Journal of Forest and Wood Products
Year:2010 | Volume:62 | Issue:4|Papers Count:11

The aim of this study was investigating the parameters of dowel joint placed in MDF in order to obtain a formula to estimate ultimate bending strength. Dowel joint, one of the joints type, in placed in both form of corner and cross that widely used in the furniture manufacture, because of its low cost, easy utilization and need to hole placed. In this study, the effects of diameters 6, 8 and10 mm, penetration depth 8 and 12 mm on the resistance of dowel joint against the ultimate bending strength were investigated. The results show that the highest ultimate bending strength of dowel joint in MDF possessed to the 8 diameter and 12 penetration depths. Finally, it has been found that the ultimate bending strength (Wb) of the joint can be predicted by means of the formula Wb=(d1/2+w/3+e/3) Wt, where Wt=withdrawal strength, the width of the rail, e=the distance from the rail centerline to the neutral axis, and d1 is the spacing between two dowels.

Recently, natural resource economists have studied ecosystem value of natural resources and its role on human welfare. These studies have made a considerable progress in valuation of environmental as well as ecological services that an ecosystem can offer. Determination of existence value of Arasbaran forest and measure of individual’s willingness to pay (WTP) based on contingent valuation method (CVM) and dichotomous choices (DC) are objectives of this research. Logit model was used for measuring of individual WTP and estimation parameters of the model are based on method of maximum likelihood (ML). In continue the marginal effects of involved variables change in considered model is determined using by factor for calculating of marginal effects. The results indicated that 87.5% of individuals have willing to pay for existence of Arasbaran forest. The mean WTP of individuals for existence value of Arasbaran forest was estimated 16589 Rls per month, also the existence annual value was estimated 5216779 Rls/ha. The results revealed that Arasbaran forest had considerable existence value. Thus, this value provides enough justification for policy makers to sustain this forest.

Mangrove community in Sirik area is one of the most important habitats of Rhizophora mucronata and Avicennia marina in Iran. There is different structure of mangrove community as well as special environmental characteristics in this region. In this study to be proved by IRS 2004 satellite images and sampling by line plot and systematic base line methods, 37 plots with an area of 28.6 m2 were selected. The length of each line plot was almost 100 meter. In each line plot module parameter of the stand such as height, crown height, diameters of crown, and number of sapling in species, density and percentage cover of stands of the trees were measured. There are three type of mangrove stands including; 1-pure stand of Rhizophora mucronata in bank of the creek, 2-pure stand of Avicennia marina in the end of lines toward the land and 3-mixed stand which occur between the mentioned stands. Investigation of homogeneity of mangrove structure was performed by ANOVA which showed significant differences in 95% level in all stand types. Average of number of seedling showed regeneration in pure Rhizophora mucronata stand is more than unmixed stand of Avicennia marina. The results showed in mixed stands Avicennia marina have low generation, low density and low height of trees, comparing to Rhizophora mucronata which suggests that grey mangroves in this stands might be defeated.

Road is one of the most important and obvious extractable feature in satellite imagery. Automatic road extraction from satellite imagery has many advantages such as updating data bases by spending less time and cost. The aim of present research is the automatic extraction of forest roads map using Liss_IV sensor imagery of IRS_P6 satellite. Because of frequent irregular objects in forest, roads are very complicated for extracting automatically. Therefore, the designed methodology for this research was in a way that can deal with this problem. For this aim, image of the study area was classified into two road and non road areas by a fuzzy logic. Then, morphological mathematic algorithm was used to extract the existed roads. By this method, forest roads map was extracted automatically with 88% overall accuracy. Also, morphological mathematic algorithm showed a great ability for recovering road line that was hidden or was cut off under forest canopy.

The effects of seed source elevation and size on germination and seed vigor index of chestnut-leaved oak (Quercus castaneifolia) seed were investigated in the laboratory. The acorns were collected from three locations in Loveh forest, northeastern Iran, from elevations of 400, 1000 and 1600 m a.s.l., and classified into three different size classes including small (S), medium (M) and large (L). Using a completely randomized full factorial design, 900 acorns were sown in optimum growth conditions (8h light in 30oC and 16 h darkness in 30oC) for 40 days, and their germination emergence was recorded every other day. The results showed that all examined acorns had good average germination capacities (GC), from 80% to 99%. Seed source and seed size had significant effects on acorns germination and vigor index (p<0.05). Consequently, reduced seed source elevation and increased seed size promoted seed vigor index (VI), seedlings root and total biomass. Large acorns from lower altitudes showed higher germination rate and vigor. It was concluded the importance of provenance and seed size determination in seeding and seedling production programs. Furthermore, such variations effect on initial Q. castaneifolia seedlings vigor. Such studies with planting seed size classes in different altitudes can define the value of seed source and acorn size effects on chestnut-leaved oak seedling establishment with more validity, and determine the proper seed size class for planting in each condition.

This research studied the historical aspects of rural exploitation systems of forest, rangeland, and agricultural areas in Chetan village which is located in Kojoor district, Noshahr County, Mazandaran province in the north of Iran. The research process apply semi structured and none structured interviews, participatory observation, and study of historical documents as well as field survey. Exploitation system of the mentioned area was divided in to three different historical context period, which are different in main characteristics in ownerships relations, including: a) about 300 years ago to the late of Qajar dynasty b) the late of Qajar dynasty to 1963 when the forest and rangeland in Iran were nationalized and c) from 1963 up to now. The effect of ownership component as an important element in different exploitation methods was also analyzed in each period. Different kind of ownership systems, such as collective, private in the family level and private in the clan level, endowment, and their mixtures, for different applications such as livestock grazing, preparing fodder from tree leaves, making charcoal, preparing construction wood for housing, gathering non wood forest products and so on, have been existed in this area. These kinds of ownership methods were established owing to political as well as historical context which were out of the villagers control, also development of rural community along with time.

This study has been conducted to investigate the suitable forest territorial organizing in the northern Zagros. In order to achieve the goal, “Group Decision Making” approach was used. The method is based on “Analytical Hierarchy Process” which is one of multi-criteria decision making methods. Following determining the decision makers group (comprised of experts from research, education and management organization), the most important criteria effective in determination of management unit in northern Zagros were identified. The second questionnaire was designed to determine the rate of each criterion to choose the best alternative. Using the appropriate software (Expert Choice) the questionnaires were analyzed considering geometric mean the expert’s opinions. The results indicate that eight main factors are effective in management unit determination. These factors are as follow according to their importance: 1) social acceptance, 2) homogeneity of the goals, 3) unity of the manager, 4) using “one” forestry method in management unit, 5) similarity of the management unit and forest stand, 6) economic efficiency, 7) physiography and 8) area of “the management unit”. There were three main alternatives in managing Zagros forests. The results of this study indicate that the best choice among three alternatives is considering the family conventional territory as management unit in the northern Zagros followed by village conventional territory and watershed.

In the present study, the effective factors on distribution of coppice and high stands in traditional forest management of central Zagros in two customary properties including Sarableh town and Cheshmeh Khazaneh village were investigated. In order to obtain this goal, forest types based on canopy cover, diameter, high, origin and understory farmlands were surveyed by GPS.  Then the collected data were used as inputs for GIS. By digitizing the map of region (scale: 1:5000), the slope, aspect, elevation, proximity to population centers and road were created and the map of forest types were overlaid with them. The results showed that most of coppice stand occurs in gentle slopes, low elevations, north and eastern aspects and near to population centers. Meanwhile, high stand occurs in high elevations, steep slopes, distant from population centers and west and southern aspects. The road had not any role in distribution of stands. In understory farmlands disregard to other factors only high stand may occur.