Quantitative development of velvet maple (Acer velutinum Boiss.) afforestation in Emamzadeh Abdullah- Amol 20 years after thinning

This research was started in 1995 in order to investigate the effect of thinning on the young plantations of velvet maple (Acer velutinum Boiss.). The silvicultural interventions comprised three main treatments (medium and heavy thinning), two secondary treatments (3-year and 5-year rotations) in the fully randomized design with three replications. There were 9 sample plots in the experimental design with an area of 0.3-0.4 hectare each. A full calipering of the future trees was done after 20 years and 6 thinning operations. The results for DBH, total height, trunk height and trunk diameter showed significant differences between the control treatment and thinning intensities. However, no significant difference was observed between the secondary sub- treatment (circulation 3 years and 5 years) and the intersection between the main and sub plots treatments for DBH, total height, trunk height and trunk diameter. For the intensive thinning treatment, the largest value of 32.95 cm was observed for the DBH, while the lowest value of 27.39 cm was observed for the slight thinning. In addition, the largest height of 24.42 m was observed for intensive thinning, whereas the lowest rate of 23.63 m was observed for the control treatment