Grassland-Atmosphere Interactions: Analyses Using Coupled Ecophysiological, Ecosystem, Micrometeorology, and Mesoscale Atmospheric Models

9524129考古努尔这项研究旨在发展以数字方式评估草原生态系统对与温室气体，特别是二氧化碳(二氧化碳)水平增加相关的大气变化的反应的能力。目前，我们进行这些评估的能力至少有三个主要缺陷。首先是缺乏计算机模型，这些模型已经针对草原上的野外二氧化碳暴露实验进行了校准和测试。因此，这项研究的重点将是与科学家合作，在堪萨斯州进行一项正在进行的野外暴露研究。为此，将使用现有的草原生态系统功能以及植物对二氧化碳和天气的反应模型。其次，忠实地代表当前对植物生理学的理解的模型必须与代表土壤分解、养分循环和水分储存和流动等过程的模型相结合，以了解整个生态系统如何对大气变化做出反应。例如，养分循环速率可能会限制植物对二氧化碳浓度升高的积极反应。拟议的研究将采用最先进的植物生理和土壤过程模型。第三，陆地生态系统与大气的水、碳和能量交换过程对生态系统对大气变化的反应具有潜在的重大影响，但在过去的模拟研究中很少得到检验。这项研究将把生态和大气模型联系起来，以评估大气过程的作用，特别是大范围的水蒸气和能量通量。这些结果将通过改变植物的水分利用效率和由此产生的营养循环率的反应来反馈到植物的生长。通过将这些不同的模型联系起来，将探索草原、气候以及气候和草原之间的相互作用。

9524129 Coughenour This research is to develop capabilities for numerically assessing the responses of grassland ecosystems to atmospheric changes associated with increasing levels of greenhouse gases, particularly carbon dioxide (CO2). Currently, there are at least three major deficiencies in our abilities to perform these assessments. The first is a lack of computer models which have been calibrated and tested against field CO2 exposure experiments in grasslands. Accordingly, a focus of this research will be to collaborate with scientists working on an ongoing field exposure study in Kansas. An existing model of grassland ecosystem function and plant responses to CO2 and weather will be used for this purpose. Secondly, models that faithfully represent current understanding of plant physiology must be coupled with models that represent soil processes such as decomposition, nutrient cycling and water storage and flows to understand how whole ecosystems respond to atmospheric change. For example, it is possible that nutrient cycling rates will constrain otherwise positive plant growth responses to elevated CO2. Linked state-of-the-art plant physiological and soil process models will be employed in the proposed research. Thirdly, terrestrial ecosystem processes of water, carbon and energy exchange with the atmosphere have potentially significant effects on ecosystem responses to atmospheric change but have been poorly examined in past modeling research. This research will link ecological and atmospheric models to assess the role of atmospheric processes, particularly large-scale fluxes of water vapor and energy. These results will feedback onto plant growth through altered plant water use efficiency, and resultant responses of nutrient cycling rates. Grasslands, climate, and the interactions between climate and grasslands will be explored through linking these various models.