LAUSR

PREMISE Many studies have assessed the various responses of alien plants to changes in overall nutrient or different nitrogen (N) availabilities. However, in natural soils, nutrients are present as different elements (e.g., N and phosphorus [P]) and forms (e.g., inorganic and organic). Few studies have explored whether invasive and native species differ in their responses to varying P availability and forms. METHODS We grew five taxonomically related pairs of common herbaceous, invasive and native species alone or in competition under six different conditions of P availability or forms and assessed their growth performance. RESULTS Invasive species overall did not produce more biomass than native species did in the various P conditions. However, the biomass response to organic forms of P was, relative to the response to inorganic forms of P, stronger for the invasive species than that for the native species and agreed with invasive species mainly allocating biomass to the root system under organic P conditions. CONCLUSIONS While invasive species were not more promiscuous than the native species, they took great advantage of the organic P forms. Therefore, the invasion risk of alien species may increase in habitats with more organic P sources.