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ŠUMARSKI LIST 5-6/2019 str. 48     <-- 48 -->        PDF

Protecting forests and at the same time utilizing them can lead to difficulties when it comes to decision making in forestry operations. As a result of the removal of logs, damage occurs at different rates for the soil, the remaining stand, and the products produced (Bayoğlu, 1972; Gürtan, 1975; Acar, 1994). The stand soil is damaged in different proportions, especially when logs are removed from sloping areas. Continual log skidding over the same places causes both the dead and living soil cover to be carried away and minerals to be leached out of the soil. When the skidding process continues over the same place, mineral soil is carried away and erosion-susceptible channels are formed which cause serious problems during heavy rainfalls. After heavy winter conditions and spring rains, the erosive power of the surface runoff can create damage on the skid trails (Gürtan, 1975; Yıldırım 1989).
The environmental damage that occurs to the soil as a result of the application of log extraction skidding techniques includes the decline in the physical properties of the soil (Arocena, 2000; Makineci et al., 2007; Ozturk, 2016), reduction of plant growth and changes in species diversity, decrease of soil organic matter, humification and mineralization due to effects on the living conditions and activities of soil organisms, and nitrogen losses through denitrification (Marshall, 2000; Buckley et al., 2003; Godefroid and Koedam, 2004). Skidding also causes trauma and injury to saplings and breaks trees (Ünver and Acar, 2009; Turk and Gumus, 2015; Cudzik, 2017). Moreover, skidding operations significantly change the quality and temperature of river waters and affect the nutrient cycle in riparian ecosystems. This is primarily due to the sediment flow into drainage systems caused by skid trails (Messina et al., 1997).
Skid trails are 2.5-3.5 m-wide transport facilities that are planned before the production of the logs by first clearing the trees from the trail to make it 1 m wider than the production vehicles. These trails are planned for different slopes (0-40% from top to bottom) according to the specifications of the skidders used in the operation. The study area was limited to areas of agricultural tractor skid trails having slopes of 0-33% (Turk and Gumus, 2015).
In order to minimize negative environmental effects in the skid trails, four methods are applied. The first and the most important is the appropriate planning of the skid trail network. There are four types of skid trail networks: random, branch, parallel and direct. In this case, random skid trails result in about 25% more ground disturbance than designated skid trails. Two common patterns are the branching and the parallel skid trails (Garland, 1997). Direct patterns were observed to be the best in terms of the forested areas and density per hectare; however, little difference was found between the branch and the parallel patterns (Gumus and Turk, 2016). The second application for reducing negative effects is the method of laying logging residues on skid trails. The kinetic energy of rain along with landfilling, aggregating and erosion are reduced by this method and sheet erosion can be prevented (Balcı, 1978). In the third application, soil compaction in post-production skid trails is reduced by turning over the trail soil with the help of a ripper. In addition, in places where the skid trail is too long, a natural bump is built on top of the trails to limit soil erosion. The fourth application for the stabilization of the skid trail surface is the planting method. Biological (cultural) measures applied for this purpose include spraying a seed-filled emulsion, dry sowing and the laying of grass lawn sod.
This study investigated the sheet erosion and soil loss caused by industrial log skidding operations using farm tractors on skid trails and assessed the use of wood chips and slash to minimize this loss.
Study area – Područje istraživanja
The study area is located in the Asar district (40 ° 39 ‘ 52 “-40 ° 45 ‘ 8” N, 31 ° 17 ‘ 48 “-31 ° 27 ‘ 4” E) in the Western Black Sea province of Duzce, Turkey, where farm tractor usage is