Different responses of invasive and native species to elevated CO2 concentration

Increasing atmospheric CO2 concentration is regarded as an important factor facilitating invasion. However, the mechanisms by which invasive plants spread at the expense of existing native plants are poorly understood. In this study, three invasive species (Mikania micrantha, Wedelia trilobata and Ipomoea cairica) and their indigenous co-occurring species or congeners (Paederia scandens, Wedelia chinensis and Ipomoea pescaprae) in South China were exposed to elevated CO2 concentration (700 μmol mol−1). The invasive species showed an average increase of 67.1% in photosynthetic rate, significantly different from the native species (24.8%). On average the increase of total biomass at elevated CO2 was greater for invasive species (70.3%) than for the natives (30.5%). Elevated CO2 also resulted in significant changes in biomass allocation and morphology of invasive M. micrantha and W. trilobata. These results indicate a substantial variation in response to elevated CO2 between these invasive and native plant species, which might be a potential mechanism partially explaining the success of invasion with ongoing increase in atmospheric CO2.