DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu



ŠUMARSKI LIST 1-2/2018 str. 52     <-- 52 -->        PDF

different size were established in Kukavica virgin forest for the purpose of these measurements. Trees with dbh>10cm were measured in all stands. In the beech virgin forests within the same area, the volume of lying and standing dead wood was estimated and compared with the results on managed forests obtained and published by Koprivica et al. (2013a). We measured standing dead wood with dbh above 10 cm and all parts of lying dead wood thicker than 3 cm at the thinner end and longer than 0.3 m. Field measurements were carried out in the period from 2004 to 2011.
Data analysis – Analiza podataka
Height curves for all studied stands were obtained by Prodan’s function:
                                (1)
where h is the height and d diameter at breast height.
Diameter diversity was calculated using the Gini index and the Coefficient of variation, while the height diversity was calculated using the Coefficient of variation.
The Gini coefficient Gdbh is defined as the area between the line of perfect equality (the diagonal) and the Lorenz curve, expressed as the proportion of the area under the diagonal (Weiner & Solbrig, 1984). When measuring tree size diversity, the Gini coefficient requires trees to be ranked by size and it quantifies the deviation from perfect equality when all trees are of equal size. Diameter diversity is measured on a scale from 0 to 1, where the Gdbh would be 0 if all trees in a stand were of equal diameter at breast height, while it would equal 1 if all trees but one had a value of 0 (O’Hara et al. 2007). Solomon & Gove (1999) stated that the use of basal area or volume may provide a more accurate estimation of structural diversity than the use of the number of trees. In our research, the Gdbh was calculated using the data on the number of trees and their basal area per class of breast height diameter (O’Hara et al. 2007).
The Gini coefficient of sample plot structure is calculated using equation (2).
                , 0 ≤ Gdbh < 1       (2)
where:
baj – represents basal area for a tree with rank j (m2ha–1);
j – represents the rank of a tree in an ascending order from 1, . . ., n;
n – represents the total number of trees;
The Gini coefficient of stand structure is calculated as an arithmetical mean of sample plot coefficients.
The Coefficient of variation of tree diameters (CVdbh %) and heights (CVh %) was calculated according to Sokal & Rohlf (1981):
                                                 (3)
where s.d. is the standard deviation, and arithmetical mean of dbh and height.
Tree volume (volume of taper and branches over 3cm in diameter) was determined using a regression equation (4) which was obtained from the analytical equalization of volume tables of beech trees in Serbia (Mirković 1969).
                                                (4)
Above-ground tree biomass (B) was determined by the general regression equation (5) designed for the estimation of the total biomass of European beech trees (Wutzler et al. 2008).
                                                (5)
where:
m –         represents total above-ground tree biomass (without leaves) in kg,
d –          represents tree diameter at breast height in cm,
h –          represents tree height in m
 
Root biomass was obtained by the regression equation (6) for beech forests in Serbia (Koprivica et al. 2012).
                Br = 0.429475 + 0.182227 B – 0.00004749 9 B2           (6)
where:
Br –         below-ground tree biomass (roots) in t ha–1,
B –         above-ground tree biomass in t ha–1
The total biomass (Bt) was obtained as the sum of the biomass above and below the ground.
Above-ground carbon stock (C) was determined using the general regression equation (7) intended for the assessment of carbon stock in European beech (Joosten et al. 2004).
                                                (7)
The carbon stored in roots was determined by multiplying its biomass by a factor of 0.5 (IPCC, 2003).
The average volume, biomass and carbon stock per ha of the managed beech stands were obtained from the data collected on the sample plots. In the virgin beech stands of Danilova kosa and Vinatovača, a complete inventory was performed and the total volume, biomass and carbon stock were calculated.