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Wyszukujesz frazę "Ochal, W." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Ocena przydatności wybranych funkcji do modelowania rozkładu pierśnic w drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.)
Evaluation of usefulness of selected functions for modeling distribution of breast height diameter in black alder stands (Alnus glutinosa (L.) Gaertn.)
Autorzy:
Orzeł, S.
Pogoda, P.
Ochał, W.
Powiązania:
https://bibliotekanauki.pl/articles/988989.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany olszowe
struktura grubosci
olsza czarna
Alnus glutinosa
piersnice drzew
rozklad piersnic
rozklad teoretyczny
aproksymacja
modelowanie
funkcja gestosci prawdopodobienstwa
test Kolmogorowa-Smirnowa
diameter at breast height
diameter distribution
probability density function
kolmogorov−smirnov test
Opis:
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.
Źródło:
Sylwan; 2017, 161, 02; 101-113
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Szerokość pasma jądrowego estymatora rozkładu pierśnic w drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.) z zachodniej części Kotliny Sandomierskiej
Bandwidth of kernel estimator of DBH distribution in black alder (Alnus glutinosa (L.) Gaertn.) stands from west part of the Sandomierz Basin
Autorzy:
Pogoda, P.
Ochał, W.
Orzeł, S.
Powiązania:
https://bibliotekanauki.pl/articles/985919.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
dendrometria
drzewa lesne
olsza czarna
Alnus glutinosa
piersnice drzew
rozklad piersnic
estymacja
estymatory jadrowe nieparametryczne
kernel estimator
bandwidth
dbh structure
black alder
Opis:
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.
Źródło:
Sylwan; 2018, 162, 05; 411-421
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stała krzywa wysokości dla olszy czarnej (Alnus glutinosa (L.) Gaertn.) z zachodniej części Kotliny Sandomierskiej
Generalized height-diameter model for black alder (Alnus glutinosa (L.) Gaertn.) in the western part of the Sandomierz Basin
Autorzy:
Orzeł, S.
Pogoda, P.
Ochał, W.
Powiązania:
https://bibliotekanauki.pl/articles/991312.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
dendrometria
drzewa lesne
olsza czarna
Alnus glutinosa
piersnice drzew
wysokosc drzew
stale krzywe wysokosci
Kotlina Sandomierska
alder stands
height−diameter curve
local uniform height curve
the sandomierz basin
Opis:
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 (R²adj) 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.
Źródło:
Sylwan; 2014, 158, 11; 840-849
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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