Effects of shelter forest on rates and spatial patterns of soil erosion in a cultivated land

The ¹³⁷Cs tracer technique was used to study the effects of shelter forests on rates and spatial patterns of soil erosion in a cultivated land (CL) in the Bashang Region of Zhangjiakou City. The results showed that ¹³⁷Cs was uniformly distributed in the soil profile of CL, and an exponentially decreasing trend of ¹³⁷Cs concentration from the top to bottom layer of soil profile was observed in a shelter forest land (SFL). ¹³⁷Cs inventories in SFL along the primary wind direction (ASFL), SFL perpendicular to the primary wind direction (PSFL), and CL were estimated to be 3148.38 ± 228.91 Bq·m^–2, 2548.09 ± 202.56 Bq·m^–2 and 1687.43 ± 174.99 Bq·m^–2, respectively. ¹³⁷Cs inventories in ASFL were the highest, while those in CL were the lowest. Soil erosion rates in CL, PSFL, and ASFL were estimated to be 4446.04 ± 208.68 t·(km²·a)^–1, 2514.56 ± 181.08 t·(km²·a)^–1, and 1357.32 ± 301.56 t·(km²·a)^–1, respectively. Meanwhile, the effects of shelter forest on rates and spatial patterns of soil erosion in CL were evident. In CL, ¹³⁷Cs inventories exhibited a decreasing trend and soil erosion rates exhibited an increasing trend as the distance from FSL increased, indicating that shelter belts play important roles in protecting the CL from wind erosion because the surrounding shelter forest is mature. Simultaneously, as distance from ASFL decreased, ¹³⁷Cs inventories in PSFL exhibited an increasing trend. Additionally, ¹³⁷Cs inventories in ASFL were obviously higher than those in PSFL, indicating that PSFL experienced greater soil loss than did ASFL. These results indicate that the surrounding shelter belts play a critical role in altering the spatial patterns of soil erosion and reducing wind erosion rates in the CL in northern China.