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Wyświetlanie 1-2 z 2
Tytuł:
Wpływ trzebieży na wzrost i produkcyjność drzewostanów sosnowych na przykładzie doświadczenia w Kazlu Ruda (Litwa)
Impact of thinning on the growth and yield of Scots pine stands – a case study from Kazlu Ruda (Lithuania)
Autorzy:
Linkevicius, E.
Bijak, S.
Godvod, K.
Petrauskas, E.
Tiskute-Memgaudiene, D.
Valiukaite, R.
Sapokas, A.
Satinskas, R.
Powiązania:
https://bibliotekanauki.pl/articles/979650.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
Litwa
drzewostany sosnowe
sosna zwyczajna
Pinus sylvestris
trzebieze
wzrost drzewostanu
produkcyjnosc drzewostanow
scots pine
intermediate cuttings
growth and yield
long−term experiment
Opis:
One of the main tasks for the forest managers is to form the highly productive stands, and it is mainly performed by applying intermediate cuttings during the stand development. As the impact of thinning on the premature Scots pine, commercially most important species in Lithuania, has not been sufficiently investigated yet, our objective was to evaluate the impact of such treatments on the growth and yield of the pine stands by using data from the long term experimental plots. The described thinning experiment was established in 1983 in Kazlu˛ Ru−da (54.760395°N, 23.517736°E), in the 30−years−old Scots pine forest, growing in oligotrophic site conditions. Four square plots with the size of 0.25 ha each were set. The first one (5) was left as a control variant with no thinning, while the others were subjected to the treatments of different intensity. In variant 5A (slightly thinned) 15% of the basal area compared to the control plot was removed. Accordingly, in variant 5B (moderate thinning) 25% and in variant 5C (heavy thinning) 40% of basal area was subtracted. No additional thinning was implemented further during the experiment. Plots were re−measured at least 4 times with the last measurement in 2016, when the stand was 63 years old. The main result of this study was that after the 33 years no evident effect of various intensity of silvicultural treatments can be seen as the growth and yield of the un−thinned forest stand was the highest compared to the thinned ones. Growth and yield in the most intensely thinned stand reached 86 and 85% compared to the control variant, respectively. The best productive results were found for moderate thinning (92 and 89% of growth and yield of the un−thinned stand), while the worst – in the slightly thinned 5A variant (77 and 83% of values for the control stand). Further on, the number of trees and competition level in all plots were very different when the experiment was established. Yet after 33 years, these differences were remarkably reduced. Accordingly, the diameter distributions, being very different at the beginning of the experiment, eventually became very similar in all experimental plots. Finally, the results showed that in un− −thinned forest stand, natural mortality (self−thinning) of trees adjusted its density just in time. Thus this stand managed to keep its growing energy in later periods, avoiding degradation or destruction predicted by some theories.
Źródło:
Sylwan; 2019, 163, 09; 726-739
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zróżnicowanie bonitacji wzrostowej drzewostanów daglezjowych w Polsce
Variability of the site index of Douglas fir stands in Poland
Autorzy:
Bijak, S.
Powiązania:
https://bibliotekanauki.pl/articles/987057.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewa lesne
daglezja zielona
Pseudotsuga menziesii
drzewostany daglezjowe
wzrost drzewostanu
bonitacja wzrostowa
siedliska lesne
bonitacja siedliska
gleby lesne
rzezba terenu
Polska
site index
soil type
forest site type
relief features
pseudotsuga menziesii
Opis:
The objective of the study was to analyse the site index (SI) of Douglas fir (Pseudotsuga menziesii) stands in relation to the forest habitat type, soil type and relief characteristics. We utilised infor− mation available in the Information System of the State Forests in Poland that included selected parameters describing habitat conditions and dendrometric characteristics of Douglas fir stands. In total, processed data referred to 863 stands with a total area of 1,644.45 ha. As the SI distribution was not consistent with the normal one (Shapiro−Wilk test, p <0.0001) we applied Kruskal−Wallis or Mann−Whitney tests to assess the significance of observed differences. Site index of surveyed stands ranged from 19.9 to 47.8 m, 32.6 m on average (standard deviation of 3.3 m). Douglas fir in northern and southern Poland characterized by higher SI than in western and south−western part of the country (HK−W=83.5; p<<0.001; fig. 2). Forest habitat type significantly distinguished analysed stands (HK−W=30.1; p<<0.001). The highest SI values were observed for mixed deciduous habitats (fig. 3). For more fertile fresh deciduous habitats Douglas fir achieved slightly lower site index, while the least fertile mixed coniferous habitats are characterized by significantly lower SI. Habitat moisture variant had no significant effect on the average SI values (HK−W=2.6; p=0.269). The highest values were found in strongly fresh habitats (32.8 ±4.1 m), while the lowest in the humid variant (31.7 ±3.4 m). We found significant influence of soil type (HK−W=23.2, p<0.001) even though the average SI values for each category were relatively similar (fig. 4). The highest values were observed for Cambisols (33.3 ±3.7 m), while the lowest for Arenosols (32.1 ±3.0 m). Particle size distribution is an important factor for Douglas fir site index (tab.). We found that the heavier material (the higher the content of silt and clay), the significantly higher SI values (HK−W=16.9; p=0.001). Mean SI for stands growing on former farmlands (32.0 ±3.3 m) and on forest areas (32.7 ±3.3 m) were not significantly different (ZM−W=1.73; p=0.084). There was no significant effect of the relief forms on site index surveyed Douglas fir stands apart from the fact that stands growing on slopes are characterized by significantly higher SI (ZM−W=1.99; p=0.047).
Źródło:
Sylwan; 2017, 161, 03; 208-217
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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