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Wyświetlanie 1-2 z 2
Tytuł:
Wpływ konkurencji na przyrost grubości drzew w wyżynnych lasach mieszanych o złożonej budowie
Effect of competition on the diameter growth of trees in mixed upland forests with complex structure
Autorzy:
Śmigielski, A.
Socha, J.
Maciejewski, Z.
Pach, M.
Powiązania:
https://bibliotekanauki.pl/articles/989022.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
Roztoczanski Park Narodowy
drzewostany naturalne
drzewostany mieszane
drzewa lesne
grab
buk
jodla
przyrost drzew
przyrost grubosci
wskazniki konkurencyjnosci
competition indices
natural stands
roztocze national park
Opis:
The aim of this study was to assess the effect of competition on diameter growth of European beech (Fagus sylvatica L.), silver fir (Abies alba Mill.) and European hornbeam (Carpinus betulus L.) in forests with complex structure. For each tree we calculated set of 20 competition indexes in 4 variants for determining the scale of the competitors influence. The use of such a set of indices, allowed to describe accurately the competition between trees in the specific conditions for the particular tree species. Given species belong to the group of shade−tolerant trees. The species composition of the tree stands and their structure are the results of long−lasting natural processes, which is different than in the majority of Polish forests. The empirical material collected in the years 1993 and 2003 in four sample plots of 0.5 ha each located in natural stands of the Roztocze National Park in south−eastern Poland. The relationships between the competition and the growth were analysed using generalized additive models. This method allows to extend of the standard linear model, by taking into account non−linear function of each variable. One of the option of quantifying competition processes is the use of competition indices. The competition situation of an individual tree was described using distance−independ and distance−depend indices. Each of analysed species reacts differently on competition. Among the three analyzed species, the best competition index CI15 explained 48.3% of the variation diameter growth of European beech (tab. 2). The competition index CI3 explained only 26.1% of the variation diameter growth of European hornbeam (tab. 2). It turned out to be the worst result for the described species. The competition index CI14 explained 31.1% of the variation diameter growth of silver fir (tab. 2). Additional use of DBH in the models, increased values of the coefficient of determination, and extended the possibilities to use the developed models.
Źródło:
Sylwan; 2017, 161, 05; 365-378
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prognoza rozwoju drzewostanów lasu naturalnego z wykorzystaniem modelu według klas wymiarów
Forecast of the development of natural forest resources using a size-class growth model
Autorzy:
Gazda, A.
Miscicki, S.
Powiązania:
https://bibliotekanauki.pl/articles/972934.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
drzewostany
buk zwyczajny
Fagus sylvatica
Abies alba
modele wzrostu
las naturalny
prognozowanie rozwoju
Roztocze
leśnictwo
Bukowa Góra
jodła pospolita
model wzrostu według klas wymiarów
silver fir
increment
mortality
Roztoczański National Park
European beech
Opis:
The size−class growth model is an empirical model applicable for the prediction of the dynamics of natural forest growth. It is based on the following assumptions: (1) changes in the forest condition are determined on the basis of the sum of the changes that take place in individual size classes, (2) the trees in a given class are represented by single average tree, (3) the calculation of the future tree density distribution in size classes (fig. 1) is the main element of the prediction, and (4) the future tree density distribution is estimated on the basis of the initial structure, actual growth and mortality of trees in individual size classes. The aim of the research was to develop a size−class growth model to be used for the preparation of a medium−term forecast of natural forest dynamics. The study site is located on the Bukowa Góra Mt in the Roztoczański National Park (SE Poland). For the analyses we took all uneven−aged stands (128 ha in total) composed mostly of silver fir and European beech. The material was collected on 65 permanent sample plots every five years in the period 1991−2011. Trees with the breast height diameter (DBH)8 cm were measured on each sample plot (500 m2), while smaller trees – on three smaller concentric plots. We calculated, separately for fir and beech, the relationship between the mortality of trees and their diameter (fig. 2), the relationship between the diameter increment of trees and their DBH (figs. 3−4), the rate of saplings (h=0.3−1.3 m) growth into the first DBH class (DBH=0.1−1.9 cm). On the basis of these data, we elaborated a size−class growth model that we used to predict the development of timber resources (trees with DBH 8 cm) at 10−year intervals in the period 2001− −2041. In 2011, the predicted average standing volume was lower than the one actually measured. The forecast indicated an increase in the average standing volume (fig. 5), a reduction in the volume of ingrowth (fig. 6), an increase in the proportion of beech in the standing volume and ingrowth (figs. 5 and 7) and the maintenance of a similar density structure (fig. 8) throughout the period 2001−2041. The low accuracy of the prediction after 10 years (in 2011) was caused by the difference between the predicted and actual values of tree growth and mortality in the period 2001−2011.
Źródło:
Sylwan; 2016, 160, 03; 207-218
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
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