Global meta-analysis of water cycling response to plant mixture

Plant mixtures maintain irreplaceable ecosystem services through biodiversity conservation, guarantee food security, and buffer climate change. However, the effects of plant mixing on the water cycle remain poorly understood despite the significance of the water cycle in maintaining life on Earth. Here, we conducted a meta-analysis using a global data set of 1,631 paired observations from 88 publications to explore how plant mixtures affect seven critical water cycle processes (soil water content, runoff, infiltration, soil evaporation, canopy transpiration, throughfall, and water use efficiency). We found that plant mixtures reduced mean soil water content (1.5 %), runoff (12.3 %), and soil evaporation (7.8 %), while improving soil infiltration (42.7 %), leaf transpiration (13.5 %), and water use efficiency (40.9 %). The effect size of plant mixtures greatly depended on ecosystem types; crop mixtures significantly reduced soil evaporation (10.7 %) and runoff (22.1 %), whereas mixed forest and agroforestry systems significantly enhanced soil infiltration rates. Moreover, the effect size of the plant mixture also varied with climate (mean annual precipitation), soil properties (organic matter content, bulk density, and total nitrogen content), and management practices (crop type, fertilization, and irrigation). In plant minutes, resource complementarity, abiotic facilitation and biotic feedback may be the underlying mechanisms that regulate water cycle. This work highlights the importance of plant mixtures in facilitating positive water cycles and provide insights into the establishment of sustainable artificial ecosystems.