فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال بیست و دوم شماره 1 (بهار 1394)

Forest fires in the Iran and particularly in the northern forests had destructive effects on the physiognomy of these forests. Recognition، prevention and controlling the Scio-economic destroys caused by natural hazard is one of the main objectives of applied and educational organizations. One of the methods for prevention on forest fires is mapping the probability risk zones. In this study، map of fire probability risk for Golestan national park was prepared using regression logistic method and GIS. The effective factors on fires including climate، topography، vegetation and human factors were prepared in the GIS environment by different methods and sources. The occurred forest fires map was gathered and generated as a Boolean map. The logistic regression modelling was done using effective factors as independent variables and the occurred forest fire map as dependent variable. The obtained PseudoR²= 0. 3121 and ROC = 0. 9132 from model indicate that regression logistic could modeled forest fire probabilities on the study area. The probability fire map was classified to four low، medium، high and sever dangerous classes. The obtained forest fire probability map was assessed using the some unused occurred fire points. The assessment results showed that more of occurred forest fire points were in the medium and high dangerous classes.

In this study the results showed that aspen has less fiber length than horn beam and beech، fiber diameter and cell pit is more and cell wall thickness is less. Furthermore، the diameter of the imported birch fibers is of the most amount in the comparison of two types of beech and horen beam. The chemical component of aspen and birch wood flour consists of the least Klason lignin and the most holocellulose. The handsheet properties of CMP pulp of birch and aspen showed that the bursting strength and breaking length which is more than beech and horn beam.

Drought stress is the main factor affecting on plant growth in dry and sub-dry regions and had the most importance than other abiotic stresses at seedling establishment. So، today''s، the great amounts of biological researches are about drought stresses. In this study، the effect of drought stresses (100، 75، 50 and 25% field capacity) on seedling survival، growth (height، basal diameter، leaf area، root length، root volume and root length/ height) and physiological activities (photosynthesis، transpiration، stomatal conduction، leaf surface temperature and gas exchange) of P. atlantica seedlings were investigated in greenhouse condition. The results showed that drought stress had significant effects on morphological and physiological characteristics of Pistacia atlantica seedlings. So that، drought decreased survival، height growth، basal diameter، leaf surface، photosynthesis، transpiration، stomatal conduction and gas exchange of P. atlantica seedlings. Drought stress hadn’t significant effects on root length، root/height and leaf surface temperature of seedlings.

Rice straw in the countries without adequate woody lignocellulosic materials can be used as one of the suitable raw materials for the production of chemical pulp. But silica present in the straw causes limitations for its use in this industry and adversely affects sections such as: the raw material preparation، digester، chemical recovery system، recausticizing and paper machine as well as recovery of sodium and energy. In this study، effect of different pulping process such as soda، soda-AQ and formic acid on the desilication of rice straw black liquor at three kappa number 15، 25 and 35 has been studied. The results have shown that in soda pulping process with increasing of chemical charge and consequently kappa number decreasing from 35 to 15 led to reduction of silica deposition in the pulp from 17. 3 to 7. 4 percent while silica content in black liquor increased from 1. 34 to 11. 2 percent. The amount of silica in soda-AQ black liquor pulping was lower in comparison with soda pulping process in about 115%. The results in formic acid pulping were significantly different from mentioned conventional pulping and it indicated that silica content of pulp is increased with decreasing of kappa number from 35 to 15. So that pulp silica content at kappa number 15 was 18%. Therefore in the case of using soda-AQ and formic acid pulping of rice straw not only significant reduction of silica in the black liquor may be obtained but also production of chemical pulp without any environmental problems can more be economical.

The objective of this study was to investigate the influence of coupling agent and the content of lignocellulosic material on tensile strength and physical properties of wood/plastic composite produced from recycled polypropylene using mat forming procedure. Recycled polypropylene and three levels of Eucalyptus camaldulensis sp. wood powder (60، 65 and 70%) and 5% of MAPP were used. The results of tensile strength and physical properties were statistically analyzed using factorial experimental design. The results indicated that the tensile strength and modulus of composites containing MAPP were statistically higher than those without MAPP. These properties were increased as the content of wood powder is reduced. The interaction effect of wood powder and MAPP on tensile strength was statistically significant and composites produced using 60% wood powder and 5% MAPP were the highest. The results of composite water absorption after 2 and 24 hours soaking in water revealed that these characteristics were lower when MAPP is used or the content of wood powder is reduced. Thickness swelling and water absorption after 2 hours in boiling water showed that properties are lower when 60% wood powder or MAPP is used.

In this paper، impacts of 3 various lignocellulosic materials (as filler) and their mixture ratios with high density polyethylene (HDPE) on the physical and mechanical properties of WPC have been investigated and compared. MDF dust، soya stalk flour and poplar flour particles، with mixture ratios of 40، 50 and 60% (by weight) and HDPE were mixed using corotating twin-screw extruder. Maleic anhydrate polyethylene (MAPE) was used as coupling agent with mixture ration of 3%. Testing samples comprising، fractural، tensile and impact samples، were prepared by injection molding، and then were tested with regard to the ASTM standards. Results showed that the increment of filler percentage in 40، 50 and 60 wt. % order could improve tensile and flexural strength، water uptake and thickness swelling، significantly while impact absorbing energy was on the wane. It was found that the samples made from MDF dust، had superior physical and mechanical properties comparing two other fillers. Meanwhile، composites made with soya stalk flour showed the weak physical and mechanical properties.

Most tree characteristics such as annual growth ring are influenced by climatic changes. Dendroclimatology، a branch of Dendrochronology science، studies the effects of climate parameters such as temperature and precipitation on the characteristics of annual growth ring. To carry out this research، 30 Quercus persica coppice trees were selected in Oak forest in Khorramabad، Lorestan، Iran. We supply trees samples with disk format. Tree ring samples were taken to the laboratory and were prepared there by the handle cutter. Annual growth rings were measured by BINOCOLAR and LINTAB measurement table and TSAP software. Cross dating was performed among samples by TSAP software. Seven tree samples were deleted due to unsuitable Cross dating. Chronology of the site was prepared by ARSTAN. Temperature and precipitation data were collected from climatology station and their effects on annual growth ring were examined. The results indicated that precipitation and temperature had positive and negative effects on trees growth، respectively because of the arid and semi arid climate. Most positive and significant effect of precipitation was recognized in October and May but that of temperature was determined in September، October، November، December، July and August.

Using modern machinery for logging transfer considerable pressure to soil which causes changes and damages to soil structure. This inturn has long- term effect on micromorphological properties including size and type of soil poresis. This research was conducted to examine the recovery of compacted soil during twenty years period. The treatments included three time period (1، 10 and 20 years)، two slope classes (>20% and 20% and high traffic intensity.

Pressure sensitive adhesives are the most problematic kinds of sticky materials during paper recycling process. In this research talc as a useful additive in the paper making process with aim of physical control of pressure sensitive adhesives was used. The results showed that treatment of OCC pulp containing pressure sensitive adhesives caused reduction in both macro and micro stickies. Also addition of talc up to 1. 5 % reduced drained water turbidity. As result of talc addition to the OCC pulp screen accepted pulp and ash content raised significantly but the final paper tensile، burst and tear strengths decreased remarkably.

Salt cedar (Tamarix aphylla L. or Tamarix articulata Vahl.) is a rapid growth and salt tolerance species which has been considered as suitable tree for wood production in arid and semi-arid lands of southern Iran in addition to its common usages in desertification and sand fixation programs. In order to study the possibility of development of this tree in saline-alkaline soils of Iran central desert boundaries، this research was carried out on 6 different population of salt cedar from Sistan va Balouchestan (Khash and Zahak townships)، Yazd (Yazd township)، Qom (Qom township)، Isfahan (Kashan township) and Semnan (Garmsar township) provinces at Garmsar research station of desert in CRBD experimental design. Inventory of seedlings was carried out at beginning and end of 2012 and consisted of sprouting، Survival، number of sprouts، collar diameter of thickest sprout، height and crown vitality parameters. Results showed that in contrast with partial advantages of Garmsar and Qom population، there was no significant difference between populations and all of them showed moderate performance. Considering seedlings growth and survival we can conclude that plantation of this tree as suitable species for wood production in saline-alkaline soils of Iran central desert boundaries is possible and in this framework native populations in this region have more priority.

Fagus orientalis Lipsky - is one of the main Hyrcanian tree elements that - distributed throughout Hyrcanian forests from Astara to Ziarat vally in Gorgan. Knowing the specific characteristics of leaf stomata in these populations، in addition to its systemic value، assists to further identify their adoption to the specific ecological conditions. The seedlings of four populations in throughout the north including two elevations were transferred to the greenhouse and grown under the same environmental conditions. The stomata characteristics were studied on sampling from leaf attached to the seedling including total، close and open stomata densities in square millimeter، stomata dimensions and area، length and wide of guard cells in thousandth of micron and stomata type. The most effective traits were determinate by Factor analysis. In this method، the factors extraction was done using principal component analysis that had most variances. The Pearson correlation between the scores of the extracted factors and climate variables and altitude was used to determine the relationship between environmental factors and the traits. The results showed that the type of stomata was anomocytic and the most of traits had significant differences among the populations so that stomata density was increased from west to east، but the area of the aperture reduced. The significant correlation between stomata characteristics and the factors such as temperature، precipitation and elevation were observed. Generally، the discriminant function analysis indicated that there were differences between Kheyrood in high and down elevation and also Shastkolateh and Shafaroud populations.

The purpose of this study was to investigate and analyze quantitative and qualitative amount of dead wood in a natural untouched Fagus oreientalis forest of permanent research plot of Shast klateh by 16 ha. For this purpose all the standing and fallen dead woods، based on species and the degree of decay، with a diameter higher than 7. 5 cm، were measured. The results of this study showed that the mean diameter at breast height، soil، the number and volume of standing live trees per acre in that certain Forest stand were 39. 5 cm، 33. 2 m، 287 m and 472 of the base respectively. While the mean diameter، number and volume per acre of total dead wood were 49. 5 cm، 27. 7 dead woods and 45. 4m3. ha، respectively. Hornbeam with 58. 2% was of the maximum N/ha dead wood (standing and fallen)، while beech with 61. 2 was of the highest volume having dead wood. The results also showed that less than 30 cm diameter class with 16. 9N. ha allocated highest contribution and diameter class (70-55 cm) with a 2. 75 allocated minimum number of dead wood. In the case of volume per hectare dead wood، diameter classes greater than 75 and less than 30cm، with 32. 5 and 1. 8 have comprised maximum and minimum V. ha، respectively. 61. 5% of the total N/ha of dead woods included fallen dead wood and 28. 5% was standing dead wood. Fallen dead wood with 35. 7m3. ha (about 78. 7%) of the total amount of dead wood allocated to itself. The overall results of the study showed that dead wood allocated about 9 percent of the number and volume per hectare of live and standing stand.