Assessment of the recovery of compacted soil physical properties after skidding operations in Kuhmian forests in Golestān province

Background and purpose: Heavy harvesting machines through compaction and changes in the physical structure of the soil lead to an impact on the habitat soil, so that these effects persist for years after the harvesting operation. Most of these disturbances are in logging routes, winching routes and the location of log landings. The aim of this study was to analyze the long-term physical properties of disturbed soil, including moisture content, bulk density, macroporosity, and total porosity in abandoned skid trails within 10, 15, and 30 years after cessation of harvesting operations.
Materials and methods: This study was carried out in the Kohmian watershed located in Azadshahr county in Golestān province. The dry weight of the samples and other properties were measured in the laboratory.
Results: The results showed that after 10 years, none of the physical and biological characteristics of the soil were recovered in all the studied treatments. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. The intended treatments included three classes of traffic intensity and two levels of slope gradients. To do so, at each trail age, three traffic intensities of low, medium and severe were separated regarding the distance from the roadside landings and the routes branched from the main road. Within each traffic intensity, two slope classes <15% and > 15% were identified. A 40-meter plot was delineated and 6 soil samples were taken to the laboratory to measure the physical properties of the soil, including moisture content, bulk density, macroporosity, and total porosity. The moisture content of the samples was measured using a digital scale. The dry weight of the samples and other properties were measured in the laboratory.
Results: The results showed that after 10 years, none of the physical and biological characteristics of the soil were recovered in all the studied treatments. The dry weight of the samples and other properties were measured in the laboratory.
Results: The results showed that after 10 years, none of the physical and biological characteristics of the soil were recovered in all the studied treatments. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. The greatest non-recovery of soil physical properties was observed in heavy traffic with slopes > 15% in 10 years old skid trails. The dry weight of the samples and other properties were measured in the laboratory.
Results: The results showed that after 10 years, none of the physical and biological characteristics of the soil were recovered in all the studied treatments. The dry weight of the samples and other properties were measured in the laboratory.
Results: The results showed that after 10 years, none of the physical and biological characteristics of the soil were recovered in all the studied treatments. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. This is despite the heavy traffic of the 30-year road, soil moisture and soil porosity were restored and did not show any significant difference with the control area. However, in the slope above 15% of the 30-year path, only the total porosity had been recovered and other factors had not yet reached the recovery stage. The values of coarse-grained porosity were not recovered in any of the studied treatments even after 30 years and they need more time. A partial recovery was observed in treatments with low traffic and slope < 15% after 15 years.
Conclusion: The results of this study can be used as practical guidelines for harvesting managers in order to minimize disturbances caused by harvesting operations, limit the traffic of machines in trails with slopes > 15% and heavy traffic. It is suggested to use bioengineering techniques to enhance soil recovery and protect degraded soil a result of skidding operations in unfavorable conditions.