engleski

Beach forests vegetation in the Učka nature park (Croatia)

The area of Učka Nature Park is comprised of the Učka massif and part of Ćićarija and is characterized by its specific position on the border of Continental and Mediterranean climatic influence. One of the main characteristics of this area are beech forests. A total of 121 vegetational relevés have been made following the standard Braun-Blanquet method. Numerical analyses of floristic composition were conducted and the relevés have been compared with the relevés of Aremonio-Fagion alliance from the surrounding area of Croatia and Slovenia. For description of ecological conditions Pignatti’s indicator values were used. The following plant associations of beech forests have been established: Seslerio autumnali-Fagetum M. Wraber ex Borhidi 1963, Ranunculo platanifolii- Fagetum Marinček et al. 1993 and Omphalodo-Fagetum (Tregubov 1957) Marinček et al. 1993. Seslerio autumnali-Fagetum is widely distributed across studied area and forms a continuous vegetation belt from 800 to 1150 m. Here it occurs on all aspects and slopes. On lower altitudes (700-800 m) it occurs in separate stands on mesophilous habitats surrounded by vegetation of Ostryo-Carpinion. A part of the relevés from this association differs from the typical stands with high proportion and coverage of the thermophilous species (Ostrya carpinifolia, Acer obtusatum, Sorbus aria, Tanacetum corymbosum and others). These stands usually occure on lower altitudes and they have developed by succession of ass. Seslerio-Ostryetum. In the southernmost part of the Učka Nature Park, on a small area specific stands of beech forest are developed surrounded by the thermophilous vegetation of Ostryo-Carpinion. These are the warmest habitats of beech forests in the studied area on deep and moisture soil. Such specific habitat features as well as proximity of Ostryo- Carpinion vegetation lead to interesting combination of thermophilous (Ostryo-Carpinion) and mesophilous (Lamio orvalae-Fagenion) species. Ass. Ranunculo platanifolii-Fagetum is developed in the highest parts of the Park. On Vojak it forms more or less a compact complex intermittent by some patches of ass. Seslerio-Fagetum on thermophilous microlocalities, while on other sites it occurs in isolated stands with more humid and cooler microclimate on higher altitudes within the ass. Seslerio-Fagetum. In general, this association occurs on the highest altitudes, largest terrain slopes and in coldest habitats. Stands of this association on investigated area are very poor in their floristic composition in comparison to the other areas where this association occurs. This can be explained by the fact that Učka is a mountain which rises directly from the sea and is subjected to the influence of the Mediterranean climate from almost all directions. Besides, the mountain massif above 1100 m is very small and there is not enough space which could create favourable conditions for the growth of higher number of high-mountain species.

beech; forest vegetation; Učka

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