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ŠUMARSKI LIST 5-6/2019 str. 49     <-- 49 -->        PDF

widely preferred for log extraction. The study area has a northern aspect with an altitude ranging between 410 and 1600 m a.s.l. The average annual rainfall is 816.7 mm/year and average temperatures ranges from below 0.4 to 28.5 °C during the summer, with an annual average of 13.01 °C.
The study area forests are managed as high forests and have mixed stands that include Fagus orientalis Lipsky, Pinus sylvestris L. and Abies nordmanniana ssp. bornmüllerina Mattf. The silvicultural method used is the clear cut system. Trees to be removed are felled, delimbed, topped, and bucked into logs motor-manually. The scheduled amount of timber extraction was 27,548.70 m3/year for the research period. The study area covered 5274 ha of forested land and had a total of 78 km of forest roads. The soil type of the sample fields was generally sandy clayey mud. Four skid trails in the production compartment Nos. 84 and 85 located within the borders of the Asar Forest Management were designated as the test sites.
The study area has typically appropriate ground skidding features, with slopes ranging from 0 to 33%, and the extracting activities are carried out successively using farm tractors as the suitable vehicles under these conditions (Erdaş et al., 2007).
Establishment of the runoff plots – Utvrđivanje ploha otjecanja oborina
A runoff block (sample field) was established for each of the four designated test sites. Two of the blocks had 9% and the other two 18% sloping trails. Two of the blocks were planted with conifers and the other two with deciduous stands, with two facing north and the other two facing south (Table 1). Each block had three runoff plots. One of the runoff plots was left empty for the control (CNT), while wood chips (C) and slash (S), respectively, were deposited in the other two. The wood chips plots were laid without compacting with 20 kg (4 kg m−2) of wood chips at a thickness of exactly 1 cm. The wood chips were obtained from a private workshop in the region of the study area. In the slash plots, branch-leaf logging residues obtained from the test area was placed so as to cover the whole of the plot (1.5 kg m−2). The 1 × 5 m plots were established with the long sides parallel to the slope direction. The sides and upper edges of the plots were constrained by 20 cm-wide metal sheets, with 10 cm of these sheets buried in the soil. The joints of the sheets were suitably connected and sealed with silicone to prevent leakage of water at the sides. An inlaid structure was formed by inserting a plastic nylon layer at the bottom edge and the runoff water was deposited in a collection tank (Fig. 1). The runoff water was measured by scale cylinders in the collection vessel and converted to mm units according to the plot area of 5 m2 (Zengin, 1997). In order to protect the plots, the study area was surrounded by a fence.
Water sample collection and laboratory analysis – Prikupljanje uzoraka vode i laboratorijska analiza
In determining the amount of the runoff, the amount of runoff passing into the soil after a rainfall was measured and recorded. Measurement of the runoff accumulated in the collection tank was carried out using scale cylinders. During the study, the runoff measurements were recorded repeatedly after each rain. The amount of runoff occurring after prolonged and heavy rainfall was measured on the same day or the next day. In this way the risk of exceeding the capacity of the storage tanks was prevented. When rainfall was not long term or severe, monthly measurements were taken. Nine measurements were taken from the study area throughout September 2014‒March 2016. A total of 108 water samples were collected from the test sites, 36 each from the control, wood chips and slash plots. After the measurement and recording process was completed, the runoff in the storage tanks was completely drained.