A novel thermal index improves prediction of vegetation zones: Associating temperature sum with thermal seasonality

► EWI is a novel index that integrate temperature sum and thermal seasonality. ► Several indices are compared for Taiwan vegetation zone classification and mapping. ► The classification schemes of Taiwan vegetation are tested with 651 plots data. ► The EWI provides a generally superior prediction of vegetation with climate data. ► The EWI can improve the predictive accuracy of warmth index.