## 3 Results and Discussion  
### Location Environment (Topography, Forest Physiology, Soil Properties) of the Study Area  
The topography and forest physiognomy of WSG cultivation sites are summarized in Table 1. In general, all the cultivation sites were sloped terrain with slope gradient ranging from 5 to 35\({}^{\circ}\); the slope direction varied from east, north, southeast, southwest and northeast; and the sites were 330-920 m above sea level. On the other hand, D and E cultivation sites were identified as broad-leaved forest, and all other cultivation sites were identified as mixed forest of conifer and broad-leaved. Among the cultivation sites, the average TH was maximum in the F cultivation site (26.8 m), and the average DBH was maximum in the A cultivation site (36.1 cm). Furthermore, the chemical properties of soil samples are summarized in Table 2. Soil samples were classified as sandy loam and sandy clay loam based on their soil texture. The soil pH of all cultivation sites has been recorded as acidic soil, and the I cultivation site showed the significantly lowest value compared to other cultivation sites. Organic matter (OM), total nitrogen (TN) contents and cation exchange capacity (CEC) were significantly higher in the A cultivation site, whereas the available phosphate (avail. P2O5) content was significantly higher in the B cultivation site compared to other cultivation sites. Furthermore, potassium (K) content was recorded at a range of 0.08 to 0.31 cmol\({}^{+}\) kg\({}^{-1}\), calcium (Ca) in the range of 0.10 to 6.99 cmol\({}^{+}\) kg\({}^{-1}\), magnesium (Mg) in the range of 0.05 to 1.07 cmol\({}^{+}\) kg\({}^{-1}\) and sodium (Na) in the range of 0.03 to 0.09 cmol\({}^{+}\) kg\({}^{-1}\), which belongs to the group of exchangeable ions. Forest vegetation is formed by interaction with the environment, and among the forest environments, soil characteristics are majorly affected by the vegetation, and it varies significantly according to the difference in the presence of the particular species of trees [29]. Therefore, the growth and production of WSG cultivated in forest regions have a significant correlation with forest soil and tree species [30]. The organic matter content is higher in broad-leaved forests than in coniferous forests in forest soil because the accumulation of fallen leaves from the trees determines the organic matter content [31; 32]. Among the WSG cultivation sites, soil organic matter and total nitrogen content are significantly high in mixed forests with high diversity of deciduous broad-leaved trees [33]. This is because broad-leaved forests contain more organic carbon sources such as fallen leaves than coniferous forests, where organic matter is slowly decomposed [34]. In this study, OM, TN and CEC were high in the WSG cultivation sites with a high percentage broad-leaved tree.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Cultivation Sites**} & \multicolumn{2}{c}{**Topography**} & \multicolumn{2}{c}{**Forest Physiology**} & \multirow{2}{*}{**Percentage**} \\ \cline{2-2} \cline{4-7}  & \multirow{2}{*}{**Slope**} & \multirow{2}{*}{**HASL \({}^{a}\)**} & & \multicolumn{2}{c}{**Average**} & \\ \cline{3-7}  & & & & **TH \({}^{b}\)** & **DBH \({}^{c}\)** & \\ \cline{2-7}  & \(\circ\) & **Detection** & **m** & & **m** & **cm** & **\%** \\ \hline \multirow{4}{*}{A} & \multirow{3}{*}{32} & \multirow{4}{*}{Southeast} & \multirow{3}{*}{920} & Broad-leaved & 21.5 & 31.0 & 80.0 \\  & & & & Conifer & 36.0 & 56.7 & 20.0 \\ \cline{1-1}  & & & & Total & 24.4 & 36.1 & 100 \\ \cline{1-1}  & & & Broad-leaved & 22.8 & 14.8 & 35.7 \\ \cline{1-1}  & & & Conifer & 19.0 & 13.0 & 64.3 \\ \cline{1-1}  & & & Total & 20.4 & 13.7 & 100 \\ \cline{1-1}  & & & Broad-leaved & 14.7 & 12.8 & 81.8 \\ \cline{1-1}  & & & Conifer & 31.5 & 29.6 & 18.2 \\ \cline{1-1}  & & & Total & 17.8 & 15.9 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Location environments of 13-year-old WSG cultivation sites.