Matović Bratislav, PhD

The influence of elevation on the forest development and also on more structural elements is evident. The aim of this paper is to research the impact of elevation on the relationship between diameter at breast height (DBH), tree height (H), crown length (L) and stem volume (V). In the area of the Pelister National Park in North Macedonia, 22 experimental plots (EPs) were established in the even-age Pinus peuce Gris. stands with an average age of 90 years. The EPs were of a circular form and covered an area of 500 m2 each; 6 of them were established at 1150 meter above sea level (m asl), 7 at 1350 m asl and 9 at 1550 m asl. DBH, tree height, and crown length of 481 trees were measured in all EPs. The DBH – H model was prepared in accordance with Prodan, as well as nonlinear (polynomial) regression for the relation between DBH and L and nonlinear (power) regression for the relation between DBH and V. The stem volume was calculated with a formula by Parishko for Pinus peuce Gris. The quadratic mean of DBH, average Loray height, average crown ratio, and the density of the stands were also calculated. The relationship between DBH and H, L, and V was examined with Pearson correlation and root mean square deviation (RMSE). The differences between averages of H, L, and V from the EPs were tested with analysis of variance (ANOVA) with an elevation class (1150, 1350 and 1550 m asl) as single factor. The density of stands was 490, 429 and 409 trees per ha on 1150 m, 1350 m and 1550 m asl, respectively. The average DBH was 39.8 cm, 46.5 cm and 45.5 cm, and Loray height was 23.9 m, 24.1 m and 22.6 m at 1150 m, 1350 m and 1550 m asl, respectively. Crown ratio (CR) pointed out different results on the different elevations, with the average value of 40.5%, 43.7%, and 39.3% at 1150 m, 1350 m, and 1550 m asl, respectively. Differences between average structural elements at different elevations can be confirmed with ANOVA with a significance of p<0.05 and F of 3.4 for H, the significance of p<0.05 and F 3.2 for L data and p<0.05 and F of 9.7 for the value of V. In that way, the regression model for H is higher at a lower elevation, the tree has a longer crown length at lower elevation and also has a bigger volume at lower elevation. From the results, it can be concluded that the elevation has an influence on the relationship between DBH on the one hand and H, L and V as structural elements on the other hand. It can be said that at higher elevation trees have a smaller average height, DBH, and volume and have longer crown length than trees at lower elevation.

Forest ecosystems represent one of the largest and most important ecosystems on Earth, containing close to 80% of the biomass of our planet. As such, they play a significant role in the global carbon cycle because through photosynthesis, forests absorb more carbon than they emit and thus accumulate it. The most important species in deciduous forests in Europe, European beech (Fagus sylvatica L.), is of exceptional importance from the aspect of carbon storage. Considering that the state of carbon in pure beech forests is poorly investigated in the western part of the Balkans, the need for total carbon research was imposed to complete the picture of its stocks and factors that impact it. Research on total carbon (TC) storage in uneven-aged pure beech stands in the western part of the Balkans was carried out in three regions located approximately at the same latitude, but different longitude, imposing different macro-habitat characteristics. This research aimed to determine the TC stock and to examine the effects of orographic factors, stand canopy, and macroclimate on its values. TC stock in forest biomass was determined using appropriate regression equations and formulas, while soil organic carbon stock was determined using ICP forests methodology. Effects of different factors on carbon stock were examined using ANOVA (Type II Sums of Squares), General Linear Hypothesis Test (GLHT), and regression analyses. It was found that the largest TC stock is located in the region of Eastern Serbia (SRB) where its macroclimate is classified as suitable for hornbeam and sessile oak or mixed beech-oak stands. It was found that anthropogenic activity plays a significant role in the size of the carbon stock stored in above-ground biomass via alteration of forest canopy. The results also indicate that Aboveground Carbon (AGC) stocks are approximately proportional to Belowground Carbon (BGC; C in belowground biomass + soil C) stocks. What makes the difference is the structure of BGC, as the share of Soil Organic Carbon (SOC) is higher in the regions of Eastern Republic of Srpska (ERS) and Western Republic of Srpska (WRS), which are climatically classified as highly suitable for beech. Further analysis has shown that the amount of SOC decreases with increasing aridity levels. Given the results, management goals should be aimed at increasing the stock of biomass for the sake of carbon sequestration and for reducing the adverse effects of climate change, as a large amount of carbon can be stored in the above-ground and belowground biomass.