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Long-term impact of selection cutting management on frequency of stem deformity in mixed beech forests of northern Iran

Tavankar Farzam, Nikooy Mehrdad, Lo Monaco Angela, Picchio Rodolfo

Drewno : prace naukowe, doniesienia, komunikaty

2021

vol. 64, nr 207

5--26

The aim of this study was to evaluate the long-term effect of selection cutting management on the stem quality of the trees remaining in the forest. For this purpose, three parcels managed for three decades by selection cutting were selected as managed stands (MP), and two protected parcels without tree felling as control stands (PP). First, the frequency of deformed stems in each parcel was determined for a circular 1000 m2 area of each plot by systematic sampling of 100 m × 100 m grid sections, and then a stem deformity index was estimated for each of the deformed stems. The results showed that the frequency of stem deformity in MP (6.5%) was significantly lower than in PP (20.7%) (p < 0.01). In addition, the frequency of all types of stem deformities in MP was significantly lower than in PP. Furthermore, selection cutting management reduced the indices of twisting, decay, conicity, forking, and ellipticity by 58.4%, 53.9%, 34.7%, 8.4% and 6.8%, respectively. The results for the correlation between frequency of stem deformity and tree diameter at breast height (dbh) showed that the curves followed a parabolic shape in both MP (r = 0.83) and PP (r = 0.80), where the frequency of deformed stems decreased with increasing dbh (up to 75 cm in MP, and up to 65 cm in PP), and then increased with larger dbh. Selection cutting management, regardless of tree species, improved the stem form. Decay accounted for a high proportion (24.1%) of the total deformity in MP, mainly due to logging damage. Overall, the results of this study show that selective management has been successful in improving the quality of tree boles in the studied mixed beech stands. Regular and long-term stand monitoring and statistical quality control (SQC) may be a good approach to aligning ecological and economic goals in forest management.