Document Type : Research Paper
Authors
1
Associate Prof., Faculty of Natural Resources, University of Tehran, Karaj, I. R. Iran
2
M.Sc., Graduate, Faculty of Natural Resources, University of Tehran, Karaj, I. R. Iran
3
Prof., Faculty of Natural Resources, University of Tehran, Karaj, I. R. Iran
4
Assistant prof., Faculty of Agriculture and Natural Resources, University of Urmia, Urmia, I. R. Iran
5
Expert of Forestry, Faculty of Natural Resources, University of Tehran, Karaj, I. R. Iran
Abstract
This research aimed at determining the economic planting interval, planting pattern, and rotation age for high-yield black poplar in the West Azerbaijan Province, Iran. For this purpose, a decision support system called the bio-economic model was employed. The model simulates the dynamics of stand’s bio-economic variables over time. The statistical population consists of poplar farmers and timber merchants in Orumiyeh and Naghadeh counties where black poplar plantations were highly concentrated. Biological data were collected using full calipering inventory (diameter) and systematic random sampling (height and wet wood density). The economic data (stumpage price and costs) were obtained through a field survey based on a semi-structured interview. Multiple regression analysis and OLS estimator were used to estimate the biological (e.g., growth and yield) and economic (e.g., planting cost) sub-models. By integrating sub-models within an Excel spreadsheet, a bio-economic model was constructed for black poplar plantations. Finally, land expectation value (Faustmann formula) was simulated over a wide range of planting intervals, planting patterns and rotation age. As a result, the economic planting interval/pattern and rotation age of average-fertility plantations appeared to be square, 2.5´2.5 meter and 12 years while the common standards are rectangular, 3´1 meter and 8 years, respectively. The results revealed that implementing economically optimal planting and harvest standards increase the per-hectare merchantable volume production, quadratic mean diameter and land expectation value by 56, 46 and 143 percent, respectively. Further research will be required to model and to optimize the growth response of poplar plantations to management activities (e.g., ploughing, fertilization, irrigation, vegetation control, and thinning).
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