فصلنامه جنگل و فرآورده های چوب
سال شصت و چهارم شماره 4 (زمستان 1390)

In this investigation، paper strengths from feed stock، refined and unrefined stocks were studied after OCC pulp fractionation and handsheet production. For this purpose، OCC pulp was fractionated by pressure screens into long and short fiber fraction. Then، feed stock and long fiber fraction were separately refined using a laboratory refiner. To produce a «recombined stock»، the long fiber pulp fraction and short fiber pulp fraction were mixed with each other. Consequently، strength properties of the recombined stock were measured and compared with those of unrefined and refined feed stocks and also with other fractions of pulp. Results indicated that overall strength properties of refined feed stock papers were higher as compared with the recombined stock paper. Also we observed that Tear index of the long fiber fraction، was higher than other pulp fractions. Tensile، Burst and SCT indexes of refined long fiber fraction were higher rather than other fractions. In addition Tensile، RCT and Scott bond indexes of refined feed stock were higher than other pulp fractions. Generally، results showed that، fractionation and recombination process is not a suitable and useful method for OCC pulp and paper strength improvement but OCC pulp refining is a better method to increase OCC pulp and paper strengths.

In this research، the effect of cationized CMP fines on newsprint pulp properties was investigated. The fines were first separated using a Dynamic Drainage Jar (DDJ) apparatus and then the cationic groups were established and firmly fixed on fines by chemical reactions and grafting with copolymerization mechanism so that the surface electrical charge of fines was changed to cationic. The cationized CMP fines were added alone and also together with polymeric retention aid، the cationic poly acryl amid، in newsprint furnish at three levels of consumption (low، medium and high) and the pulp properties including drainability (freeness)، first pass retention and also zeta potential and filtrate cationic demand variations were measured and compared with the control sample (pulp with only cationic poly acryl amid which is the main retention aid polymer in Mazandran Wood and Paper Industries Company). The results showed that although the cat ionized CMP fines by themselves could not have good effects on newsprint pulp quality، by cooperation with cationic poly acryl amid، the pulp quality and also retention aid polymer efficiency were increased. Indeed، the cationized CMP fines have a synergic effect on retention aid polymer efficiency. Therefore، the use of cationized CMP fines with cationic poly acryl amid can be recommended for increasing pulp drainability and first pass retention.

Withdrawals resistances of screws driven into commercial wood plastic composite (WPC) panels in both face and edge directions have been measured and the results have been compared with those of conventional medium density fiberboard (MDF) and particleboard. Three types of screws namely; sheet metal screw (gauge # 4، 8، 10، 14)، wood screw (gauge #8) and drywall screw (gauge #8) were used. The results have indicated that withdrawal resistances of screws in WPC panels in both directions increase as screw diameter. Similar increases were observed when pilot holes diameter were increased close to the root diameter of the screws. Beyond this limit، increasing the pilot hole diameter up to the nominal diameter of the screws، significantly reduced withdrawal resistance. No significant differences were observed between different types of screw. Face and edge withdrawal resistances of screws in WPC panels were higher as compared with those of MDF and particleboard panels.

Populus caspica Bornm. is an endemic tree species growing in Hyrcanian forests of Iran. It grows on alluvial soils، appears as individual and groups and regenerates naturally، particularly by root sprouting. Despite the importance of this species in forest restoration، its seedling propagation is some to extent difficult. In February 2008 cuttings of P. caspica originated from 1-year branches of a mature tree were planted as Randomized Complete Blocks Design (RCBD) in four replications in a nursery in Koloudeh of Amol، north of Iran. Treatments were 1) soil bed consisting of loamy، loamy-sand and sandy-loam، and 2) cutting buds consisting of 2-bud cutting and 3-bud cutting. At the end of the first growing season، loamy soil with 70% and 3-bud cuttings with 80% had the maximum germination rates. Survival was 38%، 33% and 28% in loamy، loamy-sand and sandy-loam soils، and 40% and 24/6%، in 3-bud cuttings and 2-bud cuttings، respectively. The greatest plant fresh mass was belong to loamy soil (165 gr) and 3-bud cutting (140 gr). The biggest rooting and total fresh mass as well as height growth and collar diameter growth were found in 3-bud cutting grown on loamy soil. It can be concluded that growing “3-bud cuttings on loamy soil” is the most favorable treatment for propagation/seedling production of P. caspica in this nursery.

Remote sensing systems، especially hyperspectral remote sensing require fundamental knowledge of spectral reflectance of desired tree species for recognizing tree species and mapping forest type. Field spectrometry as a field of remote sensing، dealing with determination of these spectral characteristics tries to provide the spectral libraries for different objects. The objectives of this study were 1) investigating the relationship between spectral reflectance and nitrogen content and 2) investigate the species spectral separability of alder، oak and ironwood leaves based on nitrogen varying in species and to define the best wavelength for this aim، the partial least square (PLS) analysis was used. In this study the spectral fingerprint of the most important forest tree species of the northern forest of Iran namely Alder (Alnus subcordata)، Oak (Quercus castaneifolia) and Ironwood (Parrotia persica)، were acquired. This has been carried out using a full range spectrometer during the summer 2007. A total of 330 leaf ‘pile’ spectral curves of illuminated and shaded leaves were acquired of 55 trees in altitude range between 250 and 2200 m (asl.) under a clear and cloudless sky. Following the measurements، nitrogen of the mentioned leaves was extracted in laboratory. The value of vegetation indices of illuminated leaves was more than shaded ones and the differences were significant in all species. This result has been proved by statistical results obtained by nitrogen data in lab. Based on the Partial Least Square (PLS) results it proved that nitrogen variable has the ability to discriminate species. These results showed that there was the most distinct separation between Ironwood and both Alder and Oak. There were less distinct separation between Alder and Oak. Based on the result obtained by PLS regression we could conclude that the best wavelength region for spectral separability of species is in red edge region.

In this study، the influence of two types of impact modifier on impact strength of recycled polypropylene (PP) - wood flour composites was evaluated. For this purpose، a virgin PP was thermo-mechanically degraded by five extrusion cycles under controlled conditions in a twin-screw extruder at the rotor speed of 100 rpm and temperature of 190°C. The PP (virgin and recycled polypropylene after 2nd and 5th cycles) and wood flour were compounded at 50% (w/w) wood flour loading in a counter-rotating twin-screw extruder in the presence of different impact modifiers to produce wood flour-PP composites. Ethylene vinyl acetate (EVA) and ethylene-propylene-diene monomer (EPDM) were used as impact modifiers. The results showed that composites containing recycled PP exhibited significantly lower impact strengths. Both impact modifiers increased the impact strength of the PP/WF composites but the addition of EVA resulted in the greatest improvements in impact strength. The composites containing virgin PP exhibited higher impact strengths than those containing recycled PP and EVA.

In this study the effects of three non-ionic commercial surfactants namely PEG-1000، KELA-2 and KECA-20 as digester additives at four levels of 1، 2، 3 and 4% on the CMP pulping of poplar، oxidative bleaching of the resulted pulp and its hand-sheet paper properties were investigated. The resulted pulps from the application of each surfactant with the highest screen yields and lowest rejects as well as control CMP pulps (without surfactant) were selected and bleached in two stages with H2O2. The pulping and bleaching results showed that the application of all surfactants increased accepted yield، consumption of bleaching agents and brightness of pulp whereas they lowered the opacity and yellowness of pulps compared to the control pulp. The best result was obtained with PEG-1000 (4%) which increased accepted yield by 1. 2%، brightness by 2% while decreased screen reject by 1%. KELA-2 (2%) increased accepted yield، and brightness by 0. 68% and 1. 9%، respectively. KECA-20 (1%) increased accepted yield and brightness by 1. 14% and 0. 5% respectively but decreased screen reject by 0. 87%. In addition، the prepared hand-sheet papers had higher physical and mechanical properties compared with the control.

In Iran, most of experienced foresters are aware of the many factors that influence timber sale prices on roadside. However, there are not quantitative estimates of these factors. In this research, implicit prices of timber lot characteristics were analyzed in Azarroud forestry plan, Shirgah, Iran. To estimate implicit prices, 410 timber sale lots of Azarroud forestry plan in the period 1992 to 2008 were evaluated and incorporated into a dataset. Hedonic Pricing Method (HPM), pooled data multivariable regression analysis of the Eviews 5 software were then used to estimate a model relating transaction price of timber lots to their characteristics. The model explained approximately 86% of the variation in the total sale price using characteristics of timber sale lots and the standard error was around 22875 Rial per m3 (2$ /m3) with average real price of 1027603 Rial per m3 (91$/m3)of lot. Then, the classical hypothesis of pooled least square estimator e.g. residuals normality test were evaluated. ‏The result showed that the pooled least square estimator was usefully applied. As well, the impact of lots characteristics on their sale prices including sale volume per hectare, average diameter of logs in lot, volume ratio of higher price species of group 1 (alder, maple, beech etc.) in lot, number of auction bidders, volume ratio of logs in lots, transport distance to first main road, species homogeneity index (Herfindahl) and side slope were found to be significant (p=1%). Sale volume per hectare and transport distance to main forest roads had the highest positive and negative effects on timber sale lot, respectively.

This research was conducteded to assess sunlight effects on survival of the Persian Oak (Quercus brantii) saplings، based on randomized complete block method in the form of split plots، during a 3 years period with 3 replications. Tow 2 factors and 8 treatments were considered in the design. The first factor was aspect that divided in 2 levels (N and S). The second factor was distance of saplings from seed trees that divided in 4 levels، which were near، intermediate، far and control plots. Afterwards، average survival of oak saplings was compared in 3 classes of relative light and then correlation between relative light intensity and percent survival was investigated in the whole plots. The results showed that the mean survival was 20. 9% in the northern aspect، 22% in the southern aspect and 21. 4% in the total plots. The maximum and minimum saplings survival were 77. 8% (one of the plots near the seed tree) and 0% (one of the control plots) respectively. The maximum، minimum and average relative light in sub-sub plots and in control plots were 95%، 1% and 58. 5% respectively. Also، the results of statistical analysis showed that the differences of saplings survival for both treatments of aspect factor were not significant. Except the correlation between Level 3 of second factor (the most distance of saplings from seed trees) and control treatment، the correlation between other levels of distance factor، were significant at 1% level. In this context، function of survival was better on the close plots from the seed tree than middle plots and also on middle plots than far plots. There was a negative linear relation between relative light intensity and survival of saplings (R2=69%). So we can conclude that survival of oak saplings is decreased with increasing distance from tree crown (Thereby increasing light intensity). Also، planting saplings are recommended only in plots close and middle distance to the seed trees.

The logging industry has a high rate of both fatal and non-fatal injuries in comparison to other industries. This paper deals with logging-related injuries in west forest of Guilan province. The data that had been collected by safety office of Shafaroud Company for the entire forestry sector were used. Accident and employment data were analyzed to examine patterns، frequency and severity rates of logging injuries in west forest of Guilan province from 1985 through 2009. The average annual frequency and severity rate of accidents were 17 and 0. 13 over the 24 years study period. Felling operation and chainsaw were the main dangerous job and equipment in forest logging. The majority of logging injuries occurred to workers with 10-20 years of employment (those who have 30-40 years old). Forest logging accidents were more likely to occur in the late morning and early afternoon. The results of study are helpful for diagnosing the root-cause of forest logging worker accident and help in developing preventive safety programs. This research showed that decrease in the number of work related accidents in forests is only possible with an integral approach to suitable training and use of appropriate organizational and technological solutions. On the job training by foreman and put out work out equipment and machinery can be solution.