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ŠUMARSKI LIST 7-8/2015 str. 61     <-- 61 -->        PDF

MATERIALS AND METHODS
Materijali i metode rada
Trojan fir and scots pine needles and sweet chestnut leaves that fell on the ground in the study areas where the harvesting activities were completed a year ago were manually collected in October-November 2010, put into nylon bags, labeled and brought to the laboratory. Cleaned and air-dried samples were then put into decomposition bags with a mesh width of 1 mm and a size of 20x20 cm. In order to determine the amount of moisture in the air-dried samples before taking them to the decomposition areas, a batch from each sample was weighed on a precision digital scale and oven-dried at 85 °C for 24 hours and the amount of moisture in the samples was calculated using the weight difference between air-dried samples and oven-dried samples.
In order to determine the effects of three different environments formed on stands as a result of harvesting activities (SR, LR, SMS) on litter decomposition, the decomposition bags were placed on these areas and on control areas, where no harvesting activity was performed. The number of decomposition bags placed on areas to carry out the experiment, which was planned to take eighteen months, was 360 in total for scots pine and trojan fir [2 species (scots pine and trojan fir) x 4 factors (C, SR, LR and SMS) x 3 sampling times (6th 12th and 18th months) x 3 study areas x 5 repetitions = 360]. Since the sweet chestnut harvesting area was rather small, the study was carried out on a single area and a total of 60 decomposition bags were prepared for sweet chestnut samples [4 factors X 3 sampling times X 5 repetitions = 60].
After determining the wet weights of the decomposition bags, and the needles and leaves air-dried samples in the laboratory and then oven-dried at 85oC for 24 hours (Sariyildiz et al., 2008; Sariyildiz et al., 2004; Sariyildiz, 2003). The amount of moisture in the needles and leaves was calculated using the difference between wet weights and oven-dried weights. Then the mass loss compared the initial weight was found. The decomposition constant (k) was calculated based on the Wt=W0.e–kt formula, which was used in Olson´s (1963) decomposition model and is still widely used today. Here, Wt= t refers to the remaining mass at time t and W0 refers to the initial mass. The time required for 50% mass loss was calculated based on the T50 =1/k formula and the time required for 95% mass loss was calculated based on T95 =3/k formula, which were also used by Olson.
Statistical analysis
Statistička analiza
One-way analysis of variance was used in order to determine the effects of harvesting activities on the decomposition progress for each species using the SPSS program (Version 20 for Windows). To be able to use the analysis of variance, the data must have the minimum interval scale and show normal distribution. The fact that the obtained data was quantitative meets the first assumption. One sample Kolmogorov-Smirnov (K-S) test was performed to determine whether the data conformed to normal distribution and it was found that it showed a normal distribution at α = 0.05 level of significance (p>0.05). Tukey’s honestly significant difference (HSD) test, which is one of the multiple comparison tests, was used in order to demonstrate the differences resulting from harvesting activities (p<0.05).