Journal of Forest and Wood Products
Year:2009 | Volume:62 | Issue:1|Papers Count:12

In order to keep and improve competitiveness of domestic facial tissue products, compared to those of imported ones, it is necessary to do qualitative study, find the weak points and propose the solutions. In this research, after sampling from products of two Iranian tissue manufacturers and similar imported facial tissues, a comparative survey on their quality was performed. The results show that Iranian facial tissues have suitable brightness, but they are rougher and have less wet and dry-strength and less bulk. Knowing the fact that Iranian producers use recycled fibers, the reason for better brightness may be more efficient deinking or using unprinted recycled paper. But, concerning undesirable properties, they are somehow related to the characteristics of incomplete processing recycled fibers. Therefore, in order to improve the product quality, an approach can be better recycled fiber processing. In this respect, longer soaking specially under alkaline conditions and also a gentle refining, can cause better swelling of fibers and make their characteristics closer to virgin fibers. On the other hand, regarding the product roughness, using softening chemicals in wet-end or before Yankee cylinder, improving creping procedures and also "Through Air Drying" technique can be effective solutions. Also, using multi-layer head box, in order to use strong long fibers as under-layer and short soft hardwood fibers on top layer may be advisable.

To evaluate effective factors on packaging paper print quality, random experiments were designed and tested at different level of ink and paper characteristics. Then print density and ink covering were measured using densitometer and loop criterion respectively. At the next step, each factor on output values; print density and ink covering was calculated. Employing entropy method, weight of each output was obtained. To optimize output values, the problem was formulated as a multi-objective non-linear integer mathematical programming and was solved using fuzzy method. As a result, effective factors on print density and ink covering were identified. Also the optimum value for any factor was obtained so that print density and ink covering get 100 and 92 percent of their maximum value respectively.

In this study, the microfibril angle was determined utilizing three methods; "iodine crystal deposition", "inducing cracks in the secondary wall" and "Orientation of pit aperture".  Besides, a comparison was made between these methods. Hence, samples were taken from compression and opposite side of four leaned cypress stand in cypress plantation of University of Tehran. Iodine crystal-stained sections did not produce satisfactory mocrofibril angle data because crystals hardly deposit on cell wall cracks and therefore it was impossible to determine MFA using this technique. The mean MFA of samples were measured using two other techniques. The results demonstrate good agreement between these two methods. But since it was hard to determine great MFA (more than 40 degree) using pit aperture method; it is not recommended to utilize this technique when compression and latewood are concerned. The relationship between data of these two methods was described as the following equation: Y = 9.3 + 1.3 X. Where "X" is the value of MFA obtained by the method of "inducing cracks in the secondary wall" and "Y" is probable value which will be obtained by the other method.

Since 150 years ago, the rate of CO2 in the atmosphere is increased by about 30%. Many factors affect global warming and the most important one is greenhouse gases. Among the greenhouse gases, CO2 is most important one. Enhancement of the CO2 is noticed in different environmental societies such as "Environmental Convention of Kyoto" in which the alternatives of prevention of Co2 enhancement are mentioned. To decrease the accumulation of CO2 in the atmosphere, after decreasing the amount of fossil fuel consumption, the most important alternative is carbon sequestration in terrestrial ecosystems. Regarding to carbon cycle and carbon sequestration, forest is one of the most important ecosystems; moreover, soils contain about 75%. of carbon source in land. Therefore, the effect of species diversity on the rate of carbon sequestration in organic and inorganic forest soils layers was studied. Mixed beech forest and pure beech forest stands are compared. For this study 3 layers (L,F and H) are considered for organic section and three layers (0-10cm), (10-30cm), (30-50cm) for inorganic section. The amount of carbon density and carbon content is measured in all layers. The rates of carbon content in organic and inorganic layers of soils within and between stands were different. Although the carbon content of organic layers in mixed beech stand (8.36 ton/ha) and pure beech stand (8.5 ton/ha) didn't show any significant difference, the carbon content of inorganic layers in mixed beech stand (287.54 ton/ha) and pure beech stand (332.69 ton/ha) showed significant difference. Altogether the rate of carbon content in both section in the pure beech forest soil (341.20 ton/ha) was more than that of mixed beech forest soil (295.91 ton/ha). The results may be useful for interfering in forest stands to better multipurpose and sustainable forest management.

This research was carried out in Zagros section of National Botanical Garden of Iran on three oak species: oak manna tree (Quercus persica), Lebanon oak (Quercus libani) and gull oak (Quercus infectoria). In November 2006, 30 trees of each oak species were selected; acorns were gathered from 1/4 crown area of trees and the same area exactly under crowns and were labeled separately. Wet and dry weight of acorns was measured. Qualitative characteristics of acorns including first moisture percent, weight of thousand acorns, germination capacity and insect-infested acorns were measured too. Data were analyzed and compared with same researches in natural Zagros forests. Results showed that the average number of acorns per crown area for Q. persica, Q. infectoria and Q. libani were 46.5, 52.4 and 31; first moisture percent were 32, 36 and 29; weight of thousand acorns were 12.22, 10.22 and 26.51 and germination percent were 64, 59 and 49, respectively. There was significant difference in acorn production between Q. libani and Q. infectoria in 95% level. Also there was significant difference in first moisture percent, weight of thousand acorns and germination percent between oak species in 99% level.

The purpose of this study was to investigate the sustainability level of villages which were located in or near forested area in watershed of Tang Tamoradi, province of Kohgiloie and Boier Ahmad, based on indicators of sustainable development approach. We used secondary data from censuses which were done on 1985-1995-2005 and also administrated questionnaire as main instrument to gather data. The validity of questionnaire was confirmed by a panel of experts and reliability determined through calculation of Cronbach's Alpha coefficient which equaled to 0.78 and showed that the instrument was suitable for our purpose. The statistical population included 198 households in 19 villages which have resided in 7 districts, named Samane Orfi. The sample size was estimated through Cochran formula, 80 households were selected for the study by using optimum allocation clustered sampling. Data analysis was accomplished McGranahan Method to determine the weightings of indicators as well as cluster analysis to determine the levels of sustainability. Findings indicate two districts (Samane Orfies) were "sustainable", three "unsustainable" and two "relatively sustainable". Results also showed that 52.6 percent of villages were "sustainable", 31.6 percent "unsustainable" and 15.8 percent "relatively sustainable". The finding of the research can contribute to policy formulate for future rural sustainable development programs in the area.

Despite advantages of wood and other natural fibers as filler or reinforcement in filled plastics, hydrophilic character of natural fibers acts as a barrier in devolvement of wood/thermoplastic composites in some applications. Hydrophilic character of wood renders wood/thermoplastic composites to absorb water when the composites are exposed to water or humid conditions. The water absorption by wood/thermoplastic composites leads to mechanical loss. Since heat treatment of wood increases the stability of wood against water, in this research, preheat treatment of wood before blending with the polymer was used as a tool to decrease water absorption and its detrimental effects on the composites mechanical properties. Wood pre-treated at different temperatures (175, 190 and 205oC) was blended with high density polyethylene (HDPE) at two loadings (25 and 50%). In order to examine the compatibility of treated wood with the polymer (HDPE), coupling agent content was considered as a variable factor as well (0 and 2%). As wood/thermoplastic composites absorb water very slowly, boiling in water for two hours was used to accelerate the process of water absorption. Physical and mechanical measurements of composites with 25% wood content before and after two hours boiling in water showed that preheat treatment of wood and coupling agent content did not affect the water resistance of the composites. In composites with 50% wood content, the water resistance of composites depended on the temperature of wood preheat treatment and coupling agent content. Pre-treatment of wood at 190 and 205oC decreased the water absorption, swelling thickness and mechanical loss of the composites in large extent. But pre-treatment of wood at 175oC did not influence water resistance of composites significantly. Adding 2% coupling agent improved the water resistance of the composites with 50% wood content especially when untreated wood was used as filler. Boiling in water for two hours increased the strain at maximum load of composites containing 50% wood in their formulations.

Due to differentiation ecosystem units and related soil physico - chemical and biological characteristics, 268.7 ha-1 of lowland forests in Khanikan were studied. Vegetation data and information (trees, shrubs, and herbs) were collected from 60 sample plots with systematically random method (20m×20m) which were then analyzed by using TWINSPAN program. The data were classified into five ecological groups. Some of physical, chemical and biological characteristics of soil, such as soil acidity (pH), bulk density, saturation moisture, electrical conductivity (EC), organic carbon, total nitrogen, cation exchange capacity, available phosphorous, soil texture, lime, biomass of earthworms, litter carbon, and litter nitrogen were measured. Principal component analysis (PCA) was used to determine correlation as well as distribution in each ecological group of environmental factors. It was noticed that 1st, 3rd, 4th ecological groups had the highest correlation with the 1st axes whereas 2nd and 5th ecological groups demonstrated the highest correlation with the 2nd axes. The results indicated that the ecological group’s distribution pattern was mainly related to soil characteristics such as pH, bulk density, texture, phosphorous, organic carbon, nitrogen, and CEC.

Tree felling is the most important component among tree harvesting components which has strongly effect on the tree harvesting processes. Manual tree felling is the most labor-intensive component of all harvesting operation and frequently represents a bottleneck in production. This research was carried out in 220 & 225 compartment of Namkhaneh district in Kheyroud Forest. Objectives of this study were time study of tree felling operation, estimating of productivity and costs of chainsaw, developing regression model and estimating crew, machine and budget. Factor affecting total felling time regression model (increasing order of importance) were DBH of harvested tree, direct of felling regard to the lay and inter-tree distance. The hourly production of chainsaw felling with and without delay time were 31.6 m3/h (7 tree/h) & 68.4 m3/h (18 tree/h), respectively. Productivity of chainsaw felling was increasing related to tree DBH as power. The unit cost of chainsaw felling with and without delay time were 8000 and 3700 Rials/m3, respectively. The unit cost decreased as simple exponential equation when DBH of harvested tree increased. Total felling cycle time without delay averaged 2.98 minutes and with delay time averaged 7.23 minutes.

Heat treatment of wood causes a number of chemical and physical changes in the wood. Usually these changes have been studied on massive wood. Under this conditions, the overlapping of lignin and carbohydrates structural changes results in incomplete interpretation of changes in the main constituents of wood. To elucidate the modifications of lignin, in this study the pure lignin was treated under hydro-thermal treatment conditions of wood and its modifications were analyzed by means of FTIR, 13C NMR and HPSEC. The results showed that the cleavage of etherified bonds increased number of free phenolic groups. This resulted in activation of lignin and led to more condensed structure of lignin. Consequently, the solubility of lignin decreased in organic solvents and its molar mass distribution increased. The results indicated that the some carbohydrates derivates such as furfural participated in the condensation reaction of lignin.