Effects of the expansion of Caragana shrubs on forage yield and plant diversity in desert steppe

In this paper, we studied the effects of the expansion of Caragana shrub on forage yield and plant diversity in desert steppe by field sample surveys. The results showed that:1) the height of herbs inside shrub canopies was significantly greater than that of herbs outside shrub canopies and non-shrub grasslands (P < 0.05), and the average biomass of herbs in the planted-shrub grassland was significantly higher than that of the natural-shrub grassland and non-shrub grassland; 2) the forage yield in planted-shrub grassland and natural-shrub grassland was significantly higher than that in non-shrub grassland, and the forage yield in planted-shrub grassland was significantly higher than that in natural-shrub grassland, indicating that Caragana shrubs significantly increased the forage yield-this effect was more pronounced in planted-shrub grassland; 3) the species richness, Simpson index, Shannon-Wiener index, and Pielou index of the herbs in planted-shrub grassland and natural-shrub grassland were lower than those in non-shrub grassland, indicating that Caragana shrubs had negative effects on the diversity of herbs; and 4) Caragana shrubs significantly enhanced the dominance of the useful forage species Stipa krylovii.