Abstract: Based on the information of 82 geographical distribution locations of Excoecaria acerifolia Didr. in river valleys of Southwest China and 67 climatic factors, I analyzed the potential suitable areas and key climatic factors of E. acerifolia using Maximum Entropy (MaxEnt) and ArcGIS. The results showed that the potential suitable areas of E. acerifolia are mainly located in river basins of the eastern Himalayas, Hengduan Mountains, and Sichuan Basin of Southwest China, with the river basins of Hengduan Mountains in Yunnan and Sichuan Provinces as the core distribution areas. Precipitation of April, temperature annual range, temperature seasonality, minimum temperature of January, and maximum temperature of December are the key climatic factors affecting the potential distribution of E. acerifolia. Among those factors, precipitation of April is particularly critical, with a contribution rate of 42.29%. When the probability of presence of E. acerifolia is higher than 0.5, the ranges of the above five factors are: 49-95 mm, 23-28 ℃, 450-700, -5-5 ℃ and 7.5-13 ℃, respectively. Our results are basically  consistent with the distribution records of E. acerifolia, and can offer certain basis for the investigation and protection of germplasm resources, development and utilization of medicinal plants in the dry hot/warm river valleys, a special habitat of Southwest China.

Key words: Excoecaria acerifolia, suitable area, key climatic factor, Maximum Entropy, geographic information system.