Effects of rhizosphere interactions of grass interspecies on the soil microbial properties during the natural succession in the Loess Plateau

Natural vegetation succession is a process of interactions between plants and various environmental factors. The dynamics of soil microbes during successional stages have been intensively explored in the past two decades. The effect of rhizosphere interactions of interspecies on microbial properties, however, has received less attention. During the early stage of succession on a Loess Plateau soil from China, we investigated microbial properties in the rhizospheres of three dominant grass species: Artemisia capillaris, Artemisia sacrorum and Stipa bungeana. Experiments with monocultured and polycultured potted plants were designed to determine the effects of rhizosphere interactions on plant growth and soil microbial properties. The results showed that root biomass, shoot biomass, plant height, microbial biomass carbon (C), microbial biomass nitrogen (N), invertase and urease activities, Gram-negative and Gram-positive bacteria were significantly higher for A. capillaris than for A. sacrorum and S. bungeana in both monocultures and polycultures. Lower root biomass, shoot biomass, plant height, microbial biomass C, microbial biomass N, invertase and alkaline phosphatase activities, and levels of microbial phospholipid-derived fatty acids in polycultures relative to the monocultures indicated that rhizosphere interactions led to lower plant growth and soil microbial activities. Our study suggests that rhizosphere interactions had a significant effect on the microbial properties of plant rhizospheres. The advantage of A. capillaris over A. sacrorum and S. bungeana in growth characteristics and rhizosphere microbial conditions is likely responsible for the dominance of A. capillaris in the early stage of succession in abandoned cropland on the Loess Plateau.