Soil properties in natural grassland, Caragana korshinskii planted shrubland, and Robinia pseudoacacia planted forest in gullies on the hilly Loess Plateau, China

Revegetation plays an important role in controlling soil erosion and improving eco-environmental conditions on the Loess Plateau in China, yet little is known about its beneficial effect on soil properties in gully areas. In this study, we examined the relationship between three revegetation types and ten soil properties along five gully position transects on the loess hilly region of Ansai County, China. Three different vegetation restoration patterns in gullies included 1) an artificial Robinia pseudoacacia forest (G-Rp), 2) an artificial Caragana korshinskii shrubland (G-Ck), and 3) a natural grassland (G-Ng). After two decades of revegetation in the gully area, overall levels of C, N, P (except between G-Rp and G-Ck), and available K in the accumulated soil were similar between revegetation types in the gully areas. However, there were significant differences in levels of nitrate, ammonium, available P, and soil pH between the revegetated gullies. Soil properties mainly increased in quality from the top to the bottom of gully areas, except at the bottom of the G-Rp. Non-metric multidimensional scaling (NMS) ordinations and multi-response permutation procedure (MRPP) analyses indicated that soil properties significantly differed depending on revegetation types and gully positions. Our results demonstrate that soil properties could be improved by different revegetation types in the gully areas, and artificial plantations could significantly better improve available soil nutrients than natural grasslands in the gully areas. Thus, artificial revegetation could be a valuable measure for controlling soil erosion, and improving eco-environmental conditions in the gully areas of the Loess Plateau.