Fig. S6. Uncertainty map of the prediction of potential tree cover. The uncertainty is calculated at the pixel-level as the standard deviation among the k tree cover layers predicted from the k models developed from the k-fold cross-validation. The bimodal distribution of the standard deviation is illustrated within caption (A), showing a peak at 0% and another at 7% of standard deviation in tree cover. The resulting map (A) shows higher uncertainty in regions with intermediate potential tree cover and low uncertainty in regions with low (e.g. desert) or high (rainforest) tree cover levels. One exception remains, with higher levels of uncertainty in tropical wet forests of Central Africa (C) vs. other tropical wet forests (B).