نوع مقاله : علمی - پژوهشی
نویسندگان
1 دانشآموخته دکتری، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران
2 استاد، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران
3 دانشجوی کارشناسی، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران
4 کارشناسی ارشد، گروه مرتع و آبخیزداری، دانشکده کشاورزی و منابع طبیعی، دانشگاه تهران، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Forest harvesting, particularly through the use of heavy machinery, can disrupt soil balance and cause significant physical and chemical alterations. Skidding operations and logging activities often lead to increased bulk density, reduced porosity, and decreased soil permeability, which ultimately result in higher surface runoff, reduced soil moisture, and accelerated erosion. These changes may also negatively affect soil fertility and plant growth. Given the importance of soil permeability in maintaining forest ecosystem stability, this study aimed to assess the effects of logging activities on soil infiltration and selected physical properties across skid trails, log landings, felling sites, and a control area.
Material and Methods: The research was conducted in 2019 in Parcel 7 of the Siyahkesh forests (Series 11) within the Shanderman watershed, which underwent large-scale clear-cutting between 1985 and 1993. Four treatments were examined: log landing, skid trail, felling site, and control (natural forest). In each treatment, three random sampling points were selected, and water infiltration tests were performed using a double-ring infiltrometer. Water column height was recorded at specified intervals until the infiltration rate decline stabilized below 10% over one hour. Soil samples (0–10 cm depth) were collected to determine bulk density, organic carbon content, and texture. Bulk density was measured using the clod method, organic carbon by the Walkley–Black method, and soil texture by Bouyoucos hydrometry. Data were processed in Excel 2016 and statistically analyzed in SPSS, while stepwise regression was used to identify variables influencing infiltration rates. Additionally, cumulative infiltration means were calculated for each treatment, and infiltration curves were drawn. Using PC-ORD 5, relationships between soil physical and chemical properties (organic carbon, bulk density, porosity, sand, silt, and clay content) and treatments were analyzed to evaluate spatial patterns and similarity responses.
Results: Significant differences (p < 0.01) in soil texture were observed among treatments. The highest clay content (26.66%) occurred in the control area, while the lowest (8.57%) was recorded in skid trails. The mean organic carbon was highest in the control (4.06%) and lowest in skid trails (1.18%). Analysis of variance revealed significant differences in soil bulk density and porosity across treatments, with log landings exhibiting a significantly higher bulk density compared to the control (p < 0.05). Stepwise regression indicated that bulk density was the only variable significantly affecting infiltration rates (p = 0.00). The lowest cumulative infiltration (38.7 mm) occurred in log landings, while the highest (57 mm) was found in the control. Similarly, infiltration trends showed that log landings had the lowest mean infiltration rate (2.4 mm), whereas the control exhibited the highest (57 mm).
Conclusion: The findings demonstrate that forest harvesting and machinery traffic substantially alter soil physical properties, particularly by reducing infiltration capacity. The most pronounced decline in soil permeability was observed in log landings and skid trails, mainly due to compaction from machinery movement and log pressure. In contrast, natural forest areas maintained the highest infiltration capacity, attributed to greater soil porosity. To mitigate these negative impacts, appropriate management practices such as restricting machinery traffic and adopting soil rehabilitation methods are recommended.
کلیدواژهها [English]
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