Effects Of Soil Nutrient And Interspecific Competition On Traits And Nitrogen And Phosphorus Acquisition Of Invasive And Native Plants

Biological invasion is one of the hotspots in ecology,and soil nutrients have important effects on the growth and expansion of invasive and native plants.We conducted a greenhouse experiment with two invasive plants(Alternanthera philoxeroides and Wedelia trilobata)and their native congeners(A sessilis and W.chinensis)in different soil nutrients.We measured the growth and functional traits as well as nitrogen and phosphorus acquisition efficiency to test whether invasive species obtain nitrogen and phosphorus more efficiently than native species,and whether functional traits can reflect nitrogen and phosphorus acquisition and soil microbial status.Results showed that soil nutrient level and nutrient heterogeneity affected functional traits of both invasive and native species.Without interspecific competition,with soil nutrient increased the leaf nitrogen content of A.sessilis decreasedand that of A philoxeroides increased.With interspecific competition,soil nutrient heterogeneity can decrease the root phosphorus content of W.chinensis,but increase that of W.trilobata.Increasing soil nutrient significantly promoted the growth of invasive and native species.Soil nutrient heterogeneity promoted the growth of A.sessilis and W.chinensis.Interspecific competition decreased the total biomass of A.sessilis in the high nutrient level,but increased the root shoot radio of W.chinensis in the medium nutrient level.The nitrogen acquisition efficiency of A.philoxeroides and W.trilobata increased continuously with soil nutrient increased.The phosphorus acquisition efficiency of the four species was the highest in the middle soil nutrient level.There were significant positive relationships between rhizosphere soil microbial carbon and root nitrogen,but significant negative relationships between the acquisition efficiency of leaf nitrogen,root nitrogen and leaf phosphorus and leaf dry matter ratio.The leaf dry matter content can reflect the nitrogen and phosphorus acquisition efficiency and the root nitrogen may reflect the soil microbial carbon.