Forests play a significant role in mitigating the effects of climate change and regulating the biogeochemical cycles. Water use efficiency (WUE) is an important indicator that links the carbon and water cycles in terrestrial ecosystems. In the present study, WUE of major forest formations of India was calculated from 2003 to 2018 as the ratio of Moderate Resolution Spectroradiometer (MODIS) Gross Primary Productivity (GPP, MOD17A2H) to evapotranspiration (ET, MOD16A) using the Google Earth Engine platform. The spatial distribution of WUE was mapped and the inter-annual and monthly variations were analysed. The mean annual WUE of forests ranged from 1.78–2.02 gC kgH₂O⁻¹. It was observed that tropical thorn forests had the highest WUE (3.52 ± 1.08 gC kgH₂O⁻¹) and moist alpine scrub had the lowest WUE (1.05 ± 0.17gC kgH₂O⁻¹) among the forest type groups of India. WUE of forests showed an increasing trend with latitude and decreasing trend with elevation. To understand the influence of various bio-meteorological drivers on WUE and their importance in governing these influences, Random Forest (RF) algorithm was used. The bio-meteorological drivers were able to explain 65% of the variability in WUE. Temperature was identified as the most important driver in influencing the WUE of forests. Based on the findings of the study, it can be expected that the global increase in temperature would negatively affect the WUE of the major forest formations of India.

森林在减轻气候变化的影响和调节生物地球化学循环方面发挥着重要作用。水资源利用效率（WUE）是联系陆地生态系统碳循环和水循环的重要指标。在本研究中，使用 Google Earth Engine 平台计算了 2003 年至 2018 年印度主要森林形成的 WUE，即中分辨率光谱仪 (MODIS) 总初级生产力 (GPP, MOD17A2H) 与蒸散量 (ET, MOD16A) 的比率。绘制了WUE的空间分布图，分析了年际和月度变化。森林的年平均 WUE 范围为 1.78–2.02 gC kgH ₂ O ^-1。据观察，热带荆棘林的 WUE 最高（3.52 ± 1.08 gC kgH ₂ O^-1 ) 和潮湿的高山灌木在印度的森林类型组中具有最低的 WUE (1.05 ± 0.17gC kgH ₂ O ^-1 )。森林WUE随纬度呈增加趋势，随海拔呈递减趋势。为了了解各种生物气象驱动因素对 WUE 的影响及其在控制这些影响方面的重要性，使用了随机森林 (RF) 算法。生物气象驱动因素能够解释 WUE 中 65% 的变异性。温度被确定为影响森林 WUE 的最重要驱动因素。根据研究结果，可以预期全球气温升高将对印度主要森林形成的 WUE 产生负面影响。