Exploring water use and production dynamics of an indigenous African dry forest in south-western Zimbabwe

Monitoring carbon and water vapour dynamics over a landscape helps in understanding ecosystem functioning. The study sought to determine ecosystem stability and production. We evaluated trends and step changes in water use efficiency (WUE), rainfall use efficiency (RUE), evaporative index, rainfall, evapotranspiration (ET) and carbon use efficiency (CUE). These remained stable throughout the study period. Miombo woodland and savannah had significantly (p < 0.05) higher actual ET (ETa) and production compared to Vachellia and Teak clusters. The Vachellia and Teak clusters became sources of carbon during the dry season. Xylem rehydration and convergent evolution could explain high production in the Miombo cluster during the dry season. Despite relatively small spatial coverage (12%), the Vachellia cluster contributed production similar to Teak and Miombo woodlands clusters due to soil fertility. Teak had the highest CUE (62%) but lowest NPP, possibly due to high respiration. The relationship between rainfall, NPP and measures of ecosystem stability was unimodal, indicating the upper limits of landscape production. The low RUE of the Teak cluster suggests that this cluster was more sensitive to disturbance. Monitoring carbon and water fluxes dynamics help to identify the onset of ecosystem change to enable implementation of requisite interventions.

Automated summary

Monitoring carbon and water vapour dynamics over a landscape helps in understanding ecosystem functioning. The study evaluated ecosystem stability and production, finding that Miombo woodland and savannah had higher actual ET and production compared to Vachellia and Teak clusters. Teak had the highest CUE but lowest NPP, indicating sensitivity to disturbance. This monitoring helps to identify the onset of ecosystem change and implement necessary interventions.