Biological Control of Land Surface Atmosphere Exchange: An Ecosystem Approach

陆地表面水、二氧化碳和能量交换的生物控制是改变气候和气候变化的重要因素；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。已经采用了简单的生物物理模型来处理陆地表面/气候相互作用，但尚未考虑营养可利用性或草食等生态系统过程对质量和能量通量的控制。据推测，营养物和草食等生物控制显著影响植被介导的质量和能量通量，当通量最大时，这些生物效应最大。初步的景观尺度过程研究表明，叶片氮和氮利用效率是调节交换的关键参数，并且在矮草地和高草地上都具有较高的空间振幅。建议分析生态系统对质量和能量通量的控制，并建立一个设计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，并可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。该项目将评估利用该模型进行空间外推的地理信息系统和基于遥感的技术，包括新的高光谱分辨率传感器的应用。选择空间模拟空间分辨率的几种方法将相对于康扎和中原LTER站点测量的区域二氧化碳和水通量进行比较和评估。该项目的直接阶段将解决(1)耦合模式在选定地点模拟季节通量的能力和(2)现场光谱仪探测模拟所需的植物冠层特征的能力。项目团队非常优秀。学校的住宿和设施都很好。这项研究应该对解决放牧生产和可能的气候变化的影响等问题产生重要的结果。生态系统研究项目建议设立一个奖项。

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.