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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:
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:
Uproszczony model rozkładu pierśnic jednowiekowych niepielęgnowanych drzewostanów sosnowych (Pinus sylvestris L.)
Simplified model of diameter distribution for even-aged unthinned Scots pine (Pinus sylvestris L.) stands
Autorzy:
Jagiełło, R.
Beker, C.
Powiązania:
https://bibliotekanauki.pl/articles/986956.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
dendrometria
sosna zwyczajna
Pinus sylvestris
drzewostany sosnowe
drzewostany jednowiekowe
drzewostany niepielegnowane
rozklad piersnic
rozklad uproszczony
rozklad gamma
diameter distribution
gamma poisson
scots pine
unthinned stand
Opis:
Although modelling of the diameter at the breast height (DBH) distributions has long history, theoretical discrete distributions have not so far been used for this purpose. In this study we use measurements covering 25 years (six inventories) without silvicultural influence on 14 even−aged Scots pine (Pinus sylvestris L.) stands to develop the DBH distribution models. Analysed stands are located in Murowana Goślina Forest Experimental Station (W Poland). The objective of the study was to elaborate the most simplified model that applies stand variables easy to assess and uncomplicated theoretical distribution. We employed two−parameter Gamma Poisson (GP) distribution and compared it to Weibull (W) and Sb Johnson (SbJ) ones. When maximum likelihood estimation (MLE) was used, GP gave similar results to W and both were slightly worse than SbJ. We found that both DBH standard deviation and stand density have substantial impact for model bias when above distributions used. Stepwise regression analysis was used for obtaining linear equations for parameter prediction of GP distribution. Then, GP model was simplified by removing standard deviation of DBH (SDD) from equation for overdispersion parameter. Results showed slight increase in mean of error values (i.e. modified Reynolds e index and root mean square error) for simplified model (SGP) compared with those for model including SDD, but differences in means were insignificant. Minimal and mean DBH represent enough variability of diameter distribution to obtain appropriate model based on Gamma Poisson distribution. Error was only 5% greater from four−parameter SbJ (MLE) distribution with similar range: 8.2−28.8% against 5.1−25.5% for SGP and SbJ respectively. The presented model can be used in many branches of forestry for more accurate calculation of stand level variables, when additional allometric equations employed, for instance assimilation apparatus volume or below− and aboveground biomass.
Źródło:
Sylwan; 2017, 161, 10; 822-830
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rozkłady teoretyczne najlepiej aproksymujące strukturę pierśnic w drzewostanach świerkowych regla górnego w rezerwacie przyrody "Śnieżnik Kłodzki"
Theoretical distributions in approximation of breast height diameter structure in upper mountain zone Norway spruce stands in 'Snieżnik Klodzki' nature reserve
Autorzy:
Sinica, P.
Tomusiak, R.
Tkaczyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/989425.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
regiel gorny
rezerwat Snieznik Klodzki
drzewostany swierkowe
swierk pospolity
Picea abies
piersnice drzew
rozklad piersnic
aproksymacja
rozklad teoretyczny
dbh distribution
stand structure
native type forests
picea abies
Opis:
The study on the structure of Norway spruce old−growth stands of original provenience in upper mountain zone was carried out in a nature reserve ‘Śnieżnik Kłodzki', located in the Lądek Zdrój Forest District (SW Poland). The fieldwork was conducted in three spruce stands located at the altitude of 1,215 and 1,235 m a.s.l. The breast height diameters (dbh) of living trees were characterized. The aim of this study is to characterize the structure of dbh of trees in spruce stands of subalpine forest. Implementation of the objective will be associated with the characteristics of empirical distributions dbh and an indication of theoretical distributions of continuous random variable best approximating the structure of dbh. The comparison of empirical dbh distributions with 36 theoretical distributions were carried out, but goodness−of−fit tests proven statistically significant compatibility with seventeen of them: beta (4−parameter), Cauchy, exponential power, folded normal, gamma (3−parameter), generalized logistic, Laplace, logistic, loglogistic, loglogistic (3−parameter), lognormal (3−parameter), noncentral chi−square, normal, smallest extreme value, triangular, Weibull and Weibull (3−parameter). The dbh distributions in upper mountain spruce stands are the best fitted with logistic distribution, and subsequently loglogistic (3−parameter), generalized logistic and Weibull (3−parameter) distributions. That four distributions can be used in individual tree growth models while generating structure dbh of trees in the stand. The knowledge of dbh structure in protected stands could be helpful in shaping spruce stand structure in planned silvicultural treatments, and shows the need for silvicultural treatments in upper mountain spruce stands.
Źródło:
Sylwan; 2016, 160, 11; 905-914
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wzorzec rozkładu pierśnic drzew wielowarstwowego drzewostanu jodłowego Gór Świętokrzyskich
Pattern of breast height diameter distribution in a multilayer silver fir stand in the Swietokrzyskie Mountains
Autorzy:
Bruchwald, A.
Dmyterko, E.
Łukaszewicz, J.
Niemczyk, M.
Wrzesiński, P.
Powiązania:
https://bibliotekanauki.pl/articles/989331.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
Gory Swietokrzyskie
drzewostany jodlowe
jodla pospolita
Abies alba
rozklad piersnic
metoda BDq
diameter distribution
abies alba
bdq method
Opis:
In Poland, the majority of silver fir stands is characterised by a single−layer stand structure. The current silvicultural activities aim at obtaining multilayer stands, which requires a clearer definition of the structure, and more precisely, a better knowledge of the pattern of diameters at breast height (DBH) distribution. The aim of the research was to develop a pattern of DBH distribution of trees in a multilayer silver fir stand in the Świętokrzyskie Mountains (central Poland) using the BDq method, through the mathematical determination of function parameters, including the productive capacity of the habitat. The application of this pattern will allow the selection of the management methods aimed to obtain and then maintain model stands with a different layer structure. The research was based on the empirical material collected in 56 stands that were characterized by both a single− and a multi−layered structure. They grew in coniferous forest habitats, mostly in the upland mixed coniferous forest, upland mixed deciduous forest and upland deciduous forest or mountain forest. One big (up to 1 ha) or 3−5 smaller (0.04 ha) sample plots were established in each stand in which diameters at breast height of all trees and heights of usually 25 trees, selected from the entire range of diameters, were measured. These were used to determine the height growth curve equation coefficients and then the height of each tree. For each stand the basal area was calculated and a graph for DBH distribution was prepared. Site index was established using the original empirical equation. In order to develop a model for multilayer fir stands, individual parameters of the equation 5, such as the basal area (B), the target diameter at breast height (D) and the coefficient q were to be determined using the BDq method. Taking into consideration only stands with one−tailed DBH, individual parameters of the function were found to be associated with site index. Empirical equations were developed for the determination of B and D, and, based on the DBH distribution graphs, coefficient q associated with site index was also calculated (tab.). The developed DBH distribution pattern is a mathematical description of the target fir stand. When the value of stand parameters approaches those of the model stand, it should be managed using the shelterwood cutting system, which results from the spatial variation in the stand height structure, and consequently from the need for different silvicultural treatments in different stand fragments.
Źródło:
Sylwan; 2016, 160, 09; 741-750
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele struktury grubości w dwu- i wielopiętrowych drzewostanach z udziałem jodły Abies alba Mill. i buka Fagus sylvatica L.
Models of diameter structure in two- and multi-storied stands with fir Abies alba Mill. and beech Fagus sylvatica L.
Autorzy:
Pach, M.
Podlaski, R.
Powiązania:
https://bibliotekanauki.pl/articles/989729.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany mieszane
struktura grubosci
drzewostany dwupietrowe
drzewostany wielopietrowe
jodla pospolita
Abies Alba
buk zwyczajny
Fagus sylvatica
rozklad piersnic
rozklad Weibulla
rozklad mieszany
tree diameter modelling
forest complex structure
weibull mixture model
Opis:
The objectives of the study were (1) to determine the models of diameter at breast height (dbh) distributions in two− and multi−storied mixed stands with fir Abies alba Mill. and beech Fagus sylvatica L. as well as (2) to assess the usefulness of single Weibull distribution and two−component mixture of Weibull distribution to approximation of empirical dbh distributions for distinguished models of dbh structures. In the Świętokrzyskie Mountains, 21 sample plots ranging in size from 0.2 to 0.4 ha were established. To identify the models of dbh distributions, in two− and multi−storied stands with similar empirical dbh distributions, the hierarchical cluster analysis (HCA) with the Jaccard's measure and the Ward's minimum variance agglomeration method were used. To approximate dbh distributions, the single Weibull distribution and the two−component mixture of Weibull distribution were employed. In two− and multi−storied mixed stands with fir and beech, with the mean age between 50 and 70 at the dbh, four models of dbh distributions were determined (fig. 1). Two of them were decreasing, strongly asymmetric (OS and OJ models; fig. 2) and the other two were increasing in the initial phase and decreasing in the final, having two maximums (DM1 and DM2 models; fig. 3). In the stands with the complex structure mixed distribution should be used to approximate empirical data. The analysis revealed high suitability and versatility of Weibull distribution both as single form and two−component mixture.
Źródło:
Sylwan; 2015, 159, 08; 632-638
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele struktury grubości w jednopiętrowych drzewostanach z udziałem jodły Abies alba Mill. i buka Fagus sylvatica L.
Models of diameter structure in single-storied stands with fir Abies alba Mill.and beech Fagus sylvatica L.
Autorzy:
Podlaski, R.
Pach, M.
Powiązania:
https://bibliotekanauki.pl/articles/989766.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany mieszane
drzewostany jednopietrowe
struktura grubosci
jodla pospolita
Abies alba
buk zwyczajny
Fagus sylvatica
piersnice drzew
rozklad piersnic
rozklad Weibulla
forest patches
structural heterogeneity
tree diameter distribution
weibull distribution
Opis:
The objectives of the study were (1) to determine the models of diameter at breast height (dbh) distributions in single−storied mixed stands with fir Abies alba Mill. and beech Fagus sylvatica L. as well as (2) to assess the usefulness of Weibull distribution to approximation of empirical dbh distributions for distinguished models. In the Carpathians (southern Poland) and in the Świętokrzyskie Mountains (central Poland) 36 sample plots ranging in size from 0.1 to 0.4 ha were established. To identify the dbh distribution models in single−storied stands with similar empirical dbh distributions, the hierarchical cluster analysis (HCA) with the Jaccard's measure and the Ward's minimum variance agglomeration method was used. To approximate dbh distributions, the Weibull distribution was employed. Single−storied mixed stands with fir and beech, with the mean age between 50 and 70 years at the dbh, were characterised by a large diversity of dbh distributions. Three groups of stands (I, II, III) differing, among others, in average dbh were determined (fig. 1). In these groups the average dbh ranged from 23.5 to 32.6 cm, from 18.9 to 25.1 cm, and from 13.7 cm to 19.6 cm, respectively. Within these groups, seven models of unimodal distributions were selected (figs. 2−4; tab.). The models are characterised by varying degrees of asymmetry with the highest number of trees from less than 30/ha to more than 300/ha which occurred mainly in the dbh classes between 9 and 33 cm (models AS1, SM1, AS2, AS3, AS4, AS5, SM2). The results of χ² test indicate the high flexibility and suitability of Weibull distribution for modelling of such types of dbh structures.
Źródło:
Sylwan; 2015, 159, 07; 586-592
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aproksymacja rozkładów pierśnic drzew w dwugeneracyjnych drzewostanach za pomocą rozkładów mieszanych. III. Estymatory jądrowe a rozkłady mieszane
Approximation of the breast height diameter distribution of two-cohort stands by mixture models. III. Kernel density estimators vs mixture models
Autorzy:
Podlaski, R.
Roesch, F.A.
Powiązania:
https://bibliotekanauki.pl/articles/990995.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany dwupokoleniowe
rozklad piersnic
aproksymacja
rozklad mieszany
rozklad Weibulla
estymatory jadrowe nieparametryczne
two−component models
kernel density estimator
tree diameter distribution
monte carlo simulation
Opis:
Two−component mixtures of either the Weibull distribution or the gamma distribution and the kernel density estimator were used for describing the diameter at breast height (dbh) empirical distributions of two−cohort stands. The data consisted of study plots from the Świętokrzyski National Park (central Poland) and areas close to and including the North Carolina section of the Great Smoky Mountains National Park (USA; southern Appalachians). Kernel density estimators belong to a class of nonparametric density estimators. Nonparametric estimators have no fixed structure and depend upon all the data points to reach an estimate. In this study the Weibull and the gamma mixture distributions were the most versatile models. The results also support the conclusion that there are only minor differences between the parametric models and the kernel density estimates.
Źródło:
Sylwan; 2014, 158, 06; 414-422
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stan wielogatunkowego lasu naturalnego (Abies, Fagus, Picea) regla dolnego w rezerwacie Oszast na tle monokultur świerkowych w Beskidzie Żywieckim i Beskidzie Śląskim
A comparison of lower montane natural forest (Abies, Fagus, Picea) in Oszast Reserve and spruce monocultures in the Zywiecki Beskid and Slaski Beskid
Autorzy:
Jaworski, A.
Pach, M.
Powiązania:
https://bibliotekanauki.pl/articles/1316186.pdf
Data publikacji:
2014
Wydawca:
Instytut Badawczy Leśnictwa
Tematy:
lesnictwo
lasy gorskie
regiel dolny
rezerwaty przyrody
rezerwat Oszast
las naturalny
drzewostany wielogatunkowe
sklad gatunkowy
swierk pospolity
Picea abies
buk zwyczajny
Fagus sylvatica
jodla pospolita
Abies alba
klon jawor
Acer pseudoplatanus
jarzab pospolity
Sorbus aucuparia
zmiany skladu gatunkowego
zasobnosc drzewostanu
struktura drzewostanu
rozklad piersnic
smiertelnosc
odnowienia lasu
stand volume
dbh distribution
mortality
regeneration
Opis:
The aim of this research was to find out what changes occurred between 1999-2009 in Oszast reserve in the volume, species composition and diameter at breast height (dbh) distribution of the forest stand, and the number and height of regeneration. The objective was to determine what would be condition of these managed lower montane multispecies forest stands (Swiss irregular shelterwood method or selection cuttings) and what role spruce would play in them if they have not been replaced by spruce monocultures. The research was conducted on three permanent circular sample plots (s.p.), each had size of 1/3 ha. Over 10 years, standing volume of the forest stand increased on s.p. 1 (from around 562 m3 ha-1 to 649 m3 ha-1) and s.p. 3. (from 653 m3 ha-1 to 660 m3 ha-1), while decreased on s.p. 2. (from 421 m3 ha-1 to 378 m3 ha-1). The species composition, defined on the basis of volume share (averaged for the three s.p. jointly), did not undergo consistent changes. However, the relative dominance of beech over spruce was determined based on tree numbers. The average spruce mortality (averaged from three s.p.) did not exceed 10% and was slightly higher than that of beech (6%), and lower than fir mortality (15%). Nevertheless, spruce did not show any symptoms of dieback. The reasons behind its mortality were fallen trees and windbreaks. In regeneration, on the whole, beech or sycamore predominated, and the proportion of spruce and fir was small. In the future spruce and fir may even decrease further by competitive ability of dynamically regenerating beech. Abandonment of forest management to promote greater diversity of species, may favour the formation of beech monocultures, or forest stands dominated by beech, everywhere that beech is already present or will be introduced. The maintenance of stable, multispecies forest stands, with co-dominant fir, beech and spruce of native origin, requires natural or artificial regeneration of spruce and fir, manipulated to restore fir up to about 30%, and reduce spruce down to about 40%. This would be possible through the use of the Swiss irregular shelterwood method and selection system, and by continuous tending of regeneration.
Źródło:
Leśne Prace Badawcze; 2014, 75, 1; 13-23
1732-9442
2082-8926
Pojawia się w:
Leśne Prace Badawcze
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aproksymacja rozkładów pierśnic drzew w drzewostanach dwugeneracyjnych za pomocą rozkładów mieszanych. II. Testy zgodności
Approximation of the breast height diameter distribution of two-cohort stands by mixture models. II. Goodness-of-fit tests
Autorzy:
Podlaski, R.
Roesch, F.A.
Powiązania:
https://bibliotekanauki.pl/articles/993354.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany dwupokoleniowe
rozklad piersnic
aproksymacja
rozklad mieszany
testy zgodnosci
two−component mixtures
tree diameter distribution
nonparametric goodness−of−fit tests
discrete null distribution
Opis:
The goals of this study are (1) to analyse the accuracy of the approximation of empirical distributions of diameter at breast height (dbh) using two−component mixtures of either the Weibull distribution or the gamma distribution in two−cohort stands, and (2) to discuss the procedure of choosing goodness−of−fit tests. The study plots were located in the Świętokrzyski National Park (central Poland) and in the Southern Appalachian Mountains (eastern USA). The results of the goodness−of−fit tests (chi−squared, Kolmogorov−Smirnov, Cramér−von Mises, and Anderson−Darling), normalised bias and normalised root mean square error, indicate that dbh empirical distributions of two−cohort stands are compatible with the mixture models investigated. The chi−squared test and the generalization of the Anderson−Darling test to discrete distributions should be used to assess whether empirical dbh data are consistent with a hypothesized null distribution.
Źródło:
Sylwan; 2013, 157, 09; 652-661
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aproksymacja rozkładów pierśnic w dwugeneracyjnych drzewostanach za pomocą rozkładów mieszanych. I. Estymacja parametrów
Approximation of the breast height diameter distribution of two-cohort stands by mixture models. I. Parameter estimation
Autorzy:
Podlaski, R.
Roesch, F.A.
Powiązania:
https://bibliotekanauki.pl/articles/994450.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany dwupokoleniowe
rozklad piersnic
aproksymacja
rozklad mieszany
estymacja parametrow
two−component mixtures
tree diameter distribution
weibull distribution
gamma distribution
starting strategy
Opis:
Study assessed the usefulness of various methods for choosing the initial values for the numerical procedures for estimating the parameters of mixture distributions and analysed variety of mixture models to approximate empirical diameter at breast height (dbh) distributions. Two−component mixtures of either the Weibull distribution or the gamma distribution were employed. The study plots, representing two−cohort stands, were located in the Świętokrzyski National Park (central Poland) and in the Southern Appalachian Mountains (eastern USA). A new strategy using three methods for choosing initial values (min.k/max.k for k=1, 5, 10; 0,5/1,5/mean; wp) for maximizing the likelihood during parameter estimation for mixture models for small and large plots is proposed.
Źródło:
Sylwan; 2013, 157, 08; 587-596
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dokładność określania wybranych parametrów rozkładów pierśnic drzew w drzewostanach sosnowych za pomocą naziemnego skanowania laserowego
Accuracy of the selected tree diameter distributions parameters assessed using terrestrial laser scanning in Scots pine stands
Autorzy:
Zasada, M.
Sterenczak, K.
Powiązania:
https://bibliotekanauki.pl/articles/994333.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
dendrometria
zasoby drzewne
inwentaryzacja
drzewostany sosnowe
powierzchnie probne kolowe
rozklad piersnic
dokladnosc
skanowanie laserowe
forest inventory
circular sample plots
quadratic mean diameter
percentile
skewness
kurtosis
Opis:
When using such methods as terrestrial laser scanning (TLS), one of the major factors influencing the accuracy of stand characteristics determination is the visibility of trees on a sample plot, which is often obscured by the shadow effect caused by trees located closer to the plot center. Because of this, the percentage of the identified trees and basal area depends on the distance from the plot center: the accuracy of stocking determination decreases as the plot radius increases. The values of such stand characteristics as average breast height diameter, standard deviation of tree diameters and percentiles of the tree diameters' distributions assessed based on all trees and the visible trees only are not significantly different from each other for circular sample plots with 20 m radius. Skewness and kurtosis are not significantly different in plots with radius of 5 and 10 meters. For the 15 m plot radius the difference was significant for about 15% of the analyzed plots. The obtained results correspond with previous findings that report that on the circular sample plots with radius up to 15 m the errors for the number of trees and basal area are relatively small and can be accepted in the practical inventory. The results support the circular sample plots size optimization, including measurements performed using a point cloud.
Źródło:
Sylwan; 2013, 157, 12; 883-891
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kształtowanie zróżnicowanej struktury drzewostanów w warunkach nizinnych
Promoting diverse forest stand structure under lowland conditions
Autorzy:
Brzeziecki, B.
Drozdowski, S.
Bielak, K.
Buraczyk, W.
Gawron, L.
Powiązania:
https://bibliotekanauki.pl/articles/994357.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
Puszcza Bialowieska
drzewostany
struktura drzewostanu
struktura warstwowa
struktura gatunkowa
ksztaltowanie struktury
postepowanie hodowlane
struktura grubosci
rozklad piersnic
metoda BDq
białowieża forest
close−to−nature silviculture
stand structure
silvicultural planning
stocking control
Opis:
The paper presents preliminary results and experiences concerning promoting diverse structures in forest stands dominated by light demanding tree species, i.e. those that prevail under conditions of Polish lowlands. Data was collected in the ‘Control Unit Browsk 28C', established in 2002 in the managed part of the Białowieża Forest (eastern Poland) and surveyed again in 2011.
Źródło:
Sylwan; 2013, 157, 08; 597-606
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelowanie rozkładów pierśnic młodocianych drzewostanów brzozy brodawkowatej na gruntach porolnych za pomocą dwuparametrowego rozkładu Weibulla
Modeling dbh distribution of young silver birch stands on former agricultural lands with the 2-parameter Weibull distribution
Autorzy:
Zasada, M.
Powiązania:
https://bibliotekanauki.pl/articles/991512.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
dendrometria
drzewostany mlode
grunty porolne
drzewostany brzozowe
brzoza brodawkowata
Betula pendula
piersnice drzew
rozklad piersnic
modelowanie
rozklad Weibulla
betula pendula
secondary succession
diameter distribution
weibull
Opis:
The paper presents the diameter distributions of young silver fir stands (Betula pendula Roth.) growing on former agricultural lands described using the 2−parameter Weibull distribution. Various methods of parameters' estimation were tested: maximum likelihood method, method of moments and percentile approach. It was found, that the diameter distributions in such birch stands can have various shapes and forms – from close to the exponential to almost normal. The shape parameter were not affected by the age of the stand, but the scale parameter was strongly correlated with age. The most efficient methods for the tree diameter distribution modeling using the 2−parameter Weibull distribution are the method of moments and the maximum likelihood method. However, the obtained results does not exclude the percentile method, which is relatively simple and can be further modified for obtaining better results.
Źródło:
Sylwan; 2013, 157, 04; 268-277
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kształtowanie zróżnicowanej struktury drzewostanów z wykorzystaniem metody BDq
Application of the BDq method in uneven-aged stands silviculture
Autorzy:
Brzeziecki, B.
Kornat, A.
Powiązania:
https://bibliotekanauki.pl/articles/973764.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
struktura drzewostanu
ksztaltowanie struktury
rozklad piersnic
metoda BDq
diameter distribution
stand conversion
stocking control
sustainable yield
uneven−aged
silviculture
BDQ method
Opis:
The BDq method, a tool of stocking control in uneven−aged stands, with a special reference to the problem of determining diameter structure of cuttings, is introduced. Both theoretical foundations, as well as a practical application of the BDq method are presented on the example of conversion of two−storied stands, consisting of silver fir and Scots pine, to stands characterized by a plenter−like structure.
Źródło:
Sylwan; 2011, 155, 09; 589-598
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
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