Assessment of the effects of lowland forest plantation harvesting operations on soil physical properties (Case study: watershed No. 13, northern forests of Iran)
Document Type : Research Paper
Authors
1 Department of Forestry and Forest Economics, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
2 Professor, Department of Forestry and Forest Economy, Natural Resources Faculty, University of Tehran
3 Department of Forestry and Forest Economics, Faculty of Natural resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
Abstract
Harvesting and skidding operations in lowland forest plantations can have significant impacts on the physical properties of the soil. This study aimed to investigate the effect of machine traffic intensity on key soil physical properties, including bulk density, porosity, gravimetric moisture content, and penetration resistance. The research was conducted in the second series of the Tanyan region, located in watershed No. 13. Sampling was performed in four zones: three levels of traffic intensity (low, medium, and high) and a control area. Samples were collected from machine wheel tracks and adjacent undisturbed areas using steel core samplers and a pocket penetrometer. The results indicated that as traffic intensity increased, soil bulk density increased, while porosity and moisture content decreased. Compared to the control area, the soil in the skidding trail showed an average increase in bulk density of 9% and a decrease in porosity of approximately 4%. Furthermore, penetration resistance in the trafficked path was 55% higher than in the control area, indicating significant compaction of the surface soil layer caused by heavy machinery. Statistical tests also confirmed significant differences in soil physical parameters between the skidding trails and the control area. Given the environmental consequences of skidding, especially in moist and sensitive forest areas, it is recommended that harvesting operations be planned by carefully considering soil moisture conditions, selecting appropriate machinery, and designing optimal skid trails. Implementing these measures can play a crucial role in reducing soil compaction, preserving the stability of forest ecosystems, and ensuring the sustainable utilization of natural resources.
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