بررسی برخی ویژگی‌های کمی و کیفی توده ارس (Juniprus excelsa) امین‌آباد فیروزکوه

In order to investigate on qualitative and quantities characteristics of Juniper stands, a 613 ha case study area was chosen in the Aminabad of Firouzkoh. In this study, the stratified sampling method was used and the study area was stratified to homogenous regions based on slope, aspect and geological unites in GIS environment. By combining the slope and aspect maps, we made the landform unit map. Landform unit map and geology map were then overlaid to produce the homogenous unit map. Then 42 units randomly selected for forest inventory and in each unit randomly one point specified as centre of cluster. After visiting the study area, the Juniper coverage were observed only in 20 clusters and others clusters were bare and without Juniper coverage. In conclusion, in the 20 clusters containing the Juniper trees, center and other 4 points around them in main geographical aspect in distance about 50 meters from centre of cluster have considered as plot with 1000 m² area. In each plot, tree height, diameter at breast height, coppice or seeding crop, sexuality, crown canopy area, slope percentage and geographical aspect were measured and computed for each cluster in terms of hectare. Relation analysis by ANOVA test was used for differentiation test between clusters based on qualitative and quantities characteristics of Juniper stands. The results shown that in the study area the juniper stands are as irregular even aged stands with the left skew ness in point of distribution of trees in diameter class. Results showed an intense decreasing in 30 cm diameter class regenerations due to human activities and close to road and village of Aminabad. In addition, result of canopy cover density in the study area showed that the Juniper stand of Aminabad is thinner in comparison with other studied Juniper stands. The mean, maximum and minimum of tree density in each plot was 31.5, 170 and 0 in hectare respectively. The mean, maximum and minimum tree height in the study area was computed 4.9, 10 and 2 meter, respectively. The maximum measured DBH of juniper trees was 62 centimeters. Also the mean, maximum and minimum canopy cover of study were 750, 2470 and 0 m², respectively. According to qualification, the percent of seeding crop trees in the whole stand is more than coppice trees and between male, female and ambisexual, we can see females are more than the other kinds.