TECO: Carbon Balance of a Wheat Ecosystem from Source to Sink in Response to Free-Air CO2 Enrichment and Soil Nitrogen

TECO：小麦生态系统从源头到汇的碳平衡对自由空气二氧化碳富集和土壤氮的响应

• 批准号: 9619047
• 负责人: Gerard Wall
• 金额: --
• 依托单位: USDA , Agricultural Research Service
• 依托单位国家: 美国
• 项目类别: Interagency Agreement
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-10-01 至 1999-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9619047&HistoricalAwards=false
• 关键词: TECO; Carbon; Balance; Wheat; Ecosystem

9652613 Wall The uncertainty regarding whether plants and ecosystems will respond to elevated atmospheric CO2 when nutrients are lacking under field conditions is one of the most important questions facing global change research. To help resolve this quandary, two CO2 by soil nitrogen experiments are being conducted on the wheat ecosystem in an open field using the free-air CO2 enrichment (FACE) approach. This proposal covers two important components of the carbon cycle -- photosynthesis (source) and belowground biomass distribution (sink) -- and thus will insure that all important physiological processes that are explicitly influenced by atmospheric CO2 enrichment are incorporated within an accurate comprehensive plant growth model responsive to elevated CO2 and changing climate variables called ECOSYS. Besides validating ECOSYS with regard to the interactions of CO2 and soil nitrogen supply, other important objectives are to determine the interactive effects of elevated CO2 and limiting soil nitrogen supply on (a) acclimation (down-regulation) of photosynthesis and (b) root growth and plant-soil nutrient status. Measurements of individual leaf and whole-canopy photosynthesis, respiration, and transpiration rates are being made throughout the season to quantify the diurnal and temporal source of carbon into the wheat ecosystem. Individual leaf photosynthesis will be integrated to whole-plant and community level and compared with measurements of whole canopy CO2 and H2O vapor fluxes. Similarly, soil cores are being taken at several crop growth stages, frozen, and stored. Nitrogen and carbon content of the root tissue will also be ascertained to determine if any atmospheric CO2 concentration influences the C/N ratio.

9652613 Wall 当田间条件下缺乏养分时，植物和生态系统是否会对大气中二氧化碳含量升高做出反应的不确定性是全球变化研究面临的最重要问题之一。为了帮助解决这一难题，我们正在露天田地的小麦生态系统上使用自由空气二氧化碳富集 (FACE) 方法进行了两项土壤氮二氧化碳实验。该提案涵盖了碳循环的两个重要组成部分——光合作用（源）和地下生物量分布（汇）——因此将确保受大气二氧化碳富集明确影响的所有重要生理过程都纳入准确的综合植物生长中响应二氧化碳浓度升高和气候变量变化的模型称为 ECOSYS。除了验证 ECOSYS 关于 CO2 和土壤氮供应的相互作用之外，其他重要目标是确定 CO2 升高和限制土壤氮供应对 (a) 光合作用的驯化（下调）和 (b) 根系生长的相互作用影响和植物土壤养分状况。在整个季节对单片叶子和整个冠层的光合作用、呼吸和蒸腾速率进行测量，以量化小麦生态系统的昼夜碳源。单叶光合作用将整合到整个植物和群落水平，并与整个冠层 CO2 和 H2O 蒸气通量的测量结果进行比较。同样，在作物的几个生长阶段采集土芯，进行冷冻和储存。还将确定根组织的氮和碳含量，以确定大气二氧化碳浓度是否影响 C/N 比。