## 4 Discussion
This could be true in a controlled setting free of anthropogenic and other natural disruptions. Different tree variables, such as tree type, height, basal area, stem volume, etc. determines the nature of forest community and growing stock characteristics of the forests. Growing stock-based estimation of biomass and carbon stock are reliable and valuable sources [40; 41]. The current study reported stem density of 317.70 ha\({}^{-1}\) at lower altitudinal ranges followed by higher and mid-elevation ranges with values of 290.93 ha\({}^{-1}\) and 280.36 ha\({}^{-1}\), respectively, which is quite within the range of [PERSON] et al. [37] but lower from the findings of [PERSON] et al. [17]. The recorded stem density in the current work is in line with the expected range (133 to 620 trees ha\({}^{-1}\)) from a different region of Pakistan, as documented by [PERSON] et al. [61]. In contrast to this result, [PERSON] et al. [51] documented low stem density while working on carbon stocks of subtropical forests from the same region. The present stem volume of 62.69 m\({}^{3}\) ha\({}^{-1}\) in _Monotheca_-dominant forests is comparable to the estimated volume of _Olea ferruginea_[37] but lower from the findings of [PERSON] et al. [41]. Generally, the numbers of small diameter trees are much higher in comparison to larger diameter trees [36]. Altitude highly influences the ecosystem structure, composition, and biomass by altering different factors of the environment, including precipitation, temperature, slope, aspect, soil properties, etc. [62]. In this sense, the main aim of our study was to expose the impact of altitude on vegetation and soil organic carbon. Soil carbon is an integral part of a particular ecosystem. Several different factors like length of time, vegetation type physical and biological condition of soil significantly affect the carbon sequestration capacity of soil [63]. During the current work, SOC (T ha\({}^{-1}\)) were reported in increasing order with the altitude. Zone-I, located at a lower elevation, documented 16.69 T ha\({}^{-1}\), Zone-II at mid elevation reported 24.53 T ha\({}^{-1}\), while the Zone-III, presented at high altitude, recorded maximum values of SOC (36.21 T ha\({}^{-1}\)). A similar increasing pattern was also documented by [PERSON] and [PERSON] [58], which is in agreement with the present study. In contrast to the present study, SOC (T ha\({}^{-1}\)) was reported in a decreasing manner along the altitude gradient in various soil carbon studies [64; 65; 66]. This decreasing pattern of carbon was associated with a slow mineralization and nitrification process at the higher elevation. The increasing tendency of carbon with increasing altitude in our study could be due to greater SOC (T ha\({}^{-1}\)) stability at higher elevation ranges. Wood harvest effects the soil carbon as it reduces the amount of litter production [40]. In our study, the forests located at lower elevation are more prone to local communities for wood harvest, due to which a smaller amount of litter and resulting carbon stock is available at lower elevation as compared to higher elevation. In the current study, we studied the relationship between stem density and diameter by developing regression models (polynomial cubic, Figure 2). Adjusted R\({}^{2}\) for the middle elevation was 0.59, followed by lower elevation (R\({}^{2}\) = 0.55) and higher elevation (R\({}^{2}\) = 0.51), showing the presence of numerous individuals in the small diameter classes. We investigated the link of stem diameter to stem density (Figure 3) by polynomial cubic, where R\({}^{2}\) = 0.57 shows the positive significant relationship. Tree diameter is a prominent and measurable variable for tree Basal area, as trees having a greater diameter will have a high Basal area. The presence of large girth trees in _Monotheca_ forests resulted in high Basal area in comparison to the finding of [PERSON] et al. [67]. However, the current Basal area (10-26 m\({}^{2}\) ha\({}^{-1}\)) supports the results of [PERSON] et al. [61].