Mixed-species plantations can alleviate water stress on the Loess Plateau

In recent years, the ability of mixed-species plantations to cope with environmental changes has been a focus of research. Despite compelling evidence indicating that mixed-species plantations can provide many economic, environmental and social benefits, whether they can also enhance regional stress responses to drought remains unclear. Therefore, a meta-analysis was conducted based on 457 field observations to assess the effects of different planting patterns on the soil moisture of 500 cm on the Loess Plateau. The results showed that both monoculture and mixed-species plantations consumed significant soil moisture content. However, compared with monoculture plantations, mixed-species plantations were better able to maintain the soil moisture at 0-400 cm. Soil moisture content varied by topography, climate, vegetation species and planting age. We observed that afforestation was a good choice for areas with the high precipitation ( > 500 mm), the middle elevation (1200-1600 m) and slope (20-30 degrees). Furthermore, the arbors mixed with shrubs did not significantly consume the soil moisture content and was more sensitive to the change in planting ages. In addition, the response sizes of soil moisture among different vegetation species were negatively correlated with the initial soil moisture content. We therefor concluded that mixed-species plantations, especially arbors mixed with shrubs were conducive to enhancing drought resistance in arid and semiarid regions. In considering future afforestation activities, planners need to be aware that different environments support different vegetation species and patterns. This study provides a reference and guidance for the scientific planning and sustainable development of forest ecosystem in arid and semiarid regions.