engleski

Structure and crown damage degree as a significant factor of natural regeneration in National parks of Croatia

Tree crowns and forest soil are basic factors of all life processes in the stand. The impact of crown in the stand is manifold and is manifested at: seed crop, assimilation, soil crown cover, light, precipitation, "stand climate", soil temperature and humidity, mineralization and humification of organic soil matter ; regarding volume of wood increment, trunk dimensions are directly dependent on the productive crown capacity. Crown, being a component of the stand structure, is the basic indicator of conditions of natural regeneration and maintaining permanent self-regenerative capacities (sustainability) of the forest stand. Horizontal crown projections and evaluations of phenotypic tree properties have been recorded on experimental plots: biological location-layer, crown quality, trunk quality and crown damage degree. Crown projection layouts were digitalized (program package AutoCad 2000) and by the use of planimeter, soil cover, which is significant indicator of conditions of stand regeneration, was calculated. Research results showed that the soil cover was too great, >96%, and that the natural regeneration without the influence of anthropogenic factor is questionable. Crown damage assessment was carried out by uniform method prescribed by ICP Forests (International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests). The species assessed were common beech (Fagus sylvatica L.), silver fir (Abies alba Mill.) and evergreen oak (Quercus ilex L.). The results pointed to high share of crown transparency, >60%, fir in particular. The reasons for this are: too many overripe trees, too many plants per one unit of area accompanied by too high crown transparency and the need for management operations. The condition for the forest ecosystem on the territory of National parks to be kept in balance, without its physiological weakening, is appropriate management, since only in such a way shall we be able to achieve basic principle of forestry, i.e. sustainability and sustainable development.

National parks; crown projections; crown damage degree; natural regeneration; beech; fir; evergreen oak.

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