فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال شانزدهم شماره 2 (تابستان 1388)

This study was performed to investigate the effects of refining on the mechanical and optical properties of waste newspaper. Waste newspapers were prepared from Gorgan Ettelaat newspaper Agency and were cut to 5 centimeter pieces, and then were soaked with sufficient distillated water. After 1 day fibers were separated by disintegrator and freeness values for each pulp before and after refining were measured. Waste newspaper was refined by PFI mill at 1000, 2000, 3000, 6000, 9000 revolutions, respectively. Handsheets were made from each revolution according to TAPPI standard T 205om-97, and then compared with control sample. Analysis of variance was conducted using completely randomized design, then mean values were compared using Duncan’s test, and finally the normalization equations were used to determine the best treatment. The results showed that increasing refining revolution increased burst, tensile and folding strength, brightness and density but decreased freeness, bulk, thickness, tear strength and opacity. Normalization equations showed that the best paper can be made from refining revolution of 9000.

In this research, the possibility of using high percentage of lignocellulosic fibers in making natural fiber-thermoplastic composite was studied. Three weight percentages of bagasse flour namely 40, 55 and 70 percents were chosen. MAPP was used as coupling agent at two weight percentages of PP, namely 0, 4 and 6 percents. Tensile strength was measured applying Instron 6025. The results showed that with increasing bagasse flour percentage, tensile modulus of elasticity improved, but tensile stress, tensile strain and work at proportional limit decreased. Also, addition of the coupling agent led to the improvement of tensile stress and tensile modulus of elasticity and decreasing work at proportional limit and tensile strain.

In this research the productivity and cost of Komatsu D60 bulldozer in earth working operations of secondary forest road was studied in Lolet forests, lied in one of the Tajan river watersheds. The daily work elements of the machine including productive time, unproductive time, technical, operational and personal delays for 12 days and in two slopes of 30 to 50 and 50 to 70 percents were investigated by time study method. To estimate the daily productivity, the cross sections of road were taken every 20 meters and then their section areas were calculated. The hourly cost of bulldozer and system was estimated by conventional method. Comparison of the results by Tokey test showed no significant difference between the length of constructed road in the slopes 30 to 50 and 50 to 70 percents. This was also true for earth working volume, but, hourly earth working volume and work volume in each meter of the road increased with increasing the hillside gradient and the length of constructed road was reduced. The mean production rates for bulldozer in the slopes 30-70 percents in productive time were 144.92 m3/h and 22.87 m/h. The hourly costs for the bulldozer and system were estimated 121890.7 and 286890.7 rials, respectively. Finally, the costs of each cubic meter of the earth work and each meter of the road excavation by bulldozer in the slopes 30 to 70 percents were 1979.65 and 12544.41 rials, respectively.

Initial growth of Quercus castaneifolia (C.A.Meyer.) seedling in competition with Rubus fructicosus L. was investigated in a Caspian lowland intervened forest located in Noor city, north of Iran. The research was conducted as factorial experiment in three replications. For this purpose, seedlings of 3 and 5 mm in collar diameter (CD) were planted in areas a (covered with Rubus), b (without Rubus) and, c (removed from Rubus) in 0.5 m radius around each Quercus seedling and studied for a two growth periods. The results revealed that 1-year and 2-year survivals and height increments in seedlings with greater CD were greater than those with smaller CD. Survival was highest in 1-year seedlings in the area covered with Rubus, and in 2-year seedlings in the area covered with Rubus and removed from Rubus. Although in 1-year and 2-year periods, height increment was not different in Rubus treatments but CD increment was highest in the area removed from Rubus. The results of the second year growth showed that seedlings with larger CD had higher survival and larger height increments. The CD increments of seedlings was also greater in the area removed from Rubus. From results of two years investigation it can be concluded that in the areas occupied by Rubus, planting Quercus seedling with larger CD, and removing Rubus around the seedling, provides suitable condition for establishment of Quercus seedling.

Chestnut-leaved Oak (Quercus castaneifolia) is one of the most important industrial species of the northern forests of Iran. Regeneration of this valuable species is limited due to several problems such us pests and the fungal diseases. In order to isolate and identify the fungi associated with Oak seed, sampling was carried out during 2007 in Shast-kalate forest at Gorgan. Collected seeds were separated into two section: outer section of seed (crust) and inside seed section (endosperm) and then their surface was sterilized with 0.5% sodium hypochlorite. Each section of seed was separately tissue cultured on potato dextrose agar media in 4 replicates. After sub-culture and providing fungi pure cultures, various species isolated and identified by spores characteristics, their size and colour, including: Aspergillus flavus, A. niger, Curvularia affinis, Trichoderma harzianum, Trichothecium roseum, Eurotium rubrum, Penicillium implicatum, and Diplodia sp. The fungi, E. rubrum, T. roseum, T. harzianum, and Diplodia sp. were observed only in the outer seed section by 35%, 41%, 7% and 23% frequency, respectively. The fungus C. affinis observed only inside seed section by 39 percent frequency. The fungi, A. flavus, A. niger, and P. implicatum were observed in the both sections of the seeds. The highest frequency of fungus related to P. implicatum by 74 percent frequency within seed section. The result indicate higher frequency and diversity of the fungi in the outer section of the seeds than within the seeds. More over, there is always a saprophyte fungus on the acorn seeds, during several isolation. This is the first report on fungi associated with Oak seed in Iran.

The oriental arborvitae habitat with an area of 223¬ha. is located on 20 km south of Fazel¬Abad, Golestan province. The lowest and highest of its height are 820 and 1680 m.a.s.l. The floristic-physiognomic investigation performed by walked-field procedure at 2nd seasonal sequence showed that flora of this region includes 173 plant species that belong to 147 genera and 65 families, of which 5 species are endemic to Iran. The families of Asteraceae (17 species), Papillionaceae and Rosaceae each one contained 13 species and Lamiaceae (10 species), Brassicaceae (9 species), Poaceae (8 species), Apiaceae, Boraginaceae and Caryophyllaceae each one contained 6 species along with Scoropholariaceae which contained 4 species, were the most important families, which include 53.2 percent of total species. According to Raunkiaer method, Hemicryptophytes (37%), Phanerophytes (24.8%), Therophytes (20.8%) and Cryptophytes (11%) were the most important structure groups of the local biological spectrum while according to Suzuki-Arakane method caespitose Hemicryptophytes (31.2%), Therophytes (20.8%), broad-leaved deciduous trees & shrubs (19%) and Rhizome-Geophytes (5.8%) were the most important life forms. The chorological study using Zohary method reveales that plants of Euro-Siberian region (24.3%), Irano-Turanian (23.1%), Hyrcanian province (11.6%) and Euro-Siberian and Irano-Turanian region (8.7%) are the most important chorological groups in the habitat and other chorotypes lie in the lower importance level.

Identification of the best vegetation indices (VIs) for use in quantitative analyzes of vegetation is one of the important issues for ecologists. The objective of this study was sensitivity evaluation of vegetation indices to a stand volume for identification of the best vegetation index (VI) in stand volume estimation using a statistical sensitivity method. Also, another objective of this study was to compare results of stand volume estimation using sensitivity function and the best subset regression. We also evaluated sensitivity of VI relative to another VI using relative sensitivity function. In this study, 99 plots 60m×60m each were used with systematic cluster sampling method. In each plot, data on tree species, diameter at breast height, stand height and geographic coordinates of each plot center were recorded. The vegetation indices were created using Landsat ETM+ data. In order to analyze the relationship between stand volume and vegetation indices, average digital number of pixels within 2×2 pixels window were extracted from vegetation indices. The result of the sensitivity function showed that NDWI and Greenness had high sensitivity compared to DVI, RAI and GEMI in stand volume estimation, respectively. Therefore, NDWI and Greenness were selected for estimating stand volume using satellite data. Also, the result of the best subset regression analyses showed that DVI and NDWI were best for estimation of the stand volume. The regression model with NDWI and Greenness could better predict stand volume (adjusted R2=55.4%) compared to DVI and NDWI (adjusted R2=43.5%). This is a 12% increase in adjusted R2. The results showed that relative sensitivity of NDWI to GEMI and Greenness is high. Generally, the sensitivity function expresses the change in sensitivity of a VI through the range of allometric characteristics, it is irrelevant of the unit or magnitude of vegetation indices and it tests the significance of the sensitivity with t-or-z statistic is useful for evaluation of sensitivity analysis of vegetation indices and identifying the best vegetation indices in quantitative and qualitative assessment of forested area.