جستجوی مقالات مرتبط با کلیدواژه "عملیات پیش حمل" در نشریات گروه "جنگلداری"

Tractor-based logging systems are the most common type of small-scale equipments. Farm tractors equipped with a 2-wheel trailer are mostly used to perform forwarding operations of pulpwoods and fuelwoods in the Hyrcanian forests of Iran. This study was carried out in Gorazbon district of Khyrud forest. The aim of the study was to evaluate effects of slope gradient، tractor traffic intensity over skid trails and soil depth on brown soil bulk density (BD)، total porosity (TP) and penetration resistance (PR) with clayey loam to loamy texture. The trial was conducted under the completely randomized factorial design at three replicates and three treatments، including: three slope gradients (0-10% (downhill)، 10-20% (downhill) and 0-10% (uphill))، three traffic intensity classes (<5، 5-10 and >10 passes) and four soil depths (5، 10، 15 and 20 cm) on skid trails and undisturbed locations adjacent to the study area. Results indicated that mean BD was significantly influenced by slope gradient، traffic intensity and soil depth. Skid trail on the uphill tractor forwarding slopes، showed the greatest value among the other ones. Results showed that TP significantly decreased as number of machine passes increased and high level of decrease occurred after further than 10 machine passes performed (TP= 38. 6%). Skid trail on the uphill tractor forwarding slopes showed the greatest PR value among the other ones. Penetration resistance increased significantly by increase in soil depth under the skid trails. Skid trails with 0-10% slope (downhill) had the lowest BD and PR values، whereas the trails with 10-20% slope (downhill) had the moderate values and the trails with 0-10% slope (uphill) had the highest compaction values. Overall، it might be concluded that forwarding operations with farm tractor should be planned in gentle slopes and uphill forwarding should be excluded from ground-based logging systems، if it’s possible.