engleski

The establishment and preservation of a balanced structure of beech-fir stands

Beech-fir forest management in Croatia is currently faced with problems of irregularly structured stands. This is manifested in a considerable proportion of mature trees of large-dimensions, poor increment, the non-existence of vertical structure and the absence of satisfactory and permanent natural stand regeneration. The characteristics of such structures indicate a similarity with virgin forests in their terminal stage. On the assumption that a balanced selection structure may only be achieved with intensive and systematic management, the goal is to highlight the relationship between management and stand structure" development". Based on the conducted and published research dealing with concrete forest sites of fir and beech, the following elements of planning the management and structure of irregularly structured fir-beech stands are discussed: 1. The disappearance of a selection structure and the accumulation of growing stock of large trees with diameters over 70 cm during the past 50-year period resulting from prescribed and performed low-intensity cutting operations ; 2. The applicability of the prescribing cut form (based on growing stock difference before and after the selection cut and the rate of current annual volume increment), which is doubtful in condition of large growing stocks and low rates of current annual volume increment ; 3. Transition time, recruitment and structure of regeneration as an indicator of the currently disrupted stand structure ; 4. Prediction of planned intensity and structure of selection cuts, recruitment (stand regeneration) and "development of stand structure during future cutting cycles, which indicate the need for cuts of higher intensity (over 25%) in the initial cutting cycle and gradual improvement of the disrupted selection structure ; and 5. The results that indicate the negative effect of basal area of fir and beech trees with diameters exceeding 50 cm on natural fir regeneration, as well as the occurrence of natural young growth of regenerated fir (developmental stage of young growth) 5 years after the selection cut of stronger intensity (24%).

silver fir; common beech; distributed selection structure; selection cutting intensity; increment.

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