| 1. |
- Lohmander, Peter, et al.
(författare)
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Optimal forest management based on growth data from the Iranian Caspian Forest
- 2016
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Konferensbidrag (refereegranskat)abstract
- Forest management in the Iranian Caspian Forest is optimized via harvesting decisions based on individual trees. The theory of optimal control in discrete time, stochastic dynamic programming, is applied. The optimization program utilizes new basal area growth and volume functions for beech, estimated via data from the Iranian Caspian forest.Recent information about the degree of price variation is used in the optimizations. The optimal control function is defined as a reservation price function, which is determined via backward recursion. The optimal reservation price function and the optimal expected present value function are determined for alternative levels of interest rate and risk. Furthermore, the optimal harvest year and optimal harvest diameter frequency distributions are determined for different degrees of risk and rate of interest.
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| 2. |
- Mohammadi Limaei, Soleiman, et al.
(författare)
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Non-market valuation of forest park using travel cost method : (case study: Saravan forest park, north of Iran)
- 2017
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Ingår i: Austrian Journal of Forest Science. - 0379-5292. ; 134:1, s. 53-74
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research was to evaluate the non-market products of a forest park in north of Iran. Required socio-economics data were collected using questionnaires. Travel cost method was used to estimate the economics and recreational values. Regression analysis was used to estimate some socio-economics variables on behavior of forest park visitors. The economics and recreational values of forest park calculated via the demand function. The results of regression analysis showed that the variables such as required time to access the site, travel cost, monthly income, age and education effect on visiting people to the forest park. The results showed that there is a linear relation between required time to access the park and number of visitors. The results indicated that there is a polynomial relation between the number of visitors and the travel cost. The results of regression analysis showed that there is a third degree polynomial relation between the number of visitors and income. Furthermore, the results of demand function showed that the daily value of recreational site or consumer surplus is 68319800 Iranian Rials. The results of this study can be a powerful tool to improve the quality of environmental services and expand service and infrastructure quality of the study area.
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| 3. |
- Mohammadi Limaei, Soleiman, et al.
(författare)
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Optimal Forest Management Using Stochastic Dynamic Programming Approach – A Case Study from the Hyrcanian Forests of Iran
- 2023
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Ingår i: Journal of Sustainable Forestry. - : Taylor & Francis. - 1054-9811 .- 1540-756X. ; 42:1, s. 120-134
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to estimate the optimal forest harvest considering economic and environmental objectives in an uneven-aged forest in the north of Iran. Required data were collected such asstumpage price, harvesting variable costs, growth, volume, basalarea, sequestrated carbon, carbon dioxide storage, and price. The required input models for optimization were estimated using the collected data. A stochastic dynamic programming technique was used for optimization. The results indicated that the harvesting volume was higher when only the economic objective was considered instead of considering economic and environmental objectives. The results also indicated that the harvesting volume would occur at a higher level of volume per hectare if we only consider the environmental objective. The results showed that the expected present value was higher when economic and environmental objectives were considered simultaneously. The results indicated when interest rate increased, the harvesting time and the expected present value decreased. The results showed that the expected present value increases with increasing the risk. The results of this study can be a guideline for optimal forest management.
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| 4. |
- Mohammadi Limaei, Soleiman, et al.
(författare)
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Recreational values of forest park using the contingent valuation method : (case study: Saravan Forest Park, north of Iran)
- 2016
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Ingår i: Journal of Forest Science. - 1212-4834 .- 1805-935X. ; 62:10, s. 407-412
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research was to evaluate the economic values of Saravan Forest Park, north of Iran. The contingent valuation method was used for this propose. In order to do this research, 480 questionnaires were used. The questionnaires were distributed randomly among the visitors in different seasons. A linear logit regression model was used to estimate the relation between dependent and independent variables. The software including MS Excel, Eviews and Shazam was used for statistical analysis of variables, mathematical calculation and parameter estimation of the logit model. Results indicated that the variables such as proposed entrance fee, monthly income, non-governmental organization membership, moralizing view on the environment and natural resources as well as length of stay have significant effects on willingness to pay for the recreational use of the study area. Results showed that 91.19% of people were willing to pay for the recreational value of the forest park. Results also showed that the total annual recreational value of the forest park is 22,761.6 million IRR.
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| 5. |
- Mohammadi, Zohreh, et al.
(författare)
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Estimating the aboveground carbon sequestration and its economic value : case study: Iranian Caspian Forests
- 2017
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Ingår i: Journal of Forest Research. - 1341-6979 .- 1610-7403. ; 63:11, s. 511-518
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study is to estimate the aboveground carbon sequestration and to determine the economicvalue of forests in carbon sequestration as a way of mitigating climate change. This research was conductedat Asalem forests in the north of Iran. In order to estimate the amount of annual carbon sequestration, theannual volume growth of stand was determined using the diameter increment data and tariff. The amount ofcarbon sequestration was estimated based on wood density and using the allometric equation. The carbonmodel was obtained for each species. The value of sequestrated carbon in stumpage and the net present valueof carbon sequestration were determined in order to estimate the economic value of carbon sequestration.Results indicated that the annual volume growth per hectare and the carbon stored are 6.023 m3·yr–1 and2.307 t·ha–1, respectively. Finally, the carbon sequestration value of stumpage and the net present value ofcarbon sequestration are 11,023.753 and 790.361 (10,000 IRR·t–1·ha–1), respectively. Our results are very usefulin estimating the total economic value of Asalem forests and other Iranian Caspian forests in the future.
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| 6. |
- Mohammadi, Zohreh, et al.
(författare)
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Estimation of a basal area growth model for individual trees in uneven-aged Caspian mixed species forests
- 2018
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Ingår i: Journal of Forestry Research. - : Springer. - 1007-662X .- 1993-0607. ; 29:5, s. 1205-1214
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to estimate a basal area growth model for individual trees in uneven-aged Caspian forests. A survey was conducted in order to find a natural forest without any harvesting activities, a so called ‘untouched forest’ and an area was selected from the Iranian Caspian forest. Three sample plots in the same aspect and of the same forest type were selected. In each plot, total tree height, diameter at breast height, distance of neighbor trees and azimuth were measured. Thirty trees were selected and drilled with increment borer to determine the increment model. Regression analysis was used to estimate the growth model. Results show that, for individual trees, there is a significant nonlinear relationship between the annual basal area increment, as the dependent variable, and the basal area. The results also show that the basal area of competing trees has a positive influence on growth. That the increment is higher with more competing neighboring trees is possibly because plots with higher volume per hectare and more competition, most likely also have higher site index or better soil or better site productivity than the plot with lower volume per hectare.
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| 7. |
- Mohammadi, Zohreh, et al.
(författare)
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Estimation of growth model in uneven – aged forests : Case study: Iranian Caspian forests)
- 2017
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Konferensbidrag (refereegranskat)abstract
- The aim of this study was to estimate a diameter growth model for individual trees inuneven –aged Caspian forests. Three sample plots in the same aspect and of the same foresttype were selected. In each sample plot, full callipering was conducted and the parameterssuch as total tree height, diameter at breast height, distance of neighbor trees and azimuthwere measured. In each plot, 30 trees were selected and drilled with increment borer, inorder to determine the growth model. Regression analysis was used to estimate the growthmodel. The analysis shows that, for individual trees, there is a strongly significant nonlinearrelation between the annual basal area increment, as the dependent variable, and the basalarea of the individual trees. The results also show, that the basal area of competing trees, inthe sample, has a positive influence on growth. The estimated result that increment is higherwith more competing neighbor trees is probably obtained because of the following reason:The plots with higher volume per hectare, and more “competition”, most likely also havehigher “site index” or “better soil” or “better forest production conditions” than the plotwith lower volume per hectare.
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| 8. |
- Mohammadi, Zohreh, et al.
(författare)
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Linear programming approach for optimal forest plantation
- 2017
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Ingår i: Journal of Forestry Research. - : Springer Science and Business Media LLC. - 1007-662X .- 1993-0607. ; 28:2, s. 299-307
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research was to identify species suitable for plantation. We first identified species for potentially suitable for plantation based on ecological capabilities regarding soil properties. We determined the area of plantation for different species based on ecological capabilities. Then, we collected relevant data such as growth patterns of different species, labor requirements for plantation and plantation cost. A linear programming model and two integer linear programming models were used for optimization. The appropriate species based on ecological capabilities were ash, elm, maple, oak and bald cypress. A linear programming model was used based on ecological capabilities classification to determine the land area of different species for plantation. Then, two integer linear programming models were employed to select the species for plantation. We set ecological properties unequal for all of the species in the first run of the integer programming model. Two groups were classified: group one included maple and ash; group two included bald cypress, oak and elm. The second integer programming model assumed equal ecological properties for all the species. Results of linear programming showed that maple and bald cypress were appropriate for plantation at the site and their plantation areas should be 151.3 and 355.3 ha, respectively. Results of the first integer linear programming model showed that maple and bald cypress would be economically profitable for plantation. The results of the second integer linear programming model showed that only bald cypress would be appropriate for plantation.
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| 9. |
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| 10. |
- Abedi, Tooba, et al.
(författare)
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Optimal rotation age of Populus deltoides considering economic value of timber harvesting and carbon sequestration
- 2018
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Ingår i: Austrian Journal of Forest Science. - 0379-5292. ; 135:4, s. 315-342
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research is to determine the optimal rotation age of Populus deltoides plantations regarding to the timber and carbon sequestration values in the north of Iran. Two plantation types with a tree density of 3 by 3 m and of 3 by 4 m were considered in Choobar forest, northern Iran. Net present value (NPV) of timber and carbon were used for determining the optimal rotation age. Data on volume increment, carbon content, revenue, timber and carbon prices were collected to estimate NPV. In this study, we considered the effects of different plantation cost, land value and discount rates on the optimal rotation ages. Our results indicated, if economic value of timber is considered, optimal rotation ages were 10 and 8 years for 3 by 3 m and 3 by 4 m density, respectively. Optimal rotation ages considering carbon sequestration, in addition to timber value, increased to 14 and 11 years for the same two densities, respectively. Thus, integrating carbon sequestration value with timber economic value increased the optimal rotation ages and in turn change the optimal forest management. Sensitivity analysis indicate that optimal rotation ages increased with increasing plantation cost and decreased with increasing interest rate, while our results suggested that the optimal rotation age is not sensitive to the land value. Our results are important for land managers and carbon projects to optimize the used forest management practices.
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