Comparisons of Irradiance Utilization Efficiency by Invasive Chromolaena Odorata and Its Three Co-Occurring Species in One Planted Understory

High irradiance utilization efficiency is one important character for some invasive plants. Chromolaena odorata is one noxious invasive species originating from Latin America, which had spread widely in most tropical and subtropical areas. To explore why C. odorata perform better than native plants in the understory of planted forests, we compared the irradiance utilization efficiency between invasive C. odorata and three co-occurring species (Merremia vitifolia, Pueraria phaseoloides, and Litsea monopetala). We found that C. odorata had lower leaf thickness but higher specific leaf area, net photosynthetic rate per leaf thickness and photosynthetic nitrogen use efficiency than the three native species. The photosynthetic resistance to irradiance damage was stronger for C. odorata than for the three native species. These traits may have contributed to the higher performance of C. odorata than native plants, which may in turn facilitate its invasion in the understory.