Journal of Wood and Forest Science and Technology
Year:2018 | Volume:25 | Issue:4|Papers Count:8

Background and objectives: Getting informed about of land uses patterns and knowing the changes of each land use, during the time is the one of the prerequisites for the correct uses of land. During the last decades many methods of this regard have been developed. One of these methods is the use of landscape metrics. Landscape metrics are quantitative indices that describe compositional and spatial aspects of landscape. The most important impose on these studies is that changes into landscape patterns strongly affected landscape function. Due to the special ecological position of the Arasbaran biosphere, and some destructive factors such as over-grazing, high acreage of agricultural fields and encroachment of human-made structures into natural ecosystems, the area has witnessed a noticeable rate of land degradation during the last decades. Therefore, the main objective of this study was analysis of land use and land cover changes using ecological landscape metrics. Materials and methods: At first, the multi temporal Landsat images dated 1990, 2002 and 2014 were provided. Based on former knowledge from study area and study aim, satellite images were classified in seven classes including high forest, low forest, agriculture, grassland, barren land, water and urban area. For quantitative landscape metrics for each land use map, we used Fragstate software. Selected metrics included CA, PLAND, NP, LPI, MN_SHAPE, ENN, IJI, DIVISION and SHDI. Results: The result of calculating CA, PLAND and NP metrics showed that forests were degraded and urban area and barren land were extended. Decreasing the index of the largest patch (LPI) and increasing indexes of contagion-interspersion (IJI), ENN and DIVISION for forest area indicates the destruction and disintegration of these lands. In landscape level the number of patches has increased over the time, which represents the intensity of negative and defamatory change during the study. Also, the increasing of Shannon's diversity index confirms the increasing diversity of patches in the regions as a result of increasing patch numbers and changes in landscape. Contribution of each category in altering other LULC categories was also calculated to provide an improved understanding regarding current LULC change processes in the area. Grassland is the most invasive category against low-density forest such that it occupies this category for 815 and 1, 219 hectares during both time intervals, respectively. Conclusion: The result of calculating metrics and change detection showed the changes in the second period (2002-2014) were more intense than the first period (1990-2002). Based on the results can be mentioned that during of study the landscape in Arasbaran region completely fragmented. Also consider spatial diversity and dispersion of land uses, there is a possibility of degradation and land use change in the future. Accordingly, there is a need to develop a suitable program to prevent unwanted changes in the landscape and maintain its spatial continuity. Development in the future should be programmed based on sustainable development principles and attention be pay to protection, maintenance and ecosystem management.

Background and objectives: Abarkooh cypress (Cupressus sempervirens L. var. horizontalis (Mill) Gord) is one of the oldest trees in the world. Because of its prolonged life, the plant has tolerated many adverse environmental conditions, so if this valuable treasure is propagated, it can produce a large plant population with the ability to withstand extreme environmental conditions Tissue culture is one of the best methods for protection and propagation of in danger and rare plants such as this plant. Materials and methods: This study was conducted to determine the best culture media and concentration of BA in micropropagation of Abarkooh cypress plant. In this research, different culture media such as Murashige & Skoog (MS) and modified MS contained ½ MS, ¾ MS, MS without ammonium nitrate, MS with ½ nitrogen, source MS with modified vitamin-1 and 2 group by three concentrations of BA (0, 0. 1 and 1 mg/l) in establishment phase and five concentrations (0, 1, 1. 5, 2 and 5 mg/l) in proliferation phase were used. Experiments were performed in factorial and completely randomized design with five replications. Results: In establishment phase the highest length and number of shoots as well as the lowest percentage of browning were obtained in ½ MS culture medium. All culture media except MS with ½ nitrogen source, maintained greening degree. By increasing the BA concentration in establishment stage, length of shoots significantly, increased. However, the highest length of shoots was obtained in culture media supplemented by 1 mg/l BA. In all media with modified nitrogen source or without it, length and number of new shoots significantly decreased in compare other culture media. In proliferation phase, the highest number and length of shoots were obtained in ½ MS culture medium supplemented by 2 mg/l BA and the highest greening degree was recorded in cultured explants ½ MS and ¾ MS culture media. According to the results, by increasing BA concentration in proliferation stage, length and number of shoots significantly increased, but the greening degree significantly decreased. Conclusion: Generally, proliferation rate, length and number of shoots greatly depended on nutrition of explants and kind of culture medium. According to the results of this study, ½ MS culture medium supplemented by 1 mg/l BA in establishment stage and 2 mg/l BA in proliferation stage, is recommended.

Background and Objective: Remaining wood in the forest after cutting decreases the wood quality by the activity of the destructive factors of the wood, especially the fungi. Thus the quality of the wood produced by the low-quality wood is not durable and Increasing the damage of wood products consumers and increasing the need for cutting trees and destroying the forest. The purpose of this study was to measure the amount of damage to the beech bolts trees after three periods four months (12 months) of storage in the forest and compares it with the beginning of the period and identify the destroyer fungi that appeared. Materials and Methods: This research was carried out in part of One in Shastkolah forestry project in Gorgan on Fagus orientalis. 15 billets from 30 cm diameter class and length of 220 cm from a beech tree and all were healthy, inside the field under the same conditions and in contact with soil stored. The Billets were numbered and cut at 50 cm intervals at each stage and transferred to the wood working room for physical and mechanical experiments, dried at the wood working room in the open air, and then dry density, basic density water absorption, volumetric Shrinkage, End and side Hardness, Toughness and Static bending were measured based on conventional methods and related standards. Statistical analysis of the results was performed by ANOVA test and comparison of averages with Duncan's test (using Spss16 software). Observed fungi were collected and identified with valid sources. Furthermore, the percentage of changes in the measured characteristics was compared. Results: The results showed that white decay fungi Lenzites betulina and soft decay fungi Annulohypoxylon multiforme appeared on the Bolts. The results of analysis of variance at 95% confidence level, there is a significant difference between the Remaining time and physical and mechanical properties of beet bolt. According to the results, with increasing storage time in forest, dry and basic density, End and side Hardness, Static bending Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) decreased, but the percentage of water absorption increased. The most significant changes in the characteristics of wood were after 12 months of storage in the forest. The greatest change in the physical properties of wood was the percentage of water absorption and lowest was dry density. The greatest change in the mechanical properties of the wood was the Toughness and the least was the modulus of elasticity. Conclusion: This study showed that the quality of beech wood that stored in contact with soil in the forest were reduced due to the activity of destroyer fungi causing white decay and soft decay significantly. The important note was that wood degradation for important properties such as Toughness was 77% after 12 months, which indicates a significant decrease in wood quality and its economic value reduced due to the decrease in density and the weight of Billets And loses its initial performance, So it recommended that wood be transported from forest to the industry in the shortest time possible, so that quality And its economic value, and with a longer durability of wooden products, and fewer trees will be cut off to supply the timber needed for the community and protect forests and environment.

Background and objectives: Wood price prediction has an important role in the marketing and sales of wood products, and has always been of interest for managers. Price prediction will cMuesnmoHsnMtts tio ntowMHdentasnwoodni duetHynM dnwillnbooetntasnfoHsetnmM MgsHe’ nk owlsdgsnto optimize harvest operations in terms of species, time interval and the related area. The aim of this research was to use price time series of different species to predict the expected average price and investigate of the historical price trends in the Caspian forests. Materials and methods: First of all, historic stumpage price data of main species were collected for the period of 24 years from 1993 to 2016. Then, in order to determine the stumpage price the variable costs were deducted from the wood price beside forest roads. Consumer price Index (CPI) in base year 2012 was used for deflation of stumpage price. Investigation of the stationary stochastic process of time series was tested by generalized Dickey Fuller test from unit root tests using EVIWS 10 software. Then validity of regression models was investigated by multiple regression analysis using SPSS23 software. Finally, the mean expected price of different species was estimated by the parameters of the autoregressive models. Results: The results showed that real prices in past periods had random fluctuations, and the nonstationary hypothesis of time series was rejected. Regarding the parameters of the regression models, the mean expected prices based on the first-order autoregressive processes were estimated include 253. 75, 141. 89, 252. 42, 88. 231, 163. 63 and 123 (ten thousand Iranian Rials/m3) for studied species respectevily including beech (Fagus orientalis Lipsky), hornbeam (Carpinus betulus L. ), maple (Acer velutinum Boiss), alder (Alnus subcordata C. A. M. ), oak (Quercus castanifoli C. A. M. ), ironwood (Parrotia persica (DC) C. A. M. ). Conclusion: This research has shown that forecasting the expected price of species and controlling the price changes as well as its related factor is essential for forest managers and planners to optimize forest management. Determining the expected prices is required identifying potentialities, investigating the underhand obstacles and compiling comprehensive plans. Furthermore, is an indication of wood market situation. Thus, with awareness of the mean expected prices and their fluctuations will help forest managers for decision making in harvest scheduling. It will also assist wood and paper industries sectors to produce at lower costs and secure the raw materials.

Background and objectives: 0The wood is used for its aesthetic appearance and at the same time its high mechanical strength, but it also has some-disadvantages that limit its application. Wood modification is a science to improve undesirable properties of wood. Thermal modification is a useful method to develop dimensional stability and biological resistance. Heat treatment degrades the fire resistance of wood. The main disadvantage of wood is its flammability. Lignocellulosic burns because the cell wall polymers undergo pyrolysis reactions with increasing temperature to give off flammable gasses. Primary impregnation of wood with borates has been found to reduce flammability of thermally modified wood. Boron compounds work efficiently as the fire retardant for cellulosic materials. Boron compounds are recognized as inexpensive, easily applicable and environmentally safe preservatives. The aim of this study was to investigate the effect of heat treatment and primary impregnation of Fir wood with borax on the fire resistance, thermal behavior and dimensional stability. Materials and methods: Specimens were prepared to dimensions of 150 (L) ×100 (T) ×20 (R) mm and were impregnated with %7 aqueous solution of borax for 40 minutes at the pressure of 4 bars. Heat treatment was carried out at the temperatures of 170 ◦ C and 190 ◦ C in oven for 3 hours. Specimens were prepared according to ISO 11925 standard specifications to measure fire retarding properties including ignition time, glowing time, carbonized area and mass loss within the burning process. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were carried out under air at a heating rate of 10 ° C/min The temperature was heated from the room temperature up to 600 ° C. Long-term dimensional stabilities were measured. Results: Heat treatment of specimens caused mass loss. The impregnation of wood with borax reduced the mass loss during heat treatment. Heat treatment decreased ignition time. Borax postponed the ignition time of thermally modified wood. TGA thermograms showed that residual char amount was increased in borax preimpregnated-heat treated specimens compared with thermally modified specimens. Char provided insulation and also inhibited propagation of heat. DSC thermograms determined that for borax reimplanted-heat treated specimens rate of formation of the volatile products reached its maximum at a lower temperature in comparison to thermally modified specimens. During the heat exposure borax formed glassy films on the wood that may inhibit mass transfer of combustible gases. Long-term immersion results confirmed that volumetric swelling and water absorption of thermally modified specimens decreased due to enhancement of hydrophobicity. Volumetric swelling and water absorption of borax preimpregnated specimens increased due to enhancement of hydrophylicity. Conclusion: Thermally modified wood was susceptible to burning and its fire resistance was decreased. Primary impregnation of Fir wood with borax postponed ignition time and glowing time and eventually increased fire resistance. The lowest carbonized area and mass loss was obtained in borax preimpregnated-heat treated specimens. Thermal analysis showed sharp mass loss for thermally modified wood in comparison to borax preimpregnated-heat treated specimens. Borax increased the resistance of thermally modified wood to thermal degradation and altered pyrolysis route of wood and leaded to the inhibition of the flame spread. In other words borax decreased the Tmax (maximum degradation temperature). Borax preimpregnated-heat treated specimens of Fir wood decreased dimensional stability in comparison to thermally modified wood.

Background and objectives: Paper recycling has been greatly developed as a suitable approach to use waste paper and as a huge source of cellulose fibers in recent years. Regarding to the structural characteristics of these fibers, which differ largely from those virgin fibers; the first and most important challenge of their application is to modify them for reusing in papermaking industry. It seems that if these fibers are repeatedly used, their applicability will reduce. Although the impact of recycling number for these types of fibers on the paper properties has always been taken into consideration, but there are not many reports available in the literature review. Recent studies show that layer-by-layer technique is a good way for modifying the cellulose fibers characteristics and improving its quality. In this technique, cellulosic fibers and counter-ionic particles are placed in an interaction media. During the interaction, ionic particles are absorbed by fibers surface mainly via electrostatic absorption. Thus, the fibers network strength would improve considerably. Therefore, in the current study, the Kraft paper recovered three times at first. The possibility of modifying of three times recovered Kraft fibers has been investigated using layer-by-layer a technique in order to develop the bonding potential of the fibers. Materials and methods: Kraft fibers were first recycled three times. Then, the three times recycled fibers were treated by 1 % cationic chitosan and 1 % anionic carboxyl methyl cellulose (CMC), based on the oven dry (OD) weight of fibers, by using layer-by-layer method. The treatment was applied to form one, two and three double layers of pair polymers on the fiber surface. To form a consecutive double layer, 500 ml of fiber suspension with consistency of about 0. 6 % was mixed with chitosan and CMC solutions for 10 minutes by using dynamic drainage jar (DDJ) machine. Paper sheets with base weight of about 80± 5 g/m2 were prepared from the pulp samples and their characteristics were evaluated according to TAPPI standard methods. In addition, SEM micrographs were prepared from the papers to evaluate the changes in the structure of the fiber surface. Results: The alternate variation of zeta potential confirmed the formation of chitosan and CMC layers on the surface of Kraft recycled fibers. The evaluation of paper strengths showed that the fibers bonding has been developed by treating the three times recycled Kraft fibers with layer-by-layer method, through absorbing of these two strength-enhancing polymers. Meanwhile, paper apparent density, tensile index, internal bonding, and tensile energy absorption have significantly increased. However, the bending stiffness of the paper has shown a significant decrease due to the increased in paper density (decrease in thickness). In addition, based on SEM results there was a clear difference between the surface of treated and untreated fibers, which indicated the absorption of polymers, leading to the development of bonds between the fibers, and paper strength. Conclusions: It can be concluded that it is possible to modify the bonding-ability of three times recycled Kraft fibers by using layer-by-layer technique. This method can be applied to assemble multilayers of chitosan and CMC polymers on the fiber surfaces, to improve the strength properties of the resulting paper.

Background and objective: In this study, for the useful consumption of residue materials that have no specific consumption and are waste, it was started making the particleboard from the mixing of corn stalk, wheat straw and industrial wood particles. Then, the physical and mechanical properties of the boards were measured. Because of the consumption of these raw materials that have a low price (if possible), it can reduce the cost of production of this type of product. Materials and methods: For this purpose, corn stalk, wheat straw and industrial wood particles at levels of 0: 100, 25: 75 and 50: 50, press temperature of 160 and 180° C and 12 percent of urea formaldehyde resin based on the dry weight of the particles were used for the production of particleboards. The physical and mechanical properties of the boards including thickness swelling within 2 and 24-hour immersion in water, bending strength, modulus of elasticity and internal bonding were measured and all the data were statistically analyzed. Results: The results of this research showed that the increase in corn stalk and wheat straw in the mixture showed in increased thickness swelling within 2 and 24-hour immersion in water. It means increasing the amount of corn stalks and wheat straw had a negative effect on the thickness swelling of the boards. The amount of bending strength, modulus of elasticity and internal bonding decreased with the increase of corn stalk and wheat straw particles in the boards and there was a significant difference between different levels of wheat straw and corn stalks. Also the press temperature increase from 160 to 180 ° C had a significant effect on all the properties of the boards and improved the physical and mechanical properties of the boards. Increasing the temperature of the press also had a significant effect on all the properties of the boards and improved the properties. Conclusion: According to the results of this research, using corn stalk, wheat straw and industrial wood particles, increased significantly the dimensional stability of the boards. Bending strength, modulus of elasticity and internal bonding in control samples showed the highest values. But compared to the properties of the boards produced by EN standard, using 25% corn stalk and wheat straw, 12% urea formaldehyde resin and press temperature of 160 ° C, can be produced particleboards with favorable properties. This is a positive result for the use of mixing this kind of agricultural wastes including corn stalk and wheat straw, following that the prevention of environmental pollution caused by the burning of these compounds.

Background and objectives: Impregnation of wood with different monomers and their conversion to the un-leachable reacted polymers inside the wood causes a new product which is called wood polymer. The furan compounds such as Furfuryl alcohol (FA) is commercially used for wood modification, producing then wood polymer. Wood is impregnated with FA, convert to the polyFA by heating. Furfural which is in fact the primary raw material in the manufacture of FA is extensively manufactured in Iran from residues of sugar cane. Furfural could not be easily polymerized alone like FA; however it is an aldehyde which can react with urea to make polymer network. In this study, the possibility of furfural/urea polymer along with acidic catalyzer (maleic anhydride) was evaluated for the improvement of physico-mechanical properties of birch wood. Methods and Materials: Birch wood (Betula sp. ) imported from Russia was used for experiments. With a double treatment procedure Furfural+Urea/Maleic anhydride was impregnated into the wood according to a 2 steps vacuum/pressure technology: (1) diluted furfural in water and methanol, followed by (2) Urea/Maleic anhydride aqueous solution. For making comparison between the results, a commercial formulation based on the FA was also used as a reference. The mixes impregnated into the wood were polymerized by heating. Then, different physico-mechanical properties of wood samples were measured according to the standard guidelines of ISO 13061 series. Results: The proportion of Furfural+Urea/Maleic anhydride was appropriately selected, and approximately 60 to 80% were converted to the polymer. The leaching rate of the products once polymerized within the treated wood was around 4% which is comparable to the results of commercial formulation based on FA. The weight percentage gain (WPG) of the wood samples varied between 27 to 57% depending on the furfural concentration in the treatment solutions. Despite the bulking effect, the density of samples after treatment increased significantly. The water absorption during samples soaking in the water is clearly linked with the WPG, and decreases with the increase of WPG. The volumetric swelling of the samples treated with the combination of furfural+urea/maleic anhydride also follows the same trend. However, the lowest volumetric swelling was obtained with the treatment with FA. The mechanical resistance evaluation showed that wood treatment by furfural +urea/maleic anhydride reduced the hardness and the impact bending of wood, while static strength such as the modulus of rupture, modulus of elasticity, and compression parallel to the grain increased. The treatment with FA also reduced the resistance of wood against impact bending. Conclusion: Wood treatment with the complex of furfural+urea/maleic anhydride, especially at high WPG levels, has a good potential for improving most wood properties. The high acidity of furfural based solution is one of the issues requiring additional studies. If the alkaline pH is used, the curing of the resin will be disturbed and the leaching rate will increase. On the other hand, acidic pH also has a negative impact on wood properties.