Mario Božić

Long-term and country scale projection of even-aged forest management: a case study for Fagus sylvatica in Croatia

Abstract Out of the 901,848 ha forests of the European beech (Fagus sylvatica L.) in Croatia, 383,473 ha are even-aged beech forests with irregular age-class structure. Potential forest management of the even-aged beech forests (including the conversion of coppice even-aged beech forests) was studied using a dynamic model system, in the context of long-term planning at the national level in Croatia. Three management policy scenarios were defined regarding the area control method, that is, planned area for annual regeneration felling was given as a function of (1) total forest area (conservative approach scenario–CAS), (2) area of stands older than 50 years (moderate approach scenario–MAS), and (3) area of stands older than 80 years (intensive approach scenario–IAS). Projections of future trends in the annual area of regeneration, age-class distribution, standing volume and annual felling, and thinning cut were obtained for each scenario. Management according to the Scenario 3 would lead to achievement of a best age-class balancing and more sustainable management in the next 50 years. The structure of the growing stock and the quality of harvested timber would also improve as a result of this approach. Intensive regeneration felling (4460 ha per year) and conversion of coppice forests (420 ha per year) is required to reach this goal.

Stand growth models for more intensive management of Juglans nigra: A case study in Croatia

Abstract The study focuses on the development of stand growth models for more intensive management of black walnut (Juglans nigra L.) plantations in Croatia. In total, 48 plots were sampled (ages between 3 and 91 years) and, on average, 28.3 trees (between 17 and 43 trees) were measured [diameter at breast height (dbh), total height, two crown diameters, increment core] on each plot. Management scenarios with rotations of 50, 60, 70 and 80 years were developed under three different management regimes: conservative (CAS), high individual tree growth (HTGS) and high stand growth (HSGS). Indicators of competition (current annual increment in dbh, basal area and crown area) were used for scheduling thinning and the intensity of interventions for the intensive scenarios. Depending on the management options and rotation, final stand densities varied between 105 and 210 trees ha−1, mean dbh between 30.4 and 46.1 cm, and total heights between 25.9 and 29.5 m. The mean annual increment in total volume varied between 7.1 and 11.0 m3 ha−1 per year under different rotations and management options, yielding in total accumulated volume of 529–666 m3 ha−1. The CAS yielded the lowest and the HSGS the highest total volume, and HTGS yielded the highest mean dbh.