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Bonitacja wzrostowa dębu szypułkowego (Quercus robur L.) pod okapem drzewostanów sosnowych

100%
Paluch R.
Sylwan
|
2020
|
tom 164
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nr 03
The aim of the study was to compare the site index of common oak growing under the canopy of Scots pine stands with the values typical for this species on a given habitat. The research was carried out in 20 Scots pine stands with well−developed lower layers of common oak occurring in the fresh mixed forest habitat. The analyzed stands were located in 5 forest districts in central and north−eastern Poland. To determine the real age of oaks and their height, 5 under canopy common oaks from the group of the highest ones were selected and felled. The total sample size was therefore 100 trees. Cut trees were divided into sections of 1 m in length, what gave the greatest accuracy to determine the dendrometric parameters. From the middle of each section a sample for testing was taken. It was found that the oak undergrowth growing about 30−40 years under the pine canopy on a fresh mixed forest habitat, usually achieved II−III site index class, while on a mixed fresh coniferous forest habitat it was III−IV class. These site index classes are typical for the stands growing in full access of light, so no adverse changes in site index class were observed as a result of the pine canopy occurrence for 30−40 years (tab.). Oaks growing for more than 40 years under the canopy of pine obtained worse site index class than the average for a given habitat, so the complete exposure of undergrowth for the light should not be extend for too long in time. Common oaks responded with increased height to full exposure. This reaction was definitely more pronounced for the younger oaks at age of 30 than for the older ones at age of 70. The height growth curves of under−canopy common oaks differed from the model curves according to Bruchwald et al. [1996] and stand volume and increment tables [Szymkiewicz 1962], especially in the initial (juvenile) phase, which indicate the occurrence of differences in growth under the pine canopy and without cover (figs. 2 and 3).
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Metoda obliczania rocznej produkcji biomasy w zbiorowisku lesnym w zaleznosci od wysokosci i wieku drzewostanu

80%
Sulinski J.
Acta Agraria et Silvestria. Series Silvestris
|
2007
|
tom 45
89-119
Referring to the Czarnowskis formula describing tree-stand height growth rate, a definition of height growth benchmark of site quality and a formula for its calculation have been developed. Besides, a formula connecting the height growth benchmark of site quality and the annual tree-stand biomass production has been constructed. The above benchmark was developed on premises that in clear-cut managed stands: (1) product values for annual maximum height growth and the age at which it takes place as well as (2) tree-stand height at which the annual height growth rate reaches maximum values are specific for any tree species irrespectively of the site quality. A formula connecting annual biomass production and height growth benchmark of site quality has been developed on premises that the highest possible annual biomass production as calculated for given tree species in a forest community is no lower than the site productivity. The coefficients values applied in respective formulae were calculated basing on data taken from the growing stock tables for five tree species: Scots pine, Norway spruce, European fir, European beech, and English oak. In total, the data for 148 height curves were taken into consideration while the annual biomass production was analyzed for 23 tree-stands. The developed formulae are of use for practical purposes however their applicability is to be restricted in the same way as restricted is the applicability of the growing stock tables that have been used for these formulae identification.
3
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Zróżnicowanie bonitacji wzrostowej drzewostanów daglezjowych w Polsce

80%
Bijak S.
Sylwan
|
2017
|
tom 161
|
nr 03
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 information 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).
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