The objective of this study was to predict the changes of vegetation distribution due to unsuitable environmental conditions for tree species. The habitat of forest vegetation is determined by environmental factors, such as temperature and precipitation. It is useful to apply the thermal and hydrological gradients for assessing the current distribution of forests and for predicting the future changes of forest habitats. In this study, we applied the Warmth Index (WI) and the mean Minimum Temperature Index of the Coldest month (MTCI) as the thermal indices. For hydrological indices, we employed water supply index, moisture input index, and wetness index. The thermal and hydrological indices are based the past and future climatic data from Korea Meteorological Administration and National Institute of Meteorological Research. The future climatic data was under the A1B scenario of the IPCC. Then, we defined a new Plant Functional Types (PFTs) according to optimal habitat ranges of the thermal and hydrological indices for the selected tree species, so called the ‘Thermal Analogy Groups (TAG)’ and ‘Hydrological Analogy Groups (HAG)’. As a result, we could predict the potential changes in forest distribution of Korea from the past (1971-2000), the near future (2021-2050), and the far future (2071-2100).