Determination of economically optimal rotation age of (Popolus deltoides) in Guilan Province

The aim of this research was to determine the optimal rotation period in poplar, in which the net present value will be maximized regarding to the stumpage price, rate of interest and annual growth. Data such as annual growth, stumpage price and discount rate were used in order to determine the optimal rotation period. First of all a growth model of poplar tree was predicted. Results indicated that a quadratic model with significant level of 0.05 is the best model, based on annual growth and volume per hectare. Although, the results indicated that a cubic function is the best model for determination a relationship between age and stock with significant level of 0.05. Then, the stumpage price was predicted based on autoregressive model. Finally, the optimal rotation period for different plantation density was determined, based on price and growth models as well as different rate of interest. Results indicated that the optimal rotation age will be variable and between 8 to 25 years, due to different rate of interest and plantation density.