Feasibility of planting shrubs in arid areas from a water balance perspective

Large-scale afforestation in drylands has ignited considerable debate. However, the water balance and the influencing factors of afforestation in these areas remain unclear, limiting our understanding of water cycles in drylands. We conducted a long-term monitoring of ecosystem water fluxes from 2021 to 2023, utilizing eddy covariance techniques and micro-lysimeters to quantify the water sources, losses, and balance associated with artificially planted Haloxylon ammodendron shrubs on the northeastern edge of the Tengger Desert in China. Dewfall accounted for approximately 19–34 % of precipitation, representing an important component of the water balance in arid areas that lack runoff and groundwater recharge. The mean annual evapotranspiration (ET) was close to the sum of precipitation (150 mm) and dewfall (35.9 mm). The change in soil water storage (ΔS) to a depth of 1 m was minimal (4.4 mm), indicating a nearly neutral water balance. The influence of precipitation on the water balance was more significant than that of ET. In the drought year of 2023, lower precipitation, combined with reduced dewfall and soil water storage (SWS), led to a mild negative water balance. Conversely, in the wet year of 2021, higher precipitation and dewfall resulted in a positive water balance. Correlation analysis and random forest modeling identified relative humidity, solar radiation, soil temperature, and moisture content as key factors influencing components of the water balance. Our findings indicated that, with scientific planning and appropriate density, the planting of shrubs in arid areas is a feasible strategy in terms of water balance.