Understanding the Effect of Revegetated Shrubs on Energy, Water and Carbon Fluxes in a Desert Steppe Ecosystem Using STEMMUS-SCOPE Model

Abstract. Revegetation is one of the most effective ways to combat desertification and soil erosion in semiarid and arid regions. However, the perturbation of revegetation on ecohydrological processes remains to be studied, especially its effect on the complex interaction between the hydrological processes and vegetation growth under water stress. This study evaluated the effects of revegetation on the energy, water and carbon fluxes in a desert steppe in Yanchi County, Ningxia Province, Northwest China, by simulating two vegetated scenarios (shrubs-grassland ecosystem and grassland ecosystem) using STEMMUS-SCOPE model. The model was validated by field observations from May to September of 2016–2019. The simulated energy, water and carbon fluxes in 2016 and 2019 were used to evaluate the difference between two vegetated scenarios. Higher leaf area index and root water uptake of C3 shrubs (Caragana Intermedia) resulted in the increased carbon fixation (+ 82 %) and transpiration (+ 99 %) in the shrubs-grassland ecosystem compared to C3 grassland ecosystem. In both scenarios, turbulent energy was dominated by latent heat flux, which was stronger in the shrubs-grassland ecosystem (+ 13 %). With the remarkable increase in transpiration, revegetation induced the soil water losses, especially the soil water content within the 0–200 cm soil depth (- 19 %), and exaggerated the excess of water consumption over the received precipitation. These results emphasize the importance of accounting for energy and water budget in water-limited ecosystems during ecological restoration, to prevent soil water depletion. As an example, the consequence of increased transpiration should be further examined.