ISPA, Bordeaux Science Agro, INRA, 33140, Villenave d'Ornon, France.
CSIC, Global Ecology Unit CREAF-CSIC-UAB, E-08193, Bellaterra (Catalonia), Spain.
Sci Rep. 2017 Sep 5;7(1):10580. doi: 10.1038/s41598-017-09643-x.
Water stored underground in the saturated and subsurface zones below the soil are important sources of water for plants in water-limited ecosystems. The presence of deep-rooted plants worldwide, however, suggests that the use of groundwater is not restricted to arid and seasonally dry ecosystems. We compiled the available data (71 species) on the relative contribution of groundwater to plant water estimated using stable isotopes and mixing models, which provided information about relative groundwater use, and analyzed their variation across different climates, seasons, plant types, edaphic conditions, and landscape positions. Plant use of groundwater was more likely at sites with a pronounced dry season, and represented on average 49 per cent of transpired water in dry seasons and 28 per cent in wet seasons. The relative contribution of groundwater to plant-water uptake was higher on rocky substrates (saprolite, fractured bedrock), which had reduced groundwater uptake when this source was deep belowground. In addition, we found that the connectivity between groundwater pools and plant water may be quantitatively larger and more widespread than reported by recent global estimations based on isotopic averaged values. Earth System Models should account for the feedbacks between transpiration and groundwater recharge.
储存在地下饱和带和土壤以下的地下水是水分限制生态系统中植物的重要水源。然而，世界各地存在深根植物表明，地下水的利用不仅限于干旱和季节性干旱生态系统。我们编译了可用的数据（71 种），这些数据是关于使用稳定同位素和混合模型估算的植物水分中地下水的相对贡献，这些数据提供了有关相对地下水利用的信息，并分析了它们在不同气候、季节、植物类型、土壤条件和景观位置下的变化。在明显的旱季，植物更有可能利用地下水，平均而言，旱季地下水占蒸腾水的 49%，雨季占 28%。地下水对植物水分吸收的相对贡献在岩石基质（风化壳、破碎基岩）上更高，当这种来源在地下深处时，地下水的吸收会减少。此外，我们还发现，地下水池与植物水之间的连通性可能比基于同位素平均值的最近全球估计所报告的要大得多且分布更广。地球系统模型应该考虑蒸腾作用和地下水补给之间的反馈。
