Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and （or） the understory of closed forests, indicating the plant＇s performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate （RGR）, leaf root ratio （LRR）, leaf area ratio （LAR）, total leaf area, and lower root： shoot ratio （RSR）. Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency （PNUE） and photosynthetic energy use efficiency （PEUE） especially in low light and （or） unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency （WUE） indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and（or） light limited conditions, in which higher leaf construction cost（CC） compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light an
Eupatorium adenophorum is a noxious invasive weed that is distributed throughout subtropical areas worldwide.Enemy release may be at least one of the reasons underlying its success as an invader.In this study,we observed damage to the epidermis,cortex,phloem,cambium,and xylem tissues of roots and stems around the root collar of E.adenophorum growing in an experimental field in Yunnan Province,southwest China.The damage was caused by Dorylus orientalis,a polyphagous ant feeding on the weed and resulted in the death of the plants by interrupting nutrient exchange between shoots and roots.This ant showed selectivity for the invader to some extent.The finding of D.orientalis and other native enemies indicate that E.adenophorum may gradually naturalize in introduced landscapes.In addition,this ant may have potential for use as a biocontrol agent against the invader.
