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ŠUMARSKI LIST 7-8/2015 str. 64     <-- 64 -->        PDF

DISCUSSION
Rasprava
According to the study results, forest harvesting activities (C, SR, LR and SMS) affect litter decomposition in various micro ecologic areas that occur in the remaining stand in great extent. As well as this, it is seen that the effect of forest harvesting activities on the litter decomposition is not in the same direction for every species.
Decomposition rates did not significantly change for the Trojan fir and sweet chesnut at 6th month. Only for the scots pines species, decomposition rates between SMS and LR micro ecological areas did differ significantly. The decomposition rate was much more in LR as the local heat was increased in LR and so it increased the soil microorganisms’ activities. However, the decomposition in SMS was detected to be happening rather slowly than the other micro ecological areas as the top surface of the soil was eroded.
At 12th month, there were statistically differences in the decomposition rates of scots pines and sweet chestnut species occurred in the remaining stand on micro ecologic areas. However, at the end of the 18th month, only in the species of sweet chestnut, there was a statistical difference on the areas under the SMS and LR. It is thought that these differences were caused by the microorganisms in the soil. Decomposition rates in LR and C were higher than in SR and SMS due to probable high temperature that affect the number and activities of microorganisms.
In general, at the 18th month, the decomposition rates of scots pines and Trojan fir needles were close to each other. On the other hand, the leaves of sweet chestnut were decomposed faster than the other two species. It was found that there were differences on the decomposition rates of needles and leaves in micro ecologic area that occurred at the end of harvesting activities. Also, there was no significant difference between the decomposition rates of sweet chestnut in the C and in SR. Moreover, there was no significant difference between the LR and SMS.
The effects of chemical differences in leaves of various species on the decomposition rate in various geographical and climate conditions are defined (Swift et al., 1979; Berg and Ekbohm, 1983; McClaugherty and Berg, 1987; Taylor et al., 1989; Sariyildiz, 2002; Sariyildiz et al., 2004; Sariyildiz et al., 2008). In this study, the field experiments for each tree species were carried out under the same climatic and geographic conditions.
The decomposition rates showed different speed order among the species. Bird and Chatarpaul (1988) found that the decomposition rate was ordered from ascending to descending as; complete tree method > uncut area > random harvesting. Decomposition of leaves in litter bags was significantly greater (P<0.05) on harvested plots than on the uncut plot (U), and was greater on the whole tree harvest plot (W) than on the conventionally harvested plot (C). In the same study, maple tree k values were ordered according to the harvesting images after 2 years later: the order was shown as ascending to descending from whole tree harvest, conventional harvest and uncut forest. However, in this study, the decomposition rates at 18th was given as; for the scots pines needles the decomposition order: LR > C > SMS > SR from ascending to descending; for the Trojan fir needles order was LR=SR>C>SMS. Also for the sweet chestnut leaves the order was given as: C > SR > LR > SMS.
Since the chemical composition of the fir and pine needles was constant, differences in k rates likely resulted from changes in microclimate or soil organisms (Kranabetter, J. M. and Chapman, B. K. 1999). In the study that is done by Cakıroglu (2011) it was found that decomposition rate constant (k) was 0.254 for the Trojan fir. The needed time for the needles to decompose by 95 % was 11.8 years for the Trojan fir. The mass loss in Trojan fir needles was defined as 36.1 %. This study also has similar results with the study that was done by Cakiroglu (2011) (Table 2).
Sarıyıldız and Kucuk (2008) found that k values for the north slope groups, the time which was needed for the decomposition of top, hill and slope of north slopes by 95 % is 8.1, 7.6 and 7.1 (year), respectively. These values for the scots pines were found as 7.8, 6.9 and 6.4 (year). The same values in south slopes showed that decomposition by 95 % for the Trojan fir was 9.6, 9.0 and 7.6 year and for the scots pines the time that was needed for the decomposition was found as 8.3, 8.0 and 7.4 years. In this study, similar findings exist. Moreover, year differences were seen in various harvesting activities areas, such as minimum year was 7.2 and the maximum year was 5.3 in scots pines. Also, in Trojan fir the minimum year difference was 0.7 year and the maximum year was 5.9 years. In the sweet chestnut it was 0.3 year in minimum values and 9.6 years for the maximum values (Table 2). Sarıyıldız (2002) pointed out that the changes that can occur in the soil conditions in time would affect the chemical structure of the leaves and by this way; it would also affect their decomposition rates. This situation clearly showed that in our study, forestry harvesting activities changed the top soil surface structure and this change would had a bare effect on the decomposition. 
Consequently, the wood harvesting activities in the forest, which forms the whole of the ecosystem, can be defined as the human intervention. This is a must for the supply of the endless human needs. In this study, it was examined that the differences occurred on the needle and leaves decomposition rates in micro ecologic areas where human intervention is especially seen on the forests. Accordingly, it was found that harvesting activities affect litter decomposition in micro ecologic areas in remaining stand in great extent. To present this effect more clearly, studies should be done which would detect both chemicals in the leaves and the soil minerals.