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1
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Rozkład przyrostu grubości na przekroju poprzecznym drzewa w górskich drzewostanach świerkowych

100%
Ochal W.
Sylwan
|
1998
|
tom 142
|
nr 11
69-86
2

Nadziemna biomasa drzew w młodych drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.)

100%
Ochal W.
Acta Agraria et Silvestria. Series Silvestris
|
2013
|
tom 51
The aim of this study was to specify the above-ground biomass structure of black alder as well as to assess the influence of habitat conditions on biomass size and on allometric relation between biomass and breast height diameter. The empirical material consisted of 67 sample trees in age from 6 to 20 years selected from 17 stands growing on two types of forest habitat. The average share of stem wood in aboveground biomass of trees was 61.04%, branches 18.89%, bark and leaves 11.31% and 8.76% respectively. The fact that the examined stands constituted habitat type did not substantially influence either the biomass size or the relation between biomass and breast height diameter.
3
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Struktura i dynamika przyrostu grubosci drzew w drzewostanach swierkowych masywu Skrzyczne

100%
Ochal W.
Sylwan
|
2000
|
tom 144
|
nr 01
75-85
4
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Dokladnosc okreslania piersnicowego pola przekroju drzewostanow bukowych na podstawie powierzchni probnych

100%
Ochal W.
Sylwan
|
2007
|
tom 151
|
nr 11
10-21
5
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Tendencja wzrostowa wierzcholka i stopien defoliacji koron drzew w drzewostanach sosnowych wzrastajacych w wybranych regionach przemyslowych Polski poludniowej

63%
Socha J., Ochal W.
Sylwan
|
2002
|
tom 146
|
nr 05
53-60
6
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Effect of seedling production method on the growth of Pinus sylvestris L. on reclaimed post-industrial sites in Poland

51%
Socha J., Orzel S., Ochal W., Pietrzykowski M.
Dendrobiology
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2022
|
tom 88
7

Biomass of underbrush and conditions for its occurrence in stands of the Niepolomice Forest

51%
Orzel S., Socha J., Forgiel M., Ochal W.
Electronic Journal of Polish Agricultural Universities. Series: Forestry
|
2005
|
tom 08
|
nr 1
8
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Modele bonitacyjne dla gatunków lasotwórczych Polski opracowane na podstawie tablic zasobności

51%
Socha J., Ochal W., Grabczynski S., Maj M.
Sylwan
|
2015
|
tom 159
|
nr 08
The objectives of this work was to develop a site index models for main forest−forming tree species in Poland based on data from published yield tables. The research material include growth series of birch, European beech, common oak, red oak, European hornbeam, European ash, Norway maple, small−leaved lime, black alder, trembling aspen, locust, Douglas fir, silver fir, European larch, Scots pine, and Norway spruce. Six algebraic difference models were preliminary selected for the construction of site index model. When selecting a potential models an assumption was made, that the index system should be characterized by good fit to the empirical data, polymorphism, variable asymptotes for different sites and equality of the site index and height at a certain base age. To estimate parameters of individual models all possible combinations among height−age pairs for each tree were used. The selection of the best model was based on fit criteria describing: proportion of variance explained, error range and standard deviation of the residuals. Best fitting model was selected basing on the sum of ranks from individual criteria and for each individual tree species a separate model was selected, which fits the best growth series from the yield tables. For 16 out of 19 species, the best fit statistics were demonstrated by the model developed on the base of the function [2]. Developed models may be used both in forestry practice and forestry research in order to estimate site index for analyzed tree species.
9
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Szerokość pasma jądrowego estymatora rozkładu pierśnic w drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.) z zachodniej części Kotliny Sandomierskiej

51%
Pogoda P., Ochal W., Orzel S.
Sylwan
|
2018
|
tom 162
|
nr 05
Set of ‘nonparametric’ methods, that don’t make a priori assumption about functional form of empirical distribution was developed as an alternative to the parametric distribution modeling. The kernel estimators are one of such methods, that can be used to describe the frequency of data representing for example DBH records. Kernel smoothing requires the choice of weighting function and bandwidth also called as smoothing parameter or window. The lack of comprehensive analysis on the applicability of particular bandwidth selection methods to model DBH structure gave an impulse to present investigation aimed at determining value and variability of smoothing parameter in black alder stands. The optimal bandwidth was obtained according to six different variants of plug−in method proposed by Altman and Léger. Presented investigations were based on DBH measurements collected in 163 managed black alder stands aged from 6 to 89 years, growing in the west part of the Sandomierz Basin (S Poland). We measured in total 22,530 black alders, from 48 to 359 in individual stand. Stands were characterized by: age, quadratic mean diameter, basal area, mean height, Reineke’s stand density index and standard deviation of DBH. Smoothing parameter was obtained by means of plug−in method with the pilot bandwidth selected by: Silverman’s rule of thumb (nrd0), Scott’s method (nrd), unbiased cross−validation (ucv), biased cross−validation (bcv), method of Sheather and Jones (sj) and one−stage method of Wand and Jones (onestage). The bandwidth was first obtained to real data, then to 100 bootstrap samples of 5, 10, 15 ... and 100 trees from each stand. Smoothing parameters were characterized by mean and variance. Relationship between values of smoothing parameter and stand characteristics was determined. Finally the influence of sample size on value and variability of bandwidth was assessed. Value and variability of smoothing parameter in black alder stands are determined by stand age, sample size and method of bandwidth choice. There is a close relationship between bandwidth and the mean height (r from 0.75 to 0.83), quadratic mean diameter (r from 0.79 to 0.88) and standard deviation of DBH (r from 0.84 to 0.93). Potentially these stand features can be used to predict smoothing parameter values. Minor changes of bandwidth for samples containing above 50 trees together with persistence of standard error give an objective grounds for defining optimal number of diameters, that are necessary to kernel estimation of DBH distribution.
10

Biomasa i roczna produkcja drzewostanow mieszanych Puszczy Niepolomickiej

51%
Orzel S., Socha J., Forgiel M., Ochal W.
Acta Scientiarum Polonorum. Silvarum Colendarum Ratio et Industria Lignaria
|
2005
|
tom 04
|
nr 2
63-79
11
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Produkcyjność górskich drzewostanów świerkowych średnich klas wieku w zależności od wysokości ich położenia nad poziomem morza

51%
Orzel S., Socha J., Ochal W.
Sylwan
|
1999
|
tom 143
|
nr 05
37-45
12
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Struktura grubosci wybranych drzewostanow sosnowych wzrastajacych na zrekultywowanych dla lesnictwa obiektach pogorniczych

51%
Ochal W., Pajak M., Pietrzykowski M.
Sylwan
|
2010
|
tom 154
|
nr 05
323-332
13
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Dokładność stałych krzywych wysokości dla drzewostanów olszy czarnej (Alnus glutinosa (L.) Gaertn.)

51%
Ochal W., Orzel S., Siudak K., Zamyslewska M.
Sylwan
|
2016
|
tom 160
|
nr 08
The study presents the assessment of the accuracy of two generalized height−diameter models, such as skwB [Bruchwald et al. 2001] and skwO [Orzeł et al. 2014], developed in Poland for black alder (Alnus glutinosa (L.) Gaertn.) stands. Verification of these models was conducted on empirical material that was collected in 127 alder stands located in the western part of Sandomierz Basin (southern Poland). Selected alder stands aged 6−89 years, while average breast height diameter ranged from 4.5 to 43.0 cm and average height from 6.3 to 32.7 m. The stand density varied from 222 to 4360 trees/ha. The accuracy assessment for uniform height−diameter curves was based on the analysis of single tree absolute error distributions. Synthetic indicators of goodness−of−fit, such as: average and standard errors, coefficients of variation and determination were calculated based on absolute errors. The final evaluation of the compared uniform height−diameter models results from the structure of the goodness−of−fit measures that was observed within all analyzed stands and within age classes of 20 years. The efficiency of uniform height−diameter models was also compared with stand height−diameter curve, which was developed based on the Näslund function. General height−diameter models overestimated height in alder stands on average from 0.26 (1.67) to 0.19 m (1.39%), based on skwB and skwO models, respectively. Bias depended on the age of stand and decreases from almost 3% in I age class to nearly 0.5% in IV and V age class. For both analyzed models, a positive systematic error was observed for the standardized breast height diameter. Bias in estimating the height of single stand depended on the accuracy of stand height estimations. In case of estimation based on the measurements of three trees height, bias in single stand can range from –13% to +14%. Due to the range and nature of observed systematic errors, uniform height curves should be applied to groups of stands that have different age and breast height diameter structure, as it allows for partial reduction of the error.
14

Związek dokładności modelu zbieżystości z wielkością pobranej próby

51%
Socha J., Grabczynski S., Ochal W.
Acta Agraria et Silvestria. Series Silvestris
|
2012
|
tom 50
The aim of this work was to determine a sample size needed to develop a taper model. Relationship between sample size used in development of taper model and the accuracy of the tree volume and stem profile determination was analyzed. On the basis of conducted analysis there was determined both minimal and optimal sample size necessary to correct elaboration of local tree taper model.
15

Biomass and annual production of common alder stands of the Niepolomice Forest

51%
Orzel S., Forgiel M., Socha J., Ochal W.
Electronic Journal of Polish Agricultural Universities. Series: Forestry
|
2005
|
tom 08
|
nr 1
16
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Dokładność określania świeżej masy strzał jodły na podstawie przeliczników wagowo-objętościowych

51%
Ochal W., Wertz B., Grabczynski S., Orzel S.
Sylwan
|
2018
|
tom 162
|
nr 04
The paper describes the accuracy of estimation of silver fir stem fresh mass on the basis of volume to weight conversion factor, derived from samples, collected from few different places along the stem. The research material contained 13 sample trees selected from homogenous 70−years old stand, situated in mountainous area of the Beskid Sądecki in Polish part of the Carpathians (S Poland). Volume over the bark of sample trees was calculated with section−wise method and the whole stem fresh biomass was directly weighted. For each sample tree three stem discs were collected at ⅙, ½ and ⅚ of tree height, their weight and volume were precisely determined and the biomass conversion factors (equivalent of stem density) were calculated. The assessment of the accuracy of whole fresh stem biomass was conducted according to five variants: for the biomass conversion factors derived from each individual stem disc (lower, middle or upper), from weighted mean density and on the basis of the constructed mixed model, where relative height and diameter were treated as fixed effects and influence of individual trees was included as a random term. The volume of sample fir stems ranged from 0.15 to 2.22 m³, while their fresh biomass varied between 138.1 and 1896.7 kg. Obtained results show that variation of the density was higher within stems than between them (coefficient of variation amounted to 8.4% i 3.3% respectively). The average density increased along stem, from 835.6 kg/m³ for lower part (⅙H) to 986.8 kg/m³ for the upper part (⅚H). Estimating the biomass on the basis of just lower stem disc resulted in the average relative error equal to –5.8%, while for middle stem disc the error was +1.2%, and for upper disc +11.3%. The use of conversion factors derived from weighted average density of all three stem discs resulted in average bias equal to –1,7% with standard error 1,0%. Despite the presence of mean bias of –2.3%, the constructed density model gave the most precise estimation of the stem biomass (standard error 0.7%), which indicates the reasons for its further improvements and usage.
17
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Biomasa i roczna produkcja drzewostanow debowych Puszczy Niepolomickiej

51%
Orzel S., Ochal W., Forgiel M., Socha J.
Sylwan
|
2006
|
tom 150
|
nr 05
30-43
18
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Ocena przydatności wybranych funkcji do modelowania rozkładu pierśnic w drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.)

51%
Orzel S., Pogoda P., Ochal W.
Sylwan
|
2017
|
tom 161
|
nr 02
We evaluated the usefulness of ten theoretical probability density functions for the approximation of the breast height diameter distributions in managed alder stands growing in the western part of the Sandomierz Basin (southern Poland). The study material consisted of measurement results for 22,530 alders obtained for 844 circular sample plots, established in 163 stands aged 6−89. In the area of particular stands, from 2 to 10 age−dependent circular sample plots sized 0.01−0.10 ha were systematically arranged. We evaluated the following theoretical probability distributions: normal (N), double normal (P−N), Johnson SB (J), Weibull (W), beta (B), Burr (Bu), gamma (G), log−normal (L−N), log−logistic (L−L) and Birnbaum−Saunders (B−S). Additionally the usefulness of the W, B, Bu, G, L−N, L−L and B−S distributions with omitted location parameter was tested. The goodness−of−fit of each probability density function was assessed based on the Kolmogorov−Smirnov statistic, the root mean square error and ranks established on their basis. It was found that DBH distribution of majority stands is characterized by right−sided asymmetry and negative kurtosis. It was showed that the best distribution for the breast height diameter structure approximation of alder stands is the Johnson SB (J) distribution. To describe the frequency of thickness, normal (N) and log−logistic (L−L) distribution should not be used. Elimination of location parameter significantly affects usefulness of probability density functions to modeling empirical distributions of breast height diameter. Gamma and Burr distributions with omitted location parameter gave the best results in description the frequency of breast height diameter. In certain situations, these distributions can also be used to describe the structure of breast height diameter of alder stands.
19
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Nadziemna biomasa i roczna produkcja drzewostanow sosnowych Puszczy Niepolomickiej

51%
Orzel S., Forgiel M., Ochal W., Socha J.
Sylwan
|
2006
|
tom 150
|
nr 09
16-32
20
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Stała krzywa wysokości dla olszy czarnej (Alnus glutinosa (L.) Gaertn.) z zachodniej części Kotliny Sandomierskiej

51%
Orzel S., Pogoda P., Ochal W.
Sylwan
|
2014
|
tom 158
|
nr 11
The study shows that the accuracy of tree height approximation by means of investigated functions is not modified by the age or site conditions of the analysed alder stands. The widest range of tree height variability was explained by Schnute (M5) function. Higher values of adjusted coefficient of determination (R2 adj) are usually obtained when the height of black alder stands in the western part of the Sandomierz Basin is determined with M2 height−diameter curve.
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