جستجوی مقالات مرتبط با کلیدواژه « مازودار » در نشریات گروه « جنگلداری »

The aim of this study is to investigate the quantitative changes in the biometric indices of Lebanon oak (Quercus libani Oliv.) and gall oak (Q. infectoria Oliv.) during pollarding process. In a part of the two pollarded strands in northern Zagros of Iran, in which three years had passed from its last pollarding, the name of woody species was recorded and diameter (dbh), total and crown heights, and two perpendicular crown diameters were measured before and after pollarding in a full callipering assessment of all trees (dbh ≥ 5 cm). The results showed that in the pollarding process, crown height and crown area of oak trees decreased on average 15.73 and 30.06%, respectively. In both studied species, the reduction of crown area is significantly more than the crown height. In terms of reduction in crown height and crown area, there was no significant difference between Q. infectoria and Q. libani trees. The most decrease in crown height (27.99%) and crown area (44.85%) indices on diameter classes are related to Q. infectoria trees belonging to the 35 cm diameter class and Q. libani trees belonging to the 55 cm diameter class, respectively. The results indicate a higher decrease in the crown area compares to the crown height of oak trees due to pollarding practice; therefore, it is necessary to partially compensate for this decrease in the crown area by leaving some branches during each pollarding operation, because preserving the canopy is very important for Zagros-forest ecosystems. The only way to conserve these resources is to create a participatory approach as part of the transitional forest policy.

This study aimed to investigate the response of Gall oak (Quercus infectoria Oliv.) to pollarding. Therefore, a less-disturbed stand (1.4 ha) and a pollarded stand (1.7 ha) were selected. Five rectangular plots (20×30 m) were established in each selected stand by random sampling. In each plot, tree species, diameter at breast height (DBH), total height, trunk height and crown diameter for all trees (DBH ≥ 5 cm) were recorded. In addition, 18 tree samples were taken in each studied stands to assess the diameter increment of Gall oak. A pair of increment cores per sample tree was taken 50 cm above ground level, in which annual radial increment was measured and further multiplied by 2 to derive the annual diameter increment. Then, the diameter increment distribution of Gall oak trees in identical diameter classes was determined for the period of 1984-2010. The mean radial increment of two cores extracted from each sample tree was used in the calculations. The results showed that the average diameters, total height, trunk height, crown height and crown area were significantly lower (p

This research was conducted for the first time in Iran on Northern Zagros Forests close to Halou village located 40 km far west of Baneh City at Kurdistan province. 120 sample trees of Gall oak (Quercus infectoria) were selected, using stratified random sampling method and their seed amount was measured, using different methods of visual surveys (Whitehead, Christisen-Kearby and Modified Graves), then the achieved data were correlated with the crown counting data. Stem diameter at breast height and big and small diameters of crown of the trees were measured. In early September, just prior to acorn fall, each tree was surveyed; using the visual survey methods and its acorn density (acorns number/m2 crown area) was calculated, using crown counting method. The results showed that 24 of the sampled trees had no acorn and average acorn density was 7.2. Overall, weak acorn production of Q. infectoria was observed, based on the estimated visual survey indexes and the best visual estimation method was Whitehead (r2=0.87). Finally, usefulness of the visual survey methods was confirmed due to their simple application, acceptable accuracy and low labor costs

Study of sexual regeneration of oak species in Zagros forests is very important considering to sever degradation of these forests and decreasing of seed origin oaks. Acorn production is the first step in the sexual regeneration cycle which has an important impact on forest sustainability. Regarding to difficult process of acorn counting, there is unfortunately, no adequate information about acorn production of Zagros native oaks. Therefore, this research was conducted using Koenig visual method for the first time in the western oak forests of Iran. The study was carried out in a section of northern Zagros forests near to Halou village located in 40 km west of Baneh, Kurdistan province. At first, 90 gall oaks (Quercus infectoria Olivier) were selected using stratified random sampling method. For each tree, all of acorns were counted with two 1) crown counting and 2) Koenig visual estimation. Result showed that the mean, minimum and maximum of acorns number/m2 crown area were 10.3, 0.1 and 278.9, respectively. These values were 158.8, 3 and 2917 for the acorns number per tree, which indicates that total acorn production was poor in the study area. Finally, the best regression model was calculated to estimate total number of acorns using Koenig visual estimation method. Obtained model showed a high correlation which is applicable for easy estimation of acorn number of other gall oaks in the studied forest in the next years.