جستجوی مقالات مرتبط با کلیدواژه "بهینه سازی" در نشریات گروه "جنگلداری"

Over time, the development of human settlements and activities has led to an increasing demand for natural resources, including ecosystem services, which subsequently drives changes in land use. As the process of land allocation establishes a link between the natural environment and human resources, the competition among conflicting land uses becomes significantly important in this context. Various tools are employed to address conflicts among land uses and simulate changes in land use. The CLUMONDO model is one such tool that employs various ecosystem services in the allocation and transformation of land uses, allowing for the simulation of land use changes and land cover. In this research, the CLUMONDO model was utilized to predict the extent of changes in demand for major land uses within the Qareh-Sou watershed over a 10-year period (2020-2030). Variables such as slope, aspect, elevation, the number of neighboring urban cells in a 7x7 grid., temperature, precipitation, distance from rivers, distance from urban areas, and distance from roads were incorporated into the model. An optimization approach was implemented to simultaneously enhance carbon sequestration capacity and designate additional residential areas in a specific scenario. The analysis of results was conducted using Idrisi Terrset and ArcGIS software. The findings indicated that over the next 10 years (2020-2030), land use changes for constructed areas and dense forests followed an increasing trend, while semi-dense forests and agricultural lands experienced a decrease due to their conversion into other land uses. This transformation was aimed at enhancing ecosystem services. This study showcases the possibility of harmonizing diverse, and at times conflicting, services in a way that also addresses human needs

As one of the most widely used models for fire spread simulation, cellular automata models commonly require appropriate parameters and the optimized coefficients. The main aim of this study was to compare the basic models of cell automation set by previous studies and optimized models using the Bee Colony Algorithm (ABC) to predict the rate of fire spread in a reforestation area in northeastern Golestan province, Iran. Furthermore, a sub-objective was to test the ability of optical and radar sensors (Sentinel 1 and 2) for mapping the vegetation stand type and density required for fire spread modeling. Following pre-processing and extraction of vegetation indices, vegetation type and density were mapped by the Random Forest algorithm. The accuracy assessment showed that the best result was obtained by combining the optical and radar data (Kappa coefficient (KC) = 0.75 and Overall accuracy (OA) = 0.81). Moreover, the fire spread was modeled using previous and optimized coefficients from previous studies. Model coefficients were optimized based on environmental conditions using the BCA algorithm and were compared with the occurred fire to improve the results and comparative evaluation. The results showed that the optimized models were more consistent (Sorenson coefficient (SC) = 0.78; KC = 0.74 and OA = 0.93 for Alexandridis et al., 2011; and SC = 0.78; KC = 0.74 and OA = 0.92 for Alexandridis et al., 2008) with the observed fire than the other applied cellular automation models.

The aim of this research is to determine the optimal stock level in Hyrcanian forest of Iran. In this study, a goal programming techniques was used in order to estimate the optimal stock level of different tree species considering economics, environmental and social issues. Multiple objectives in the process of decision making were considered to maximize the net present value, carbon sequestration and labor. Regression analysis was used to develop a forest growth model. In addition, an allometric function was used to determine the amount of carbon sequestration. Expected mean price is estimated using wood price and variable harvesting costs to determine the net present value of forest harvesting. The fuzzy analytic hierarchy process is applied to determine the weights of goals using questionnaires filled by experts in order to determine the optimal stock level. Results showed that the optimal volumes were 256.2 m3⋅ha-1, 61.2 m3⋅ha-1, 38.8 m3⋅ha-1, 20.4 m3⋅ha-1 for, and 20.4 m3⋅ha-1 for beech, hornbeam, oak, alder and the other species, respectively. Furthermore, the results indicated that the total optimal volume is 397.005 m3⋅ha-1.

This research considers the optimal rotation age regarding to the carbon sequestration value in populous deltoides plantation in Choobar located in Guilan Province, north of Iran. First, the volume increment is determined by stem analysis method and carbon sequestration is determined by combustion in an electric oven. Then, Net present value (NPV) of carbon is calculated by using volume increment, carbon amount, interest rate, adjusted price of carbon and net revenue in order to determine the optimal rotation age. Faustmann model was used in order to determine the optimal rotation age. Data such as volume increment, carbon content, revenue, timber and carbon prices are used to estimate the NPV. The study also evaluates the effects of different cost of plantation and discount rates on the optimal rotation ages using NPV approach. Results showed that when economic value of carbon sequestration is considered, optimal rotation ages is 27 years. Sensitivity analysis is done for interest rate, cost of plantation, and carbon price. As cost of plantation increases, the optimal rotation age also increases and the net present value decreases. With the increase in carbon prices, the age of optimal rotation age decreases and the net present value increases.

Forest operations consist of all technical and administrative processes to develop technical structures and facilities. Transportation, is the stage where there is greatest potential for savings, is the subject of this research. The transportation of logs is performed in two stages; transport from forest to road sides and transport from road sides to terminals or customers (such as sawmills and pulp mills). The transportation of logs is very costly with a high percentage, in the range of 15 to 20%, of the cost of timber. From the public’s perspective, logging trucks are perhaps the most visible sign of forest industries. The problem of planning the transportation from forest road sides to customers is complex. The goal of the transportation planning is to construct schedules for the trucks, such that all customer demands are satisfied on time with minimum trucking costs. From the forest industry’s perspective, transporting logs from the forest to the mill is becoming the largest single component of wood supply costs for many suppliers around the world. Since transportation costs make up a large proportion of the overall costs, even small increases in efficiency can significantly reduce costs. There is, therefore, considerable interest by forest industries worldwide in new work procedures, decision support systems that can lead to reductions in overall transport costs and numbers of trucks on the road. This research objective is to develop transportation plan to minimize haul costs and determine the cost of secondary transportation from forest management to mills. This study has been carried out in forest management in Hyrcanian forest and mill that consume wood products in north of Iran. In order to determine the total cost of secondary transportation at total 46 forest managements and 38 mills are considered and are investigated by using NETWORK2000. The results show that if all forest managements can send their products (logs, pulpwood, fuelwood, and swan-lumber) to all mills there are 1748 routes for wood transportation that among them minimum cost is 1600 Rial/m3 and maximum cost is 633600 Rial/m3. With use of NETWORK 2000, in total 368 routes chosen among 1748 routes as optimal cost routes. In this case maximum cost is 380000 Rial/m3 and in this case 253600 Rial/m3 is saved and economized in transport costs.

Hyrcanian forests are the only forests designated for commercial timber production in Iran. Ground-based skidding is the most common timber harvesting system used in these forests, but due to low road density (1- 2m/ha), large parts of the forests are still inaccessible. To facilitate timber harvesting in the forest, it has been proposed to increase the road density up to 20 m/ha. The aim of this study was to incorporate the estimated skidding costs through a time study into existing transportation planning tool, NETWORK 2000 software package to help decision making on forest road building. This method was applied toGorazbon district in Hyrcanian forests, where 244 links were built for analysis. The study used continuous time studies based on empirical data for this logging method. The resulted regression model is a function of skidding distance. The best solution found by NETWORK 2000 indicated that all proposed roads should be built to minimize the total skidding and road building costs.