Predicting the current and future cultivation regions of Carthamus tinctorius L. using MaxEnt model under climate change in China

Change in future climate will either expand, contract or shift the climatic niche of many species and this could lead to shifting of their geographical ranges. Prediction of suitable cultivation regions through modeling has evolved as a useful tool for the assessment of habitat suitability and resource conservation to protect medicinal plants. We modelled current and future distribution of C. tinctorius based on three representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5) for the year 2050s and 2070s using a maximum entropy model (MaxEnt) and geographical information system (GIS) in China. For modeling procedure 99 occurrence records and 11 Worldclim environmental factors was used in this paper. The results show that the area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate model performance. All of the AUCs were greater than 0.970, thereby placing these models in the “Excellent” category. The jackknife test also showed that maximum temperature in March (tmax3), maximum temperature in February (tmax2), maximum temperature in November (tmax11), precipitation in July (prec7) and precipitation in August (prec8) were the main variables. From the area of current distribution, of the total 6276666.77 km2 (65.36%) area, 27.28% area (2619895.88 km2) was highly suitable for safflower in China, and the highly suitable area (with suitability between 66 and 100) was mainly concentrated in Sichuan (2.74%), Yunnan (2.09%), Shaanxi (1.82%), Hubei (1.76%), Guizhou (1.66%), Henan (1.66%) and Hunan (1.64%). Xinjiang was the largest suitable area, which accounts for 9.70%. It was worth noting, realized niche was little planting in Sichuan province due to market and economic price factors, social factors and other factors. Compared to the current distribution, the total area of the poorly suitable regions and moderately suitable regions for safflower under the three RCPs (RCP2.6, RCP4.5 and RCP8.5) would increase in 2050s and 2070s. However, the total area of the highly suitable regions under the three RCPs (RCP2.6, RCP4.5 and RCP8.5) in 2050s and two RCPs (RCP2.6 and RCP4.5) in 2070s would decrease. This research would provide theoretical suggestions for the protection, cultivation management, and sustainable utilization of C. tinctorius resources to face the challenge of global climate change.