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ŠUMARSKI LIST 3-4/2013 str. 50     <-- 50 -->        PDF

height above 2.6 m (b), apart from the dbh and the height to the snapped point, the length of the missing tree part was assessed if possible. It was naturally important not to measure this part in the lying position. In the subsequent assessment of wood volume, the estimated length of the missing part was added to the height of the snapped tree in order to determine the total tree height. When it was not possible to assess the length of the missing part, only the tree height below the point of snapping was measured. The measurements of old stumps and trunk parts of snapped trees below 2.6 m in height (c) included the measurements of heights and mid diameters. The volume of dead trees whose dbh and height had already been determined, i.e. we knew the sample plot tariff series, was determined in the same way as the volume of living trees, i.e. by applying the regression equations that are an analytical expression of the volume tariffs for beech in Serbia, calculated after Mirković (Koprivica and Matović, 2005). The volume of old stumps and dead trees snapped at a height up to 2.6 m was calculated using Huber`s simple formula.
In the lying position, dead wood occurred in several forms: a) whole uprooted trees, lying trunks, trunk parts or branches, b) old uprooted stumps (more than a year old), c) lying processed but abandoned assortments, d) stacks of cordwood. The measurements didn’t include trees from recent cutting operations or operations that are still underway, stumps up to one year of age, as well as processed assortments that were about to be removed from the stand.
Measurements included all unprocessed (a, b) and processed (c) tree parts whose length was above 0.3 m and top diameter above 3 cm. The diameter was measured halfway along the length of the trees. The length was measured with an accuracy of up to one decimeter and the diameter of up to one centimeter. Several cross diameters were measured halfway along the length of processed wood to obtain the approximate value of the mean diameter. The volume of all measured tree pieces was determined by Huber simple formula.
A stack of cordwood (d) was measured by determining its length and height. On sloping terrains, the length of a stack was measured horizontally and its height vertically. The volume of a stack expressed in cords (stacked cubic meters) was subsequently converted (with appropriate coefficients) into the volume expressed in cubic meters.
The volume of each piece of dead wood in the lying position, snags and old stumps was individually converted per hectare, by multiplying it with a coefficient 20 (10000/500). The data were then statistically processed and sorted.
Apart from measuring, the state or degree of dead wood decomposition was determined. The following categories can be distinguished: a) sound wood, b) weakly decayed wood and c) decayed wood.
The state of dead wood was determined by applying ocular assessment and mechanical wood pressing. It is accepted that sound wood (a) is fresh dead wood with the bark attached, but without live branches and signs of serious decay (less than 10 % of volume). Weakly decayed wood (b) is wood with the signs of initial decomposition, with or without the attached bark; the wood is still hard and up to 1/3 of the diameter is affected by decay (10–40 % of volume). Decayed wood (c) is in the later stages of decomposition (over 40 % of volume) with soft sapwood and partially hard heartwood and more than 1/3 of diameter affected by decay.
All pieces of dead wood were either with or without the attached bark. If they had bark, it was included in the measurement of diameter.
For the purpose of estimating deadwood biomass, i.e. converting its volume into biomass, we used the wood density that was empirically determined as a ratio of its weight in the dry-oven state (105 °C) and the volume of wood in the original state (Marjanović et al., 2010). According to these authors, depending on the degree of decomposition (1–5), beech has the following wood density values:
Degree of decomposition 1 relates to living wood above ground, and degree 5 to completely decomposed wood. In our case, the degrees of deadwood decomposition are as follows: 2 (sound wood – less than 10 % of decayed volume), 3 (weakly decayed wood, 10–40 % of decayed volume) and 4 (decayed wood, more than 40 % of decayed volume).
Biomass of the roots of stumps and snags was determined by regression equation for European beech (Wutzler et al., 2008)
                m = 0.0282 d2.39 (1)
m – root biomass in kg
d – dbh in cm
Dbh of felled trees was calculated from the stump diameter by applying the regression equation for beech trees (2) based on Panić’s data (Nikolić and Banković, 1992).
                d1,3 = 0.651965 dp + 0.000766 dp2 + 0.000013 dp3     (2)
d1.3 – dbh in cm
dp – stump diameter in cm (at the height of 0.2–0.3 m)