فصلنامه منابع طبیعی ایران
شماره 4 (زمستان 1387)

Soil erosion by water is considered as one of the major threats for sustainable land management. In Iran, soil erosion studies has begun since 40 years ago, but there is no native model to evaluate soil erosion yet. This research is the first attempt to develop a new erosion model, based on the fuzzy logic approach. The study is took place in Latian Dam basin, Iran. Using GI Systems some effective factors on soil erosion including geomorphologic, lithology, topographic, climatic, hydrologic, vegetation, land use and soil properties factors that contain 81 indices, were analyzed using correlation matrix, cluster analysis and Kruskal-Wallis test. The effects of 19 factors were significant which used to develop conceptual model. To quantify conceptual model, a fuzzy modeling approach was used. Seven fuzzy operators were used within a GI System for determining erosion hazard. The results show that the erosion map derived from fuzzy Gamma operator (?=0.8), has the best prediction of soil erosion hazard over the study area and its overall accuracy is up to 92%. Predicting the amount of specific sediment yield of the 3 sub-watersheds of the study area was done using multivariate regression analysis with stepwise method using a data set of eight input parameters. The results indicated that the equation that included variables of erosion coefficient and area of sub-watershed stated adjusted square correlation coefficients (R2adj=99.09%). The results suggest that fuzzy approach is very useful to predict soil erosion and sediment yield over the study area.

Most of the hydrological systems are very complicated and it is not possible to understand them completely. Therefore, simplification is necessary to understand or control of a part of the system behavior such as water balance relationships. Hydrological models are simple structure of complicated systems in hydrological cycle in the nature. The first goal of a hydrological model is to predict complicated system function and evaluate the impact of any kind of changes on system behavior. This will help us to better understand processes of the system. In this research SWRRB hydrological model was used to simulate water balance relationship in Kasilian watershed located in Mazandaran province. SWRRB is a continuous hydrological model. This model was calibrated and evaluated in Kasilian watershed. The simulation error in calibration and evaluation steps was estimated using MAE, RMSE and NASH criteria. Significance and insignificance of difference between observed and estimated runoff values was evaluated using Z factor. Model sensitivity analysis with respect to the different variables was investigated. The result of this research showed that the model can simulate annual runoff more accurate than monthly runoff. On the other hand, in comparison between monthly and daily runoff, it can be seen that simulation of monthly runoff is more reliable than daily runoff. In this research, it has been shown that the model is sensitive to length of the data.

One of the important issues in design of river structures as well as determination of proper life time is having adequate information of sediment load in the rivers. Thus, several methods have been suggested for estimation of suspended loads. One of the hydrological techniques is rating curves method that is based on the best fitting line to drawing between values of flow discharge and suspended loads respectively. Seasonal variability is one of the errors which origins in sediment rating curves that disregarded to accurate estimation of suspended load. In this research seasonal classification, by analyzing annuals hydrograph on the sampling time with 6 hydrological methods in 3 different seasons for estimated suspended loads and the best fitting method and season was determined in Glinak hydrometric station of Taleghan Basin. The results showed that the quality of primary data is the most important parameter in accuracy and precision of the estimations. However classified total data have considerable affect on decreasing error estimate and also due to the increasing precision (decreases MAE) and accuracy (StDev decreasing) estimates 6 and 77.8%, respectively. Finally, the best determination methods for estimating process in the research which are suitable for total data, two rating curves and FAO methods for rainy season data, CF2 method for flood season data classes, one rating curve method for dry season class and FAO method. Also, discharge-sediment load data from flooding season are the best seasonal classes among the methods in case of minimum error.

Among natural hazards, flood is perhaps the most destructive one which imposes high damage to human communities, facilities, industrial and agricultural areas. Frequency analysis and our knowledge of the probability of occurrence or return period of floods will help us in planning and risk reduction of the floods. In this study, the method of L-moments was applied for regional flood frequency analysis in Halil Rood basin, Jiroft. For regional homogeneity and finding discordant stations, two H and D measurements showed that the region is homogeneous without discordant station. After selecting at-site distribution, the goodness-of-fit-test, ZDIST showed the LN3 distribution to be the best regional distribution. The area of watershed was also found the parameter of multiple regressions which is used for estimation of flood with different return periods at ungauged watersheds.

Understanding the processes involved in infiltration and percolation in soils is one of the important factors in evaluating the generation of runoff, the supply of soil water and the potential for recharge. Percolation is the process of entry moisture from the upper soil layer to lower layers. The rate of percolation depends on the type of soils at the location considered and on the moisture content of the upper soil layer. For a given location, this rate is a function of the actual infiltration rate and the moisture content of the upper soil layer. In this research three parameters of the maximum soil moisture content, maximum and minimum infiltration capacity rate as inputs are used to calculate variation of soil moisture, and infiltration rate during a rainfall event. Numerical results show the effects of surface flow, storm rainfall intensity and soil moisture variability on the percolation rate in ten minutes time interval in Kechik catchment of Golestan province, Iran.

Acording to empirical evidences, first step of any successful intervention in sutainable natural resources development process is identifying needs of local people and other stakeholders as well as recognition of their contributions in order to effective participating in all step of process. With regard to this comment, in this paper as result of a descriptive research based on survey strategy, tried to identify some patterns related to local people's participation in development of mangrove forests in south of Iran (Boushehr province coasts). Validity of questionnaire as data gathering instrument, confirmed by selected experts and Coronbach Alpha coefficient (equal to 67% - 79% range by different parts of questionnaire) used to confirm its reliability. Data collected were analyzed using the Statistical Package for the Social Sciences (SPSS) based on appropriate statistics. In descriptive findings, items and patterns related to mangrove forests utilizations, causes of forest degradation, local participation attitudes, participation areas and procedures, in process of several categories, information and communication channels where illustrated. Inferential tests (F and T-student) results showed differences of participative attitude of respondents based on some variables such as age, education level, participation in rural project and membership of local institutions. Using stepwise regression led to a linear equation including age, number of livestock (ownership), recourse to governmental offices and membership period of local institutions as independence variables and R2Ad coefficient indicated that this linear equation explained about 60% variance of participative attitude of local people as dependence variable.

25 seedlings of Caucasian oak (Quercus castaneifolia) were planted by spacing of 1*1m in Pilambra research station, Guilan province, north of Iran. Prior to transplanting, seedlings were root-pruned in three levels of 15, 20 and 25 cm and some of quantitative characteristics of plants were compared to those of un-pruned controls in 3 replications after six growing seasons. A total of 300 seedlings in completely randomized blocks were studied. Considering the criteria of rhythmic shoot extension, branching mode and orthotropic branch differentiation the architectural model of the Caucasian oak was identified as Rauh model. The results showed that root pruning has a significance influence on diameter and height growth of oak seedlings. The collar diameter, dbh and height of seedlings were 60.5mm, 40.5mm and 616.3cm, respectively which were the highest measurements among the treatment of root pruning in 20cm. The un-pruned seedlings showed better results than those of pruned in 15cm and 25cm. All differences were significant at level of p<0.05.

Sustainable development and optimum implementation of forest management planning requires forest road network (main and secondary roads). However, road construction in mountainous area is interference in unknown and virgin forest which leads to ecosystem disturbance. So, knowing of geological, geo morphological properties and soil mechanic from which road passes, is of great importance in properties decision making in order to lower the cost of road construction. Soil is the main constructive materials in forest roads and of course forms forest bed. It is possible to understand the engineering soil properties through studying the soil mechanic. Due to expenses of soil analysis, reducing soil samples to its minimum and maintaining its validity are of great importance in soil mechanics in forest roads. In this research, based on geomorphological properties such as slope, aspect, altitude, etc, zonation of study area was done and divided into homogenous units based on landform using GIS. After preparing landform map, one soil sample and totally 24 samples were taken in units from which road passes.Then soil properties like normal moisture (%), bulk density and soil texture were analyzed. By grouping soil analysis and their classification based on moisture (%), texure and porosity new homogenous regions were formed that are equal in characteristics such as geomorphology and soil. So it can be a base for soil sampling and soil mechanics studies. Based on this study, sample number decreased to 13 and costs of analysis have been reduced due to creating homogenous regions.

Having knowledge about quantitative and qualitative characteristics of forest stands and continuous measurement of impacts of executed methods is a fundamental principle for performing, monitoring of forest management based on nature rules and decision-making in silviculture management of forest. Single selection method which is one of the close to nature silviculture methods, aims to achieve an uneven-aged and mixed forest. Tree marking in this method needs to precise statistical data about tree distribution in diameter classes. To determine the quantitative characteristics as well as biodiversity, rare species, old trees and also dead trees, 768.4 ha virgin forest of Gorazbon district in Kheyrud educational- experimental Forest was studied with full callipering method. All trees with dbh> 10 cm were assessed and volume and number of species in diameter classes, large trees with dbh> 100 cm and all dead trees were inventoried separately at each compartment. The average of number and volume of trees per hectare in Gorazbon district are 297 and 338 sylve, respectively. However, beech trees consist of 31% of total number of tree in Gorazbon district, but this species comprises of 57% volume of this district. Proportion of rare species such as sweet cherry, mountain ash, ash and elm are less than 2 tree per hectare. The average volume per hectar of dead trees was 4.2 sylve which was counted to 1.2 % of total volume of Gorazbon district. Considering the large area and analyses of data which was carried out for the first time, results of this research showed that full inventory method provided important and essential data for precise performing of selection method, especially single selection method.

There is increasing pressure worldwide for maintenance of forest sustainability. Concerns about environmental and social issues associated with forest sustainability - such as effects on biodiversity changes, area, vitality, health, wood and non-wood production of forests - have led to international agreements and programs for improving forest management practices. One of the problems that forest experts are facing in Iran is the existence of cow-pens and the effects of livestock grazing on forest trees. This research aims to study the effects of grazing resulting from cow-pens on tree species diversity. For this purpose, two compartments in which cow-pens exist and two ones out of reach of livestock were selected in Gorazbon District belonging to the experimental Forest of Kheyroud. In both regions the forest types are Fageto-Carpinetum. Using 100% inventory and sampling methods, heterogeneity and evenness indices of Shannon and Simpson were calculated. Heterogeneity indices of Simpson and Shannon-Wienner and evenness index of Shannon were greater in grazed region, but evenness index of Simpson were approximately the same in both regions. Using t test for Shannon index, there is a significant difference between 100% inventory and sampling method in grazed region with 13 sample plots, but in ungrazed region, the difference is not significant with 23 sample plots.

Although environmental plans performance, development of green areas and provision of recreational facilities for filling leisure time are necessary, lack of financial resources for reviving and providing appropriate recreational facilities makes natural resources management not only to evaluate these resources but also use people's contribution in order to conserve and revive these areas. Therefore, this research will discuss an assessment of the outdoor recreational value of Nabovat Park in order to estimate a visitor's willingness to pay (WTP) for recreational benefits, based on contingent valuation (CV) and dichotomous choice. For determination of visitor's willingness to pay Logit model was employed, the estimation parameters being based on methods of maximum likelihood (ML). The results indicate that 72% of visitors are willing to pay for recreational values at the Nabovat Park. People is willing to pay 3300 Rials for per visit of the park. The total recreational annual value was estimated at 140,049,660.7 Rials/ha for the park. Consequently, results show that people care about urban green areas.

Population increasing and land decreasing for solid waste disposing is the reason for the problems of municipal solid waste dispose in Iran. Also almost 70% of municipal solid waste in Iran is made of perishable materials and much of solid waste is made of plastic, paper and paperboard, metal and glass which all these materials are able to be recovered. Therefore, composting and recycling is the reason for reducing the material volume to landfills, environmental problems and also economical benefits. For priority determination of recovery and composting, qualitative and quantitative reorganizations of municipal solid waste are necessary. About 140,000 people live in Shahreza, and almost 90 ton municipal solid waste is produced daily. Landfill is 5 kilometer far from east of the residential area. For physical analysis, sampling of Shahreza municipal solid waste performed in landfill randomly. Sampling was performed in four seasons, each season for one week and each day about 20 samples (a sample = 0.5). In fact, in each season the sampling has been repeated 140 times. Six components that were made of perishables, metal, plastic and PET, of each samples were separated. Afterwards, mean percent of components was calculated daily, seasonal and annually from summer 1384 to spring 1385. For chemical analysis, sampling of perishables was performed in landfill randomly, in four seasons and each season about 14 samples and moisture content of samples and carbon to nitrogen ratio was measured. The results showed that 71.61% of Shahreza municipal solid waste is made of perishables. These materials consist of 69.69% moisture and 22.16% C/N. Each of the above mentioned components is comprised of plastic 7.57%, paper and paperboard 7.64%, glass 2.09%, metal 2.04% and PET 0.35% that by recovery and composting about 9, 768, 578, 580 Rials in landfill is avoided to waste annually. By considering sanitary and environmental damages, the percent and price of each of the components, recovery priority and composting was determined as follows: composting, plastic, paper and paperboard, metal, PET and glass recycling.

Based on a study performed, about 200 to 400 thousand ton per year waste date palm leaves are available in Iran. In this research, chemical composition, fiber dimensions and soda pulping from five main date palm leaves in Iran were investigated. Specific gravity of different samples has been determined to be in the range of 0.44 - 0.50. Average fiber length and diameter were 1400 and 17.5 micrometers, respectively. Cellulose content varied from 35 to 44% and the klason lignin content was 12 to 15 %. Acetone soluble extractive content was varied from 1.35 - 3.23 %, hot water extractive content was very high from 16% to 19% and ash content was also high varied from 4.5 - 7.75 %. The results of soda pulping of mixed date palm leaves have shown that, good quality high yield and low yield pulps can be produced which are suitable for making different grades of papers.

Mechanical tests were conducted on matched small clear specimens of populus wood, which is a fast growing piece. The tests were made by adopting D143-06 specification of ASTM standard. modulus of rupture and modulus or elasticity, tension parallel to grain and tension perpendicular to grain, compression parallel to grain and compression perpendicular to grain, shear parallel to grain, cleavage, hardness, nail withdrawal and toughness of this species were measured. Density and shrinkage rate of this species were also measured as well. The target for measuring mechanical properties of populus was to determine its clear wood strength for establishing corresponding design value. In the case of green state these values were obtained: modulus of rupture 38. 1 (N/mm2) and modulus of elasticity 6297 (N/mm2), tension parallel to grain 64. 6 (N/mm2) and tension perpendicular to grain 1. 9 (N/mm2), compression parallel to grain 20. 1 (N/mm2) and compression perpendicular to grain at limit point 2. 0 (N/mm2) and in the 1 mm deformation 3. 5 (N/mm2) و shear parallel to grain 4. 0 (N/mm2), cleavage 27. 5 (N/mm2), side hardness 1. 5 (KN), nail withdrawal 0. 56 (KN) and toughness 2. 6 (Kg. m). In the case of air dried state these values are obtained: modulus of rupture 65 (N/mm2) and modulus of elasticity 8097 (N/mm2), tension parallel to grain 73. 3 (N/mm2) and tension perpendicular to grain 3. 2 (N/mm2), compression parallel to grain 34. 8 (N/mm2) and compression perpendicular to grain at limit point 4. 3 (N/mm2), shear parallel to grain 4. 9 (N/mm2), cleavage 42. 3 (N/mm2), nail withdrawal 0. 43 (KN). The average physical properties are density (apparent) 0. 38 gr/cm3 and shrinkage: (radial) %3. 2, (tangential) %5. 2 and (volumetric) %8. 4.

The capability of acetylated poplar particles in manufacturing particleboard was investigated. The acetylation degrees at high, medium, and zero (control) levels and position of treated particles were considered as variables. Then the effects of these variables on practical properties of manufactured boards were investigated. The results indicated that application of 50% acetylated particles (on the basis of board's weight) caused to improve dimensional stability of manufactured boards up to 50 %, however the strength properties decreased to some extent. Increasing acetylation degree caused to enhance dimensional stability while the mechanical properties were decreased. The application of acetylated particles on surface layers led to bending strength loss in comparison with single layered boards. Although utilization of acetylated particles caused to decrease bending strength but it remains still above the levels established by standards such as DIN 68763 and ANSI A 208/1 – 1993 and resulted particleboards have suitable and acceptable properties. The results showed less water absorption and thickness swelling three – layer particleboard in comparison with single-layer particleboards after immersing in water for 2 and 24 hours.

Determination of the effective criteria in decision making to select production manager in furniture industries is main activity to increase the unit's efficiency. For know – how of effective criteria in manager selection, 9 units were searched in the country. These criteria were divided into five major groups and 10 sub-sections. A hierarchy was constructed based on five major groups of criteria. Analytical Hierarchy Process then established the weights of the indicators. The result showed that Overall Inconsistency Index is 0.01 and among 12 effective criteria in manager selection for furniture industry, importance of training, acquisition of technical knowledge in experiment, acquisition of technical knowledge in theory, internal social communication and lateral skills have high priority, respectively.

The effect of rainbow fungus (Coriolus versicolor), an Iranian native fungus, on the color reduction of bleach plant effluent was studied. The effective variables in this research were time, temperature, pH, and biomass amount. To investigate the independent effect of each variable on color reduction, the other variables were kept constant considering the optimum growth conditions of fungi stated in literature. The highest color reductions were observed after each independent variable treatment; time of 6 days (59%), pH of 3 to 4(45%), biomass amount of 12 g/l (42%), and temperature of 25°C (50%). Considering the observed results, it can be concluded that the rainbow fungus can efficiently reduce the color of bleach plant effluent from pulp plant.

In order to determine suitable indices for vegetation cover and production assessment based on remote sensing data, simultaneous digital data with field data of summer rangeland in south of Mazandaran province were analyzed. During 3 years monitoring vegetation cover including annuals, grasses, forbs and shrubs and total production data of sixty plots in each site (1 square meters) were collected. The Global Positioning System (GPS), geometric correction, histogram equalization and images digital numbers were converted to reflectance numbers. In the next stage, intrinsic indices, soil-line related indices and atmospheric corrected indices were generated. For determining suitable indices, linear regression model was used. The results showed that there are significant relationships between satellite data and vegetative characteristics. Among indeces, VI10 with annual covers, VI6, VI10, MIRV1 with grasses cover, PD312, VI9, MIRV1, GVI indices with forbs cover, MIRV2, VI6, VI10 with shrubs cover, VI12, MIRV2, VI5, fuse2 and total cover and MIRV1, MIRV2, VI5, Tgr with total production, showed significant relationships. Generally introduced indices presented accurate quantitative estimation of the parameters. Therefore, it is possible to estimate vegtation cover and range production as important factors for range monitoring using landsat ETM+ data.