Natural resource management requires knowledge of terrestrial evapotranspiration (ET). Most existing numeric models for ET include multiple plant- or ecosystem-type specific parameters that require calibration. This is a significant source of uncertainty under changing environmental conditions. A novel ET model with no type−specific parameters was developed recently. Based on the coupling the diffusion (via stomata) of water and carbon dioxide (CO₂), this model predicts canopy conductance based on environmental conditions using eco-evolutionary optimality principles that apply to all plant types. Transpiration (T) and ET are calculated from canopy conductance using the Penman-Monteith equation for T and a universal empirical function for the T:ET ratio. Here, the model is systematically evaluated at globally distributed eddy-covariance sites and river basins. Site-scale modelled ET agrees well with flux data (r = 0.81, root mean square error = 0.73 mm day^–1 in 23,623 records) and modelled ET in 39 river basins agrees well with the ET estimated by monthly water budget using two runoff datasets (r = 0.62 and 0.66, respectively). Modelled global patterns of ET are consistent with existing global ET products. The model's universality, parsimony and accuracy combine to indicate a broad potential field of application in resource management and global change science.

自然资源管理需要了解陆地蒸散 (ET)。大多数现有的 ET 数字模型包括多个需要校准的植物或生态系统类型特定参数。这是不断变化的环境条件下不确定性的重要来源。最近开发了一种没有特定类型参数的新型 ET 模型。基于耦合扩散（通过气孔）水和二氧化碳（CO ₂)，该模型使用适用于所有植物类型的生态进化最优性原则，根据环境条件预测冠层电导。蒸腾 (T) 和 ET 是根据冠层电导计算的，使用 T 的 Penman-Monteith 方程和 T:ET 比率的通用经验函数。在这里，该模型在全球分布的涡度协方差站点和河流流域进行了系统评估。场地规模模拟的 ET 与通量数据（r  = 0.81，均方根误差 = 0.73 毫米天^– 23,623 条记录中的 1）非常吻合，39 个河流流域的模拟 ET 与使用两个径流数据集的每月水预算估计的 ET 吻合得很好( r = 0.62 和 0.66，分别）。建模的 ET 全球模式与现有的全球 ET 产品一致。该模型的普遍性、简约性和准确性相结合，表明在资源管理和全球变化科学中具有广泛的潜在应用领域。