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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 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
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