Journal of Wood and Forest Science and Technology
Year:2012 | Volume:19 | Issue:2|Papers Count:14

In order to determine the ecological groups in Sisangan Forest Park and study its relationship with soil variables, reserve area of the park (approximately 543.5 hectare) were evaluated. Total 46 systematic-selected sample plots, about 400 m2 (20×20 m) for estimation of tree, shrub and herb vegetations in the field of mixed Bux tree, pure stands and non-Bux were almost equal numbers were selected. TWINSPAN vegetation analysis program was used to classify ecological groups which resulted formational of three above mentioned groups. After site classification, indicator species values were accounted by IV method. Soil acidity, moisture content, electrical conductivity, organic carbon, total nitrogen, available phosphorus and potassium, soil texture and ratio of organic carbon to total nitrogen in each plot at the depth of 0-15 and 15-30 cm were determined. Significant consideration of soil variables within groups, one-way analysis of variance and Duncan’s group mean comparison range were applied; and for gradient analysis of soil factors PCA was used. Sample plots in PCA and DCA showed that each samples of plant groups were stayed closed together and they form the idiosyncratic groups. Statistical analysis showed that soil acidity, available potassium, electrical conductivity, organic carbon, ratio of organic carbon to total nitrogen, moisture content and soil texture are the basic characteristics’ variability in ecological region.

Study of forest structure is one of the basic requirements to achieve the objectives of close to nature silvicultural treatments. The study of forest structure in northern parts of the country is a new and important approach, besides more attention should be paid on the necessity of the structure of local oak forests, due to the harsh environment and its sensitivity. For the purpose of this research, three representative sites were carefully selected after a concise field and map recognition at the Golestan province mountainous forests (Derazno, Shirinabad, and Loveh). At each site, 4 sample plots with one hectare area (100×100 m) were established according to a random systematic design. In addition, at four parts of each sample plot a subplot (15×15 m) were determined for regeneration study. At each main plot, a 20×50 m plot was also established for further study of vertical and horizontal profile. The statistical packages used for all analyses were SPSS-and SVS. Results showed that, Quercus macranthera is the dominant species at site one (Derazno, Kordkoy) and site two (Shirinabad-Aliabad). Maximum crown canopy was 61% of the total (76.5% and 23.5% for Quercus macranthera and other species, respectively). At Derazno site, a more favorable condition compared to the other sites were observed. Stand mean diameter and height were 80 cm and 14.5 m, respectively. Stands diameter distributions showed an uneven-aged shape. The main issue was the fact that the regeneration density was not enough; except for site one at Derazno. The comparison of mean diameter, height, tree standing volume and basal area by using of ANOVA, and F test, suggest a significant difference, at 1% confidebce level for various sites.

Knowledge on succession stage and quantitative and qualitative characteristics of beech (Fagus orientalis, Lipsky) in natural stands of north forest made it possible to apply the best siliviculture management. Through those methods the permanent and stable forest productivity could be continued. This study was done in beech natural stands (Vatana forest project), at 1300 meters altitude. Fifteen samples with 1 ha area were selected. The qualitative and quantitative characteristics and succession stage of all trees in each sample within the plat were measured. The results indicated that mixture species in Vatana forest project is fagues orientalis-carpinus betulus and structure type of these natural stands had uneven age and irregular. The average number of trees were estimated 122 per hectare and basal area was 32.44 m2/ ha. In addition, average coefficient height and coefficient density based on Rinke density coefficient estimated 69.4% and 39%, respectively. Dominate stand height was 34.7 m, its canopy volume 454 (silv/ha) and average trunk height were 11.4 m. Average canopy height and diameter were 15.9 m and 8.6 m, respectively. Qualitative characteristics of stand indicated that 59.2% of trees trunk were free of defects. The results also showed that the most area in this plan phase transformation was destroyed. The initial stage of transformation succession is rarely observed. Optimal stage of development is more rapid than initial succession and most of then observed to be in latter stages.

In this workresearch, the effects of layering technique effect of on the surface quality of particleboards made with with poplar particles on surface quality were as evaluated. In sample preparation, three the variable factors of experiment were consisted of used including difference between type of surface layer particles (poplar and industrial), resin content (8 and 10% percent), and press time (4 and 5 minutes). The property that was studied in this research was surface roughness. In fact, theseis factors demonstrateing situation of smoothness profile in particleboard surface layers and it is very important in many applications. Results showed that poplar particles presence in surface layer of the panels, ledcause to improvement of surface quality, significantly. The effete of press time on surface quality of boards was inversely significant. With increasing press time increasing, the surface roughness was decreased. In other hand, with increasing resin content from 8 to 10% percent in surface layers, all of the properties, especially surface quality were improved. It should be noted that, manufactured boards with 8% percent resin had higher surface quality than values have been provided in the relevant standard, and there was no significant difference between boards made of poplar in surface with 8 and 10% percent resin content. Finally, to obtain high physical and mechanical properties and efficiency, application of poplar particles in the surface layers along with, using of 8% resin content andand 4 minutes for press time was found to have as the best results in terms of physical and mechanical propertiescondition.

In this study, the kinetic of Soda pulping from bast, core and whole stem of kenaf (cultivar 7615) was evaluated. The Klason and acid soluble lignin content based on oven dry weight (O.D.) were found to be 17.2% and 3% for the core fibers, and 8.5% and 3.85% for bast fibers, respectively. For Soda pulping from bast, core and whole stem Cooking conditions was alkaline charge 40 g/L (as NaOH based on O.D. fiber), liquor to wood ratio 20/1, cooking maximum temperature from 140 to 170 oC (based on raw material) and the cooking time from 0 to 1500 min. (based on maximum temperature and raw material). The results indicated that delignification in kenaf bast and core fibers were completed during three phases and activation energy required for delignification in final phase were 85.89 kJ/mol and 94.53 kJ/mol for the bast and core, respectively. Rate constant of delignification in final phase for core in temperatures of 155, 160, and 170oC were 39 ´10-4, 70×10-4 and 93×10-4 (min-1), and for the bast in temperatures of 140, 145, 150, and 155 oC, were 30×10-4, 41×10-4, 53×10-4, and 73×10-4 (min-1), respectively. Temperature of 155oC was chosen for pulping for whole stem because in this temperature, second and third phases are observable in both of the bast and core.

Forest canopy leaching changing based on the different factors, is an effective factor causes to increase nutrition in a short time. We investigated the effect of seasons on the variation of base-cations (Ca2+, Mg2+, Na+and K+) in throughfall and forest floor leaching of the beech species in the mixed Hyrcanian beech forest in Golestan province, Iran. Throughfall and forest floor leaching samples were taken through a year (2008/12/21 to 2009/12/21). Amount of base-cations in throughfall and forest floor leaching (Ca2+, Mg2+, Na+and K+) were compared by One-Way variance analysis in the different seasons. Results showed that the amount of Ca2+, Na+and K+in throughfall were different in seasons significantly except for Mg2+ (p<0.05). Also all base cations were significantly different in forest floor leaching (p<0.05). The most and least cation leaching in throughfall and forestfloor leaching belonged to K+ (112.11 and 65.75 Kg ha-1year-1) and Mg2+ (6.1 and 4.5 kg ha-1 year-1), respectively. Forest canopy leaching increased the nutrition in soil solution especially in summer and fall that soil is dry and competition is intensive. So this process caused the competition between trees and organisms decreased and efficiency product increased finally. So the information of leaching intensity in different seasons is necessary for the economicmanagement programming to use the best leaching process.

The main purpose of this study was to determine rapeseed oil heat treatment effects onPopulus deltoides wood dimensional stability. For this purpose, free defect specimens with the dimensions of 2×2×2 cm were cut from poplar sapwood.The heat treatments were carried out at the temperatures of 180, 200 and 220oC for 2 and 4 h. Changes in weight and volume of the treated samples were measured.All samples were soaked in water for 5 days. Then, the water absorption and dimensional changes were determined. By the heat treatment with rapeseed oil, the specimen weight increased and volume of the specimens decreased. Linear relationship was obtained between sample volume reduction due to heating treatment, and time and temperature. The heat treatment improved the dimensional stability of poplar wood. With increasing temperature and time of treatment, the anti-swelling efficiency (ASE) was increased. At the temperature of 220 oC and 4 h treatment, ASE was 69%. In addition, water absorption of the treated samples was reduced. For instance at condition of 220 oC and 4 h the ASE was 135.7% less than that for the control sample.

In this study, the effect of propionylation on the weathering resistance of eastern cottonwood was investigated. The samples were propionylated under different reaction temperatures and times, and then the treated samples were exposed to natural weathering for 180 days. The color change of the propionylated wood was evaluated before and after weathering for time interval (40, 80 and 180 days). In addition, the surface roughness of the specimens was measured before and after weathering. The statistical analysis was done using Kruscal Wallis at the confidence level of 95% showed that propionylation reduced significantly the color change (turning grey) due to weathering. The color change reduced when the WPG increased. At the end of the exposure time to weathering, the surface roughness of the treated samples was 16.4% less than that for the control (untreated) samples but the difference was not statistically significant.

The purpose of this study was to investigate the effect of silver and copper nanoclouids on the thermal conductivity of particleboard. For this purpose, nanoclouids with concentration of 4000 (ppm) in four levels of 0, 5, 10 and 15% were applied to the particleboards with the consumed resin, then thermal conductivity of the boards were measured at four temperature profiles (45, 50, 55 and 60 oC). The results showed that with increasing nanoclouids content, the thermal conductivity increased, and the samples containing silver nanoclouids indicate higher thermal conductivity than the samples containing copper nanoclouids at the same conditions. With increasing temperature, thermal conductivity of the boards increased. The increased of thermal conductivity of compact wooden plates was as a positive factor in production process in terms of cost reducing and increase efficiency of the products.

Fast-growing tree species such as poplar have important role in supplying raw wood materials. The main purpose of present study was to evaluate the impact of climate variables (namely temperature and rainfall) on poplar growth. Samples were collected using increment borer from poplar trees around city of Sari, Iran.Ten samples were extracted and then prepared for measuring and analyses. Tree ring widths were measured by Corel Draw 10 graphical program and using dendrochronological methods analysis. Time series span were recorded 27 years (1982-2008). Quality and measuring control were performed using COFFECHA and computed tree ring index by ARSTAN program. Analysis showed that sensitivity is 25% and correlation coefficient between trees was 50%. Comparing the tree ring index with annually recorded climate variables showed that increasing of temperature in July had negative effects on annual growth. In addition, rainfall in April had positive effects on annual growth of poplar trees. Finally, it is to be noted that poplar is a sensitive tree to high temperature and its growth is decreased in dry condition.

This study was conducted to investigate the effect of planting space on specifications of trunk form in terms of tapering, eccentricity, elliptical stem well as height and diametric growth and basal area ofAcer velutinum. For this purpose from each treatment including planting space of 1×1, 1.5×1.5 and 2×2 meters, four trees from Shastkalateh traning forest, Gorgon Iran, were cut and above mentioned factors were determined. The results showed that with increase in planting space, annual diameter growths were significantly increased. Maximum and minimum basal area was related to planting space of 2×2 and 1×1 m2, respectively. However, with increase of planting space, tapering, eccentricity and elliptical trunk were increased, but the difference was not considrable.

The biological reserve ofBiota orientalis with 195 hectare, which was located 23 km far from south of Fazelabad Gorgan, were studied. The dominant species of this area isPlatycladus orientalis which is natural and native in the north part of Iran in Fazelabad. Observations showed that many stands ofPlatycladus orientalis had sever physiological weakness. Most of trees had shriveled.T. Ephebea. Results showed that the range of dryness in different diameters and ages were different and also with increasing density of lichen, growth of trees decreased salient.