Figure 1

The projected global climate suitability for ESC under the historical climate, (a) without irrigation, (b) with 2.5 mm in the summer and 1.5 mm in the winter top-up irrigation and (c) with a composite risk irrigation scenario (where areas are not under irrigation, the EI of the natural rainfall scenario is mapped, while with areas under irrigation the EI of the irrigation scenario is mapped), using the CLIMEX EI. Slash indicate the distribution countries of tree-of-heaven. Green points indicate the distribution locations of tree-of-heaven. Yellow indicates areas of marginal suitability (0 < EI ≤ 10); Orange indicates areas of moderate suitability (10 < EI ≤ 20); Red indicates areas of optimal suitability (EI ≥ 20). The map in this figure was generated by ArcGIS 10.1 (ESRI, Redlands, CA, USA, http://resources.arcgis.com/en/home/).