Biological Control of Land Surface Atmosphere Exchange: An Ecosystem Approach

生物控制水、二氧化碳和陆地表面的能量交换是改变气候和气候变化的一个重要因素；它的研究需要考虑生态系统变化的时间和空间尺度上的生物物理过程。简单的生物物理模型已经被用来研究陆地表面/气候的相互作用，但还没有考虑到通过养分可获得性或草食等生态系统过程对质量和能量通量的控制。假设营养物质和草食等生物控制显著影响植被介导的质量和能量通量，并且当通量最大时，这些生物影响最大。初步的景观尺度过程研究表明，叶片氮素和氮素利用效率是调节交换的关键参数，并且在两个被建议的地点(短草地和高草地)都具有很高的空间幅度。建议分析生态系统对质量和能量通量的控制，并开发一个用于景观到区域尺度的模型。该模型明确考虑了生物物理和生态系统过程的特征时间变化率的变化，并且可以使用遥感输入来驱动。过程研究将发展植物和生态系统变量与光谱特征之间的关系。该项目将使用该模型评估基于地理信息系统和遥感的空间外推技术，包括新的高光谱分辨率传感器的应用。几种选择空间模拟空间分辨率的方法将与在Konza和中原LTER站点测得的区域二氧化碳和水通量进行比较和评估。该项目的下一阶段将涉及(1)耦合模式模拟选定地点的季节性通量的能力，以及(2)野外光谱仪探测模拟所需的植物冠层特征的能力。这个项目团队非常优秀。机构的住宿和设施都很好。这项研究应该产生对解决有关牧场生产和可能的气候变化影响的问题很重要的结果。生态系统研究计划建议颁发一个奖项。

Biological control of water, carbon dioxide and energy exchange at the land surface is an important factor modifying climate, and climate change; its study requires consideration of biophysical processes over time and space scales of ecosystem change. Simple biophysical models have been employed to address land surface/climate interactions, but controls over mass and energy fluxes by ecosystem processes such as nutrient availability or herbivory have not been considered. It is hypothesized that biotic controls such as nutrients and herbivory significantly affect vegetation-mediated mass and energy fluxes, and that these biological effects are largest when fluxes are largest. Preliminary landscape-scale process studies suggest that leaf nitrogen and nitrogen use efficiency are key parameters regulating exchange, and have high spatial amplitude at both proposed sites (short- and tall- grasslands). It is proposed to analyze ecosystem controls over mass and energy fluxes and develop a model designed for use at landscape to regional scales. The model explicitly considers variation in characteristic time rates of change of biophysical and ecosystem processes and may be driven using remotely-sensed inputs. Process studies will develop relationships among plant and ecosystem variables and spectral features. This project will evaluate GIS and remote sensing-based techniques for spatial extrapolation using the model, including applications of new high spectral resolution sensors. Several approaches for choosing spatial resolution for spatial simulation will be compared and evaluated relative to measured regional carbon dioxide and water fluxes at the Konza and Central Plains LTER sites. The immediate phase of this project will address (1) the ability of coupled models to simulate seasonal fluxes at selected sites and (2) the ability of field spectrometers to detect plant canopy characteristics necessary to the simulations. The project team is excellent. Institutional accommodations and facilities are quite good. The research should produce results important to resolution of questions on grazing land production and the effects of possible climate change. The Ecosystem Studies Program recommends that an award be made.