Although many studies have documented the effects of global warming on invasive plants, little is known about the effects of warming with different DTR (asymmetric warming) on plant invasion. We tested the impact of asymmetric warming on four invasive and four native species of the family Asteraceae. Four temperatures (control and three warming by 3°C with different DTR) of wintertime and summertime were set, respectively. Control (Tc) was the mean temperature, and the three warming patterns were symmetric (i.e. equal night-and-day) (DTRsym), increased (DTRinc) and decreased (DTRdec) DTR warming.
Results/Conclusions
No significant impact of asymmetric warming on seed germination was observed. The invasive plants had greater biomass than the native ones under all the temperatures, and warming caused the invasives allocate more biomass to stem. This suggests that warming may increase the invasiveness and benefit the northward expansion of the invasives. Consider merely the impacts of the three warming patterns on the invasives per se, previous studies of the symmetric warming DTRsym may have overestimated the benefit of invasives due to warming. However, DTRdec decreased the biomass of the natives more greatly than the invasives, compared with the corresponding symmetric warming DTRsym, which suggests a different conclusion when we compared the impacts of warming on the invasives with those on the natives. Therefore, conclusions regarding the effects of future warming should be made cautiously because the different controls or references and warming with different DTR may lead to different estimation of invasion.