## 3 Results
### The Effect of Damaging Factors on the Composition and Structure of Pine Stands on Degraded Lands
#### 3.2.1 The Compositional Diversity of Pine Stands

Table 4: _Cont._  
Figure 12: The diameter\(-\)height relationship in EP2: (**a**) RP1 and (**b**) RP9. Figure 13: The diameter\(-\)height relationship in EP3: (**a**) RP4 and (**b**) RP9. _In the case of the stands with lower age (45 years)_, the diversity of pine stands, both pure or mixed with broadleaved species (EP1), located in the FD\({}_{3}\) sessile oak-common beech stand, on very strongly eroded and ravenous lands, is characterized by various compositions composed of Scots pine (26 to 42%) mixed with black pine (55 to 73%). The difference is represented by broadleaved species (manna ash, white alder, locust, etc.) that were naturally installed (Figure 14a,b). Sea buckthorn, used to make vegetally reinforced terraces but also introduced in the aforestation composition in an intimate mixture with pines (Table 1), especially on very strongly eroded lands, ensured both the consolidation of the lands and the improvement of the soil. After the closure of the massif, the sea buckthorn dried up, favoring the development of young pines, which led to a greater structural diversity of pine stands. In general, the variability of pure pine stands from the diameter and height perspective is reduced, with the variation index (cv%) under 30%. The populations are relatively homogenous if we consider the participation of all species in the stand (Table 5). Analyzing the height of the trees, when the two species are mixed, the superiority of the height of the Scots pine compared to that of the black pine was found. The determination coefficients (R\({}^{2}\)) express a strong relationship between diameter and height (Figure 15a,b) for the Scots pine tree population. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **EP-RP** \\ **Species** \\ \end{tabular} } & \multicolumn{8}{c}{**Statistical Parameters**} \\ \cline{2-13}  & \multicolumn{4}{c}{**Basal Diameter (cm)**} & \multicolumn{4}{c}{**Total Height (m)**} \\ \cline{2-13}  & \(\bar{\mathbf{d}}\) & **Median** & **s** & **cv (\%)** & **Min** & **Max** & \(\bar{\mathbf{h}}\) & **Median** & **s** & **cv (\%)** & **Min** & **Max** \\ \hline
**1–5 total** & **15.19** & **15.10** & **3.57** & **23.55** & **6** & **26** & **13.89** & **14.40** & **2.49** & **17.95** & **4** & **17** \\ \hline Pi & 15.92 & 15.60 & 2.96 & 18.58 & 10 & 23 & 14.84 & 14.95 & 1.73 & 11.69 & 9 & 17 \\ \hline Pi.n & 14.89 & 14.30 & 3.75 & 25.23 & 7 & 26 & 13.49 & 13.90 & 2.40 & 17.85 & 6 & 17 \\ \hline An.a & 14.90 & 15.00 & 0.36 & 2.42 & 15 & 15 & 12.76 & 13.30 & 0.92 & 7.24 & 12 & 13 \\ \hline
**1–9 total** & **12.64** & **12.70** & **3.21** & **25.37** & **6** & **20** & **10.80** & **10.95** & **2.43** & **22.54** & **5** & **16** \\ \hline Pi & 14.53 & 14.70 & 2.35 & 16.19 & 8 & 20 & 12.81 & 12.85 & 1.63 & 12.72 & 7 & 16 \\ \hline Pi.n & 11.97 & 11.80 & 3.17 & 26.50 & 7 & 19 & 10.04 & 9.85 & 2.23 & 22.28 & 5 & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: General statistic parameters for diameter and height in pine stands with age of 45 years. Figure 14: Composition of pine stands studied in EP1: (**a**) RP5 and (**b**) RP9. _In the stands aged over 70 years old_ (Table 6), _in the internal forest-steppe site_ (_Ssd_) EP4, the pure stands of Scots pine and black pine are the main species, with over 60% proportion of participation in compositions (Figure 16a,b) on moderately to strongly eroded lands (E1 and E2), and they are complemented by disseminated broadleaved species or from natural regeneration (sycamore, elm, Tatarian maple, manna ash, etc.). The broadleaved species appeared in low proportions (not more than 15%) after the installation of pine species. We found a high proportion of participation in compositions by black pine species compared to Scots pine (Figure 17).