فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال هجدهم شماره 1 (بهار 1390)

This research project aimed to investigate the scientific performance motivators in agriculture and natural resources by means of measuring attitude approach. The population consisted of 300 agriculture and natural resources faculty members from agricultural and natural resources colleges as well as from the Academy of Sciences of Islamic Republic of Iran who were selected through purposive sampling methodology. The data collection was done using a questionnaire which was validated by a group of experts. Its reliability as measured by Cronbach’s alpha was 0.87. Findings revealed that, graduate students’ proposals; scientists’ curiosity and interests; scientific journals’ trends; society needs; and public organizations’ grants got the first to last ranking orders in selecting research topics. Esteem needs were the most important determinant of scientists’ motivation in agriculture and natural resources researches. Scientists’ satisfaction played a great role in national agricultural development. Also, availability of “research grants and budgets and research materials and tools” recognized to be the most important challenge of agriculture and natural resources researches.

In order to evaluate the effect of moisture content (MC) on the electrical resistance (R) of poplar wood, three poplar trees (P. deltoeides) were selected and harvested in the Shast Kalateh forest in Gorgan, and eight matched clear specimens with dimensions of 27/510 cm were taken from each one. The electrical resistance and the corresponding internal temperature values of each specimen were measured simultaneously with a gradual increase in temperature between 15-100 oC, separately. The test was repeated for several turns and all of the specimens were weighed at the beginning and end of each run. All of the specimens were oven-dried with temperature of 103±2 oC for 24 hours at the end of the test to calculate the MC values corresponding to each electrical resistance and internal temperature values of each specimen with assuming the linear changes of MC of wood during each run of testing. The analysis of variance (ANOVA) at the 95% confidence level by SPSS14 software showed that the difference between different temperature values was significant, and electrical resistance decreased at a constant MC by the increase of temperature. Thus, eight linear models were evaluated to determine relationship between MC and electrical resistance at different temperature values, separately. According to the ANOVA test of the correlation coefficient, the best equation was chosen and moisture content-electrical resistance curves at different temperatures were drawn based on it. The results have shown that the electrical resistance decreases with increasing of moisture content at all temperature values with a same slope, but the slope of the curve decreases at the high temperature values (close to 100 oC).

The ecological potential assessment of forest sites introduces an index or indices that show the potential of forest site for fulfillment of special different roles of forest. Khanikan forest at Chalous needs precise investigation for assessment as indicator of lowland forests in forest ecosystems of northern Iran with considering its location position in Caspian lowland and different values. The woody groups of Khanikan forest were assessed using fuzzy set theory and regression analysis on the basis of soil characteristics including pH and carbon, nitrogen and phosphorus content. In this theory, a range of numbers with partnership possibility degree is considered instead of one number for assessment of ecological potential. 180 sample plots, each 400 m2 were designed for estimation of woody elements by systematic randomly method. Number and presence percent of woody species were recorded by measuring of canopy cover diameter. Mixed soil samples were dug in four corner and center of designed sample plots from 0-30 cm depth. Totally, 180 woody groups were recognized consisting Carpinus betulus L., Parrotia persica DC., Cratagus Pentagyna W., Querecus castanifolia C.A.M., Buxus hyrcana P., Diospyrus lotus L., Ilex aquifolium L., Ulmus glabra H., Mespilus germanica L., Alnus glutinosa L., Pterocarya fraxinifolia L., Acer insign B. Ficus carica L., and Ruscus hyrcanus L. These species were dispersed in samples plots with different ratios. The soil characteristics were incorporated in fuzzy system as input data for assessing forest groups. Triangular membership functions were defined for each characteristic. 81 fuzzy rules were recorded on the basis of investigated property. Weights incorporated in every fuzzy rule and assessment classes were constituted. Finally, assessment classes of interred data to fuzzy system were designed, separately. The assessment results showed that forest groups with pure combination of Hornbeam species had higher potential on the basis of soil characteristics compared to other groups. Stepwise regression method indicated that the ecological potential of forest groups is predictable using soil pH.

In order to capability investigation on Landsat-7 Satellite ETM+ Data in Separability Forest Type and mapping in the Zagros Region, a small window digital data dating July 2001 from Ghalajeh Forests in the Kermanshah province were analyzed. Ground data were provided the cluster sampling method and with 0.36 ha. No radiometric error was found then the quality investigations. Orthorectification was implemented using 55 Ground Control Points and RMS Error equal 0.39 the X axis aspect and 0.46 the Y axis aspect. Atmospheric correction was implemented using of Cost model. Vegetation indexes to produce appropriate for soil reflectance effect decrease. Synthetic bands were generated using some suitable processing methods to produce the spectral arithmetic bands like principal component analysis and Tasseled Cap transformation. Multispectral and panchromatic data were fused using HIS and statistics-based pansharp fusion techniques. Selection of the appropriate bands for classification was performed using divergence separability index. Classification was done by supervised method using maximum likelihood (ML), minimum distance to mean (MD) and parallel epiped (PPD) classifiers. Accuracy assessment of classified maps was performed by ground truth map. The results showed that the classified map using maximum likelihood classifier could be better than other maps with an overall accuracy 68% and Kappa coefficient 0.29 for Oak and mixed forest types. Results generally showed a moderately capability ETM+ data to provide forest types map in the Zagros forest. These study would suggest the utility of best spatial resolution imagery and in other regions.

In this research, effect of Using Hornbeam and Beech Branch Woods in Admixture with Birch Stem Wood on Their CMP Pulp Properties. Using percentage of branch woods, with 20% constant content for Birch stem wood, were 0, 16, 40, 56 and 80 in final mixture of hardwoods. The Results indicated that cooking time, to reach 85% yield and under same cooking condition, and also refining quantity, to reach 300 ml constant CSF freeness, were decreased with increasing portion branch woods (P<0.01). Moreover, despite a little decrease (P<0.01) in the optical and mechanical properties of the produced hard sheets by addition of branch wood in the hardwood stems wood, using 40% of branch wood in final mixture of the initial materials for making CMP pulp is recommended.

In this study, the possibility of using canola stem residues for particleboard manufacturing was studied. The ratio of canola straw to the industrial particles was as 25:50, 50:50, 75:25 and 100:00 percents, respectively. Urea formaldehyde resin was used as binder at three levels of 8, 10 and 12 percent based on oven dried weight of particles and the press time was at three level of 5, 6 and 7 minutes. Control samples were made of industrial wood particles. Then, mechanical and physical properties (modulus of rupture, modulus of elasticity, internal bonding and thickness swelling after 2 and 24h soaking in water) of the produced boards were measured. The results indicated that increasing canola straw to wood particles, resulted in increasing the bending strength and modulus of elasticity of the boards. Also, increasing the amount of resin and press time improved the mechanical and physical properties of the boards. Precisely Speaking, using canola straw in mixture with industrial particles up to 25%, 12% resin and press time of 7 minutes resulted in producing boards with appropriate physical and mechanical properties which are suitable for interior uses.

Rehabilitation of arid and semi-arid regions by tolerant native plant cover is a primary concern to create a sustainable balanced ecosystem. Thus, the existing plant species of the region should be recognized together with a comprehensive survey and study of the environmental factors such as climate and soil conditions which affect the establishment of these plant species. This paper attempts to examine the effects of soil physico-chemical properties on some distinctive vegetative characteristics of Gum arabic (Acacia arabica Wild var. nilotica), in Tangestan flood water spreading experimental station at Bushehr province. A cluster sampling scheme was designed and applied. Each cluster consists 4 square sample plots, each 1600 square meter (40×40 meters). The vegetative characteristics (collar diameter, tree height, crown diameter at two major directions) were measured and recorded carefully. At the center of each cluster, soil samples were collected at 0-20 and 20-45 cm depths to evaluate major soil characteristics such as Soil acidity, electrical conductivity, nitrogen, phosphorus and potassium content and sand, clay and silt percent. For the analysis of variance, the factorial experimental in completely randomized design was used. The comparison of means was done using Duncan's new multiple range tests. The results suggest a significant difference at one percent statistical error level between the mean collar diameters of upland and downland subdivision basins, where, downland exhibits more favorable condition. The canonical correlation analysis suggests a significant correlation at one percent statistical error level between vegetative characteristics of Gum arabic and some distinctive soil properties, i.e., the finer soil texture results a better condition for crown canopy development.

This paper attempts to examine the effect of water spreading on soil physico-chemical properties, and vegetative characteristics of Common mesquite. For this, on the basis of flood water discharge, three sections of lands were accurately selected at Kosar water spreading experimental station, in Tangestan, Bushehr province. In each section, 6 profiles were digged out and studied; meanwhile soils samples were collected from 0-45 cm depth to evaluate their further characteristics. The vegetative characteristics of Common mesquite were studied at 1600 square meters sample plots selected as a cluster of each 4 sample plots around each profile (40×40 square meter). Analysis of variance of Soil major characteristics (EC, pH, N, P, K, Clay, Silt and Sand percents) suggested a significant difference at one percent statistical error level between the sections. The CCA process, suggests that Clay percentage has a strong correlation with crown diameter of Common mesquite.