Silvopastoral Systems Enhance Herbaceous Plant Richness and Abundance in the Low Hilly Area of Western Henan Province, China

Although silvopastoral systems are widely recognized to improve ecosystem services, empirical evidence regarding their long-term effects on herbaceous diversity during succession remains scarce. In 2011, we established a silvopastoral experiment in the low hilly area of western Henan Province, China. Four pure forest plots—poplar (Populus simonii, PS), oriental thuja (Platycladus orientalis, PO), Chinese cork oak (Quercus variabilis, QV) and black locust (Robinia pseudoacacia, RP)—were planted on natural wasteland, with perennial alfalfa (Medicago sativa, MS) intercropped to form silvopastoral systems (PS-MS, PO-MS, QV-MS, RP-MS), with a natural wasteland plot serving as the control (CK). In July 2024, we investigated the species density, richness, and aboveground biomass of herbaceous communities across all plots. Species composition differed significantly between MS and CK, PS-MS and PS, and PO-MS and PO. Silvopastoral systems and MS generally exhibited higher density, richness, and biomass than pure forests and CK. Furthermore, MS and silvopastoral systems showed uniform density and biomass across slope positions, whereas CK and pure forests had higher values downslope, along with shifts in relative biomass. Except for MS and PS-MS, all plots had higher species richness downslope. Soil nutrient properties were closely correlated with the biomass, richness, density, and functional groups. These findings indicate that silvopastoral systems can significantly increase herbaceous density, richness, and biomass and alter species composition, with the effects varying by the dominant tree species.