تأثیر فعالیت‌های چوبکشی زمینی بر خصوصیات خاک جنگل‌های اسالم گیلان

Abstract
Introduction
One of the most important principles in the exploitation of forest resources is to minimize the amount of damage to the soil and reproduction during exploitation operations. Estimating the amount of these damages can play a significant role in forest management. As a result of the traffic of exploitation machines, the forest soil undergoes destruction and changes. For example, the decrease in soil carbon deposition causes large changes in the concentration of atmospheric carbon dioxide and as a result, reduces the proper functioning of the ecosystem. Logging paths are paths that are created spontaneously as a result of going back and forth from a specific strip (for pulling wood by a tractor) on the forest surface. These routes are defined by the authorities before the start of exploitation operations for the movement of tractors and skidders, so that as a result, the whole area of the parcel, trees and saplings are not damaged, which sometimes obstructs the harvesting (such as stones and so on) in the way of logging, it is done and it is sufficient. The main purpose of these routes is the removal of wood from the forest. As a result of this activity, they lead to negative effects on the balanced system of the forest, including soil degradation and the production of runoff and sediment in the region. Although the use of ground logging system causes the most environmental problems, it is a common operation to remove wood from the cutting area, which causes compaction in the soil. Several studies have been conducted in different parts of the world to investigate the effects of logging on the physical and chemical properties of soil. The results of these studies have shown that ground logging causes soil compaction and increases the soil bulk density. The highest amount of these factors was also observed in the place of wheel tracks. Also, the results of the studies have shown that the intensity of soil compaction at a depth of 0 to 10 cm is higher than at other depths and the amount of organic matter in logging paths has been recovered after 7 years. In most of the studies conducted regarding the effects of logging, most of the physical properties of the soil have been taken into consideration, while other structural and chemical properties of the soil are equally affected by this activity and are transformed. In this regard, in the present study, all the chemical and physical indicators of the soil have been considered in order to investigate the impact of logging activities on them. Examining changes in soil properties alone is not capable of responding to management guidelines. Also, by examining and determining the changes of soil indicators in logging routes with different time history, it is possible to maintain the quality of the soil and help to renew it. Therefore, in this research, the effects of changes in time intervals on the variability of physical and chemical indicators of soil due to logging routes have been investigated.

Methodology
Series 1 Nav Asalem belongs to watershed No. 7 Nav within the forest area of Talesh city under the supervision of the General Directorate of Natural Resources and Watershed Management of Gilan province. The forest cover is suitable and in good condition in terms of regeneration. The developed soil texture is mostly heavy to slightly heavy and in the area of shallow soils it is medium to light. The soil types in the studied plots are forest brown soil and forest washed brown soil. Linear sampling method was used to collect information. Then, at intervals of 50 meters, a sample line of 7.5 meters length was laid down on the logging paths perpendicular to the path, considering the center of the logging path. Then, at the beginning, on the wheels, and also at the end of the transect, soil sampling was done. Also, soil sampling was done at a distance of 30 meters from the logging roads (control area). Finally, 27 soil samples were collected from the depth of 0 to 10 cm using cylinder. By using soil samples, soil texture characteristics, apparent specific gravity, true specific gravity, total porosity, acidity, electrical conductivity and organic carbon percentage were measured. Analysis of variance and Duncan's mean comparison test were used to analyze the data.

Conclusion
The results showed that there is no significant difference between the measured properties (with the exception of the soil subsidence resistance) in the logging roads and the control area. The results of the investigation of soil subsidence resistance also showed that there is a significant difference between logging routes and the control area in relation to this index. In general, the presence and movement of exploitation machines in the forest causes many changes in the physical and chemical properties of the forest soils, as a result of which other major changes occur in the forest environment. In the current research, by examining the effect of ground logging operation on the soil properties of the logging routes, it was concluded that most of the investigated properties (with the exception of the soil subsidence resistance characteristic) were recovered after 5 years. Although the research results showed that there is a difference between the average characteristics of the investigated area and the control area, but these differences were not statistically significant. Therefore, it can be said that the soil of the logging roads has been able to return to its original state approximately within a period of 5 years. It seems that changing the logging routes after a maximum of 5 years and creating new logging routes (provided no new damage is caused to the forest ecosystem) or creating a consecutive rest period for the existing logging routes can restore the soil indicators of the forest ecosystem should be accelerated.

Keywords

"Soil recovery", "Asalem forests", "land logging", "exploitation operations"
Abstract
Introduction
One of the most important principles in the exploitation of forest resources is to minimize the amount of damage to the soil and reproduction during exploitation operations. Estimating the amount of these damages can play a significant role in forest management. As a result of the traffic of exploitation machines, the forest soil undergoes destruction and changes. For example, the decrease in soil carbon deposition causes large changes in the concentration of atmospheric carbon dioxide and as a result, reduces the proper functioning of the ecosystem. Logging paths are paths that are created spontaneously as a result of going back and forth from a specific strip (for pulling wood by a tractor) on the forest surface. These routes are defined by the authorities before the start of exploitation operations for the movement of tractors and skidders, so that as a result, the whole area of the parcel, trees and saplings are not damaged, which sometimes obstructs the harvesting (such as stones and so on) in the way of logging, it is done and it is sufficient. The main purpose of these routes is the removal of wood from the forest. As a result of this activity, they lead to negative effects on the balanced system of the forest, including soil degradation and the production of runoff and sediment in the region. Although the use of ground logging system causes the most environmental problems, it is a common operation to remove wood from the cutting area, which causes compaction in the soil. Several studies have been conducted in different parts of the world to investigate the effects of logging on the physical and chemical properties of soil. The results of these studies have shown that ground logging causes soil compaction and increases the soil bulk density. The highest amount of these factors was also observed in the place of wheel tracks. Also, the results of the studies have shown that the intensity of soil compaction at a depth of 0 to 10 cm is higher than at other depths and the amount of organic matter in logging paths has been recovered after 7 years. In most of the studies conducted regarding the effects of logging, most of the physical properties of the soil have been taken into consideration, while other structural and chemical properties of the soil are equally affected by this activity and are transformed. In this regard, in the present study, all the chemical and physical indicators of the soil have been considered in order to investigate the impact of logging activities on them. Examining changes in soil properties alone is not capable of responding to management guidelines. Also, by examining and determining the changes of soil indicators in logging routes with different time history, it is possible to maintain the quality of the soil and help to renew it. Therefore, in this research, the effects of changes in time intervals on the variability of physical and chemical indicators of soil due to logging routes have been investigated.