Responses of Root Hydraulic Conductivity to Elevated CO2: Patterns and Mechanisms

大气中二氧化碳浓度的上升可能对陆地生态系统造成严重后果。这些影响往往是在直接影响植物的碳吸收和损失方面进行审查。然而，CO2水平升高可能会通过间接影响（包括对水和养分等其他资源的吸收和使用）导致原生生态系统和作物生态系统的性能发生重大变化。在大多数原生生态系统中，水是最有限的资源。因此，CO2水平上升对植被吸收和利用水分的任何影响都会影响植物和生态系统的生产力，并影响水文生物圈-大气反馈。到目前为止，有一些证据表明，CO2浓度升高可能会降低叶片对水分流失的抵抗力，但对土壤中其他水流成分的潜在变化知之甚少，通过植物和大气。拟议的研究将审查大气二氧化碳预计上升对许多森林和农作物物种的影响。更具体地说，根导水率，往往构成一个主要的障碍，水流的影响将被检查。沿着的初步结果与理论的考虑表明，高CO2可能会导致根系吸收和运输能力的显着变化。拟议的研究还将研究可能最好地解释为什么CO2会影响根系水分运输特性的机制。研究结果将对植物和生态系统生长对未来气候的响应模型具有重要的实用价值。该研究还旨在确定物种反应的潜在差异，从而提供对CO2影响生物多样性和种群动态的更大规模生态过程的机械理解。最后，本研究将从事K-12以及本科生在本研究的概念和实验方面。

Rising atmospheric CO2 concentration could have serious consequences for terrestrial ecosystems. These effects are often examined in terms of direct influences on carbon uptake and losses by plants. However, elevated levels of CO2 may result in significant changes in performances of native and crop ecosystems via indirect effects involving uptake and usage of other resources such as water and nutrients. In most native ecosystems, water is the most limiting resource. Therefore, any impact of rising CO2 level on water uptake and usage by vegetation will affect plant and ecosystem productivity as well as affecting the hydrologic biosphere-atmosphere feedbacks. To date, there is some evidence that elevated CO2 may reduce foliage resistance to water loss but considerably less is known about potential changes in other components of water flow within the soil, through the plant and to the atmosphere. The proposed study will examine the effects of projected rise in atmospheric CO2 on a number of forest and crop species. More specifically, effects on root hydraulic conductivity which often constitutes a major barrier to water flow will be examined. Preliminary results along with theoretical considerations indicate that high CO2 may result in a significant change in root uptake and transport capacity of water. The proposed study will also examine the mechanism(s) that may best explain why CO2 would affect root water transport properties. The results will have significant utility for models of plant and ecosystem growth responses to future climates. The study is also designed to determine potential differences in species responses thus providing a mechanistic understanding of CO2 affect on the larger scale ecological processes of biodiversity and population dynamics. Finally, the study will engage K-12 as well as undergraduate students in conceptual and experimental aspects of this research.