Abstract: In this paper,a comparative study was made on the growth,morphology, biomass allocation,and photosynthesis of two invasive plant species Ageratina adenophora and Chromolaena odorata under five soil phosphorus levels,aimed to know how the test plant species acclimate to the changes of soil phosphorus level,evaluate which plant traits were associated with the invasiveness of the two species,and know whether the increased level of soil phosphorus could facilitate their invasion.The results showed that the two species had considerable phenotypic plasticity and ?phosphorus acclimation ability.At low phosphorus levels,their root mass ratio increased,which could enhance the nutrient capture ability,while at high phosphorus levels,their specific leaf area,maximum net photosynthetic rate,light saturation point,and chlorophyll and carotenoid contents per unit area were high,and the assimilative capacity and area increased,which could facilitate their carbon gain.A.adenophora had higher phosphorus acclimation ability than C.odorata.With the increase of phosphorous level,the relative growth rate,total biomass,branch number,leaf area index,and maximum net photosynthetic rate of the two species increased significantly,and most of the parameters were not decreased significantly under over-optimal phosphorus level.The two species could grow better under high phosphorus levels which were usually excessive and/or harmful for most native species,and enhanced soil phosphorus level might promote their invasion.At high phosphorus levels,the two invasive plant species might shade out native species through increasing their plant height,branch number,and leaf area index.The two species could maintain relatively high growth rate under high phosphorus levels in dry season when native plant species almost stopped growing.The ability that the invasive plant species could temporally use natural resources which native plant species could not use was also associated with their invasiveness.

Key words: Capsicum frutescens, Metapopultion, Simulated insect pest, Modular, Compensatory response, Plant growth analysis, Principal component analsis