IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2003 | Volume:56 | Issue:1-2|Papers Count:14

Nowadays, modeling is a tool in management science, and planning techniques are one of the important management factors in order to allocate scarce resources to obtain maximum benefits. Unlike industry, for planning process in agriculture and natural resources, decision makers need to optimize various objectives simultaneously. This research was conducted to suggest and compare different alternatives for optimum utilization of resources in Garmabdasht (sub-watershed of Gorgan), using goal programming as well as socioeconomic and environmental objectives. The results showed that the proposed pattern using goal programming has acceptable and flexible outputs when compared to the other linear programming techniques.

Wind erosion is a main problem in arid zones, such as Yazd province. Every year, over 20,000 m3 dust falls down on Yazd city, an area of about 7000 hectares. 15% of these materials are variety of salts, specially halite, gypsum and lime. The origin of these salts is evaporation of salty water and deposition of salts on the subsoil. Studies indicate that each year about 15 to 45 ton salts precipitate on subsoil. Then, the salts transform to crystals, increasing the susceptibility of soils to wind erosion. In this project, the effects of three major salt types (i.e., halite, gypsum and lime) on wind erodibility changes of two kinds of soil textures (i.e., loamy clay sandy and sandy) were investigated. After every 3 months, the soils were irrigated by 5 kinds of salt solutions. Changes in soil erodibility potential (AP) were determined using wind tunnel, under wind speed of about 12 m/s at 20 cm height. Finally, data were collected using split-plot design over the location and time and analyzed by SAS software. Then, data means were compared by Duncan multiple range test.Results indicate significant differences between the effects of salts applied in this research. The results indicated double effects of salts on wind erodibility of soil at various density. Low density of halite increased wind erodibility whereas high densities of halite decreased wind erodibility as it formed salty crust on the soil surface. Voiceovers, gypsum and lime at low densities decreased erodibility of soil by wind. However, at high densities, they changed to crystal, finally leading to hollowness and increasing soil wind erodibility.In this research, other variables including pressure consistency of the soil surface (PC), Electrical Conductivity (EC), Sodium Absorption Ratio (S.A.R) were also studied.

The importance of landslide and mass movements, their complexity and heavy costs to forest roads, was the main reason for the continuation of the studies done in 1994 as an M.Sc. research project, which was conducted in Kheiroud-Kenar Research Forest. The previous studies made clear some of the mass movement characters, such as its classification, mechanical behaviors, moisture, Gradient curves, unrestainery slope. Then, it became necessary to study the sample area with regard to ground water level, shear resistance, rainfall frequency and intensity, base material, topography in order to be able to calculate and design the drainage and structures for the stabilization of landslide and mass movements and finally to be able to calculate the costs involved. Thus, the objectives of this research were: 1. To have the basic knowledge of impact on shears strength and slope stability analysis, 2. To have directions for calculation and design of structures and drainage networks to stabilize mass movements and landslides, and 3. To be able to estimate and compare the cost of repairing and rebuilding of the moving part of the road, as well as the costs of constructing a new connecting part of the road.The results of this study showed that due to the repetitive high costs, repairing and eventually changing the route were not a good decision. Instead, constructing a new connecting road-piece could have been a better solution for the same area.

In order to determine the most appropriate gap size for improvement of natural regeneration by primary felling of the schelterwod system (preparatory and seed cuttings), 18 gaps of 1-2, 4-5 and 9-11 are (6 replications in each gap size) were selected randomly in northern aspects 1200-1400 m a.s.l., located in regeneration compartments of Seri One, in Shourab forest management plan, Golband district. Depending on their size, some 1 m2 microplats were chosen in these gaps in order to measure the frequency, height and collar diameter of the saplings regenerated after the cutting.The results showed that with increased gap size, contrary to maple (Acer velutinum), beech (Fagus orienalis Lipsky) frequency decreased. Within the investigated gaps, saplings frequency ranged between 4-9 per m2, mean height between 20-100 cm and collar diameter between 4-6 mm. In gaps of 1-2 are and 4-5 are, height and collar diameter while in gaps of 1-2 are saplings frequency were greater than those in larger gap sizes. Generally, it can be deduced that regeneration characteristics, from viewpoint of establishment and growth, are more limited in greater gaps (9-11 are) but are benefited by more favorable conditions in smaller gaps (1-2 and 4-5 are), where removal of tree elements is possible as a single tree. In deed, this research recommends that in order to improve natural regeneration, marking area must not exceed 5 are when marking is performed to remove the crown canopy, which is created by primary cuttings of the shelterwood system (preparatory and seed cuttings) and the selection system.

In the present study, the effect of MAPP as the compatibilizer on the mechanical properties of wood-flour polypropylene composites was investigated using Dynamic Mechanical Analysis (DMA). Composites were made at 25 and 50 percent (by weight) fiber contents and 1 and 2 percent compatibilizer. Controls were also made at the same fiber contents but without the compatibilizer. Static mechanical tests including tensile and bending tests were performed. Temperature scans in the range of -60° to +120°C was done. Results indicated improvements in the mechanical properties as a result of adding comatibilizer. MAPP had negligible effects on the main transitions while the effect of fiber content on the intensity and temperature of alpha transition was almost proportional to the fiber content. Glass transition remained unchanged when adding MAPP while an increase in fiber content slightly shifted this transition to lower temperatures. Mechanical loss factor spectra showed that above +40°C energy loss became more pronounced when compatibilizer was absent.

To provide an optimal plan for future development of cellulosic industries of the country using bagasse as raw material, some executive limitations such as capital, potential market, and the quantity of existing raw material must be taken into consideration. To this end, the results obtained from multi attribute decision making models (MCDM) were utilized. Hence, the utilities resulted from using TOPSIS model in fuzzy state were considered as technical coefficients of objective function in Integer Linear Programming model. The resulted integrated model, including 15 variables and 25 executive constraints, was used to determine production capacity as well as consequence of establishing and exploiting cellulosic industry units in a five-year period. Based on this research, production of 350,000 MT printing & writing pulp & paper, 133,500 MT Medium Density Fiberboard (MDF), and 66,750 MT Particleboard (PB) was planned.

In this study, the influence of the fungus Coriolus versicolor on the durability of sapwood and heartwood of Poplar (Populus deltoides) in natural state and treated with CCA (Copper/Chromium/Arsenic) was evaluated. CCA is a kind of water borne preservatives which was used in this study for treating specimens under vacuum and pressure (Bethel procedure) at 3 percent concentration. In order to conduct this evaluation, Kolleschale method according to DIN 52176 and B.S. 838: 1961 was used in a completely randomized block design. Specimens were contaminated with cultured fungus for fourteen weeks (24°C, 75% relative humidity). After this period, weight reduction, Compressive strength (Parallel to grain) and hardness of specimens were measured. Weight reduction of heartwood was higher than sapwood and that of control samples were much higher than treated ones. Compressive strength (Parallel to grain) of sapwood was higher than heartwood and that of treated samples higher than control samples but regardless of influence of fungus, CCA reduced the compressive strength. There was no significant difference between the hardness of sapwood and heartwood, but hardness of samples was higher than control samples but regardless of fungus, CCA increased the hardness.

In this paper, the defects of System of National Accounts (SNA) concerning environment and natural resources are indicated, empirical studies on natural resources depreciation calculation in SNA are introduced, and importance of interaction between environment and economics is discussed. Then, by presenting a Kynesian model, the green GNP s trend is shown. For accounting depreciation, Hartwick s adjustment at three levels (deplete able resources, renewable resources and pollutions) is presented. Finally, the practical methods to assess depreciation accounting for natural resources are discussed. Estimating the depreciation led us from conventional GNP to reach green GNP.

The aim of this research was to investigate the effects of soil characteristics and elevation gradient on distribution of two Artemisia species (Ar. sieberi and Ar. aucheri). After identification of the species sites in Vard Avard, Garmsar and Semnan, data on vegetation, soil and topography were collected. Sampling was conducted in the key area of each site based on randomized-systematic pattern. The area of each plot was determined by minimal area method according to plant species and variation while number of plots was determined based on the characteristics of the sites studied. Data were analyzed using principal component analysis. The results showed that the most important factors affecting the distribution of mentioned species were elevation and such soil characteristics as organic matter, nitrogen, texture and gypsum.

In order to study the relationships between plant cover and geomorphological units, the baroon area was selected. This area is located in north west of Iran (west Azarbaijan province) 4.5 km north of Chalderan city between 39° 6min 21" to 39° 14 min 3" north latitude and 44° 29min 28" to 44° 20min 20" east longitude. Recognizing the important role of ecological resources, it is known that they must be identified prior to any land evaluation. Thus, as the first stage of land evaluation, the climatic condition, physiography, geology and geomorphology were studied. Then, the plant coverage was determined using maps of the slope, aspect, hypsometry and geomorphology. The results indicated that there was a relationship between plant communities and geomorphological units in the mountainous unit. In this study, Astragalus (Stenonychium) parrowianus Boiss et Haussk was introduced as the key species of colored melange formation.

An efficient management system is necessary to facing various environmental challenges. Systematic and ecosystematic approaches in natural resource management demand understanding all parts of ecosystem and their relationships, a necessity for various planing and decision making. Grazing is one of the most important processes in rangelands ecosystem. In range exploitation style, which exists in Iran, human impacts on this process and on (to graze) has special importance to research. This study focused on the role of human on grazing process that was carried out among herders of eastern Alborz through participatory research. During the research period, a total of 179 persons were interviewed among which 70 cases were interviewed during participation and passing the one night to several nights at the residence of herds. Interview notes were analysed via content analysis approach.From the results of this study, a model was presented which relays on human role in spatio-temporal regulation and focuses on grazier instead of grazer. This model has four spatio-temporal levels: first level called (CHARAGAH) is an area which is allocated to grazing during a period of a year. Second level is (RUGAH), a supposed division of CHARAGAH determined for grazing during one or several days. Third level is (TOWGAH), a part of ground allocated for grazing during several minutes to hours. Last level is (KALAFGAH) that means small area of stopping and biting. Finally, from this study, rethinking on theory and practices as well as considering human role as grazier in grazing plan is recommended.

By knowing and taking good care of highland mountainous ecosystems, one can better protect the natural habitats, biodiversity, soil and water of these susceptible areas. In this regard, it is necessary to understand and be aware of the effects of interaction between ecological biotic and abiotic factors on plants as efficient tools in planning and management. The present research was carried out in Hezarjarib estival rangelands, Zarem rood of Tajan subwatershed in (Alborz mountains) based on polar ordination (Berry & Curtis) and using Sorenson index in order to figure out the similarities between plant communities of the area which was determined by the floristic-physiognomic method. For better interpretation and understanding of plant distribution pattern, in addition to using isohyetal, height with respect to sea level and aspect maps, at least three soil profiles were studied in the direction of dominant slope to characterize the physico-chemical properties of soil. In this research, six plant communities were recognized. The above communities were among three groups of shrub land deciduous scrub Carpinus, woodland evergreen Juniperus and cushio – grasses formation, based on the ordination. The analysis of the effects of ecological factors showed that with a reduction in rainfall, the Carpinus community was replaced by Juniperus communities and then by cushion-grasses formation ones. Also, this research showed that the ecological niche of the Juniperus communities had steeper slopes, low-depth soils with low amount of organic matter and high sand, gravel and lime percentages. However, the Carpinus community was distributed in deep soils with more organic matter and low percentages of sand, gravel and lime. The cushion-grasses formation communities were located on low and relatively flat slopes. The changes in Ec and pH of the soil were insignificant.

Iran is rich in plant diversity because of its large area and topographic and climatic variations. Knowing the types of vegetation is necessary in order to better manage rangelands. In this research, using Wittaker plot for three soil types of Gomishan, i.e. New Delta/Floodplains of Atrak, Neo- Caspian and Loss Deposition, the species richness was investigated, and the relationship between species richness and other factors were established. In each soil type, soil samples were taken from 0- 50 cm depth and water table level was measured in soil profiles. The factors measured were pH, EC, SAR and soil texture. It was found that there was not significant difference between slope of New Delta/Floodplains of Atrak and Neo-Caspian soils, so their species richness was equal. However, the difference between the two types and Loss Deposition was statistically significant. Based on empirical formula of Kovda, water table was calculated to be lower than the critical level in Loss Deposition, so it had no effect on soil salinity. However, it was at critical level in other two soil types and had significant effect on soil salinity as examined by multi-factor regression relationships. Only EC had a significant effect on species richness. An equation was developed to correlate the numbers of species per area unit with EC.