Effects Of Exotic Invasive Plants On Growth And Nitrogen Acquisition Strategy Of Native Plants

Biological invasion is a widespread ecological phenomenon. Exotic plant invasion will change biodiversity and ecological environment quality in invaded place, and threaten the global ecological environment and economic development. In order to understand what the effect of exotic invasive plants on growth and nitrogen acquisition strategy of native plants. In this study, we conducted a greenhouse experiment with two invasive plants (Alternanthera philoxeroides and Wedelia trilobata) and their native congeners (A. sessilis and W. chinensis) across monoculture and mixture plantings, to explore the effect of invasive plants represented by A. philoxeroides and W. trilobata on the growth and nitrogen acquisition strategy of native plant represented by A. sessilis and W. chinensis through 15N isotope tracer method. The results showed that:1. Congener interspecific competition had a positive effect on the growth of A. philoxeroides, while heterogeneric interspecific competition had a positive effect on the growth of A. sessilis. Congener interspecific competition and heterogeneric interspecific competition had no effect on other species.2. Exotic invasive plant A. philoxeroides and W. trilobata had no effect on soil nitrate, ammonium and microbial biomass nitrogen of native plants A. sessilis and W. chinensis.3. The nitrogen source preference pattern of four species was ammonium> nitrate> glycine. Congener interspecific competition reduced the nitrogen uptake rate of W. trilobata and A. sessilis respectively. Heterogeneric interspecific competition reduced the nitrogen uptake rate of W. trilobata, A. sessilis and W. chinensis respectively. Congener interspecific competition and heterogeneric interspecific competition had no effect on nitrogen uptake rate of other species.4. Because the impact of interspecific competition, ammonium is the favorite nitrogen of A. philoxeroides, A. sessilis and W. trilobata. Congener interspecific competition increased nitrate uptake by the W. chinensis. Heterogeneric interspecific competition increased nitrate uptake by the A. philoxeroides and A. sessilis. Heterogeneric interspecific competition transformed nitrogen source preference of W. chinensis from ammonium> nitrate and glycine to no obvious nitrogen source preference. Congener interspecific competition and heterogeneric interspecific competition had no effect on nitrogen source preference of other species.