Temporal and spatial responses of soil carbon and nitrogen to artificial lakes in different degraded grasslands

The construction of artificial lakes in different degraded grasslands may improve the ecological environment of adjacent degraded grasslands, positively affect the nutrient flux in degraded grassland soil, and accelerate the restoration of degraded grasslands. In this study, the dynamics of soil nutrients at six different distances (10 m, 60 m, 100 m, 150 m, 250 m, and 600 m) from the artificial lake and differences among three years (2014–2016) were analyzed. The results were as follows: soil moisture and soil nutrients (organic carbon SOC, total nitrogen TN) in different degraded grasslands showed the " near-lake effect” in the short 3-year period after the lake was built, and soil moisture and soil nutrient content near the lake was higher. The soil moisture, organic carbon, and total nitrogen in the upper soil (0–10 cm) were higher than those in the lower soil (10–20 cm), the soil nutrients in the heavily degraded grassland (HG) were lower than those in the lightly degraded grassland (LG). In 2016, the TN at 150 m from the lake was ordered HG (2.03 g·kg^–1) < LG (2.78 g·kg^–1). The SOC in the HG increased by 10% (10 m), 44% (60 m), 48% (150 m), and 54% (250 m). However, the SOC in the LG only increased at the distance of 10 m from lake with increasing years, being up to 53%. The TN decreased with increasing years and decreased by 11% (HG) and 16% (LG) at 150 m from the lake. The results showed that the artificial lake affected the soil nutrient flow of adjacent degraded grasslands, especially in regard to distance, and exhibited some regularity.