Photosynthetic capacity of Erigeron canadensis L. may be more critical to its growth performance than photosynthetic area

Light acquisition and utilization may be vital to the successful invasion of invasive plants. Photosynthetic area and photosynthetic capacity are the two key indicators affecting light acquisition and utilization. Nevertheless, few investigators have verified the contribution intensity of photosynthetic area and photosynthetic capacity of invasive plants to their growth performance in the invaded communities, particularly under various invasion levels. This study aimed to evaluate the contribution intensity of photosynthetic area and photosynthetic capacity of the invasive weed Erigeron canadensis L. to its growth performance under various invasion levels. This study also elucidated the functional divergences in photosynthetic area and photosynthetic capacity between E. canadensis and natives in the communities under various invasion levels of E. canadensis . The invasion levels of E. canadensis were classified into the following three types: (I) without invasion, (II) light level of invasion, and (III) high level of invasion based on its relative abundance in the invaded communities. Photosynthetic capacity of E. canadensis was significantly greater than that of natives in the communities under E. canadensis invasion regardless of the invasion level. Photosynthetic area of E. canadensis was significantly lower than that of natives in the communities under E. canadensis invasion regardless of the invasion level. The direct effects and the indirect effects of photosynthetic capacity on the growth performance of E. canadensis were obviously higher than those of photosynthetic area. Thus, photosynthetic capacity of E. canadensis may be more critical to its growth performance than photosynthetic area during its invasion process.