Han River Basin Support Group, Presidential Water Commission, Hanam 12902, Republic of Korea.
Center for Built Environment, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Sci Total Environ. 2021 Jun 15;773:145519. doi: 10.1016/j.scitotenv.2021.145519. Epub 2021 Feb 2.
Water use efficiency (WUE) is an environmental factor to account for the metabolism of terrestrial ecosystems using various climate systems and vegetation types. It is estimated by the ratio of gross primary productivity (GPP) to evapotranspiration (ET), the largest carbon and water fluxes with respect to plant respiration. In this study, the WUE was calculated using GPP and ET from the community land model version 4.0 (CLM4.0), inclusive of the prognostic carbon-nitrogen model in the community earth system model (CESM). The estimated WUE in East Asia was analyzed for climate zones, land cover types, and water- and energy-limited zones, with aridity index (AI). Spatial variations from 2001 to 2015 in annual WUE gradually increased as latitude decreased, though small year-to-year differences appeared between monthly GPP and ET. Monthly WUE was lower in summer than fall because the water loss rate in summer was higher than the carbon assimilation increase. The WUE under arid conditions (AI<0.5) was lower than under humid conditions. The GPP, ET, and WUE were higher in the forest, savannas, cropland, and permanent wetland with dense vegetation or abundant water resources than in other land cover types. The WUE was lower in water-limited zones than in energy-limited zones due to the low amount of water to use for the physical processes of GPP and ET. Based on this study, we identified general spatial and temporal variations of carbon fluxes in East Asia with various climate zones and land cover types.
水分利用效率（WUE）是一个环境因素，用于说明陆地生态系统在不同气候系统和植被类型下的新陈代谢。它通过总初级生产力（GPP）与蒸散（ET）的比值来估算，这是与植物呼吸有关的最大碳和水通量。在这项研究中，利用群落土地模型版本 4.0（CLM4.0）中的 GPP 和 ET 计算 WUE，其中包括群落地球系统模型（CESM）中的预测碳氮模型。分析了气候带、土地覆盖类型以及干旱指数（AI）下的水分和能量限制区东亚的 WUE。从 2001 年到 2015 年，随着纬度的降低，年 WUE 的空间变化逐渐增加，尽管 GPP 和 ET 的月际差异较小。由于夏季的水分流失率高于碳同化的增加，夏季的月 WUE 低于秋季。在干旱条件（AI<0.5）下的 WUE 低于湿润条件。森林、热带草原、农田和永久性湿地等高植被或丰富水资源的土地覆盖类型的 GPP、ET 和 WUE 高于其他土地覆盖类型。由于用于 GPP 和 ET 物理过程的水量较少，水分限制区的 WUE 低于能量限制区。基于这项研究，我们确定了东亚具有不同气候带和土地覆盖类型的碳通量的一般时空变化。
