2.4 Analysis of multivariate environmental similarity surface
We used the multivariate environmental similarity surface (MESS) to analyze the degree of ecological change of PWD in the distribution area in the future. The reference layer of bioclimatic factors was determined using MESS analysis. The similarities among bioclimatic factors under different climatic conditions and the set points of bioclimatic factors in the refence layer (similarity, S) were calculated. Because the value of S was positive, the smaller the value, the more significant the climate difference was; no difference existed because the value of S was 100. The value of S for at least one bioclimatic factor was beyond the refence range because the value of S was negative. The environmental change at the point was good (Elith et al. , 2010). The prediction was made by running the “Density. Tools. Novel” tool in the MaxEnt .jar file in the command window.