Browsing by Author "Gül, AU"

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    Optimising Anatolian Black Pine (Pinus nigra) and Turkish Red Pine (Pinus brutia) seedling production in state forest nurseries of Turkey
    Gül, AU; Üçler, AO; Gümüs, C; Yücesan, Z
    Aim of study: In this study, Anatolian black pine (Pinus nigra) and Turkish red pine (Pinus brutia) seedling production at different ages were planned with linear programming method and maximizing the seedling revenues was aimed. Material and Methods: In this respect, according to the assumptions used in the model, fields in various sizes such as 10000 m(2) area for one year old, 20000 m(2) for two years old, 30000 m(2) for three years old and 40000 m(2) for four and five years old seedling were separated in the nursery. On the other hand, balanced seedling production in consecutive years and consideration of demand increase or decrease on the seedling production at any ages were main goals. For this, developed model was solved in three different formats deal with rapid demand increase (RDI), slow demand increase (SDI) and demand decrease (DD) scenarios. Main results: Obtained results showed that if there is a rapid increase in demand, largest present value was 385310 $ and total produced seedling number was 905262. Realization of slow demand increase has led to reduction of 6658 $ (1.73%) in present value, and 17461 piece in produced seedling number. However, reduction of demand decrease caused to occur present value 24989 $ (1.93%) and produced seedling number 61479 piece (6.79%) less. Research highlights: By controlling the seedling production amount and process, more effective usage of nursery area can be possible as well. By the way it can be possible to endure nursery costs and reach quality targets more efficiently.
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    Examining Some Functional Characteristics in Subalpine Pure Oriental Spruce (Picea orientalis (L.) Link) Stands in Turkey
    Üçler, AÖ; Yücesan, Z; Oktan, E; Demirci, A; Yavuz, H; Gül, AU
    This study was carried out in order to state the functional differences between the pure oriental spruce stands in subalpine zone. In the research, the pure oriental spruce stands in the subalpine zone were evaluated according to their wood production (F1), erosion control (F2), water production (F3), grass productivity-wild life habitat (F4), scenic beauty (F5) and avalanche prevention (F6) functions. Functional characteristics were rated as a scalar value between 1 (the worst) and 5 ( the best) according to some observations, and exact differences were fixed between the functional characteristics of the treeline and the timberline stands. Determinations were realized in total of 46 sampling plots. 23 of the sampling plots were in treeline and 23 of them were in timberline. According to the results the F1, F2 and F6 values in the timberline were more effective than treeline stands. However F3, F4 and F5 values in the treeline were more effective than timber line stands. The average F1 value was 1.22 in the treeline and 3.04 in the timberline, F2 value was 3.0 in treeline and 3.61 in timberline, F3 value was 2.91 in the treeline and 2.43 in the timberline, F4 value was 3.35 in the treeline and 2.74 in the timberline, F5 value was 3.70 in treeline and 3.43 in timberline. Average F6 value was 3.52 in the treeline and 3.57 in the timberline. The functional values from treeline and timberline stands were compared by discriminant analysis and 41 of the sampling plots (89%) were estimated in their real groups.
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    Efficiency Determination of the Forest Sub-Districts by Using Fuzzy Data Envelopment Analysis (Case Study: Denizli Forest Regional Directorate)
    Safak, I; Gül, AU; Akkas, ME; Gediklili, M; Kanat, SM; Portakal, SÜ
    Until this study an efficiency evaluation study had not been carried out down to the level of forest sub-districts in Turkey. In this research, it is aimed to evaluate the efficiency of the forest sub-districts in the Denizli Forestry Regional Directorate using fuzzy data envelopment analysis (Fuzzy DEA) for years 2007 and 2009. Fuzzy DEA solutions were carried out using the data range. Fuzzy data was established by defining the lower, central and upper limits on the basis of the triangular membership function. These data are converted into interval data considering the approach of Zimmermann (1991) a cutting set. Thus, the upper and lower limits of efficiency values were obtained at five different alpha (0; 0.25; 0.50; 0.75 and 1.00) using fuzzy data envelopment analysis. Then inefficient forest sub-districts were listed from best to worst using the Minimax Regret-Based Approach.
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    Calculation of uneven-aged stand structures with the negative exponential diameter distribution and Sterba's modified competition density rule
    Gül, AU; Misir, M; Misir, N; Yavuz, H
    Depending on Sterba's modified Competition Density Rule [Sterba, H., 1975. Assmann's theorie der grundflachenhaltung die Competition Density Rule det Japaner Kira, Ando und Tadaki. Cbl. f.d. ges. Forstw. 92, 46-62], the maximum basal area (G(max)), quadratic mean diameter (d(Gmax)), and stem numbers (N-Gmax), for uneven-aged stands of Abies nordmanniana in the Black Sea Region in Turkey were calculated. Then, an exponential diameter distribution as a function of dominant height for these stands was obtained by solving nonlinear system of equations, which uses the maximum basal area (G(max)) and the stem numbers (NGmax) as input values, and gives diminution coefficient (q) and the number of stems in the largest diameter class (N-1) as outputs. The results are in accordance to Sterba and Monserud's findings [Sterba, H., Monserud, R.A., 1993. The maximum density concept applied to uneven-aged mixed species stands. For. Sci. 39 (3), 432-452] on the slope of the maximum density line, and with Susmel's [Susmel, L., 1956. Laws and the variation of the parameters in uneven-aged normal forests. L'Italia Forestale e Montana XI (3), 3-14] concept of decreasing q with increasing dominant height. (c) 2005 Elsevier B.V All rights reserved.