## 2 Materials and Methods
### Generation of Thematic Maps for Environmental Factors  
To generate the composite suitability map, thematic maps for environmental factors such as elevation, aspect, and slope were created using a digital elevation model (DEM) with a spatial resolution of 10 m \(\times\) 10 m, generated from a 1:5000 digital topographic map in shapefile format provided by the National Geographic Information Institute of South Korea. The forest type (tree species) was derived from the 1:5000 large-scale forest-type map in shapefile format provided by the Korea Forest Service, and regions unsuitable for GE cultivation, such as non-stocked forest land, grassland, and orchards, were removed before creating the thematic map. To obtain precise results, the soil depth and texture were analyzed using a 1:5000 large-scale forest soil map in shapefile format provided by the Korea Forest Service. For factors not included in the large-scale forest soil map in shapefile format, such as soil moisture, organic matter content, and drainage, thematic maps were created using the 1:25,000 5 th forest soil map provided by the Korea Forest Service. All thematic maps were generated in the raster format with a spatial resolution of 10 m \(\times\) 10 m.  
To create thematic maps for the temperature factors, this study calculated and utilized the geo-temperature index (gT; \({}^{\circ}\)C). WorldClim versions 1 [42] and 2 [43], and CHELSA (Climatologies at High Resolution for the Earth's Land Surface Areas) version 1.2 [44] are excellent datasets for understanding the climate of terrestrial areas worldwide. However, \begin{table}
\begin{tabular}{c c c c} \hline
**Factor** & **Criterion** & **Rank** & **Weight** \\ \hline Elevation (m) & 700\(\leq\) elevation \(<\) 700 & 2 & 0.67 \\  & \(<\)400 & 3 & 0.33 \\ Aspect & Southeast & 1 & 1 \\  & Others & 2 & 0.5 \\ Slope (\({}^{\circ}\)) & \(<\)15 & 1 & 1 \\  & 15\(\leq\) & 2 & 0.5 \\ Forest type (tree species) & _Quercus acutilsima_, _Q. mongica_, & 1 & 1 \\  & _Q. variabilis_, Another _Quercus_ spp. & & \\  & Others & 2 & 0.5 \\  & 60\(\leq\) & 1 & 1 \\ Effective soil depth (cm) & 30\(\leq\) depth \(<\) 60 & 2 & 0.67 \\  & \(<\)30 & 3 & 0.33 \\ Soil texture & Loan, Sandy loam & 1 & 1 \\  & Others & 2 & 0.5 \\  & Moderately moist & 1 & 1 \\ Soil moisture & Slightly dry, slightly moist & 2 & 0.67 \\  & Dry, wet & 3 & 0.33 \\  & 4\(\leq\) & 1 & 1 \\ Organic matter content (\%) & 2 \(\leq\) organic content \(<\) 4 & 2 & 0.67 \\  & \(<\)2 & 3 & 0.33 \\  & Good, very good & 1 & 1 \\ Drainage & Moderate & 2 & 0.67 \\  & Poor & 3 & 0.33 \\ Growing season temperature (April–November) (\({}^{\circ}\)C) & 15 \(\leq\) temperature \(<\) 30 & 1 & 1 \\  & Other & 2 & 0.5 \\ Active growth period temperature (June–October) (\({}^{\circ}\)C) & 20 \(\leq\) temperature \(\leq\) 25 & 1 & 1 \\  & Other & 2 & 0.5 \\ Summer temperature (June–August) (\({}^{\circ}\)C) & 30\(\leq\) & – & Exclusion \({}^{\times}\) \\ Winter temperature (December–February \({}^{\circ}\)C) & \(\leq\)\(-\)15 & – & Exclusion \({}^{\times}\) \\ \hline \end{tabular} \({}^{\mathrm{a}}\) Winter in South Korea spans December of the current year to February of the following year. \({}^{\mathrm{a}}\) Regions identified as extreme-temperature regions are excluded from the composite suitability map.  
\end{table} 
Table 1: Factors selected for suitable GE cultivation site analysis and weight assignment based on these criteria. with a spatial resolution of approximately 1 km\({}^{2}\), they are deemed suitable only for large-scale regional analysis. In this study, we focused on a small-scale area and thus generated and used thematic maps for temperature factors with a relatively higher spatial resolution of 10 m \(\times\) 10 m. The geo-temperature index represents the relative temperature variation with elevation (\(EL\); m), considering the temperature lapse rate (\(TLR\); \({}^{\circ}\)C/m), base elevation (\(BaEL\); m), and base temperature (\(BaT\); \({}^{\circ}\)C) (Equation (2)).