Diameter structure of the stand and time of passage: An analysis in primeval forests janj and lom in republic of srpska (Bosnia and Herzegovina)

Abstract

The research was carried out in primeval forest stands of beech, fir and spruce (Piceo-Abieti-Fagetum illyricum) on brown dolomite soils (Janj) and dominantly shallow limestone soils (Lom). The diameter structure is typical for primeval forests with the participation of large trees in which physiological weakening is visible, especially in the Lom primeval forest. At the same time, the stands are characterized by the specifics of the transition from the terminal to the initial development phase, with a very pronounced lower floor of the stands where beech and fir dominate. Significant differences in the size of the diameter increment are characteristics for fir, which in the Lom primeval forest has a significantly higher diameter increment at the same diameters than in Janj. The current diameter increment of fir in Janj is 2.3 mm/year and in Lom 4.5 mm/year. The average current thickness growth of spruce in Janj is 0.2 mm higher on average than in Lom and amounts to 2.9 mm/year. The current thickness growth of beech in Lom is significantly higher (4.9 mm/year) than in Janj (2.3 mm/year). The average time of passage is the highest for fir in the Janj primeval forest and for the whole stand is 45 years, and the lowest for spruce in the Lom primeval forest 22 years. Beech trees in the lowest diameter classes have a significantly shorter time of passage than fir and spruce. Fir in the Janj forest has an average relative age of 85 years higher than in Lom. Spruce shows the largest difference in relative age between primeval forests in thinner diameter classes, and unlike fir, the difference in age decreases with increasing diameter.