## 3 Results
### Biomass and Carbon Stock  
The mean stem biomass in the stands of lower elevation ranges (63.88 T ha\({}^{-1}\)) was significantly higher than stands of elevation zone-II (39.86 T ha\({}^{-1}\)) and zone-III (51.28 T ha\({}^{-1}\)). The dominant species shared 95% to the total stem biomass (Supplementary Materials Table S1). Among the other associates, _Acacia modesta_ shared 1.71%, followed by _Olea ferruginea_ (1.29%). The remaining 24 minor associates collectively shared 1.39% of the total stem biomass. A similar tendency was also recorded for total biomass with 66.85 T ha\({}^{-1}\) for the lower elevation zone followed by stands the higher and middle altitudes, respectively. The current study also highlights the biomass carbon of all woody tree species (Table 4) and understories vegetation (Supplementary Materials Table S2) in three different elevation groups. In the tree stratum, the total amount of biomass carbon stock in lower elevation ranges was 51.81 T ha\({}^{-1}\), of which the dominant (_Monotheca_) and co-dominant species (_Acacia modesta_) shared 95.6% and 2.6%, respectively. _Ziziphus muntiana_ and _Olea ferruginea_ were among the other major contributing species, adding 0.25 T ha\({}^{-1}\) and 0.24 T ha\({}^{-1}\) to the total carbon stock, respectively. Only 41.42 T ha\({}^{-1}\) of carbon was calculated for the _Monotheca_-dominated forests located at high altitudinal ranges, while this value is lowest for group-II (31.95 T ha\({}^{-1}\)), located at elevation range from 1000 m to 1399 m asl (Table 4). Likewise, an increasing trend of soil carbon (T ha\({}^{-1}\)) was also observed along the altitudinal gradient. Understory vegetation in each altitudinal range mainly consisted of grasses, herbs, and shrubs. Among grasses, _Saccharum munja_, _Saccharum spontaneum_, _Sorghum halepense_, and _Cenchrus spinifex_ were more common, while major shrubs were _Dodonaea viscosa_, _Justicia adhatoda_, _Cotonester microphyllus_, _Ziziphus munumularia_ and _Ricius communis_. The mean carbon stocks of understory vegetation at lower altitudinal ranges were maximum (0.148 T ha\({}^{-1}\)) followed by middle and higher elevation ranges with values of 0.107 T ha\({}^{-1}\) and 0.087 T ha\({}^{-1}\), respectively. Stem density, stem volume, and biomass carbon are the functions of Basal area. Stem density decreases with increasing diameter, while stem volume and biomass carbon are in direct relation with diameter. To study the relationship between stem density, stem volume, and biomass carbon with diameter (cm), regression models were developed (Figures 2 and 3). The model showed a strong relation (R\({}^{2}\) = 0.55, 0.59 and 0.51) of density for lower, middle and higher altitudinal ranges, respectively. Overall, the relationship of stem density (ha\({}^{-1}\)) and diameter (cm) is quadratic type (polynomial inverse 3 rd order) \begin{table}
\begin{tabular}{c l c c c} \hline \hline
**S. no.** & **Categories** & **600–1000 m** & **1000–1400 m** & **1400–1800 m** & **Total** \\ \hline
1 & Volume (m\({}^{3}\) ha\({}^{-1}\)) & 78.09 & 48.01 & 61.98 & 188.08 \\
2 & Stem Biomass (T ha\({}^{-1}\)) & 66.85 & 41.23 & 53.44 & 161.52 \\
3 & Total Biomass (T ha\({}^{-1}\)) & 103.6 & 63.90 & 82.84 & 250.34 \\
4 & Carbon Stock (T ha\({}^{-1}\)) & 51.81 & 31.95 & 41.421 & 125.19 \\
5 & Soil Carbon (T ha\({}^{-1}\)) & 16.69 & 24.53 & 36.21 & 77.43 \\
6 & Understory Carbon Stock (T ha\({}^{-1}\)) & 0.148 & 0.107 & 0.087 & 0.34 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Total volume, stem biomass, tree biomass and carbon stock (T ha\({}^{-1}\)) of woody tree species, under story vegetation and soil 74 of _Monotheca_ dominated forests across different elevation ranges in Pakistan.