The suitability of geographic distribution and the dominant factors of alfalfa based on MaxEnt model in Xilin Gol

The maximum entropy (MaxEnt) species distribution model combined with the existing geographic distribution record of alfalfa was employed in the present study. Ten variables correlated with growth of alfalfa (Medicago sativa) were selected for analysis which included 7 climate variables (annual precipitation, global radiation, temperature of the coldest month, mean annual temperature, the lowest temperature of green period, average temperature in August, air humidity in August) and 3 three soil variables (soil pH, soil thickness, soil organic matter content). The percent contribution of variables for alfalfa suitability and the dominant factors were calculated by Jackknife module of maximum entropy model. The results showed that AUC value of training data and test data were 0.913 and 0.889, respectively, which reached in “Accurate” level. Maximum entropy model can simulate the geographical distribution of alfalfa. The most suitable area(P＞0.50) for alfalfa cultivation were 9.8×103 km2 which mainly distributed in the south and southeast Xilin Gol and accounting for 7.7% of the total area. Meanwhile, our study also showed that the dominant factors affecting the geographic distribution of alfalfa were annual precipitation, temperature of the coldest month, the lowest temperature of green period, air humidity in August.