的影响 进行了一系列的温室实验。 5)一个建模的努力， 整合实验结果，并链接和扩展现有的 生态系统、群落和植物模型。 该计划有可能推进我们的几个方面， 了解系统一级对全球气候变化的反应。 首先，研究了加州一年生草原中CO2浓度升高的情况 将补充其他草原的二氧化碳研究，结果来自 一个在低碳储存和快速运输方面独一无二的系统， 平衡 第二，植物的矮小， 系统平衡的时间常数很小， 研究人员探讨了广泛的后果， 资源可利用性和植物种类特性。 最后，强调系统一级的反应机制， 通过链接模型集成，应该使这一结果 研究可推广到其他生态系统。

Drs. Field, Chapin and Mooney will conduct integrated studies of the responses of California annual grassland to altered resource balance, focusing on factors controlling the response of the ecosystem to elevated CO2. Their research involves coordinated empirical and modeling programs to test a series of hypotheses that potentially account for the mechanisms and feedbacks governing system-level behavior of aboveground and belowground production, decomposition, and nutrient cycling in response to altered resources. The conceptual model for the system-level effects of elevated CO2 is based on two hypotheses concerning the mechanisms of the system level responses and the loci of the direct effects. First, they hypothesize that elevated CO2 may generate novel resource balance, but the response of plant growth can be understood and predicted from responses of other variations in resource balance that change the availability of carbon, relative to other resources. Second, they hypothesize that system-level responses to elevated CO2 are driven primarily through direct effects on plants. This research program consists of five components: 1) a study of the responses of natural ecosystems to elevated CO2 in open top chambers. 2) a probe of ecosystem responses to a range of modifications, including elevated CO2, altered nutrient and water availability, and altered species composition, using artificial microecosystems in open top chambers. 3) a study of controls on decomposition and nutrient cycling with laboratory, field and microecosystem experiments using plant litter from the other experiments as well as isotopic tracers. 4) an exploration of the resource effects on plant growth, allocation, and tissue chemistry with a series of greenhouse experiments. 5) a modeling effort to integrate the experimental results and to link and extend existing ecosystem, community, and plant models. This program has the potential to advance several aspects of our understanding of system-level responses to global climate change. First, studies with elevated CO2 in the California annual grassland will complement CO2 studies in other grasslands, with results from a system that is unique in terms of low carbon storage and rapid equilibration. Second, the small stature of the plants, combined with the small time constant for system equilibration, will allow the investigators to explore consequences of a broad range of resource availabilities and plant species characteristics. Finally, the emphasis on mechanisms of system-level responses, integrated through linked models, should make the results of this study generalizable to other ecosystems.