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ŠUMARSKI LIST 7-8/2017 str. 46     <-- 46 -->        PDF

Determining the level as well as the sequence of compartments is a difficult issue to be resolved especially for large and mountainous areas. Moreover, after determining the harvest scheduling, another forestry problem arises as the determination of timber extraction system. Timber extraction defined as the transfer of wood material from compartment to the nearest forest road, is also seen as an important step in harvesting activities. Selecting the best timber extraction system according to different conditions emerges as a main planning problem for many forest managers especially working on hard terrain conditions (Pentek et al., 2008). They find it difficult to determine which system gives the highest profit, and which one takes the lesser time or requires minimum timber loss.
Various planning techniques such as linear programming, mixed integer programming, dynamic programming, genetic algorithm, tabu search or simulated annealing, have been widely used to accommodate harvest scheduling (Bettinger and Zhu, 2006; Heinonen and Pukkala, 2007; Karahalil et al., 2009; Fonseca et al., 2012; Hernandez et al., 2014; Zengin et al., 2015) or operational timber extraction problems (Lussier, 1959; Bell, 1977; Davis, 1987; Oborn, 1996; Kellogg et al., 1996; Acar et al., 2000; Chung et al., 2006; Eker and Acar, 2006; Flisberg and Rönnqvist, 2007; Bredström et al., 2010; Jaafari et al., 2015; Bont et al., 2015; Çalışkan and Karahalil, 2015; Ackerman et al., 2016).
However, very few studies have been conducted to combine two issues in one model and accommodate relatively large number of timber extraction systems. Different planning approaches such as minimizing cost, reducing timber loss or damage to the stands are performed simultaneously in this study. On the other hand, it is so important to offer many alternatives including harvest scheduling and operational planning with timber extraction system especially in mountainous areas. Therefore, the aim of this study is integrating harvest scheduling output and selecting optimum timber extraction system with a number of different scenarios including time, quantity, economic and environmental considerations for the part of mountainous İkisu planning unit in Turkey.
Study area – Promatrano područje
The part of İkisu planning unit (PU) is selected as a study area located in Giresun, in the Northern Black sea region of Turkey (446500-451300 E and 4490700-4494100 N, UTM ED 50 datum Zone 37N). The study area is characterized by steep and rough terrain which stretches across a total area of 951.8 ha in the İkisu PU (34,195.1 ha). The average