نوع مقاله : علمی- پژوهشی
نویسندگان
1 نویسنده مسئول، کارشناسی ارشد علوم و مهندسی جنگل، دادگستری شهرستان مریوان، مریوان، ایران
2 استادیار، گروه توسعه کشاورزی و منابع طبیعی، دانشکده فنی و مهندسی، دانشگاه پیام نور، تهران، ایران
3 دکتری جنگلشناسی و اکولوژی جنگل، معاون پروژه ملی مدیریت چندمنظوره جنگلهای هیرکانی، چالوس، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Natural regeneration is considered one of the most important factors affecting the survival and sustainability of natural forests. Understanding the diversity, distribution, and status of natural regeneration of woody species provides important insights into the ecological health and ecosystem services of forests and helps predict future forest sustainability. Considering the ecological and productive importance of the Hyrcanian forests, conducting a comprehensive study on the status of natural regeneration in these forests appears necessary. Therefore, the aim of this study was to investigate the quantitative status of natural regeneration of woody plant species in managed stands of the Hyrcanian forests in northern Iran.
Methodology: To conduct this study, four forest landscapes in the Hyrcanian forests were selected, including Fariroud–Zilkiroud (watersheds 22 and 23) in Gilan Province, Dohezar–Sehezar (watersheds 33 and 34) and Beliran (watershed 53) in Mazandaran Province, and Chehel Chai (watershed 92) in Golestan Province. Using a systematic random sampling method, 4 m² sample plots were established at the intersections of a 150 × 200 m inventory grid, resulting in a total of 34,723 sample plots (Fariroud: 5,345; Zilkiroud: 4,377; Dohezar: 5,185; Sehezar: 7,522; Beliran: 6,847; and Chehel Chai: 5,447) for regeneration assessment. All seedlings and saplings within the sample plots were counted, and their quantitative characteristics were measured. In each forest habitat, the quantitative status of regeneration, including tree species, growth stages, growth form, number of regenerating individuals, collar diameter, and seedling height, was identified and recorded. Natural regeneration in each habitat was classified into three collar diameter classes (< 2.5 cm, 2.5–7.5 cm, and 7.5–12.5 cm) and three height classes (< 30 cm, 30–130 cm, and > 130 cm) by woody species. Graphs and statistical analyses were performed using Excel and SPSS 26.
Results: The highest and lowest regeneration frequencies among woody species were observed for beech (Fagus orientalis Lipsky) (38.03%) and oak (Quercus castaneifolia C.A.Mey.) (0.95%), respectively. The collar diameter class of less than 2.5 cm had the highest frequency (74.13%), whereas the 7.5–12.5 cm class had the lowest frequency (9.3%). Similarly, the height class of less than 30 cm showed the highest frequency (69.38%), while the height class greater than 130 cm had the lowest frequency (10.35%). Comparison of the frequency percentages of species with collar diameters less than 2.5 cm showed the highest and lowest frequencies in the Zilkiroud and Chehel Chai habitats, respectively. The highest frequency percentage of species with collar diameters of 2.5–7.5 cm was observed in the Zilkiroud habitat, whereas the lowest was recorded in the Sehezar habitat. Comparison of regeneration frequency in the 7.5–12.5 cm collar diameter class showed the highest frequency in the Fariroud habitat and the lowest in Sehezar. Comparison of natural regeneration frequencies among woody species showed that the highest regeneration frequencies in Chehel Chai and Beliran habitats, with values of 38.11% and 40.61%, respectively, belonged to maple (Acer velutinum Boiss.), while in Fariroud habitat the highest frequency belonged to hornbeam (Carpinus betulus L.) (29.31%). In the Dohezar, Sehezar, and Zilkiroud habitats, beech showed the highest regeneration frequencies, with values of 60.59%, 90.5%, and 53.54%, respectively. The results of one-way analysis of variance (ANOVA) indicated significant differences among height and collar diameter classes, whereas no significant differences were observed among the different habitats.
Conclusion: The managed stands of the western Hyrcanian forests (Fariroud–Zilkiroud forest landscape) contained more young seedlings (collar diameter less than 7.5 cm) compared to the managed stands of the eastern Hyrcanian forests (Chehel Chai forest landscape). In contrast, the managed stands of the eastern Hyrcanian forests had a greater number of regeneration seedlings with collar diameters of 7.5–12.5 cm and heights greater than 130 cm. These findings indicate more favorable regeneration establishment in the eastern Hyrcanian forests and suggest the presence of less favorable environmental conditions in the western Hyrcanian forests.
کلیدواژهها [English]
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