Rotation Age of Populus deltoides Marshall. Based on Optimizing Net Present Value of Timber and Carbon Sequestration at the Finite Series of Identical in Guilan

The aim of this study was to determine the optimal rotation age of even-aged forests with respect to timber and non-timber values by developing the Faustmann model. We conducted the study in four regions of Populus deltoides Marshall. plantations located in the west (Hefz-Abad in Talesh), center (Choobar in Shaft), east (Chalesham in Siahkal), and coastal region (Chaf-chamkhaleh in Langeroud) of Gilan province. We determined the volume increment by the stem analysis method and carbon sequestration by combustion in an electric oven. Then, Net Present Value (NPV) of timber and carbon sequestration is calculated by using volume increment, carbon amount, discount rate, adjusted timber price by stationary autoregressive model, carbon price by non-stationary model, the marginal revenue and marginal cost at the finite series of identical. Results showed that when the economic value of timber is considered, optimal rotation ages are 6-9 years. Optimal rotation ages when carbon sequestration is considered increased to 11-15 years. Integration of carbon sequestration value into timber economic value increased the optimal rotation ages to 7-10 years.