فصلنامه جنگل و فرآورده های چوب
سال شصت و پنجم شماره 1 (بهار 1391)

In this study, Derivatization Followed by Reductive Cleavage (DFRC) method is used to investigate the structures of milled wood and dioxane lignin of Populus nigra. After carrying out DFRC reactions, the structures of constituents resulted from these two kinds of lignin were investigated by using several spectral methods such as NMR, GC-MASS and GPC. The results obtained from chromatography and spectroscopy studies of these methods have been compared. These comparative results show that the dominant structural components of these two kinds of lignin are obtained from cleavage of β-O-4 bonds. The main components obtained from dioxane lignin and milled wood lignin are 4-hydroxy-3,5-dimethoxy-1-phenyl propene and 4-hydroxy-3,5-dimethoxy-1-phenyl-γ-hydroxy propene (syringyl structures), respectively. Also, there are some guaiacyl structures in these components.

Forest road networks are essential structures to achieve the forestry aims, but these structures include most implemental and environmental costs. To minimize these costs, the effective factors have to be considered in forest road design which landslide susceptibility is one of the major factors. Road construction on susceptible terrain increase road maintenance cost and environmental impacts. Landslide hazard zonation is a method that can be applied to recognize and avoid the unstable terrain. In this research, the landslide hazard zonation map of Baharbon district in Kheyroud Research Forest was developed using a combined model, AHP and Density Area methods. First, Landslides distribution map of study area was prepared in ArcGIS using field observations and then the map of effective factors in landslide occurrence were prepared. To determine the weight of effective factors AHP was used. Afterward a bivariate statistical model, Density Area, was used for calculating the weight of classes of effective factors maps. By combining the effective factors maps and classifying the combined map with regard to breakpoints of frequency curve, the landslide hazard zonation map was developed. According to the results, 14.7%, 26.9%, 38.9%, 15% and 4.5% of the district were classified as very low, low, moderate, high and very high hazard, respectively. Finally due to lack of landslide occurrence in slope class of 0-15%, as well as it is suitable slope for road design, this class was suggested as positive control points. The other slope classes that were in low and very low hazard were defined as second priority for road design. Road building in high and very high hazard is possible, if increasing the number of culverts, also biological and mechanical reinforcements of cut and fill slopes.

Conservation and development of Zagros oak forests requires collecting appropriate seeds for reforestation and afforestation plans. For this purpose, seeds of 60 trees of Quercus brantii, infectoria and libani (20 trees from each species) were collected from forests of Baneh, western Iran. After picking up 5 trees with distinct seed weight, the correlation between seed morphological characteristics and its growing traits like seed germination parameters and primary growth of seedling was investigated. The results showed that Quercus libani had larger seeds and seedlings compare to other species, but no significant differences in germination rate were observed between these three species. Also Quercus infectoria showed highest average time of germination. Regardless of species, primary growth of seedlings was affected by different seed morphological characteristics. So that, wider, more circular, bigger and heavier seeds produced larger seedlings. This correlation was higher in Quercus brantii and lower in Q. infectoria. But, there was no significant correlation between seed morphology and germination parameters in three oak species.

This research was conducted to investigate the effect of acetylation on bioresistance of particleboard produced from acetylated wood chips of Fagus orientalis exposed to white (Trametes versicolor (and brown (Coniophora puteana) rot fungi. After 12 hours of soaking in acetic anhydride, in order to achieve three levels of weight gain,namely 5, 9 and 16%, acetylated particles were heated in an oven at 120 ˚C for 30, 90 and 240 minutes, respectively. Acetylated and nonacetylated (control) boards were produced with 10% melamine urea formaldehyde (based on the oven-dry weight of particles) and pressed. These boards were tested for decay resistance according to EN113 standard method. Results showed that by increasing the level of acetylation, bioresistance of boards increased for both white and brown rots. However, this effect was more obvious for white rot. In fact, by increasing the level of acetylation from zero to 16%, the weight loss of white brown rotted samples reduced from 21.8% to 0.97% and from 36.3% to 1.78% and for brown rotted samples declined from 32.6% to 11.3% and from 42.9% to 12.8% after 12 and 16 weeks, respectively.

In this research, the effects of different chemical reagents on physical and mechanical properties of wood flour-polypropylene composites were investigated. For this purpose, wood flour and polypropylene were compounded (at 50% fiber loading) in a counter-rotating twin-screw extruder in the presence or absence of MAPP to produce the composites. The nominal cross section of the manufactured composites was 70*10 mm2. The specimens were immersed in NaOH (10%), HCl (10 %) and NaClO (2 %). After one week of immersion, the specimens were oven- dried and changes of oven-dried weight and mechanical properties (flexural modulus, flexural strength and un-notched impact strength) were determined. The mechanical properties of the composites immersed in chemical solutions were compared with the non-immersed composites (as control). From the results, the composites immersed in NaOH exhibited higher oven dried weight whereas those immersed in HCl and NaClO exhibited lower oven dried weights. All chemical reagents significantly reduced the mechanical properties of the composites. The addition of 2% MAPP could not considerably reduce the effect of chemical reagents on mechanical properties of studied formulations.

Having accurate information regarding to performance of skidding operations is essential to improve the economic status of a project for forest managers and contractors. The current study assessed the performance of farm tractor and mule logging systems to determine optimum combination of them. For this purpose continuous time study was used. The production model was developed using multiple regression model. Independent effective variables on farm tractor productivity were identified as skid trail slope and skidding distance and for animal system productivity the effect of skidding distance and interaction of distance and slope were significant. Productivity rate of farm tractor and animal skidding were 8.40 and 1.27 m3/hr, respectively. Costs of farm tractor and mule system were estimated 15,957 and 78,434 Rials per cubic meter, respectively. The results indicated that to reach best combination of two systems, timber must be transported as far as possible on skid trails by tractor, in this case total skidding cost will be reduced by 35%. Animal skidding system still must be limited in area where there is impossible to construct skid trail.

Rainfall interception loss (I) is an important component of water balance in arid and semi-arid climate zones. The goal of this project was to quantify interception of different seasons and to determine the role of rainfall size in controlling interception in a mature semi-arid Pinus eldarica Medw. afforestation in Chitgar Forest Park near Tehran, Iran, where mean annual precipitation, and air temperature are 267.6 mm and 17.2˚C, respectively. The gross rainfall (GR) was measured based on average records of six manual collectors installed in an open area adjacent to the stand and throughfall (TF) was collected by means of forty five manual collectors, similar to GR collectors, placed randomly beneath the canopy. Interception was calculated as the difference between GR and TF. Measurements were recorded based on rainfall events from September, 2009 to May, 2010. For the study period with 30 recorded rainfall events, GR and rainfall interception loss (I) totaled 164.8 and 61.2 mm respectively. The ratio of I:GR had a range of 19.5% to 100%, with 61.4% as the average value. During this period, the cumulative GR depths of 11, 10, and 9 rainfall events in autumn, winter, and spring were 43.6 mm (I= 65.8%), 72.6 (I= 55.1%), 48.6 mm (I= 62.9%), respectively. On the event scale, there was a strong logarithmic correlation between I:GR and GR in all seasons. As the size of rainfall events increased, the ratio of I:GR decreased. The results demonstrated that intercepted rainfall represents a considerable portion of GR in P.eldarica afforested regions of the semi-arid climate zone of Iran where soil moisture is a limiting factor in plant growth and productivity.

Seedling grading is one of the main aspects of producing good quality seedling in forest nursery. It is obvious that good quality seedlings would have highly survival and performance in field after out planting. This study was conducted to grade Acer velutinum and Alnus glutinosa seedling in Shanderman and Safrabasteh forest nurseries in Guilan province. For each species, 100 seedlings were selected randomly from seedbed. Collar diameter, height, number of root and leaf area of seedlings were measured. The results indicated that there was significant correlation at 1% level, between collar diameter with number of roots, leaf area and seedling height. Furthermore, it is cleared that the seedling could be graded by collar diameter in four classes. Suitable collar diameter for Alnus glutinosa and Acer velutinum were 6 – 8 mm. and 10 – 14 mm, respectively.

Based on the results of field experiments on poplar clones in Karaj, two fast-growing Clones of Populus euramericana i.e. P.e. vernirubensis & P.e. costanzo were selected for pulping investigation. Three trees from each clone at the age of 12 years were selected and samples were cut at the breast height. Average length, width and thickness of the chips showed no significant difference. Kraft pulping variables including five pulping times (15 to 75 min.) and two chemical charges (18 % AA at 23 % Sulfidity and 20 % AA at 25 % Sulfidity) were applied. The accepted yield, kappa number and rejects measurement of pulps showed that the optimal pulping condition is cooking time 45 min and AA 18% at 23% Sulfidity. The pulps from the two clones showed no significant difference in pulp beatability to target freeness of 400 ml CSF. Bauer McNett fiber classification test showed that P.e. costanzo provides higher fiber length and lower fines content. Statistical comparison of wood production, pulp and handsheet properties of the two clones indicated that P.e. costanzo is superior clone in burst strength index and average fiber length, whereas P.e. vernirubensis is more suitable in terms of growth rate and tear strength index. Significant differences were not observed between clones in other properties.

Many characteristics of the trees including annual ring width are affected by climate variations. This research investigates the effect of temperature and precipitation on tree rings of Quercus infectoria. Twenty two healthy and thick trees were selected from oak forests located in the region near Javanrood in Kermanshah with geographical coordinations of 34° 47' 30"N and 46° 20' 6E". Samples were taken by increment borers. After preparing the sample surfaces, rings width were measured by binocular and LINTAB measurement table and TSAP software. Cross dating was carried out using TSAP software. Data of six trees were excluded because of low cross-dating indexes. ARSTAN software was used to develop the ring-width chronology. Data of temperature and precipitation were collected from the nearest meteorological station and their effect on tree-rings were investigated. The results showed that temperature had a negative effect whereas precipitation had a positive effect on rings width because of warm and dry condition of the region. Rings width was positively and significantly correlated with precipitation in March and May while temperature affected the rings width negatively and significantly in January, February and June. The effect of precipitation on tree growth was more significant than temperature.