Iranian journal of Forest
Year:2011 | Volume:2 | Issue:4|Papers Count:10

The aim of this study is to analyze and evaluate the margin market model of timber regarding to the species type, roundwood grading, and vehicle type. For this purpose, the data have been collected via interview such as producer and consumer price of beech, hornbeam, alder, and maple in year 2008 at Shafarod forests. Harvesting and transportation costs as well as the amount of residual sales have been collected via interview. The amounts of market margin, producer share from consumer price and marketing profit have been computed. The analysis of variance with significant level of 5% was performed by SPSS software in order to determine the effects of species type, roundwood grading, and vehicle type for above mentioned factors. Duncan test was used to compare the average. The results indicated that market margin is affected by kind of species and roundwood grading, and it is not affected by vehicle type. This study indicated that market margin and marketing profit decrease from beech, hornbeam, alder and maple, respectively. Market margin and consequently marketing profit were higher in lower quality of roundwood. 

The main objective of this descriptive- survey research was to study the social capital`s impact on citizen’s participation in the affairs of Tehran forest parks. The statistical population of the study consisted of the most common and popular Tehran forest parks i.e. Chitgar, Lavizan, Taleghani and Sorkhehesar, out of which a sample of 205 visitors was selected using Cochran Formula and simple random sampling method. A questionnaire was used as the main tool of study. The validity of the questionnaire was approved by the judgment of a panel of experts. In order to measure the reliability of the questionnaire, Cronbach Alpha coefficients were computed for the main scales of the questionnaire (0/86 to 0/94). The data were analyzed by SPSS-win software. Correlation analysis revealed that there were significant and positive relationships between citizen’s willingness for participation in Tehran Forest parks and social capital at 0/001 level. Results of ANOVA showed that willingness for participation in the executive affairs and managerial activities of forest parks were significantly different among citizens with different levels of social capital (at 0/005 level). Also seven variables were respectively interned in stepwise regression analysis and explained 66.2 percent of variances of citizen’s willingness for participation in Tehran Forest parks. So participation and social capital have a bilateral relationship and as social capital increases, inclination to the participation in citizen also increases. Moreover focusing on social capital criteria and its indicators has an undeniable role in urban communities and their development purposes. 

The use of wheeled skidders is well accepted practice for the extraction of timber from the forest, but this has tended to cause the greatest environmental problems. The aim of the study was to evaluate if slope gradient, number of machine passes, soil depth, and soil moisture of skid trails influence soil compaction on a fine-grained soil, and to quantify these effects. The study was designed as a factorial experiment and the effects of 0, 10, -10 and -20% slope, 5, 15 and 25 cm depth, 20-30, 30-40 and 40-50 % soil moisture and different levels of compaction were applied by varying the number of skidding cycles: 1, 5, 8, 10, 15, 20, 25, 30 passes. A Timberjack cable skidder was used and the study location was the Kheyrud Forest. An increased number of machine passages increased soil bulk density, but most of the compaction occurred after the initial few passes. Uphill skidding increases compaction more than downhill skidding. Increases in bulk density were still important at the maximum sampling depth of 30 cm. Soil bulk densities at 5, 15, and 25 cm depths on average 35, 22, and 17% are higher than densities in undisturbed soils.

Traditional husbandry of forest settlers is always propounded as socio-economico problem that prevent complete implementation of forest management plans. For resolving this problem, the organization of Forests, Rangelands and Watershed management designed two strategies; improvement and change of life style of rural in 20 family village, and strategy of movement and gathering of small village with population less than 20 families. Because of several reasons such as budget restriction, it is necessary to consider numerous quantitative and qualitative criteria to determine priorities. In this study, to determine priority of alternatives, criteria and sub-criteria (indicators) was arranged in a model evaluated using the analytic network process (ANP) with group decision making. Assessment of results confirmed optimum efficiency of this method. Furthermore, the result of evaluation showed indicators such as livestock and village population and husbandry (the source of family revenue) have the most importance in priority determination of alternatives. 

Nearest Individual sampling method is one of the distance sampling methods for estimating the plant density and canopy cover. For plant density measurements, five formulas have been developed; one by Cottam et al. (1953), Morisita (1953 and 1957), Byth and Ripley (1980) and Batcheler and Bell (1970). In this study, applicability of these formulas regarding the accuracy to estimate the density and canopy cover of Zagross Oak (Quercus persica) forests were examined in research and educational Forest of Razi University (Kermanshah province). First, 50 hectares of these forests were selected and was inventoried. Then, 50 systematic random sampling points for Nearest Individual sampling method were measured and recorded in this area. The results show that Morisita (1953) and Batcheler and Bell (1970) formulas can provide an acceptable estimate of density based on ±10% accepted accuracy, but none of the formulas could provide an acceptable estimate of crown coverage based on ±10% accepted accuracy; even though, the Batcheler and Bell formula has more accuracy level for crown coverage for this kind of forests.

Budget is one of the main tools in policy and plan implementation that its relation with political-judicial power is not investigated, yet. This research is done in order to investigate and analyze the impacts of formal and informal lobbying as the effective factors on budget allocation. Budget allocation in natural resources field is too important because of conservational functions overcoming productive functions as a result of extensive forest destructions. Also sustainable management of these resources is costly. Kohgiloye and Boyerahmad Province is selected because in this province, public institutions play important roles in natural resources management and also because of the nomadic history, ethnic roots and "relations" overcoming "rules" in policy-making and management in this province. Also Network Analysis was used to delineate formal and informal relations of organizations related to natural resources and analysis of formal and informal lobbying centers according to Degree, Betweenness and Eigenvector Centralities. The results of regression analysis of centrality measures and organizations' budget through Network Analysis showed that relating the main power center and the budget allocation and also informal lobbying could be more effective on budget allocation than formal one. Network Analysis Approach could be useful for recognizing relation and power oriented researches for better natural resources conservation and management.

Over 8 million people inhabit Tehran. The pollution of the city is increasing, in spite of numerous management plans applied. Hence, proper programs including tree planting could be of a great help in determining the magnitude of pollution absorption at different sites in the city. Using theoretical and applied approaches would cease pollution intensity. Long-term life-cycles enable trees to be the most appropriate and precise indices for such studies. In this study, 60 individuals of plane species were selected. Since different heights would impress the amounts of pollution absorption, we tried to core the same places in each tree. With the help of Tehran pollution map (measured mechanically), we were able to select the sampling trees from the most to least-polluted areas. Since the dried wood material were limited to run the experiments, we had to sample 5 cores and then tree cores were separated annually for latest 25 years. In addition to comparing air pollution absorption individually, the amount of uptake by different sites would be considered as well. The results indicate that, plane tree growths have dramatically decreased during last 10 years. Whilst, these trees are in their juvenile stage having an average DBH of 36 cm. Statistical measurements show that two regions of Saadat-abad and Azadi have relatively higher growth rates over other areas such as Yakhchal and Narmak. Comparing to the results of precipitations, it is obvious that increment fluctuations are not consistent with precipitation changes indicating the influence of other factors on growth, including the air pollution.

The purpose of this study was to study the effects of Seidlitzia rosmarinus, Haloxylon aphyllum and Tamaix aphylla on soil physico-chemical characteristics in forests of Chah – Afzal. After field inspection, three sites including planted species with Haloxylon aphyllum and tamaix aphylla and a natural forest including Seidlitzia rosmarinus ware selected. Sampling was performed with randomized-systematic method. Four transects with length of 500 m were established in the key area of each site. Soil samples were taken from two depths (0-30, 30-60 cm) under plant and in control areas, in the top and the end of transects. The measured characteristics of soil included texture, electrical conductivity (EC), acidity (pH), nitrogen (N), phosphorus (P), potassium (K) and organic matter(OM).Data were analyzed using SPSS software under windows. T-test was used to compare the data related to planted and control treatments. Results showed that Seidlitzia rosmarinus site has less amount of OM, C, C/N than control area (p<0.01). There were significant increases of (K) and decreases of (EC) in Haloxylon aphyllum site. There were significant increment of C, C/N, K, O.M, and pH in Tamaix aphylla site. In this site total measured characteristics of soil in planted areas were more than the control ones.