Journal of Forest and Wood Products
Year:2016 | Volume:68 | Issue:4|Papers Count:21

Chainsaw is an important machine for tree felling limbing and bucking in Hyrcanian forest and the major problems related to using forest machines was sound intensity. The aim of this study was to measure the sound level in occupational exposure of workers, determine the exposure time of workers and comparison of the variables among the workers. This study was carried out in Namkhaneh District in Kheyrud forest. In this study, Sound intensity chainsaw was measured every 10 seconds in undercut stage and every 15 seconds in back cut stage. Results show that the workers were faced with the sounds upper the 85 dB and time duration of exposure with noise of chain saw in tree felling was upper than the allowable limitation and standard. Comparison of two worker, considering working time duration and the corresponding sound level, with allowable values of time duration and sound level, shown between under cut and back cut stages time durations are Significant difference, such that generally in Hornbeam (Carpinus betulus) trees, in undercut stage inexperienced worker in %71 and experienced worker in %32 of working time duration and in back cut stage, experienced worker %10 and inexperienced worker in %54 of working time duration are faced with the sound level and time duration upper the allowable limitation, which these differences are corresponded to the working method and the worker experience.

In this research resistance of six tree species to logging damages (bole wound) after 12 years were studied in district 1 of Asalem Nav forests. The data of extent and severity of damages on residual trees were collected immediately after logging operation from systematic sampling with circular 0.1 ha plots in the year of 2000. The damaged trees and wounds condition were reexamined in the year of 2012. The results of this study showed the resistance of trees to logging wounds is related to their specimen, diameter and wound size (P<0.01). The Lime tree (Tilia begonifolia) had the lowest ability to wound repairing, so 76.9% of wounds were lead to wood decay and 7.7% were lead to die of tree. The Beech tree (Fagus orientalis), after the Lime tree, had the highest sensitivity to logging damagei (9U7C_so the highest frequency of open wounds (28.8%) was observed in this species. The ability of wound repairing in Hornbeam (Carpinus betulus) was higher than other species, so 78.1% of logging wounds absolutely were closed. The results showed that after 12 years 85.6% of wounds smaller than 25 cm2 in sizes were repaired. While, were not repaired any of bigger than 1001 cm2 in sizes wounds. The trees of < 20 cm in DBH had the minimum, but the trees of 41-60 cm in DBH had the maximum resistance to bole wounds. The reducing of logging damages on residual stand needs to adequate organization of felling and wood extraction operation in selection management.

Estimating of forest equipment productivity is an important aspect of managing cost in forestry, which leads to reduction of operations expenses. In other words, high capital cost in forest harvesting, is a good reason to argue forest engineering research and time modeling. This paper applied one of the Artificial intelligence subsets, which are called Artificial Neural Networks (ANNs), to predict winching time of wheeled skidder Timber jack 450C in Neka Choob forests. Continuous time study was performed to collect winching data during skidding operations. Winching time and related effective factors including slope, distance, number and volume at every winching cycle was measured simultaneously. Two neural networks type- Radial Basis Function and Multi Layer Perceptron- were used to develop winching time model. Moreover, in order to compare accuracy of ANNs and mathematical model, the regression analysis method was developed. Results showed that RBF network provided more accurate results in winching net time estimation compare to MLP neural network. The most effective variable in both networks was determined distance to the center of the skid trail. The results showed that the model developed by neural networks has more precision than the linear regression method.

Various kinds of chemicals are used in papermaking to enhance paper properties and to improve efficiency of the production process. In the presence of cationic starch as an anionic charge catcher, effects of Nano silica/cationic Polyacrylamide complex on retention, drainage time, water volume drained by Dynamic Drainage Jar and properties of paper recycled from old corrugated container were investigated. The results revealed that individual addition of CPAM is more efficient than the individual addition of anionic nano silica, regarding to the investigated properties, increase all characteristics compared to the situation without these addition. Higher volume of drained water (up to 6%) and lesser time needed for the sheet formation (up to 10%) combined with retention increment (> 2%) have been achieved by flocculation and consolidation of fines and fibers via bridging and network flocculation of pulp ingredients and contributing to charge neutralization of anionic surfaces, more and more, resulted in bigger flocs which could be retained by papermaking wire. The mentioned mechanism contributed to better bonding of paper network resulted in tensile and burst indicates improvement up to > 45% and >50%, respectively. Influence of silica anionic nanoparticle on strengthening of the flocs formed by CPAM, made higher energy requirements (> 12%) for paper tearing. In addition to higher yield of production, application of CPAM/nano silica complex resulted in a paper with higher value from quality and application point of view.

The effect of impact modifier on creep behavior of wood flour- recycled polypropylene composites has been evaluated in this work. For this purpose, impact modifier (Ethylene Vinyl Acetate) and recycled polypropylene were mixed with wood flour (50.50% w/w) as well as the impact modifier (0, 3%, 6% and 9%) by a counter-rotating twin-screw extruder to manufacture the wood flour- recycled polypropylene composites specimens. Short term flexural creep test at 30% of ultimate bending load was performed by using flexural creep equipment. The total time to complete every test was 120 min (60 min creep and 60 min recovery). Results revealed that recycled polypropylene reduce creep resistance of wood flour- recycled polypropylene composites. Also results have shown that impact modifier increase the creep deflection, initial creep, final creep, relative creep and decrease creep modulus in composites containing impact modifier. Composites containing virgin polypropylene without impact modifier exhibited higher creep resistance than other composites in this research.

The computer simulation of the wildfire behavior allows to analyses the main characteristics of the fire spread and behavior in concrete region. Temporal and spatial variations of fire behavior can be predicted using one of the semi-physical or empirical models developed over recent years. This article investigates the effect of different fuel moisture conditions on fire spread and behavior in National Golestan Park in July 2011 using FARSITE, Flam Map simulation systems, and previous ignition history. Landscape data contains the topography and vegetation spatial information along with weather data are used as simulation input. Fuel moisture conditions representing moderate, moderate-dry, dry, extreme fuel moisture scenarios were used to generate the fire behavior characteristics. These characteristics includes the fire perimeter and area for each time step provided by FARSITE and rate of spread, surface flame length, and fire line intensity as calculated parameters by Flam Map. Fire Area Simulator was validated with the real mapped fire scar by GPS mapping. Based on the results, the simulated fire spread covered 90% of the observed fire scar which was almost high, whilst overestimation was 30%. The results of simulations show that the fuel moisture reduction causes a remarkable growth on the fire perimeter and area, with an increase on both maximum and average fire spread rate, flame length and fire line intensity. The results revealed spatial variation in fire behavior parameters that is useful in prioritizing fuel treatments and guiding other wildfire risk management activities.

To compensate for some inferior properties of recycled papers, application of processing chemical aids such as chitosan can be quite effective in the wet end section of papermaking. In this study, the performance of chitosan biopolymer, individually or associated with nanobentonite was investigated as wet end additive on recycling process of white cuttings. For this purpose, the performance of this biopolymer at 0.5, 1, 1.5 and 2% (based on oven-dried pulp) were compared in a single polymer system or with nanobentonite. The results revealed that dosing different amounts of chitosan resulted in increasing tensile, tear and burst indices. Moreover, improvement in first pass retention (5 and 10% in single and nanoparticle system, respectively) and drainage (18.75 and 23.5% in the case of single and nanoparticle system, respectively) was observed, while the improvements resulted from nanoparticle system was more prominent according to the wet end parameters. It is noteworthy that increase in strength properties in presence of bentonite nanoparticle was unexpected, and on the other hand the more additive used, the more gains in paper strength properties and processing parameters was detected.

Forest roads are directions in natural habitats that used to transport wood products, secondary forest products and recreation. Constructing forest roads causes trees clearing with specified width thus lead to direct or indirect changes in forest ecosystems and forest environment. This study aims to assess the changes of diversity and richness indices in main and secondary forest roads in a part of Hyrcanian Forest. Sixteen 100-meters transects along main and secondary roads toward cut and fill slopes, were established perpendicular to the road in 0 (road edge), 5, 10, 15, 20, 30, 45, 60, 100 m distances. Within each, nine 1´2 m plots were sampled to record the herbaceous species. All transects were in Hornbeam-Beech forest type. Abundance of herbaceous species was recorded in each of the plots and was used to calculate Shannon-Wiener diversity index and richness index. Soil samples were taken from a depth of 0-10 cm above the center of each plot at 0, 5, 60 and 100 m to determine the physico-chemical properties of soil, and then transported to the laboratory. The results of this study showed that the diversity of herbaceous species in the main and secondary forest roads was not significantly different but in different distances from road edge, cut and fill slopes differences were significant. The results indicate that effect of forest roads is limited to the 60 meters of forest interior. Also based on the results of environmental factors and soil parameters, light is major factor to determinant of species abundance and distribution of them from road edge to forest interior.

Utilization of the new compatibilizers to improve matrix/filler interface adhesion and also, nanoparticles to improve the properties of WPC products have always been of interest to researchers. In this study, the effect of oxidized polypropylene in solution phase as a comptibilizer and nanoclay particles on the physical and mechanical properties of wood fiber reinforced polypropylene composite was studied. Initially, polypropylene (in solution phase) was oxidized over a period of time for 4 hours. After mixing WF, PP (50 wt %), oxidized PP (3 wt %), and nanoclay particles (0, 2, 3 wt %) in a brabander, the produced pallets formed into a mat using a 150 ´ 150 mm2 forming frame. The thickness of the final samples is 2 mm. Physical and mechanical properties of the specimens, including Tensile and flexural strength, modulus of elasticity and rapture, Impact Resistance, water absorption and thickness swelling were conducted according to ASTM. The results showed all mechanical and physical properties of the composite were improved by using the comptibilizer. Moreover, in the presence of nanoclay particles, the physical and mechanical properties, excluding impact strength were improved. nanoclay particles distribution and morphology of composites were studied with x-ray diffraction and electron microscopy. It revealed that the distribution of the nano particles in the polymeric matrix was formed in an intercalation structure.

Cercis siliquastrum is compatible to soil types and has resistance to climate changes. Therefore the study of its germination and growth condition can lead us to correct use for semi-arid lands in Iran. In this research the effect of different treatment on Cercis siliquastrum germination and growth indices was investigated and the most effective treatment was distinguished. Thus, five frequencies and five treatments as control (full light), shadow (50% light), seed size, cultivation depth and sulfuric acid (level 0-5) was done on this species in water, soil and plant laboratory of agricultural science and natural resources university of Sari. Data was analyzed as factorial test and random method by analysis of variance and mean comparison in SPSS 16 and MSTATC Softwares. The independent and reciprocal effect of the parameters was obtained too. The result showed that the independent effect of light and the reciprocal effect of depth and acid were effect on collar width. But, resultant of all parameters such as light, depth, seed size and acid were effect on vegetative characteristics as leaf number and plant height.

Fracture of mixed mode I/II in beech wood and its wood polymers has been investigated experimentally in this study. Hence, two crack systems of TL and RL were selected in which the crack planes extend along the wood fibers. This investigation has demonstrated that onset of mixed mode cracking can be predicted with a very simple fracture criterion in these crack systems. Results indicated that fracture critical loading is affected by furfurylation and also load-displacement curves of specimens were changed. Variations in fracture toughness values of mixed mode I/II can be occurred following variations of fracture critical forces. In the both crack systems, KIC/KIIC distribution trend is changed by furfurylation that indicates changing of material nature by furfurylation. Results of scanning electron microscopy (SEM) analyses indicated that micro cracks occurrence in wood polymer structure may be one of the factors caused to change in fracture toughness, these changes occur simultaneously with material nature modification followed by increasing of shear strength parallel to the grain due to polymerization.

In this study, the main papermaking characteristics of soybean straw (Glycine max) as an agricultural residue were investigated. The fiber biometry and chemical composition of soybean straw were determined. The properties of pulps from Soda, Soda-AQ and Monoethanolamine (MEA) processes were compared. The average fiber length, fiber diameter, lumen diameter, and cell wall thickness were found to be 1 mm, 26.4 mm, 15.67 mm, and 5.3 mm, respectively. Cellulose, lignin, acetone-soluble extractives and ash content were determined as 41, 19, 4.9, and 3.1%, respectively. Soda, Soda-AQ and MEA pulping under optimum conditions resulted in screened yields of 40.5, 35.5 and 49.5 % respectively. Kappa numbers of corresponded pulps were found out 30, 20 and 20 respectively. The selected pulps were refined up to 300 CSF and mechanical and optical properties of the pulps were evaluated. Maximum burst index (2.65 kpam2/g) and tensile index (54.94 Nm/g) were obtained by soda process. Soda-AQ pulp presents the highest opacity (97%) and MEA pulp shows the maximum tear index (6.52mN.m2/g) and highest brightness (30 % ISO).

Optimization of the isolation methods and utilization of the sugars present in the hydrolysates obtained from pre-hydrolyses of various lignocellulosic materials for production of new chemicals and energy is currently accounted for novel methods of biorefinery all over the world. In this study, effect of temperature (90 and 100oC), KOH concentration (2, 4 and 6 %) and Polyoxyethylene (80) sorbitan monooleate (Tween 80) (0.3 and 0.5 %) was investigated in alkaline pre-extraction of wheat straw on its extracted compounds. To hydrolyze the oligomers in the extracted liquor into monomeric sugars, a vial containing 1 mL of the extracted liquor and 20 ml 4% sulfuric acid was kept in an autoclave at 121oC for one hour. Results indicated that both weight loss of wheat straw chips and dissolved solids content in the extracted liquor increased by increasing temperature and KOH concentration, meaning that sugars removal from wheat straw and total sugars in hydrolysate increased by increasing temperature and KOH concentration. Also, the sugars removal from wheat straw chips increased by addition of Tween 80, in a manner that in equal concentration of KOH, addition of Tween 80 led to an increase in total sugars content. It is therefore concluded that addition of Tween 80 can improve yield of sugars derived from hemicelluloses extraction without increasing alkali concentration, whereby environmental pollution may decline.

One of the indicators of management and sustainability control of forest resources is the definition deforestation and degradation types. These factors hazard quantitative and qualitative of the Iranian forests. In this study with integrated approach, different forms of forest degradation identified in the forest areas with a reviews of library resources and then investigation the degree of status and priority of them in six sites of forest areas which included of Caspian, Arasbaran, Zagros, Irano-Turanian, Khaleej-Omani and Mangrove forests with expert analysis method by professors of Natural Resources Faculty, University of Tehran. Data Processing was performed using SPSS software and Friedman test. According to the survey, habitat degradation, generation decrease, forest grass cover, area reduction, soil fertility reduction, forest typology changing, trees quality reduction, stand volume reduction, structure form deformation, fire, pollution, density reduction, reduction of forest canopy, forest dieback, removal of the forest species, forest species changing, forest stratification reduction and height reduction of the stand, in order of priority, are include first to eighteen of degradation forms in forest sites. The main forms of degradation in the Caspian site is stand volume reduction, in Arasbaran site is habitat degradation, in Irano-Turanian site is soil fertility reduction, and in the Zagros and Khaleej-Omani sites are changing of structure form and in mangrove site is pollution. These results can be effective in orientation planning and protective management of forest sites for codification of control strategies and inhibiting degradation.

Knowledge of the stand condition and the gradual replacement of tree species in different development stages and phases provide appropriate information related to the close to nature treatments. Stem exclusion phase is one of the important development phases in the forest stands development. The aim of study was to analyze the characteristics of dead trees in the stem exclusion phase in the less disturbed forests of Kheyrood, northern Iran. Three sample plots were laid out in this stem exclusion phase and some properties such as diameter, height of all standing and dead trees, as well as the decay stage of dead trees were recorded. Results showed the maximum amount of mortality was observed in the 10 cm diameter class (N = 125). The proportion of snags was 39% while 61% of dead trees were recorded as log. The average volumes of standing and fallen dead trees were 31 and 69 percent, respectively. Oriental beech as dominant tree species made up 47.2 % of decaying trees following by hornbeam (36.1%) has a significant contribution in dead wood pool in this phase. Results of comparing trees mortality showed form, size, and decay class of dead trees were significantly different and the most of the dead trees was observed in the early decay stage, in small diameter class, and in form of snag. Determining of the mortality rate and the quality and quantity of dead trees in this phase of the forest stands development can be applied as guidance in forest tending interventions.

The determination of effective indicators in order to decide on the location of industrial units with the aim of optimizing the use of raw material, reduce costs and waste and marketing of products is very important. Determining the effective indicators in optimal choice for seating block board unites (with use the back of scrap plywood, twigs little low diameter wood’s) in country was target of this study. There for, after the initial studies and field surveys and interview with pundits and experts related 5 major groups (materials and products, infrastructure and environmental needs, technical construction, management policies, social and cultural infrastructure and rules and provisions) and 32 sub indicators were identified. Ever different methods for determining the effective indexes has been listed that one of these methods is the hierarchical analysis. In this method question nares was prepared and completed by qualified personal and experts. The results of these questionnaires were analyzed by Expert Choice software and the most important indicators respectively including ensure a sustainable supply of raw materials (0.201), waste of timber cutting mills, plywood and veneer (0.133) the purchase cost of raw materials (0.115), the distance of the raw material (0.058), Status of competitors in the region (0.051) and the cost of raw material shipping (0.043), were determined.

The course of consecutive experiments in this report aimed to a research or introductory identification about mechanical and acoustical properties of maple (Acer velutinum) wood. Studied factors were included quality factor (due to internal friction), acoustic coefficient, acoustical conversion efficiency as well as the modulus of elasticity (Young’s modulus) which they were all accomplished using contactless magnetic forced vibration of both ends free bar non-destructive method. The research specimens were extracted by solvent washings to reduce their extractive contents. Then their related vibrational properties were evaluated consecutively before and after each steps of successive extraction. Comparing to the previous literatures, results here showed that wood from maple is potentially utilizable in backs and ribs of Violin, Tar and wood-wind instruments. Reducing the extractive contents didn't affect the moduli of elasticity but was positive for the quality factor, acoustic coefficient and acoustical converting efficiency to improve their future acoustical performance i.e. musical instrument industry.

Aim of this research was evaluating and comparing of density (number of individuals of tree), basal area and volume characteristics for estimation of tree species diversity in degraded forests. In order to, 73 hectares of Kouhmian forests was inventory based on random systematic pattern with circular plots (100m2 and 26 plots). In each plot species, DBH and number of tree were measured and recorded. To estimate of tree species diversity was used from Simpson, Hill’s N2, Shannon-Wiener and Mc Arthur’s N1 indices and for calculation of evenness and species richness were used from Wilson- Smith’s and Margalef indices respectively. Also species importance value (SIV) was calculated. The results showed that forest structure is irregular and uneven structure. Also the results showed that in calculation of diversity and evenness indices, if density is selected as calculation criteria, amount of these indices is more than to volume and basal area that are selected as calculation criteria. The results of SIV showed that the highest value of SIV belonged to Carpinus betulus (212.52%) and the lowest value belonged to Zelkova carpinifolia (6.82%). Also Margalef index showed that amount of richness is equal to 1.13.