Modelling the geographic distribution of Malus baccata

Specimens of Malus baccata from some herbaria including the Institute of Botany, Chinese Academy of Sciences Herbarium (PE) were reidentified in light of the latest taxonomic outcome of the genus Malus Mill. and 358 valuable distribution records were selected and digitized into the geographic coordinate data. Based on these data, the updated geographic distribution is mapped using DIVAGIS. This distribution presents a pattern extending mainly from the northeast to southwest, and secondarily from northwest to southeast. There are almost equal numbers of varieties in the southwest, central and northeast regions. Nineteen climate variables of the distribution points that fall in the envelope of variables of the world climate (spatial resolution arc 30 s) were analyzed by principal component analysis. Annual precipitation, isothermality, precipitation of the warmest quarter were found to be dominant factors affecting the geographic distribution of M. baccata; moreover, there are certain niche intervals of the dominant factors among the varieties, and niche overlaps only to some outliers. The present and future potential distribution maps are predicted by BIOCLIM with current and future climate conditions that are the world climate (spatial resolution arc 30 s). The results show that some highly suitable areas of the present potential distribution migrate southeastward, the whole future potential distribution extends northward, and some most northerly distribution points disappear; the overall range of distribution reduces.