Collaborative Research: Restricted Plasticity of Canopy Stomatal Conductance: A Conceptual Basis for Simpler Spatial Models of Forest Transpiration

从与美国全球变化研究计划相关的水和碳组织最近的报告中可以清楚地看出，准确预测森林系统中的冠层气孔导度对于了解陆地表面-大气通量以及它们如何受到气候和土地利用变化的影响至关重要。事实上，土地利用的变化正在产生更多零散的景观，而这些景观在目前的陆地表面模型中并不容易反映出来。目前的森林通量模型是在这样的研究范式下发展起来的，即确定均匀的林分，在这些林分的中心进行通量测量，然后将这里了解到的情况外推到整个林分和更远的地方。考虑到植物群落的空间复杂性，这种方法既不必要也不合理。该项目试图开发一个森林蒸腾的概念模型，该模型包含气孔控制的固有空间变异性，同时保留作为气孔导度经验模型的标志的可推广性的易于处理的度量。我们的概念模型是基于这样的观点，即当水通量高且具有重要的水文重要性时，冠层气孔导度主要受水势调节。我们认为，树冠气孔导度的物种可塑性，决定了它的空间变异性和量化的挑战，遵循一个容易量化的参考电导的线性关系。从与美国全球变化研究计划相关的水和碳组织最近的报告中可以清楚地看到，准确预测森林系统中的树冠气孔导度对于理解陆地表面-大气通量以及它们如何受到气候和土地利用变化的影响至关重要。事实上，土地利用的变化正在产生更多零散的景观，而这些景观在目前的陆地表面模型中并不容易反映出来。目前的森林通量模型是在这样的研究范式下发展起来的，即确定均匀的林分，在这些林分的中心进行通量测量，然后将这里了解到的情况外推到整个林分和更远的地方。考虑到植物群落的空间复杂性，这种方法既不必要也不合理。该项目试图开发一个森林蒸腾的概念模型，该模型包含气孔控制的固有空间变异性，同时保留作为气孔导度经验模型的标志的可推广性的易于处理的度量。我们的概念模型是基于这样的观点，即当水通量高且具有重要的水文重要性时，冠层气孔导度主要受水势调节。我们认为，树冠气孔导度的物种可塑性决定了它的空间变异性和量化的难度，遵循与一个容易量化的参考电导无关的线性关系。

0405381EwersIt is clear from recent reports by the water and carbon groups associated with the United States Global Change Research Program that accurate predictions of canopy stomatal conductance in forested systems are critical for the understanding of land surface - atmosphere fluxes and how they are affected by climate and land use changes. Indeed, land use changes are producing more fragmented landscapes and these are not readily represented in current land surface models. Current forest flux models were developed under the paradigm of research in which uniform forest stands are identified, flux measurements are made in the centers of these stands, and then what is learned here is extrapolated to the entire stand and beyond. This approach is neither necessary nor justified given the spatial complexity of vegetative communities. This projectseeks to develop a conceptual model of forest transpiration that embraces the inherent spatial variability of stomatal control while retaining a tractable measure of generalizability that is the hallmark of empirical models of stomatal conductance. Our conceptual model is based on the idea that canopy stomatal conductance is regulated primarily by water potential when water fluxes are high and of significant hydrologic import. We propose that species plasticity in canopy stomatal conductance, which determines its spatial variability and challenge for quantifying, follows a linear relationship that is keyed off of an easily quantifiable reference conductance0405381EwersIt is clear from recent reports by the water and carbon groups associated with the United States Global Change Research Program that accurate predictions of canopy stomatal conductance in forested systems are critical for the understanding of land surface - atmosphere fluxes and how they are affected by climate and land use changes. Indeed, land use changes are producing more fragmented landscapes and these are not readily represented in current land surface models. Current forest flux models were developed under the paradigm of research in which uniform forest stands are identified, flux measurements are made in the centers of these stands, and then what is learned here is extrapolated to the entire stand and beyond. This approach is neither necessary nor justified given the spatial complexity of vegetative communities. This projectseeks to develop a conceptual model of forest transpiration that embraces the inherent spatial variability of stomatal control while retaining a tractable measure of generalizability that is the hallmark of empirical models of stomatal conductance. Our conceptual model is based on the idea that canopy stomatal conductance is regulated primarily by water potential when water fluxes are high and of significant hydrologic import. We propose that species plasticity in canopy stomatal conductance, which determines its spatial variability and challenge for quantifying, follows a linear relationship that is keyed off of an easily quantifiable reference conductance