Predicting the invasion distribution of three Amaranthus species (Amaranthus blitum, A. spinosus and A. palmeri) under the current and future climate change scenarios in China

The Amaranthus genus (Amaranthaceae), which includes approximately 70 species globally, poses a significant risk of biological invasion in China. The current study simulated the potential distribution of three invasive Amaranthus species ( Amaranthus blitum L., Amaranthus spinosus L. and Amaranthus palmeri S.Wats.) under climate scenarios in China. The models achieved excellent prediction performance, with A. blitum , A. spinosus and A. palmeri having area under the curve values of 0.948, 0.926 and 0.928, respectively. Temperature Seasonality (BIO4) is the primary factor influencing the distribution of A. blitum , while the distribution of A. spinosus is mainly driven by both Temperature Seasonality (BIO4) and Annual Precipitation (BIO12). The distribution of A. palmeri is determined by both Precipitation Seasonality (BIO15) and elevation (Elev). Under current climate conditions, the highly suitable areas for A. blitum and A. spinosus are concentrated in South and Southwest China, whereas those for A. palmeri , are primarily distributed in the North China Plain. Under future climate scenarios, the suitable areas for A. blitum exhibited a high degree of climate envelope conservatism, with its distribution centroid showing only a slight localized southwestward fluctuation around its original distribution. In contrast, the suitable areas for A. spinosus exhibited a slight overall expansion toward the northeast, and its centroid showed signs of retreating southwestward under SSP585-2070s. Amaranthus palmeri had a significant and long-distance shift northwestward, which is strongly linked to changing thermal conditions. This study revealed the spatiotemporal dynamics of three invasive Amaranthus species under current and future climate scenarios and provides a scientific basis for developing proactive early warning management response strategies for these invasive species in China.