Dynamics of arbuscular mycorrhizal fungi in relation to root colonization, spore density, and soil properties among different spreading stages of the exotic plant threeflower beggarweed (Desmodium triflorum) in aZoysia tenuifolialawn

Abstract

AbstractWeed invasion is a prevailing problem in modestly managed lawns. Less attention has been given to the exploration of the role of arbuscular mycorrhizal fungi (AMF) under different invasion pressures from lawn weeds. We conducted a four-season investigation into aZoysia tenuifoliaWilld. ex Thiele (native turfgrass)–threeflower beggarweed [Desmodium triflorum(L.) DC.] (invasive weed) co-occurring lawn. The root mycorrhizal colonizations of the two plants, the soil AM fungal communities and the spore densities under five different coverage levels ofD. triflorumwere investigated.Desmodium triflorumshowed significantly higher root hyphal and vesicular colonizations than those ofZ. tenuifolia, while the root colonizations of both species varied significantly among seasons. The increased coverage ofD. triflorumresulted in the following effects: (1) the spore density initially correlated with mycorrhizal colonizations ofZ. tenuifoliabut gradually correlated with those ofD. triflorum. (2) Correlations among soil properties, spore densities, and mycorrhizal colonizations were more pronounced in the higher coverage levels. (3) Soil AMF community compositions and relative abundances of AMF operational taxonomic units changed markedly in response to the increased invasion pressure. The results provide strong evidence thatD. triflorumpossessed a more intense AMF infection thanZ. tenuifolia, thus giving rise to the altered host contributions to sporulation, soil AMF communities, relations of soil properties, spore densities, and root colonizations of the two plants, all of which are pivotal for the successful invasion ofD. triflorumin lawns.