Introduction of woody and herbaceous legumes influences productivity, diversity and soil properties in a degraded grassland

Abstract

AbstractMedicago sativa (herbaceous plant) and Caragana korshinskii (woody plant) are the most important legume species planted in semiarid grassland on the Loess Plateau, China. However, the effects of introducing these legumes on the productivity, diversity and soil fertility of native grassland are not well understood. The effects of planting M. sativa and C. korshinskii on the productivity, diversity and soil properties of native grassland on the Loess Plateau were assessed over a 10‐year period. A 20‐ha area of grassland was selected for planting in 2009 and subdivided into 18 1‐ha plots with three treatments: 1) a non‐planted control (GN); 2) M. sativa (GM) and 3)C. korshinskii (GC) both planted individually, with six replicates. Ten subplots were established in each plot from which plant and soil samples were collected in August 2019. Compared with GN, GM and GC increased vegetative cover by 12.1 and 9.0%, respectively. Soil organic carbon (OC), total nitrogen (TN), ammonium nitrogen (NH4+‐N), nitrate‐nitrogen (NO3−‐N) and total phosphorus (TP) were also higher (p <.05) in the GM and GC treatments. Compared with GN, GM had no effect on native grassland productivity but did reduce species richness and evenness. In contrast, GC increased grassland productivity and maintained species richness and evenness. This suggests that C. korshinskii is the preferred legume species for grassland restoration on the Loess Plateau.