Journal of Wood and Forest Science and Technology
Year:2010 | Volume:17 | Issue:4|Papers Count:11

The Hyrcanian forests have been highly exploited in recent decades by human impacts. Easy access, abundance and variety of valuable forest yields have led to population growth density, creation of new residential areas and deforestation activities. Change detection is one of the main methods of management and evaluation of natural resources. We investigated forest changes in southern surrounding of Gorgan city using satellite imagery and aerial photos for three different dates (1966-1994-2006). In order to produce forest extent maps for 1966 and 1994 years, aerial photos of mentioned years were georeferenced by topographic maps and ground control points and digital mosaic of aerial photos were done in GIS environment. Then, the forest extent map was produced by digitizing land use borders on digital photo mosaic for two dates. We used ASTER imagery to produce forest extent map in 2006. We found no radiometric noise in the imagery. Atmospheric correction of imagery was done using Cost method and geometric correction of imagery was accomplished by orthorectification method. Also synthetic bands were generated by suitable image processing methods including ratioing and principal component analyses. After selection of the best bands based on Bhattacharya distance, imagery was classified using supervised classification and neural network algorithms. For exploring of change detection, post classification comparison technique was employed. Results showed that severe changes were occurred in forest extent during the 41 years. Around 1250.8 ha of the extent of natural forests have been reduced, but 246.29 ha were just increased in this time duration. Hence, net forest extent reduction was 1004.5 hectare. Results also showed that rate of annual changes in the first time interval (1966-1994) was larger than second time interval (1994-2006).

Common Yew (Taxus baccata) is one of the native and extinguishing speices at northern forests of Iran that is very important as a genetic reserve and, therefore, more studies are necessary for preservation and restoration of this rare forest speices. For having high value and complete preservation of gene structure, vegetative propagation is one of the suitable in use methods in this field. This research was carried out in order to achieve the most suitable direction, height and type of cutting from Yew crown. So, cuttings were collected from four main directions and two height of crown and planted in greenhouse conditions by heel and injured types as a factorial in randomized complete design. Data were analyzed with F test and Duncan multiple comparisons. Data variance analysis showed significant difference in 5 percentage error level in growth amount, new shoots and dried cuttings number. Evaluation of intercept effects was significant only for growth amount and number of new shoots. Based on the achieved data from this research, the highest growth of new shoots and growth amount belonged to cuttings of east direction, top height and injured type. Also, heel type cuttings from north direction and top crown height had the highest drying amount.

The potential use of nano technology for improving of withdrawal resistance of nail and screw in wood was evaluated. For this, the maintenance strength of nail and screw was measured under dry and wet conditions for Poplar wood (Populus nigra) coated with common paints in furniture industry and nano-particles. Specimens with dimensions of 15×5×5 cm3 (L×R×T) were cut from Poplar wood (Populus nigra), Then, nails and screws were fixed on wood specimens, with respect to the ASTM-D 1761 standard. Afterward, specimens were separately coated with acid catalyzed lacquers and nitrocellulose lacquers and polyester paints, nano-zycosil and nano-zycofil reinforced polyester. Some specimens were dried in laboratory conditions and the others, under temperature of 103±2oC in oven, Then, the maintenance strength of nail and screw was measured by a mechanical test apparatus (Instron). The results revealed that the minimum maintenance strength of nail and screw is for wet specimens and the maximum is for dry ones coated with acid catalyzed lacquers and nitrocellulose lacquers paint and Zycosil nano-particles. Zycosil nano-particles had better performance in comparison with Zycofil nano-particles. Increase in the maintenance strength of nail and screw in coated specimens with nano-particles reinforced paint is due to the formed rigid surfaces and decrease of water penetration in wood.

Particle size, board density and adhesive content are the most important factors, influencing on physical and mechanical properties of particleboard. In this study the effects of density, adhesive content and particle size on withdrawal strength of particleboard made from Populus (Populus alba) particles have been studied. Three levels of density including 0.65, 0.7, and 0.75 g/cm3, three levels of adhesive content including 8, 9.5, and 11% and four levels of particles size including +5, -5 +8, -8 +12, and -12 mesh were used Moisture content of cake, press time, press temperature, press pressure were 12%, 5 min, 180oC, and 35 kg/cm2 respectively. The results showed that particle size increased screw withdrawal resistance more than board density and adhesive percent, so there was a possibility to increase screw withdrawal resistance without increasing board density and adhesive percent. The highest withdrawal strength was obtained in particle board with density 0.75 g/cm3, adhesive content 11% and particle size +5 mesh.

This study has been conducted in order to investigate the effect of using ONP recycled fibers on the mechanical and optical properties of local mixed hardwoods kraft pulp at Iran Wood and Paper Industry (Chooka). ONP and virgin kraft pulp have been prepared from Chooka’s waste paper storage and pulping digester, respectively. ONP has been repulped in the common method as used by paper recycling industry. After determination of the initial freeness of each pulp, they have been separately refined to reach the appropriate freeness value required to produce kraft paper. The pulps, then, have been mixed at 90.10, 80.20, 70.30, 50.50 and 30.70 percentage rates of recycled fibers and virgin kraft pulp, respectively. According to the related standard test method, handsheets were made from each treatment and their mechanical and optical properties have been measured. The results were compared with those of control sample (100% virgin kraft) using ANOVA technique and classification of the means was done by Duncan test. Finally, to determine the best treatment, normalization equation was calculated. The results show that the values of tensile, tear, and burst indices, folding endurance and density of the combined papers have been increased compared with those of control sample, but the values of bulk, thickness, brightness and opacity of the combined samples have been decreased. The scores of the treatments indicate that 50 percent of recycled fibers can be used in the furnish to produce paper with suitable mechanical and optical properties.

Acquiring of customers satisfaction is an important objective for manufacturers. Determining the factors affecting consumer choice of wood products is important in deciding the competition level and judging the market status. Besides determining and rating the consumption criteria using Analytical Hierarchy Process in 2010 the study can be guide for both policymakers and inventors in this industry. Consumption criteria for wood products were determined on the basis of opinions of experts, consumers, sale agencies and academic experts, and then were categorized in three classes of Economic, Technical and Consumption each of them including eight sub-criteria. The data gathered from 144 citizens of Gorgan were compared statistically with SPSS package after being rated as income quarters using Analytical Hierarchy Process technique of Expert Choice software. The results showed that, considering the economic criteria, as the consumers income decreases, the product price becomes more important. Among the technical criteria, product design and product durability are the most important for high-income quarter and other quarters, respectively. The analysis of consumption criteria revealed that convenience is the most important for the rich and decrease in preference with reduction of income. For maid-income clan color and appearance are important. Among the criteria, the economic ones are the most influenced in purchasing wood products. While for the high-income clan, technical criteria are of high importance and moving towards low-income clan reduces its importance and makes the consumption criteria more important.

In this research the utilization of Acacia wood (Acacia salicina) in medium density fiber board production was investigated. Sample boards were made from Acacia fibers at two resin contents (10, 12%), two press temperatures (175, 185oC) and three press times(3, 4, 5 min). The results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that increase of resin content had a positive effect on MOR and MOE and thickness swelling of MDF. At 12% resin content, MOR and MOE were respectively determined as 18.97 MPa and 1912 MPa. Also thickness swelling after soaking in water for 2 and 24 hours decreased from 15.87 and 20.96% to 10.76 and 16.49%, respectively. Internal bond strength (IB) was higher at 4 min. press time than 3 and 5 min. The IB of the boards, which were made at 4 min press time, was determined as 0.63 MPa. In general, the results showed the possibility of using Acacia wood in MDF production with proper physical and mechanical properties.

The successful management in construction costing of wood dry kilns is an advantageous approach which brings us not only the assurance in service profitability but also gives rise customer’s satisfaction. The construction costing of two types of wood dry kilns, namely, prefabricated aluminum-and masonry kilns with normal operation temperature was studied. For this purpose, the construction, depreciation and maintenance costs of the kilns were determined via field trip tours and interviewing with kiln manufacturers and wood drying industry owners. The calculated costs were based on the performance of an automatic wood dry kiln which could control drying conditions (relative humidity, temperature, air circulation and ventilation) and continuously measure the wood moisture content. Consequently, the costs were estimated as a percentage of total costs. The results showed that the construction costs for masonry kilns were less than those for the prefabricated aluminum kilns. In contrast, the depreciation and maintenance costs for masonry kilns were greater than those for the prefabricated aluminum ones. Overall, the construction of prefabricated aluminum kilns are more profitably commercial in prolonged usage.

This study was conducted to compare the yield and strength properties of soda and kraft pulp produced from Populus deltoeides sapwood and heartwood. Initially fiber length, lignin content in both sapwood and heartwood were measured. Then from either sapwood or heartwood pulps were prepared with using soda and kraft processes, Handsheets were made from this pulp and mechanical properties were measured. The results showed that fiber length in heartwood is shorter than sapwood. For both sapwood and heartwood pulps residual lignin content and kappa number of the pulps made by kraft process were higher than those for soda process. Also kappa number in the kraft and soda processes from heartwood was less than sapwood. The yield of soda and kraft processes from heartwood was lower than sapwood. This study also showed that tensile, tear and burst strength of the pulps made by kraft process were higher than relevant strength for soda process and the sapwood pulps were stronger than heartwood.

The evaluation of the edge effects of forest roads on ecosystem is very useful to understand changes from forest road. With this regard, in this research the effect of main forest road construction on regeneration and biodiversity of established trees in edge of forest road was investigated at 35 m distance into forest area. An existing 10 years old road segment, with same physiographic properties, volume per hectare and species composition along the road was selected in Chamestan and Lavige Forests in Mazandaran province. Six linear transactions were set on the fill and cut edge (three transects were set on fill and others on cut edges). Trees’ regenerations were recorded on linear transactions, within circular sample plots by 2 m radius at (2.5, 7.5, 15, 25, 35 m) distances from the road edge. The results showed, no significant differences between trees’ regenerations in the cut and fill edges up to 35 m into the forest area at 0.05 level. However, the average trees’ regenerations in the fill edge were more than the cut edge along the forest road. Maximum and minimum trees’ regenerations density, were recorded in 7.5 and 2.5 m distances from the road edge. The result showed that the maximum densities of trees’ regenerations were belonged to Acer spp and Carpinus betulus species in fill edge and Diospyrus lotus species in cut edge. The comparison of the species diversity and species richness indexes indicated that, the maximum values of species diversity indexes (both Shannon-wiener and Simpson (were in 7.5 m distance and richness indexes (Minhinick and Margalef) were in 2.5 and 15 m distances from the road edge. However, no significant differences were found between indexes in the cut edge and fill edge at 35 m distance (P>0.05).