Natural regeneration of bearded alder (alnus glutinosa subsp. barbata) stands: The case of akçaabat

Bearded alder (Alnus glutinosa subsp. barbata) is one of the important tree species in Türkiye. In this study, the effects of natural regeneration and tending practices carried out in compartment no. 77 (Kzc3) bearded alder stand belonging to the Düzköy Forest Enterprise Chiefdom, where a seed tree cutting was applied in 2022, were evaluated in terms of germination, seedling growth and development, and overall regeneration success as of the end of 2025. In addition, the obtained findings were compared with the approaches used in practice, and management-oriented recommendations were developed. According to the data obtained within the scope of the study, seedlings were observed at 96 out of 180 seedling count points in the spring of 2023, corresponding to a seedling success rate of 53%. By the autumn of 2025, seedlings were detected at 172 points, and the success rate increased to 96%. Field observations revealed the presence of seedlings belonging to three different age classes within the stand. Statistically significant differences were determined among age classes in terms of seedling height, diameter, and height-to-diameter ratio. The mean diameter and height of one-year-old seedlings were 3.19 ± 0.78 mm and 20.83 ± 4.13 cm, respectively, while these values increased to 5.60 ± 1.74 mm and 34.57 ± 7.23 cm in two-year-old seedlings. The most remarkable growth increment was observed in the three-year-old seedling group, with a mean diameter of 14.97 ± 4.75 mm and a mean height of 80.59 ± 20.68 cm. While a pronounced increase in seedling height and diameter was observed with increasing age, the decrease in the height-to-diameter ratio indicated that seedlings developed a more balanced and mechanically stable morphological structure. In particular, three-year-old seedlings were found to form a structurally higher-quality regeneration layer. It was determined that three-year-old seedlings exhibit superior structural characteristics, thereby forming a higher-quality regeneration structure. Regeneration success rates remained relatively low during the first two years following regeneration; however, a pronounced increase was observed in the third year, reaching a high and acceptable level. Accordingly, the results indicate that the assessment of regeneration success in Caucasian alder (Alnus glutinosa subsp. barbata) stands should not be based solely on regeneration density, but should also incorporate age-related morphological development and the structural quality of seedlings.