Although both the general-purpose genotype hypothesis and the hypothesis of the evolution of invasiveness predict that invasive species are characterized by particular traits that confer invasiveness, what these traits are still remains unclear. A theory put forward by a CAS botanist and colleagues suggests that the success of an invasive plant in a new habitat is due to its allocation of more nitrogen to its photosynthesis. The hypothesis has been supported by their research on the metabolic comparison between an invasive shrub and five native plants. This pioneering work was reported in a recent issue of Oecologia.

  As an important contributor to the on-going trend of global change, bio-invasion is a serious ecological problem. The rampant propagation of invasive species poses a threat to the bio-diversity worldwide, the structure and functions of an ecosystem, agriculture, afforestation and animal husbandry. The study of bio-invasion is not only of theoretical significance, but is conducive to the risk assessment of an invasive species, its early prediction, prevention and scientific management. Yet, so far, none of conclusive theories is available for explaining the powerful stamina owned by an invasive species in a new habitat.

    Prof. FENG Yulong with the CAS Xishuangbanna Tropical Botanic Garden (XTBG) and co-workers suggest that an invader has higher resource capture ability and utilization efficiency than the natives. To verify their hypothesis, the researchers compared the eco-physiological traits of eight European populations of the invasive plant Buddleja davidii Franchchet and five native woody species in the aspect of nitrogen allocation. They discovered that B. davidii allocated a higher fraction of leaf nitrogen to the photosynthetic machinery than the five native species. This was the most important difference between the invader and the natives, leading to a higher resource capture ability and utilization efficiency in the invader. The invasive species might have possessed the nitrogen allocation trait before introduction. Alternatively, it might have acquired the trait by evolution after introduction. According to the evolution of increased competitive ability hypothesis, an invasive species may increase nitrogen allocation to photosynthesis by reducing allocation to defense.

    In order to further test the theory, botanists at XTBG are conducting comparisons between invasive and native species in close affinity and between invasive populations and indigenous populations of an invasive species. At the same time, their work is designed through consideration of the influence imposed by ecological conditions and ontogenetic stages.