Prediction of potential suitable region for Emex australis in China based on the optimized MaxEnt model

Objective  The aim of this paper was to analyze and predict the potential suitable regions of Emex australis in China and the major environmental variables affecting its distribution, and provide a theoretical reference for the prevention of the invasion ofE. australis into China and protection of the agricultural production and ecological security.

Method  The Jackknife was used to calculate the influence of each environmental variable on the species distribution. ENMeval was used to optimize the maximum entropy model (MaxEnt). Then the optimized model was used to predict the potential suitable region ofE. australis in China by inputting the distribution data of E. australis and the climate data under different climate scenarios.

Result  The main factor affected the distribution of E. australis was the mean temperature of the coldest month (Bio11), with a contribution rate of 27.7%. The environmental factor response curves showed that the emergence probability of E. australis was greater than 0.5, when the mean temperature of the coldest quarter ranged from 9.35 to 12.76 ℃. Results of the MaxEnt model showed that the suitable regions of E. australis in China were mainly in Yunnan, Guangdong, Guangxi and Fujian.

Conclusion  A normalized monitoring scheme should be established for the suitable area of E. australis. In the years when the mean temperature of the coldest quarter in the suitable region is good for its survival, monitoring efforts should be strengthened to prevent its colonization and distribution in China.