Worldwide ecosystem water use efficiency increased by 13.3 percent across twenty-four years, but the gains were split unevenly across different climates. Land managers expected plant water savings to rise evenly across wet and dry terrain, yet humid zones showed almost no change. Arid vegetation produced more biomass per unit of evaporated soil moisture by drawing on rising carbon dioxide in the air.
In dry soils, reduced water evaporation allowed plants to convert carbon into plant matter with greater efficiency. The vegetation functioned like a frugal engine that squeezes extra mileage from every drop of moisture. Around 2015, these arid ecosystems shifted so that efficiency became less tied to soil dampness and more dependent on absorbing atmospheric carbon dioxide. In contrast, humid forests experienced double suppression, where saturated canopies kept losing water through leaves and wet ground without gaining extra biomass.
Researchers tracked satellite and ground records across global ecosystems between 2000 and 2023 to measure carbon gain against water loss. Their attribution analysis revealed that improvements in soil water use efficiency accounted for 64.6 percent of the entire global trend. Hyper-arid ecosystems increased their efficiency by 15.9 percent over the study period, while humid regions experienced a negligible increase of 0.59 percent.
Land managers can now design region-specific restoration plans rather than applying uniform planting rules across different climates. The authors suggest using physical ground cover to stop evaporation in dry areas and adjusting tree spacing in humid forests to relieve moisture saturation.