Effect Of Simulated Warming On Photosynthetic Adaptability And Reproductive Ecology Of Invasive Solidago Canadensis,Bidens Frondosa And Native Pterocypsela Laciniata

Climate warming has been changing the ecological environment that human being survived on, which caused increasing attentioans and researches. Climate change and biological invasions are two important drivers affecting biodiversity and ecosystem services. However, their effects have usually been considered separately. This study focused on the effect of temperature enhancement on growth characteristics, biomass allocation, flowering phenology and photosynthesis characteristics of invasive Solidago Canadensis, Bidens frondosa and native Pterocypsela laciniata through the way of simulating temperature enhancement by open-top chamber (OTC) in the field. Identifying the effects of warming on invasiveness of exotic plants is very important for improving our ability to predict and control potentially invasive species. The findings of the investigation are as follows:1) Simulated warming had significantly effect on growth, biomass and its allocation of S.Canadensis, B. frondosa and P. laciniata. To compare with the control plot, the results showed that warming significantly increased heights of the three species by10.71%,12.51%and8.44%, respectively. Warming significantly decreased leaf number for the invasive plants, but there was no significant effect on native plant. For S.Canadensis, Warming significantly increased root biomass, shoot biomass and total biomass, but significantly decreased leaf biomass. Moreover, warming drive S. Canadensis allocated more biomass to stems and roots and less to leaf than CK groups. For B. frondosa, simulate warming increased the shoot biomass, flower biomass and total biomass while decreased the leaf biomass. Warming altered biomass allocation pattern, to make B. frondosa allocated more biomass to stems and flower and less to leaf than control. For P. laciniata, simulate warming increased the shoot biomass while decreased the flower biomass, roots biomass and root/shoot ratio. In sumamary, the presents study suggests that simulate warming significantly enhanced the growth advantage and biomass accumulation and altered biomass allocation pattern of invasive Solidago Canadensis and Bidens frondosa.2) For S. Canadensis, Warming has advanced the first flowering date and the peak flowering date, the end of flowering was delayed, the flowering duration was longer, the individual has better flowering synchrony and significantly increased the weight of a thousand seeds and the percent germination of seed, There were no significant differences in the flower number, relative flowering intensity and seed size between the warming treatment and control. For B. frondosa, Onset time of flowering and the peak flowering date was earlier and duration of flowering was longer in warming than in control. simulated warming could significantly promote the flowering synchrony and thousand-kernel weight while the flower number, relative flowering intensity and seed size had no significant difference. For native P. laciniata, simulated warming had little effects on the first flowering date, relative flowering intensity, thousand-kernel weight and seed size, but significantly advanced the peak flowering date and the end of flowering, the flowering duration was shortened, the flowering synchrony and flower number was significantly decreased. Based on the results above, we conclude that short-term warming could significantly advanced S.Canadensis and B. frondosa flowered earlier, prolonged flowering duration and increased the numbers of the flower, seed size and quality, and thus, enhance the reproduction investment and invasiveness of the invasive plant S. Canadensis and B. frondosa.3) To compare with the control plot, the results showed that warming significantly increased the maximum net photosynthetic rate and the net photosynthetic rate of S.Canadensis. Photosynthesis parameters, saturation intensity, chlorophyll a, chlorophyll b and total chlorophyll of S.Canadensis in OTC were no significantly increased by50%,24.25%,46.8%,45%and46.5%, respectively, but the light compensation point decreased by19.83%. These data indicate that simulated warming increased the photosynthetic ability of S.Canadensis. Moreover, the maximum net photosynthetic rate, photosynthesis parameters, saturation intensity, chlorophyll a, chlorophyll b and total chlorophyll content of B. frondosa subjected to warming wereincreased by9.02%,50%,17.31%,13.08%、6.5%、13.77%, respectively, but the light compensation point reduced by19.83%, but the changes were not significant. In OTC, photosynthetic response curve and net photosynthetic rate of P. laciniata was lower than the control plots, at the same time, warming significantly increased the maximum net photosynthetic rate and total chlorophyll content. The light compensation point, apparent quantum yield and saturation intensity of P. laciniata in OTC was not evidently effected. Based on the results above, we conclude that warming enhanced the higher photosynthetic rate and material accumulation capability of S.Canadensis, B. frondosa, tipping the scales in favor of invasive plants.In conclusion, warming significantly enhanced the growth, biomass accumulation, photosynthetic rate and reproduction investment of invasive S.Canadensis and B. frondosa, implying that simulated warming associated with global change may facilitate the invasion of S.Canadensis and B. frondosa, and may enhance the vulnerability of native communities to invasion.