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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).
Sylwan
|
2013
|
tom 157
|
nr 04
Paper analyses relationships between radial growth and seven crown−related parameters (crown length, relative length, width, slenderness, projection area and volume as well as single tree space) for ten alien and native tree species growing in 'common garden' conditions in the WULS−SGGW Forest Experimental Station in Rogów (central Poland). Significant correlation was found between 10− and 15−years mean tree−ring width and all analysed crown parameters as well as single tree space for Abies grandis, Abies nordmanniana and, except for crown length and its relative length, for Pinus sylvestris. No relationship was observed between radial increment of Larix decidua, Pseudotsuga menziesii and Quercus rubra and any of analysed crown parameters.
Przyroda coraz częściej staje się głównym motywem uprawiania turystyki. Poznanie przyrodniczych walorów i atrakcji turystycznych jest obowiązkowym elementem programów wycieczek zarówno zbiorowych, jak i indywidualnych. Odznaki turystyczno-krajoznawcze Polskiego Towarzystwa Turystyczno-Krajoznawczego (PTTK) mają stanowić próbę podpowiedzi i wskazania tych miejsc, które warto odwiedzić i poznać. Praca przedstawia odznaki krajoznawcze PTTK w kontekście propagowania poznania atrakcji przyrodniczych i form ochrony przyrody w Polsce.
The intermediate cuttings have an important impact on the stand structure and productivity. Choosing the right method of the treatment performance is the decision, which is fundamental in shaping tree stands stability. The radial increment, apart from the natural growth potential of particular species, is influenced by many abiotic, biotic and anthropogenic factors, among which one can distinguish those that influence it directly, e.g. thinning. The study objective was to determine the effect of silvicultural treatments on the increment reaction of oak (Quercus sp.) stands in the Międzyrzec Forest District (eastern Poland). The empirical material was collected in six forest stands located in the Witoroż forest range. In each stand we cored 10 dominant and co−dominant trees (representing 1st and 2(sup)nd Kraft’s biosocial classes). After the measurements of the tree−ring widths and the synchronization of incremental series, the raw and standard chronologies were elaborated for each stand. In total, we analysed 8 treatments: six early and one late selection thinnings, and one late salvage thinning (tab. 1). For each treatment, three− and five−years’ value of mean tree−ring width was calculated for the period before and after the cut. Additionally, we calculated the incremental response parameters: recovery (Rc), resilience (Rs) and resistance (Rt) indices. For the majority of the analysed treatments, the cuts resulted in an increase in average tree−ring width both in the 3−, and 5−years perspective. However, statistically significant changes in this parameter occurred only in a few cases (fig. 2). The average values of incremental response indicators show that the investigated oak stands are characterized by a significant adaptive capacity and a rapid recovery of incremental capacity in the analysed time spans. At the same time, the low values of Rt index suggest that their growth resistance to disturbance caused by the thinning is rather low. The age of the stand at the time of the treatment significantly affected the incremental response parameters of the examined oaks. The older the stand, the incremental response was less intense.
The objective of the study was to determine the impact of selected soil properties on site index of oak (Quercus sp.) stands in the Międzyrzec Forest District (eastern Poland). We utilised data rom the soil−habitat survey, which provided information about physical and chemical properties of soils and stand descriptions for 21 oak stands (tab. 1). The collected data served to determine site index (SI), defined as the stand top−height at the age of 100, and soil trophic index (SIG) that is a synthetic measure of the soil fertility. For SI and SIG distributions met the criteria of the normal distribution (Shapiro−Wilk test p−values equalled 0.118 and 0.297, respectively), we applied one−way analysis of variance, t−test and correlation analysis to determine the influence of the forest habitat type and moisture as well as soil properties and fertility measures on the site index of analysed oaks. The SI of investigated oaks ranged from 23.2 to 29.3 m, 26.5 m on average (tab. 2). It was significantly dependent on the site type (F=6.913, p=0.006) with the lowest values on oligotrophic habitat and the highest – on eutrophic one. No effect of habitat moisture content and soil type was found (t=–0.408, p=0.688 and F=2.599, p=0.076, respectively). The SIG values ranged from 20 to 36, with the average of 29.5 (tab. 2). Similarly to the site index, we found significant impact of the forest habitat type (F=5.384, p=0.015) on SIG values. Soil fertility and physical properties significantly influenced site index of the analysed oaks (fig.). We found positive correlation between SI and SIG values (r=0.566, p=0.007) as well as between SI and clay content (r=0.454, p=0.037). Chemical properties of the soils under studied stands seem to have less profound effect on site index of oak. The highest, but insignificant, correlations were found for recalculated acidity (r=–0.420, p=0.056) and magnesium content (r=0.400, p=0.071).
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