engleski

Long-term balancing of pedunculate oak forest age-class structure - influence of stand regeneration dynamics in Croatian lowlands

Balanced age-class distribution is main prerequisite of sustainable management, as well as factor of stability of broadleaved lowland forests. This is important in a context of coming climate changes and effected natural disturbances as causes of significant forest damages. Large areas of lowland forests in eastern part of Croatia were regenerated (felled) at the end of 19th and beginning of 20th centuries during short period, which caused unbalanced age structure on wider region. The high economic value of the regenerated old oak forests has been embedded in infrastructure development of Slavonia region, as in owner’s acquisition, namely Austrian-Hungarian Monarchy. One century later have appeared prerequisites for applying spatial-temporal planning models of forest regeneration with long-term aim of achievement the balanced age-class structure. The aim of this paper is to choose an optimal model, based on simulations of lowland forest development (pedunculate oak forest in management unit Debrinja – case study) according to several models of spatial-temporal stand regeneration planning and on analysing of dynamic of age-class structures development. The forest age-class structure in 1977 is used as beginning of simulation using optimal model for projection of forest development and comparison with actual development. Spatial- temporal structure of forest stands, cut amount, an average age of regenerated stands and value of cut wood were used in comparison. Simulations of the forest development according to for scenarios: a) dynamic (regeneration availability of all stands older then 80 y.), b) theoretical (0.714 % of total forest area each year), c) oscilating (regeneration availability of all stands older then 130 y.), d) conservative (regeneration availability of all stands older then 120 y.), were analysed and scenario a) choosed as optimal for comparison with actual forest development during last 50 years. If scenario model a) applying for forest stand regeneration since 1977, the balanced age-class structure would be achieved yet in 2067. Additionally, during last 50-year period there has been omitted to regenerate almost 950 ha or 21 % of the total forest area. Thereby would be achieved yield of 546, 000 m3 of wood or minimum 350 mil. kunas. Values decrease of growing stock in over mature pedunculate oak stands due to tree dieback is a consequence of prolongation of stand regeneration. Larger and indirect losses are composed in absence of balanced age-class structure achievement and consequential sustainable forest management and forest stand resistance to environmental changes. Due to increase of wood prices prolongation of stand regeneration may be considered as good management decision but sustainable and balanced management in long-term sense will be ignored. The obtained results stress and indicate on importance of applying of the models for long- term forest development projection, including models of spatial-temporal planning of stand regeneration aimed to achieve an optimal management and long-term sustainability of the lowland even-aged forests.

Even-aged forest management ; Age-class distribution ; Stand regeneration ; Lowland forests ; Spatial-temporal projection

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