Effect of thinning operations on maple (Acer velutinum) plantations (Case study: Mazandaran Wood and Paper Company's Forest Management Project)

Maple (A. velutinum) is a native species in Iran, used mostly in monoculture or mixed forest plantations. Silvicultural operations in such stands, particularly thinning might strengthen their wood production and improve their quantitative and qualitative characteristics. For this reason, two maple stands were selected which were planted during 1991 by Mazandaran Wood and Paper Company at Sari area of Caspian Forests. One of the stands (Berenjestanak District) was thinned and the other one (Chaibagh District) was unthinned (control). The systematic and random sampling method with circular plots (100m2) was implemented and 39 and 33 plots were allocated in the thinned and control stands, respectively. The measured characteristics of the species consisted of stem diameter, total height, density, stem quality, crown diameter and form factor. Results showed that there were significant differences between the two stands in respect to the measured characteristics (ρ<0.01). The average stem diameter, total height and basal area in the thinned and control stands were 19. 98 cm., 13.84 cm, 18.32 m., 17.46 m., 30.74 m2 and 15.7 m2, respectively. Overall, on time thinning operations at appropriate intensive levels are suggested for forest experts in order to reduce high plantation costs and increase wood production quality and productivity.