Journal of Wood and Forest Science and Technology
Year:2019 | Volume:26 | Issue:4|Papers Count:8

Background and Objectives: Wood chipping is an important step in wood chipboard factories. Producing high quality chips with effective dimension and size, not only guaranties high quality in final product, but also reduce produce time in secondary machines and subsequently energy consumption. The aim of this study was evaluation of effective parameters on energy consumption in drum chipper which was done in Rosenheim University of applied sciences (Germany). In this regard, the effect of wood species, cutting velocity, moisture content and wood dimensions were evaluated. For precise investigation of energy consumption in each situation of experimental design, equal weight of the trunk converted to chips. Also, chips thickness was also considered constant in all the tests. Materials and Methods: In this study, Poplus termula and Quercus Robur were used. First, samples through band saw blade ESTERER Model EB 1400 converted to lumbers with dimensions 4×8 cm and 8×8 cm. Then samples dried in chamber LAUBER TROCKNUNGSTECHNIK with automatic system to reach 18 and 40 percent moisture content. Next samples based on experimental design which were prepared with factorial design and equal weight of the trunk, feed to drum chipper. By adjusting the axis rotation speed on drum chipper, the cutting velocity was managed at 3 levels of 16, 20 and 24 meters per second. The energy consumption during the process by Multichannel precision power meter was measured. Results: After analyzing data, results showed that factors of species, moisture and cutting velocity had significant effect on energy consumption in drum chipper at 95 percent confidence level. Main effect plot showed that, Oak species compared to poplar, 40 percent moisture compared to 18 percent, 20 m/s cutting velocity in comparison with 24 and 16 accounted for less energy consumption. The results of analysis of variances showed that the main effect of thickness on energy consumption is not significant. Also results showed that, cutting velocity had the most main effect and moisture content had the least main effect on energy consumption at 95 percent confidence level. Conclusion: The results of interaction plot showed that while thickness did not have significant main effect on energy consumption, it was effective in reaction to other parameters. Oak with 40 percent moisture, 4 cm thickness and 20 m/s cutting velocity had the least energy consumption, whereas poplar with 18 percent moisture, 8 cm thickness and 20 m/s had the least energy consumption. This difference in energy consumption may be happened due to difference in texture and visco-elastic properties of two species against cutting forces. Probably in poplar species, increasing moisture content and decreasing thickness to 4 cm, increased wood deformation against cutting force and this behavior results in more energy consumption during cutting.

Background and Objectives: Wood plastic composite products have received many researches’ attention in recent years. A major part of the composite combination is lignocellulosic materials. One disadvantage of natural fibers is the incompatibility between hydrophilic natural fibers and hydrophobic polymers. This problem can be reduced by incorporation of coupling agent into the compound. Because of the adding of coupling agent, the interface between two phases of lignocellulosic fiber and polymeric matrix improve. This study was carried out with the aim of investigating the effect of two types of coupling agent on the mechanical and physical properties of the particleboard made of polypropylene-poplar. Materials and Methods: In this research, the mixing ratio of poplar wood to polypropylene at level of 90: 10 was used. Phenol formaldehyde resin used as 8% of dry weight of raw material. Two types of coupling agents of triethoxymethylsilane and maleic anhydride grafted to polypropylene in level of 6 percent based on dry weight of polypropylene were used. Coupling agents were used in two different methods including inside the resin and on the polypropylene particles. After the mixing process raw material together, mat at temperature of 180 ° C for 5 minutes under hot press was placed. The physical and mechanical properties were evaluated according to European standards set of EN. Physical and mechanical properties of panels analyzed using factorial analysis in 5% probability level. Results: The results showed that the adding of both types of silane and MAPP coupling agents improved the bending strength, modulus of elasticity and internal bonding, while decreased water absorption and thickness swelling of the boards compared to the control sample (without coupling agent). MAPP coupling agent created more favorable properties in the boards compared to the silane coupling agent. The adding method of coupling agent on the polypropylene particles in comparison with inside resin improved the physical and mechanical properties of the boards. Because in the adding method of coupling agent on the polypropylene, all of the coupling contents are placed on the polypropylene particles, and therefore, the presence of the coupling agent on the interface between the polymer phase and the reinforcement phase increases. Conclusion: According to the results of this research, the use of coupling agent increased significantly the dimensional stability of the boards. The adding of coupling agents increased bending strength, modulus of elasticity and internal bonding of boards. Compared to the properties of the boards produced by EN standard, with adding method of MAPP on the polypropylene can be produced particleboards with favorable properties for use in wet conditions (Type P3).

Background and Objectives: Root interaction is an important factor that influences enzymes exudations of plant roots in rhizosphere, which have different spatial distribution depending on root structure, species type and soil depth. There are few researches on identifying the spatial importance of rhizosphere processes in forest species. Tree species have different rhizosphere regarding to root morphology and physiology as well as nutrients needs. This research aimed to examine spatial variability of urease enzymes exudation on rhizosphere of chestnut-leaved oak and Persian maple in pure and mixed plantings. Materials and Methods: 18 modern rhizotrons were applied for this research and 12 Raster-Access-Ports placed in each rhizotron to get root exudates. These ports were in distinct depths and distances to calculate spatial variability of root enzymes exudations. Two lower depths (50 and 75 cm) were filled with mineral soil while two upper depths (15 and 30 cm) were filled with combination of litter (4% of weight). One year old seedlings of Quercus castaneifolia and Acer velutinum were planted in four treatments of species composition including pure, mixed and control (without planting seedling). Soil samplings were collected 6 months after planting in different soil depth of rhizotrons and urease activity was determined using Kandeler method. Enzyme efficiency was calculated using the differences between enzyme activities in each place and corresponding amount of control (without root) and do not show catalytic efficiency. Results: The results showed that there is significant difference in urease exudation contents of different planting compositions (P<0. 05). The most amount of enzyme exudation revealed in the pure oak and mixed planting while the lowest was in control. Spatial variability of urease activity only revealed significant difference in mixed planting treatment (P<0. 05). However spatial variability of enzyme efficiency was significant in pure maple and mixed planting treatments (P<0. 05). Urease exudation was not significant in different distances from seedlings’ collar with exception of urease efficiency in pure oak planting treatment (P<0. 05). The highest amount of urease exudation has been observed at the depth of 75 cm. Conclusion: The amount of spatial exudation of urease is mostly related to root density in different places and this is related to root interaction of planted seedlings and their root systems. This study revealed that root interaction in mixed treatment result in more urease activity and efficiency because of more suitable ecological niche. Because urease exudation in different distances from seedlings’ collar was never significant, so results showed uncertainty in spatial exudation of urease.

Background and Objectives: Beech and hornbeam are important species In Hyrcanian forests. Due to the economic and ecological importance of these species it is of importance for forest managers to have sufficient information about the structure and the tree diversity level of beech and hornbeam stands and their associated species which will be used to manage and protect these forests. Also in this study, for the first time in the study area, correlation analysis and regression analysis between biodiversity indices and independent environmental variables were performed which are essential steps in forest planning and management. Materials and Methods: For this purpose, the indices of biodiversity (Shannon-Weiner and Simpson Index) were measured separately in each sample plot and then were compared with each other. In addition, the correlation and regression of these indices with 16 eco-physiographic factors including seasonal light, mean air temperature, high altitude from the nearest drained point, topographic shafts, relative humidity, wind speed, reflection and radiation levels representing the environmental conditions of the region were obtained. Among them, only four factors had a significant correlation with biodiversity indices. These factors are air temperature near the earth surface, topographic wetness index, wind speed, and total solar radiation energy in each habitat. Also t-test was performed to investigate the significant differences between biodiversity indices of the two habitats. Results: The results showed that both biodiversity indices were higher in hornbeam habitat than beech habitat. The correlation coefficient of the mentioned environmental variables with the Shannon diversity index in each habitat indicated that the correlation coefficients of the variables with the biodiversity index in the hornbeam habitat were higher than the beech except for the correlation coefficient related to the total solar energy variation in the beech habitat which was higher, with a negative slope indicating the shade-demanding nature of beech species compared to hornbeam. Also t-test showed that there is a significant difference between the two habitats in terms of Shannon-Weiner index. Conclusion: Totally biodiversity indices have high ability in description of forest status. The advantages of these indices are high accuracy, inexpensiveness and flexibility. The results of this study showed that biodiversity indices were higher in hornbeam than in beech, which can be due to various reasons. In fact, determining biodiversity indices in forest communities firstly and then, examining and determining the environmental factors affecting the biodiversity of tree species, as well as comparing important forest habitats and communities from the perspective of these factors is of importance for proper management.

Background and Objectives: One of the issues that plays an important role in selecting the suitable seeds for plantation projects is the seed provenance effect test. Production of suitable seedlings in terms of quantitative and qualitative values mostly depends on edaphic and climatic conditions of seed origin place and planting location. The purpose of this research was to examine the effect of irrigation regime on the characteristics of Celtis caucasica seedlings collected from Karaj, Hamedan, Khorramabad, and Shiraz provenance. Materials and Methods: In order to find the most suitable irrigation treatment and to investigate different provenances of Celtis caucasica seedlings the needed seeds were collected from forests and mountains of Alborz, Fars, Hamedan and Lorestan. After collecting the seeds were planted in the polyethylene pots. All the pots had the same circumstances before seeds germination. Finally, 30 seedlings were used in four irrigation treatments including 1, 3, 5 and 8-day irrigation in three replicates for six months from early June to late November. The seedlings height, collar diameter, leaf area, root length, stem length, and seedling survival percentage at the end of the growing season were measured. Results: Tukey test results showed that the effect of seed provenance on all measured traits was significant (P<0. 05). Irrigation treatments significantly affected seedling height, collar diameter, root length, leaf area and survival on various provenance (P<0. 05). On average, the highest amount of measured parameters was for the Karaj provenance while the lowest was for Hamadan provenance. Also, the highest leaf area was related to irrigation treatment of Karaj and Khorramabad provenance. Commonly, the seedling survival in all irrigation regimes were 66. 25% but the highest survival rate was related to control treatment (71%). The highest seedling growth was observed in control treatment, while the least in 5-days treatment. Conclusion: based on the results, the seeds of dry regions were able to withstand drought stress in 8-day irrigation and had more growth than other regions. Using Karaj seeds for afforestation in Karaj is highly recommended. Since no significant difference was found among different irrigation treatments therefore it is suggested to apply an 8-day irrigation period for reducing the seedlings production cost in the nursery.

Background and Objectives: It is of importance to find drought-tolerant tree species with the aim of reviving Zagros forests. There are no enough researches about the effect of nanoparticls on the woody plants especially on their physiological features, while most of the researches have focused on herbaceous and crop plants. Therefore, in the current research, we investigated the effect of nano Sio2 on wild pistachio (Pistacia atlantica subsp. mutica) seedlings to understand the plant reaction to tension in order to find a drought-tolerant plant for rehabilitation of Zagros forests. Materials and Methods: The experiment was a factorial experiment based on completely randomized design with 126 seedlings, three replicates, six treatments of nano Sio2 (control, 100, 300, 700, 1500, and 3000 mg. l-1) for 30 days and at three levels of drought stresses (control, every other day of irrigation; moderate, every four days of irrigation; and severe drought, with no irrigation). At the end, the physiological characteristics of chlorophyll a, b, total, caratoneid, carbohydrate, proline content, and antioxidant enzymes of guaiacol peroxidase and catalase were analysed in seedlings leaves. Results: The results showed that using nano Sio2 increased different kinds of chlorophylls, caratoneid, proline content, carbohydrate, and antioxidant enzymes under drought stress. In fact the seedlings reacted differently to nano Sio2 treatments that the highest amount of carbohydrates and catalase were observed in 700 mg. l-1; chlorophyll a, b, total and caratoneid in 3000 mg. l-1, and proline and peroxidase in 300 mg. l-1. Furthermore, the different levels of drought stress reduced chlorophylls and caratoneid; while increased soluble carbohydrates, proline, and antioxidant enzymes. Conclusion: It can be concluded that the most physiological traits were increased under drought stress and the Sio2 nanoparticles had positive effect on traits of different types of chlorophyll and carotenoids. Concentrations of 300, 700 and 3000 mg. l-1 had a better effect on many of the physiological traits than the others. Reducing chlorophylls and carotenoids and increasing carbohydrate, proline and antioxidant enzymes are occurred in plants to tolerate the drought stress. Due to the lack of basic information about the resistance mechanism in endemic tree species from Zagros forests in response to nanoparticles, this study will be a great assistance to develop nano technology in wooden plants. It is suggested to study the effect of Sio2 nanoparticles for longer periods or on some more species that could be a suitable way to find better results. These results may lead into economical production of drought tolerant seedlings.

Background and Objectives: Eucalyptus species are used for afforestation in different ecological areas due to their rapid growth and high genetic diversity. This study was done to evaluate performance of some species and provenances of Eucalyptus during a 3-year period in Wastewater Station in northeast of Qom. Materials and Methods: The experiment was a factorial experiment based on randomized complete block design (RCBD) with two factors: 1) genotype at 6 levels and 2) time at 3 levels in four replications on 5-year-old Eucalyptus saplings. Irrigation was carried out using the treated wastewater of Qom city. Selected genotypes were including six provenances of Eucalyptus camaldulensis Dehnh., E. microtheca Muell. and E. rubida Deane & Maiden. Growth traits including: tree height, trunk diameter at 30 cm height, height growth, diameter growth and height to diameter ratio were measured. Statistical analysis such as ANOVA and comparison of mean was done among selected genotypes and different years and finally adaptation and growth performance under experimental conditions have been introduced. Results: The results showed that the effect of treatment (species and provenances), replication, interactions between treatment and replication, and year on tree height were significant. Mean comparisons showed that species and provenances were classified into five distinct groups and one common group; E. camaldulensis 41ch was in the highest group. Trees were grouped in 4 groups based on the diameter of trunk, E. camaldulensis 41ch and E. camaldulensis Qom were in the first and second groups. In addition based on height growth E. camaldulensis 41ch and E. camaldulensis Qom were in the first group and E. microtheca 62 and E. rubida 166sh were in the last groups. Based on the trunk diameter growth E. camaldulensis Qom was in the first group and E. rubida 166sh was in the last group. In terms of trunk height to diameter ratio, the species were divided into two distinct and three common groups, based on these results E. camaldulensis 41zh with the highest height to diameter ratio was in the first group. Conclusion: In general, the results showed that E. camaldulensis 41ch had the highest amount of diameter and height. E. camaldulensis 41ch seems to have a higher performance for industrial wood production than other species and provenances. E. camaldulensis Qom was also ranked first in terms of diameter and height growth, this seems to be due to seed origin (Qom) and adaptation to regional conditions. Overall, the results showed that E. camaldulensis had the highest rank in height and diameter growth, followed by E. microtheca.

Background and Objectives: Old trees of Quercus brantii Lindl. Var. persica and Pistacia atlantica have a special importance in Zagros forests. These trees are presented in forest sites over a long time and have endured numerous adverse climate and environmental changes and tensions and could survive. Recognizing the site ecological characteristics in relation to the trees can provide good information for presenting managerial guidelines for preserving of old trees or extending them. The present study was carried out with the aim of recognizing the ecological characteristics of the sites of Persian oak and pistachio old trees in oak forests of Ilam province. Materials and Methods: This research was carried out in a part of the forests of Ilam province, in the districts of Ilam, Sirvan, Chardavol, Malekshahi, Mehran and Dehloran. After extensive forest survey, old trees were identified and selected based on the DBH criterion. Then their geographical location including city, district, village or region and geographical coordinates, their quantitative characteristics including DBH and max & min crown diameter and their site conditions including slope, aspect, altitude, soil depth, proximity to the river or water resource were measured and recorded. Results: The results showed that the old oak trees were generally in the gentle slope class and the old pistachio trees were mostly in the relatively gentle slope class. Most of the identified old oak and pistachio trees were located in the southern aspect. The old oak trees were distributed in altitude class of 1300-1700 m above sea level, but the old pistachio trees were in 1300-1700 and 1700-2000 m altitude classes. In terms of access to running water, none of the old oak and pistachio trees have access to water resources and all feed on atmospheric precipitation. In terms of soil depth, most of the identified old trees had a suitable soil depth relative to their surroundings because of locating on gentle slopes. In terms of climatic conditions, the identified old trees were classified into four climates, according to which the old oak trees were mostly present in semi-wet cold and semi-arid temperate climates, but the old pistachio trees were mostly in wet cold and semi-wet cold climates. Crown area of old oak and pistachio trees had better response to site conditions changes than their DBH and its variability was different depending on species. Most of the identified old trees due to locating on gentle slopes have relatively suitable soil depth than their surroundings. Conclusion: The identified old trees are in desirable site locations and in fact the desirable ecological characteristics of these trees are of the reasons for their stability over their long life.