نوع مقاله : علمی- پژوهشی
نویسندگان
1 دانشآموخته کارشناسی ارشد جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعهسرا، ایران
2 دانشیار، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعهسرا، ایران
3 نویسنده مسئول، استادیار، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه گیلان، صومعهسرا، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives: Habitat edges, particularly forest road corridors, function as focal points for ecological dynamics. These linear disturbances alter microclimatic conditions through increased solar radiation, elevated temperatures, and enhanced wind exposure, thereby creating environmental filters that fundamentally reshape vegetation structure and community composition. This transformation manifests as the gradual replacement of shade-tolerant forest species with light-demanding herbaceous and pioneer species in proximity to edges. However, roads serve as the fundamental infrastructure for forest management, making their presence in forested landscapes an essential and unavoidable component of modern land use. This study aimed to investigate the effects of secondary forest roads on tree regeneration, species composition, stem density (stems/ha), and stand volume (m³/ha) in three parcels of Series 7 within Watershed 25 of the Shenroud district, Guilan Province, two decades after road construction.
Methodology: For this research, a forest road constructed in 2005 in three compartments of Series 7 in the Shenroud watershed was selected: compartment 754 (northern aspect), compartment 726 (southern aspect), and compartment 755 (western aspect). A transect sampling method was employed. Transects were established along three geographical aspects (north, south, and west), with three replicates per aspect, resulting in a total of 72 transects. Each transect measured 100 × 5 m and was positioned on both cut and fill slopes, across the three geographical aspects, and at four distances from the road (30, 60, 90, and 120 m). Within each transect, tree species and diameter at breast height (DBH) of all trees were recorded. To assess regeneration, ten systematic 2 × 1 m square microplots were sampled per transect, and regeneration frequency by species was documented. The Kolmogorov–Smirnov test was used to verify the normality of quantitative data. A two-way analysis of variance (ANOVA) was applied to compare regeneration frequency under the influence of geographical aspect and distance from the road, and Duncan’s multiple range test was used for mean comparisons.
Results: The results indicated that tree species composition on both sides of the road did not significantly change with distance from 30 to 120 m from the road. Although mean stem density and volume per hectare decreased with increasing distance from the road, no statistically significant differences were observed across slopes, geographical aspects, or distances from the road. Regeneration analysis revealed that three tree species regenerated in the study area, all of which were present across the three geographical aspects. The highest regeneration frequency on both cut and fill slopes was observed for beech (Fagus orientalis Lipsky). In the upstream area of the road, alder (Alnus subcordata C.A. Mey.) regeneration frequency was higher than that of hornbeam (Carpinus betulus L.), whereas in the downstream area, alder frequency was lower than that of hornbeam. Comparison of regeneration variables showed that regeneration abundance increased with increasing distance from the road on both the cut and fill slopes, reaching a maximum at 90 m, but decreased at a distance of 120 m, and a statistically significant difference in regeneration frequency was observed between cut and fill slopes.
Conclusion: The findings of this study demonstrate that secondary forest roads in the study area have not exerted a significant large-scale impact on adjacent ecosystems in terms of species composition and regeneration rates after two decades, except for regeneration rates between cut and fill slopes, where significant differences were observed. From a forest management point of view, the obtained results, which indicate limited negative effects of such roads, make it possible to allocate financial resources to more critical areas and provide a good example for forest road design and construction with minimal ecological disturbance in the future. As a result, rather than undertaking comprehensive and expensive road-management activities in similar situations, continued and targeted monitoring should be emphasized to support adaptive and compatible management in Hyrcanian forests.
کلیدواژهها [English]
)