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چکیده
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In the Baneh forests winter forage production from Oak leaves is a traditional and ancient management method. Pollarding is done traditionally (i.e., without any specific guideline for pollarding practice and the lack of surveillance), therefore, the performance of local users (local foresters, hereafter) can be different. The aim of this study was to evaluate the performance of local foresters on pollarded Oak stands. For this purpose, biometric indices (total height, trunk height, crown height, and crown height to total height ratio) of Quercus libani trees (i.e., dominant species in the studied stands) were used. For this research, three pollarded stands with similar physiographic conditions (slope, elevation, and altitude) and the same pollarded age, under the traditional management of three different local foresters was selected in the Baneh city, northern Zagros, western Iran. In the selected pollarded stands, using 100% inventory, collar diameter (using caliper) for all trees (collar diameter ≥ 5 cm) were measured. For the Quercus libani trees, in addition to collar diameter, total height and trunk height using a clinometer (Suunto PM-5, Finland) and two small and large crown diameters in the two perpendicular directions were measured. Normality of data was evaluated by Kolmogorov–Smirnov test. The comparison of biometric indices between three pollarded stands was analyzed using factorial experiment in completely randomized design. Comparison of mean was analyzed by Duncan test (for data with equal variances) and the James-Howell test (for the data with unequal variances). Statistical analysis and drawing of diagrams were performed in SPSS16 and Excel software. The average (±standard deviation) total height of Q. libani trees in studied stands were 6.4±1.9 m, 7.0±1.7 m, and 7.4±2.3, respectively. The results showed that total height of Quercus libani trees was significantly different among studied stands (p <0.05) and among diameter classes (p <0.01). However, interaction between diameter classes and stands on the total height was not significant (p = 0.95). The average (±standard deviation) crown height of pollarded trees was 4.4±1.7, 5.2±1.6, and 5.5±2.2 meters, respectively. According to the results, there was a significant difference among crown height of pollarded trees (p<0.05) and among diameter classes (p<0.01) in the studied stands, but the interaction of pollarded stands and diameter classes on the crown height was not statistically significant. The average (±standard deviation) crown height to total height ratio was 0.67, 0.72, and 0.72, respectively. The difference between crown height to total height ratio of pollarded trees in the studied stands was significant (p<0.01), but the interaction between pollarded stand and diameter classes on this index was not significant (p = 0.37). Maximum and minimum of crown area of pollarded trees were 30.7 and 1.85 m2. The average of crown area of pollarded trees has significant difference among pollarded stands (p <0.05) and diameter classes (p <0.01). In addition to the vegetative conditions and age differences of pollarded trees, the performance of local foresters affects their heights and crowns. Local foresters do not allow the crowns of pollarded trees get out of reach as a result of height growth. Comparison of total height of pollarded trees with non-pollarded trees (9 m) in the study area indicates that one of pollarding consequence is the decrease of total height of oak trees. The interaction of pollarded stands and diameter classes on total height was not significant. This indicates that the overall change in total height with increasing diameter in the pollarded stands has a similar tendency. The difference between the pollarded trees in terms of the crown height to total height ratio and crown area indices, which may also indicate the different behavior of the local foresters. The results indicate that local foresters use different methods of pollarding in t
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