Wyniki wyszukiwania - Biblioteka Nauki

1

Parametryczna i nieparametryczna aproksymacja rozkładów pierśnic w drzewostanach o różnej budowie pionowej

100%

Podlaski R.

Acta Agraria et Silvestria. Series Silvestris

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2013

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tom 51

EN

The objectives of this study are (i) by using selected parametric models and the kernel density estimator to compare the accuracy of approximation of the empirical DBH distributions in stands of different vertical structure as well as the approximation accuracy in the empirical DBH data sets characterised by either average, or small or large differences in the number of DBHs in the neighbouring DBH classes, and (ii) to assess the significance of differences between the selected parametric models and the kernel density estimator. Sampling was carried out in the Świętokrzyski National Park (forest sub-districts: Święta Katarzyna and Święty Krzyż). In the stands of different vertical structure the irregular DBH empirical distributions require reducing the bandwidth of the kernel density estimator. In one-storied, two-storied and selection stands one should employ parametric models, using the kernel density estimator only for the preliminary approximations. However, when approximating the empirical DBH distributions in many-storied stands the kernel density estimation can be much more useful.

2

Wpływ intensywności cięć na postać i strukturę wybranych różnowiekowych drzewostanów jodłowych w Leśnym Zakładzie Doświadczalnym w Krynicy

86%

Banas J. , Zieba S. , Bujoczek L. , Polak M. , Zygmunt R.

Acta Agraria et Silvestria. Series Silvestris

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2015

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tom 53

3

Budowa i struktura drzewostanów dolnoreglowych o charakterze pierwotnym w Babiogórskim Parku Narodowym

86%

Jaworski A. , Kaczmarski J.

Acta Agraria et Silvestria. Series Silvestris

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1990

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tom 29

4

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

72%

Jaworski A. , Pach M. , Skrzyszewski J.

Acta Agraria et Silvestria. Series Silvestris

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1995

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tom 33

39-73

PL

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.

EN

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.

5

Budowa, struktura i dynamika drzewostanow naturalnych w rezerwacie Swiety Krzyz [Swietokrzyski Park Narodowy]

72%

Jaworski A. , Podlaski R.

Acta Agraria et Silvestria. Series Silvestris

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2006

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tom 44

9-38

EN

Stands of the Święty Krzyż nature reserve are described on the basis of studies carried out in 1992 and 2002 as well as historical data concerning species composition in 1925. During the period of 10 years the stand in the study area Święty Krzyż 1 maintained characters of the growing up stage and phase of storied structure. Its volume increased from 502 to 542 m3/ha, and volume increment was 10.6 m3/ha/year. The stand in the study area Święty Krzyż 2 underwent transformation from the break up stage and regeneration phase to the growing up stage and phase of multistorey structure. Its volume increased from 201 to 264 m3/ha, and volume increment was 8.0 m3/ha/year. During the period from 1925 to 2002 the percentage of fir decreased from about 80% to 33% (Święty Krzyż 1) and 45% (Święty Krzyż 2), while this decrease during 1992-2002 amounted to 12.5 and 3.1% respectively. Most likely the process of fir decrease will be continued for next ten or twenty years, but due to a relatively abundant fir underwood, after 20-30 years its percentage in ingrowth will be increasing.

6

Budowa, dynamika, struktura i możliwości produkcyjne borów górnoreglowych na Pilsku

58%

Jaworski A. , Pach M.

Acta Agraria et Silvestria. Series Silvestris

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2010

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tom 48

EN

The purpose of the paper is to report on the structure and the potential production of tree stands in the belt of dense forest in the locality of Pilsko, which were formed as a result of connecting natural processes with various methods of cuttings. In two stands single cutting harvesting was applied, corresponding to single tree selection cutting (Einzelplenterung in German). In the third stand there was cutting in the form of small gaps which corresponds to mountain selection cutting (Gebirgsplenterung in German). In the control period (1998-2008) the stand volume on two plots, Pilsko 1 and Pilsko 3 increased from 448 to 479 m3/ha and from 237 to 298 m3/ha respectively, however, in Pilsko 2 the stand volume decreased slightly from 401 to 397 m3/ha. The increase in the volume of the stand reached from almost 5 m3/ha in Pilsko 2 to approximately 8 m3/ha per year in the other plots. The stability of the stand is ensured mainly by the presence of trees in the thinnest classes in the lower and medium layer of the stand as well as the continuous process of regeneration. In this context the stand in which cuttings were taken in the past, characteristic of mountain selection, exhibited more beneficial features. All the researched stands exhibited great differences in the age of trees which enabled them to be classified as uneven-aged stands. The age at the breast height diameter of the oldest drilled spruce was 344 years and frequently the encountered specimens of this variety are of the age of 223 and 276 years. The uneven-aged structure of the stands, however, does not simultaneously ensure a complex and stable structure. In order to form, or to maintain, stable upper mountain spruces, which are under partial active protection (outside reservations with total protection) mountain selection cutting, or cutting by a method of group selection, should be recommended. These methods of cuttings ensure the variations within the structure of the stands, which minimises the risk of large-area disintegration.