نوع مقاله : علمی - پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد جنگلداری، دانشکدۀ علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
2 استادیار، گروه جنگلداری، دانشکدۀ علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
3 دانشیار، گروه جنگلداری، دانشگاه آزاد اسلامی واحد خلخال، خلخال، ایران
4 استاد، گروه جنگلداری، دانشکدۀ علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Skid trail design, or the secondary forest road network, is usually carried out prior to tree-felling operations, with an emphasis on creating straight alignments that minimize damage to standing trees. However, in mountainous and steep forest terrains, skid trails often include numerous bends and curves due to topographic constraints. This significantly increases damage to residual trees along the trail margins, forest regeneration, soil properties, and their long-term recovery. The objective of this study was to evaluate the effect of skid trail design type, straight versus curved, on the recovery of degraded soil physical properties in abandoned skid trails after 15- and 30-years following ground-based logging operations.
Material and Methods: The study was conducted in the Kouhmiyan Forest District, Azadshahr, Golestan Province. Soil physical properties including bulk density, moisture content, macroporosity, total porosity, and penetration resistance were measured from abandoned skid trails. Two trails with ages of 15 and 30 years since logging were selected from adjacent compartments. Within each trail, two design types (straight and curved) and three traffic intensities (low, medium, and high) were distinguished. For each treatment, a 40 m² sample plot was established, subdivided into transects, and random soil samples were collected. Bulk density was measured at 0–10 cm depth using metal cylinders. In total, 90 soil samples were collected and compared with undisturbed control soils.
Results: Results showed that with increasing traffic intensity, both bulk density and penetration resistance increased. After 15 years, bulk density in heavily trafficked trails remained 27% higher and penetration resistance 116% higher than the control soils, while after 30 years these values not only failed to fully recover but exceeded control levels by 14% and 53%, respectively. After 15 years, soil moisture was 30% lower, macroporosity 24% lower, and total porosity 16% lower than the control. By year 30, soil moisture was 7% higher, while macroporosity and total porosity remained 18% and 12% lower than the control. Partial recovery of porosity, moisture, and bulk density was observed under low and medium traffic after 15 years; however, penetration resistance showed no recovery in any treatment and requires more than 30 years for full restoration. Straight trails caused less soil degradation compared to curved ones. In 15-year-old straight trails, bulk density was 9% higher, penetration resistance 56% higher, while macroporosity, total porosity, and moisture were 16%, 11%, and 19% lower than control soils. In contrast, in 30-year-old curved trails, bulk density and penetration resistance remained 6% and 88% higher than controls, while macroporosity and total porosity were still 12% and 3% lower with soil moisture 7% higher.
Conclusion: To minimize soil degradation and enhance long-term recovery of soil physical properties, protective measures such as using straight skid trails and applying slash in high-traffic areas are recommended. Careful design of permanent and straight skid trails is essential to reduce soil damage, while restorative practices such as surface scarification and spreading logging residues can help mitigate impacts and accelerate recovery of soil physical properties on skid trails.
کلیدواژهها [English]
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