Weed inhibition by sowing legume species in early succession of abandoned fields on Loess Plateau, China

A major constraint on vegetation succession on abandoned land is dominance by early successional species. Our aim was to inhibit weeds and alter the initial vegetation succession by the introduction of legume species (Medicago sativa, Melilotus suaveolens, and Astragalus adsurgens) into abandoned fields on the Loess Plateau, China. Results from our study showed that the addition of legume species strongly affected the dominance pattern of the abandoned-field vegetation. The number of naturally colonizing species was inhibited by the introduction of legume species in the first two growing seasons. The strongest effect on weed inhibition appeared by sowing Melilotus suaveolens. Vegetation cover and above-ground biomass increased after introduction of legume species and the number of naturally colonizing plant species showed a positive correlation with above-ground biomass. Later successional species like Stipa breviflora and Astragalus polycladus appeared three years following the introduction of Melilotus suaveolens, indicating that the course of old-field succession may be accelerated by introducing legume species such as Melilotus suaveolens, at least temporarily.