[Changes of climate niche of Solidago canadensis during its invasion in China]

Niche conservatism is essential for predicting the risk of alien species invasions. Currently, the changes of climate niche of Solidago canadensis during its invasion in China are still not clear. Using principal component analysis, we examined the climate niche shifts of S. canadensis during its invasion and analyzed its potential distribution in China. The results showed that, throughout its invasion in China, S. canadensis retained the climate niche characteristics of its native range (Stability index: 0.776), exhibiting strong niche conservatism. However, there were notable differences between the climate niches of the invasive and native populations. Such differences were primarily caused by the high level of niche unfilling (Unfilling index: 0.818) in its climate niche. Moreover, a certain degree of niche expansion (Expansion index: 0.224) was observed. These indicated that the invasion of this species was far from saturation and still had significant potential for further expansion in China. Therefore, the climate niche of S. canadensis primarily exhibited a conservative state after invading China, but there was also a certain degree of niche shift. S. canadensis was mainly in a stable invasion stage in East, Central, South, and Southwest China, while it was in a localized adaptation stage in the North and West China. These regions were the focus areas for prevention and control measures against S. canadensis in the future. The main climatic factors affecting the distribution of S. canadensis were precipitation of the driest month and mean temperature of the coldest quarter. During its invasion in China, the climate niche of S. canadensis shifted towards areas with higher temperature in the coldest quarter, drier in the dry season, and more precipitation in the warm and humid seasons. In conclusion, our results suggested that S. canadensis has strong adaptability, and the expansion of climate niche may further promote its invasion in China.