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Wyświetlanie 1-2 z 2
Tytuł:
Problematyka pomiarów oraz określania miąższości martwego drewna na kołowych powierzchniach próbnych
Measurement and calculation of the volume of deadwood on circular sampling plots
Autorzy:
Bujoczek, L.
Powiązania:
https://bibliotekanauki.pl/articles/989747.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
powierzchnie probne kolowe
drewno martwe
miazszosc drewna
pomiary drewna
metody pomiarow
coarse woody debris
snags
shape
decomposition
field methods
volume determination
Opis:
The paper analyzes two methods of deadwood (DW) measurements on circular sampling plots. In the first method, the volume of DW is measured within the circumference of the sampling plot irrespective of the fact whether the live tree was located inside or outside the plot. The other method requires the measurement of only that DW, which can be attributed to trees that originally grew within the sampling plot. This requires identification all debris fragments originating from those trees both within and outside the sampling plot. Additionally, the paper compares the results obtained using Smalin's and Huber's formulas and discusses the influence of decomposition stage on the calculated volume of lying deadwood. Measurements were conducted in two stands. In each of them 20 circular sampling plots (4 or 5 ares) were established. In both stands, the second investigated measurement method led to a lower mean DW volume (by 6.3% and 27.2%). In practice, it was very difficult to identify DW from the outside of the sampling plots as high trees growing close to the plot had their fragments lying up to several dozen meters away. If a tree was very fragmented upon falling, it was difficult to find all the relevant pieces of DW and determine whether they derived from the sampling plot or not. The volume of lying DW calculated according to Smalin's formula was by 5% higher. In case of 7.7% of the 194 inventoried fragments of lying DW the transverse cross−section changed from circular to misshapen. The application of formulas accounting for decomposition decreased the calculated volume of lying DW by 5.1%. Taking into consideration the time−effectiveness and accuracy of measurements, it has been found that for most stands the best method is to measure the ends of DW pieces, calculating the length of segments from polar coordinates (using the measurement principles presented in the figures). In addition, especially in measuring large trees, one should take into account changes in shape attributable to decomposition, which may influence the calculation of DW volume. It is recommended that all DW fragments within a circular sampling plot should be measured irrespective of whether the tree from which they derive grew inside or outside the plot.
Źródło:
Sylwan; 2015, 159, 10; 795-803
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dokładność określenia zasobności na poziomie warstw gatunkowo-wiekowych w obrębowej metodzie inwentaryzacji
Accuracy of volume determination on the level of age-species layers in the stratified sampling method
Autorzy:
Banaś, J.
Drozd, M.
Bujoczek, L.
Zięba, S.
Zygmunt, R.
Powiązania:
https://bibliotekanauki.pl/articles/986687.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
powierzchnie probne
forest inventory
stratification
standard error
sample plot
variability coefficient
lesnictwo
drzewostany swierkowe
warstwy gatunkowo-wiekowe
inwentaryzacja lasu
zasobnosc drzewostanu
miazszosc drzewostanow
metoda obrebowa
dokladnosc pomiaru
Opis:
Statistical representative method of inventory based on stratified sampling is used for elaborate forest management plans in Poland. Strata are created according to the dominant tree species and age of stands. First stratum include stands with age from 21 to 30 years and the interval in the next strata is 10 years. Sample plot size depends on stand age and varies from 0.005 to 0.05 ha. According to the allocation pattern number of samples is proportional to age and total area of stands in a stratum. Diversification of number and size of sample plots has a profound influence of inventory precision in an age classes. The aim of the study is to analyse the accuracy of the stand volume determination on the level of age−species strata. Research was conducted based on the data obtained from periodic forest inventory in seven mountainous forest subdistricts located in the Kłodzko Basin (SW Poland). Norway spruce stands with total area of 39,935.45 ha and 6102 sample plots were chosen for analysis. Sampling fraction, mean number and volume of trees on a sample plot, coefficient of volume variability and standard error of volume were calculated for each stratum in analyzed forest subdistricts. Sample plots with size of 0.005 ha established in young stands (21−30 years) are characterized by small number of trees (4.3−7.6 in average) and the highest coefficient of volume variability (93%). Additionally, because of low age of stands, the number of plots is also small (18 on average), which influences the low precision of volume inventory in this stratum. Standard error of volume was on the mean level of 23% in the youngest age stratum and decreased with age of stands to 5% in the stands of 41−71 years and below this level in the strata with the older stands. Increasing the plot size in the youngest stratum will be effective way to improve accuracy of forest inventory in the method based on stratified sampling.
Źródło:
Sylwan; 2017, 161, 09; 715-722
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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