Impact of climate change
Global climate is changing but its rate and impacts are localized(IPCC, 2013). Amplitude of the variation differed from area to area under future climate change scenarios. So, shifts of high suitable habitat ofA. annua would present out different patterns in different regions in the future scenarios. In our study, the ranges of high suitable area of A. annua in some areas would expand, some would remain stable, some would shrink, even disappear. In Europe, its high suitable habitat would shrink in the coast area of Atlantic Ocean, and expand in the south of Finland and the northwest of Russia. A good agreement could be observed between our simulation and the one made in other studies. Thuiller (W. Thuiller, Lavorel, Araújo, Sykes, & Prentice, 2005) stated that the total suitable area of forest herb in Europe would move strongly northwards and eastwards under future climate scenarios. In Asia, the expand area scatters in southwest border of China, and shrinks in 40°N in China. This may be caused by the unique topography. There were many mountains. And it should be point out that the high suitable habitat for A. annua in North America almost disappeared in the future. This was in accordance with previous studies about extinction risk of North American seed plant(Zhang et al., 2017). They predicted that most species belong in Artemisia would suffer distribution loss in the future.
In conclusion, we simulated the potential distributions of A. annua under current and future climate scenarios across the world, and predicted its range shift in different periods and Shared Socio-economic Pathways. In our study, with better performance than sole species distribution model, ensemble model was qualified for simulating the potential distribution of A. annua . Among 20 environmental factors, BIO9 (Mean temperature of driest quarter) had the strongest ability of shaping the range of the target species. Its potential distribution under present climate scenario was in accordance with the actual range. It was predicted that the high suitable habitat ofA. annua would decrease under the climate change in the future. Its high suitable habitats would disappear in North America, and move northeastwards in the Europe. Our simulation and forecast could be used to protect the wild resource of A. annua and provide theory guidance for field selection in its cultivation and management. Finally, we hoped that this study could make modest contribution to fight malaria.