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1 Acta Agraria et Silvestria. Series Silvestris

1 1995

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Budowa i struktura drzewostanow z udzialem buka i jawora w kompleksie lesnym Moczarne oraz pod Rabia Skala [Bieszczady]

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Jaworski A. , Pach M. , Skrzyszewski J.

tom 33

39-73

Na czterech powierzchniach założonych w drzewostanach jaworowo-bukowych i bukowo jaworowych oceniono mi.in zasobność, strukturę rozkładu pierśnic i wysokości, miąższość posuszu, odnowienie oraz stadia i fazy rozwoju. Badania wykazały m.in. zróżnicowanie zasobności od 111do 545 m³/ha, oraz innych podanych wyżej elementów w zależności od położenia n.p.m. W warunkach optymalnych drzewostany te mogą odgrywać ważną rolę gospodarzą a w częściach przygrzbietowych, zwłaszcza w najbliższym sąsiedztwie górnej granicy lasu, zapewniają wypełnienie zadań ochronnych.

Fairly undistorted stands of virgin character in Bieszczady National Park were investigated on 4 sample plots (Tabele 1, figs 1, 2, 3, and 4). The volume of the investigated stands varied from 545 m³/ha-111 m /ha (Table 2). Analysts of the species composition was carried out on the basis of the voluminal share, showing that in the studied conditions a sycamore-beech forest developed on Moczarne II plot and a beech-sycamore stands on the remaining three plots (Table 3). The total number of trees (of the diameter at breast height equal or exceeding 8 em) increases with higher altitudes above sea level (Tables 2 and 3) Beech and sycamore maple found the most favourable conditions of growth in the lowest stand at Moczarne II (index of stand quality classification was III for beech and 1 for sycamore maple) and the least favourable ones in the Rabia Skała II stand lying at the greatest altitude (index of stand quality classification V for beech and III for sycamore maple) (Tables 3 and 4) Both, the maximum and average values of tree thickness decrease with the rising altitude above sea level (Table 5). Differences in diameters at breast height expressed by the variability factor were greater for beech (from 0.49 to 0.84, Table 5) than for sycamore maple (0,16-0,29, Table 5), The distribution of D.B.H. of all the tree species confirms the multigenerational character of the investigated stands (Table 5, figs 5, 6. and 7). The values of variability coefficients of beech height (from 0.55-0.20) show a decreasing tendency with the rising altitudes above sea level (Table 6). In the case of sycamore maple the values of this trait present a different pattern. Its highest value (0.17) was found for sycamore maples growing on the lowest plot (Moczarne II 930 m a s.I.) and the smallest one (0.13) for sycamore maples in Moczarne I stand (1010 m a.s.l.) (cf also figs 8, 9, 10, 11, and 12). The comparison of the share of beeches and sycamore maples (Table 7) shows that the beech dominates in almost all the layers of the forests, particularly in the lower and medium layer and, to a smaller degree, in the highest one, though in the last case in the Rabia Skała II stand the share of sycamore maples (71.1%) considerably exceeds that of beech (18,9%). Data concerning dead and lying trees are given in Tables 8, 9, and 10. In the optimal conditions of growth the sycamore maple yields a greater share of usable assortments than the beech. One may conjecture that in cultivated forests it will be possible to improve trunk quality by applying suitable cultural practices, and to obtain a greater variety of valuable assortments (Table II). In the investigated forest, trees of normal vitality dominated. The most vigorous trees (vitality 10) occurred as single individuals (Table 12). Analysis of the number of seedlings and younger new growth in Moczarne I and II und Rabia Skała stands shows that the sowing of beech and sycamore maple is ensured, though the share of these species vanes to a great degree. Nevertheless, the numbers of older new growth dramatically decreases (Table 13). In the 3 forests mentioned above no sycamore maple up-growth (D.B.IH. 6-7,9 cm) was found (Table 13) while at the same lime it does not occur in degrees 8—15.9 cm (Table 2) or in the lowest stand layers. This observation suggest that the younger generations of this species find difficulties in surviving. One may suppose that the light conditions play a decisive role here. Great densities in the upper layer of trees bring about the shading which is too strong for sycamore maples while for the shade-tolerating beech the amount of light is sufficient. The maintenance of sycamore maple in the investigated stands of virgin character would be only possible if in the stage of destruction considerable self-thinning processes occured. The determination of developmental stages and phases is difficult (Table I) on account of single tree harvesting in the neighbourhood of some study plots (Moczarne 1 and 11). The investigation showed that the role of the stands changed as depending upon the altitude a.s.l. In omptimum habitat conditions stands of rich growing stocks develop with a participation of sycamore and beech which may play productive functions in partial nature reserves, yielding valuable assortments. Forests with a large share of sycamore should be treated as seed-stands. Owing to the characteristic storied constitution and the complex age structure beech-sycamore ridge stands (Rabia Skała II) constitute permanent and stable forest communities, ensuring the fulfilment of protective tasks in the nearest vicinity of the upper forest limit.