Structural and production characteristics of mixed forests of beech and spruce on Kopaonik [Serbia]

Mixed conifer and broadleaf forests are the most valuable parts of the growing stock in Serbia, thanks to their high productivity, ecological diversity, stability and structural complexity. The subject of this study is beech and spruce mixed forests in the area of the NP "Kopaonik". The study of structural and production characteristics of these forests is based on the data of 8 (eight) permanent sample plots of average size 0.51 ha, established within the two previously defined groups of ecological units: EJ-A Fago-piceetum luzuletosum on acid brown soil and EJ-B Fago-piceetum oxalidetosum on acid brown and brown podzolic soil. The study stands are well stocked, with a pronounced domination of spruce, especially in the category of smaller-diameter trees. Multiply toothed individual and summary lines of diameter and height structure, and their great variation width imply the structural all-agedness of these forests. Small-diameter and medium-diameter trees are dominant, and the percentage of the largest-sized trees is minimal. Average volume is above 530 m3 ·ha–1 , with mixture proportion about 0.6:0.4 in favour of spruce. Average value of current volume increment is about 9 m3 ·ha–1 , with spruce percentage about 70% and beech about 30%. Increment percent is above 3%, in which spruce accounts for more than 2%, and beech accounts for about 1%. Taking into account the altitudinal position of these forests and the resulting site characteristics which are more favourable to shade loving species, the most productive species is spruce as a typical sciophyte. However, beech productivity is also significant, and its role in the concrete conditions is multi-dimensional, from the prevention of soil acidification, to the enhancement of multiple functionality (protection, recreation, amenity, etc). Site potential, stand characteristics and inter-relationships of tree species resulted in high productivity, ecological stability and structural complexity of these forests, therefore, in future management. radical measures and felling which could disturb the established relations and dynamic processes should be avoided