Acquisition of a Free Air CO2 Enrichment Instrumentation for Studying the Effects of Changes in Atmospheric CO2 Concentration & Precipitation on Mediterranean-type Ecosystems

这一要求是建设国家的最先进的仪器，这将使研究的影响，在CO2浓度的变化对再生橡树林地在南加州。迫切需要开发和提供新的仪器，以便研究生态系统一级对二氧化碳浓度升高的反应。目前从基于室的研究中获得的数据虽然很有价值，但无法可靠地预测生态系统一级的反应。 获得生态系统一级对CO2升高的反应需要生态系统一级对CO2的操纵。目前，自由空气CO2富集（FACE）是可用于此类大规模操作的最有前途的技术。 我们建议扩大我们现有的自由空气二氧化碳富集（FACE）设施，目前 由加州查帕拉尔的一个FACE环组成，计划建造第二个控制环， 在邻近的再生橡树林地再建造六个环。我们的FACE系统允许 大气CO2浓度在相对较大的区域（177 m2）的实验操作 在不使用腔室的情况下，可能会消除或尽量减少“腔室”效应。这些 额外的环将各自保持在从当前环境（350 ppm）到大于两倍当前环境（750 ppm）的五种CO2浓度中的一种，增量为100 ppm。这一扩大的FACE设施将允许对CO2升高对生态系统源/汇状态、水通量、能量平衡、生产力、土壤养分过程和社区水平过程的影响进行大型合作研究。我们预计该设施将吸引来自世界各地的众多科学家和学生的合作，因为这是在相对大的规模上研究CO2对完整生态系统影响的独特机会，因为半干旱木本生态系统可能会对CO2做出积极反应，也是因为国际上对一般的半干旱生态系统，特别是地中海型生态系统的兴趣。 我们扩大的FACE设施不仅有助于更多地了解半干旱生态系统对CO2升高的反应，而且还将更好地预测生态系统水平的过程，包括生态系统源/汇状态，未来可能会发生变化。该设施还将允许加强国际范围内的合作，并将为学生带来无与伦比的机会。 训练 11

This request is for construction of state-of-the-art instrumentation which would allow study of the effects of changes in CO2 concentration on regenerating oak woodland in southern California. There is an urgent need to develop and make available new instrumentation allowing the study of ecosystem-level responses to elevated CO2. Currently available data from chamber-based studies, while valuable, do not allow confident predictions of ecosystem-level responses. Obtaining ecosystem-level responses to elevated CO2 requires ecosystem-level manipulations of CO2. At present, Free-Air CO2 Enrichment (FACE) is the most promising technology available for such large-scale manipulations. We propose to expand our existing Free-Air CO2 Enrichment (FACE) facility, which currently consists of a single FACE ring in the California chaparral, with plans to build a second, control ring, by constructing six more rings in adjacent regenerating oak woodlands. Our FACE system allows the experimental manipulation of atmospheric CO2 concentration over relatively large areas (177 m2) of ecosystems without the use of chambers, presumably eliminating or minimizing "chamber" effects. These additional rings will each be maintained at one of five CO2 concentrations from current ambient (350 ppm) to more than twice current ambient (750 ppm) in 100 ppm increments. This expanded FACE facility will allow large collaborative studies of the effects of elevated CO2 on ecosystem source/sink status, water flux, energy balance, productivity, soil nutrient processes, and community-level processes. We anticipate this facility will attract cooperation with numerous scientists and students from around the world, because of the unique opportunities to study CO2 effects on intact ecosystems at a relatively large scale, because of the likelihood that semi-arid woody ecosystems will respond positively to CO2, and because of the international interest in semi-arid ecosvstems in ~eneral and in Med iterranean-type ecosystems in particular. Our expanded FACE facility will not only contribute to greater knowledge about the responses of semi-arid ecosystems to elevated CO2, but will also lead to better predictions of how ecosystem-level processes, including ecosystem source/sink status, may change in the future. The facility will also allow enhanced collaboration on an international scale and will result in unparalleled opportunities for student training. 11