Water use efficiency responses in contrasting agroecosystems and land management practices in West Africa

Water use efficiency (WUE) is a key indicator of ecosystem balance, reflecting how productivity responds to hydrological constraints under climate change. However, variability in WUE and its environmental drivers across West African agroecosystems remains poorly understood. Here, we integrate multi-year (2019–2024), half-hourly eddy-covariance observations of carbon and water-vapor fluxes from four contrasting land-use types in northern Ghana: a reserve savanna forest, rain-fed paddy rice, grassland, and rain-fed cropland. WUE exhibited pronounced diurnal and seasonal variability, shaped by hydrological, atmospheric, and land-management drivers. Diurnal patterns were bimodal, with morning and afternoon peaks shifting between wet and dry seasons. During the wet season, mean WUE was highest in the savanna forest (3.1 ± 0.26 g C kg⁻¹ H₂O), followed by paddy rice (2.08 ± 0.21), cropland (1.93 ± 0.20), and grassland (1.66 ± 0.18). Seasonal analyses highlighted ecosystem-specific controls, reflecting differences in radiation, soil moisture, and cultivation practices.