فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال بیست و ششم شماره 4 (زمستان 1398)

Chips producing and wood chipping are very basic and important step in wood chipboard factories that are determinant in final products quality and price. Producing high quality chips with effective dimension and size, not only guaranties high quality in final product, but also reduce stay time in secondary machines and subsequently and 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). For this reason, the impact of wood species, cutting velocity, moisture and wood dimension was evaluated. For precise investigation of energy consumption in any situation of experimental design equal weight of the trunk converted to chips. Also, chips thickness in all the exams imagines stable.

In this study Poplus termula and Quercus Robur was used. First, samples through band saw blade ESTERER Model EB 1400 converted to lumbers with dimension 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 was prepared with factorial design and equal weight of the trunk feed to drum chipper. Cutting velocity through the speed of rotation of engine in 3 level, 16, 20 and 24 meters per second was managed. The energy consumption during the process by Multi-channel precision power meter measured.

After analyzing data results showed that, influence of species, moisture and cutting velocity had significant effect in 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 has lesser energy consumption. Also result showed that, cutting velocity had most main effect and moisture had least main effect on energy consumption in 95 percent confidence level. The result of analysis of variances showed that the effect of thickness on energy consumption is not significant.

The results of reactions showed that while thickness did not have significant effect on energy consumption but compared to other variables it had the most effect. with evaluation result, observed that Oak with 40 percent moisture, 4 cm thickness and 20 m/s cutting velocity had least energy consumption, while poplar with 18 percent moisture, 8 cm thickness and 20 m/s had least energy consumption. This differences in energy consumption can happen because of difference in texture of 2 species. This can stem from different characteristic and elastic properties of the studied species as in poplar with increasing moisture content and thickness, wood deformation against cutting force increased and finally led to increasing energy consumption.

Wood plastic composites in recent years have been the attention of many researchers. The major part the combination of these composites, lignocellulosic material constituted. The disadvantages of natural fiber can be mentioned incompatibility between the hydrophilic fibers and hydrophobic polymers. This problem can be reduced by incorporation of coupling agent into the compound. Because of the addition of coupling agent, the interface between two phases of lignocellulosic fiber and polymeric matrix improve. This study with aim of investigation the effect of two types of coupling agent on mechanical and physical properties of particleboard made of polypropylene- poplar was done.

in this research, the mixing ratio of poplar wood to polypropylene at level of 90:10 was used. Phenol formaldehyde resin used at 8 percent level of dry weight of raw material. Two types of coupling agents of maleic anhydride grafted to polypropylene and triethoxymethylsilane 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.

The results showed, the addition 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). Compared to the silane coupling agent, MAPP coupling agent created more favorable properties in the boards. The addition 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 addition 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.

According to the results of this research, using of coupling agent increased significantly the dimensional stability of the boards. The addition 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 addition method of MAPP on the polypropylene can be produced particleboards with favorable properties for use in dry conditions (Type P3).

Root interactions are the most important factor that influence on enzymes exudations of plant roots in rhizosphere, that depending on root composition, species type and soil depth, so they have different spatial distribution. Further there were restricted researches to identify the spatial significance of forest species rhizosphere processes. Tree species have different rhizosphere regarding to root morphology and physiology as well as nutrients needs. The aim of this research is to examine spatial variability of urease enzymes exudation on rhizosphere of Chestnut-leaved Oak and Persian Maple in pure and mixed planting.

18 modern rhizotrons were applied to study research goal that 12 Raster-Access-Ports placed in each rhizotron to get root exudates. These ports were in distinct depths and distances to calculating 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) combined with litter (4% of weigth). One years 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 sampling were collected 6 months after planting in different soil depth of rhizotrons and urease activity was determined by Kandeler method. Enzyme efficiency was calculated by subscripted enzyme activity in each place from corresponding amount of control (without root) and don't show catalytic efficiency.

The results showed that urease exudation contents have significant differences in planting composition (p < 0.05) while the most amount of enzyme exudation revealed in the pure Oak and mixed planting and the lowest was in control. Spatial variability of urease activity only revealed significant difference on mixed planting treatment (p<0.05). However spatial variability of enzyme efficiency was significant on pure maple and mixed planting treatments (p<0.05). Urease exudation wasn't significant in different distances from seedlings collar with exception urease efficiency in pure oak planting treatment (p<0.05).

The amount of spatial urease exudation more related to root density in different places so it is related to root interaction of planted seedlings and their root systems. This study revealed root interaction in mixed treatment result in more urease activity and efficiency because of more suitable ecological nich. Because root exudation in different distances from seedlings collar was never significant, so results showed non-confidence in spatial urease exudation. 

There are important species of beech and hornbeam In the Hyrcanian forests. Due to the economic and ecological importance of beech as well as the frequency of mixed beech-sufficient information about the structure and the level of beech and hornbeam and their associated species which will be used by Forest managers. 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.

For this purpose, the indices of biodiversity (Shannon Weiner and Simpson Index) were measured individually in each habitat and then they were compared with each other. In addition, the correlation and regression of these indices with 16 eco-physiographic factors Including seasonal light, average 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 was obtained. Among them, only four factors had a significant correlation with biodiversity index. These factors are air temperature near the surface of the Earth, 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 between the two habitats.

The results showed that both Biodiversity indices were higher in Hornbeam habitat than Rash habitat. The correlation coefficient of the environmental variables mentioned in the Shannon diversity index in each habitat indicated that the correlation coefficients of the variables with the variability index in the hornbeam habitat were higher than the rash except for the correlation coefficient related to the total solar energy variation in the Beech habitat which was higher than beech, with a negative slope indicating the nature of the friendliest shade of beech species compared to hornbeam.

the higher Shannon species diversity and Simpson uniformity index in beech habitat, confirms the tendency for this species to be mixed with its non-homogeneous trees and high competition at this stage of the sequence in beech habitat. In fact, the mass distribution of beech is a factor in the high competition and, consequently, a low index of uniformity. The results of this study showed that biodiversity indices were higher in hornbeam than in beech, which could be due to various reasons. In fact, determining biodiversity indices in forest communities firstly and then, examining and determining environmental factors affecting the biodiversity of tree species, as well as comparing important forest habitats and communities from the perspective of these factors for management purposes. Forests are important and essential.

The purpose of this research was to examine the effect of irrigation regime on the Celtis caucasica seedlings growth in the Karaj, Hamedan, Khorramabad, and Shiraz provenance.

After collecting seeds were planted to study the effect of irrigation treatments and seed provenance, seeds in the pot. All the pots had the same conditions before all the seeds, were germinated. Subsequently, were treated to four irrigation treatments including control, 3-days, 5-days and 8- days in three replicates of 30 seedlings for six months from early June to late November. The seedlings height, the collar diameter, the leaf area, the root length, the stem length, and seedling survival percentage at the end of the growing season, were measured.

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 and leaf area (p <0.05). On average, the highest amount of parameters measured at the Karaj provenance while the lowest was in Hamadan provenance. Commonly, the survival seedlings in all irrigation regimes were 70% but the highest survival rate related to control treatment. The highest seedling growth was observed in control treatment, while the least in 5-days and 8-days treatment, was observed. It is recommended to use Karaj Seeds for afforestation in Karaj.

It is suggested to apply an 8-days irrigation period for reducing the seedlings production cost in the nursery.

It is a strategic need to find drought-resistant tree species with the aim of reviving Zagros forests. There are no enough researches about the effect of nano particls on the woody plants especially on their physiological features, while most of recordes have focused on crops. Therefore, in the current research, we investigated the effect of Nano Sio2 on Wild Pistachio (Pistacia atlantica subsp. mutica) seedlings in order to finding a resistant plant for rehabilitation of Zagros forest.

The experiment was based on a completely randomized design with 126 seedlings, six treatments of Nano Sio2 (control, 100, 300, 700, 1500, and 3000 mg. l-1) for 30 days and three replicates 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 such as chlorophyll a, b, total, caratoneid, carbohydrate, proline content, enzyme peroxidase of guaiacol and catalase were analysed in treated leaves seedlings.

The results showed that levels of drought stress decreased the chlorophyll, caratoneid contents and increased the soluble carbohydrates, proline, and antioxidant enzymes. In the other words, 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 stresses made a reduction in the types of chlorophylls and caratoneid; increase in carbohydrates, proline, and antioxidant enzymes.

It can be concluded that the most physiological traits were increased under drought stress and the Sio2 nanoparticles mitigated some traits like 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 the types of chlorophyll 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 resistant mechanism in the endemic tree species from Zagros forest 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 nano particles for longer periods or on some more species that could be a considerable way to find reliable results. These results may lead into economical production of drought resistant seedlings in large scales. Keywords: Drought resistant; leaf physiological features; Sio2 Nano-particles; Chlorophyll; Pistachio.

Eucalyptus species are used for afforestation in different ecological areas due to their rapid growth and high genetic diversity. The industrial performance of some species and provenances of Eucalyptus was evaluated.

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. 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, height growth, diameter growth and height to diameter ratio were measured. Because of evergreen eucalyptus trees, vegetative traits were recorded in two stages yearly, one in early autumn (after summer heat stress) and the other in spring (after winter cold stress).

Statistical analysis such as analysis of variance and comparison of mean traits between genotypes and different years showed that the effect of treatment (species and provenances), replication and year effect 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 according to the diameter of trunk, E. camaldulensis 41ch and E. camaldulensis Qom were in the first and second groups. In addition, E. camaldulensis 41ch and E. camaldulensis Qom were in the first group and E. microtheca 62 and E. rubida 166sh respectivelygroups. The diameter trunk of E. camaldulensis Qom was in the first group and E. rubida 166sh in the last group. In terms of trunk height to diameter ratio, the species were divided into two distinct groups and three common groups, based on these results, E. camaldulensis 41zh was the first group with the highest height to diameter ratio.

In general, the results showed that E. camaldulensis had the highest ratio of survival and establishment, it had the highest growth and diameter growth and E. microtheca was in the next place. E. camaldulensis seems to have a higher performance for wood production than other species and provenances, E. camaldulensis Qom was also ranked first in terms of diameter and height growth, this 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.

Old Oak trees and Baneh have a special importance in Zagros forests. Recognizing ecological characteristics in relation to the position of old trees can provide good information for providing management solutions for preserving or extending the trees of the elderly. The present study was carried out with the aim of investigating and recognizing the ecological characteristics of the sites of oak and pistachio old trees in oak forests of Ilam province.

By forest survey , old trees was selected according to the DBH criterion and their site conditions including slope, aspect, altitude, soil depth, climate, site bed status, proximity to the river or source water were measured or recorded.

The results showed that the Oak old trees were generally were on a gentle slope and the Pistachio old trees were more on the relatively gentle slope. Most of the identified Oak and Pistachio old trees were located in the southern aspect. The oak old trees were distributed in 1300-1700 m from sea level, but the Pistachio old 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. Crown area of oak and pistachio trees had better response to site conditions changes than their DBH and its variability depending on species kind was different. Most of the identified old trees due to locating on gentle slopes have relatively suitable soil depth than their surroundings.

Considering the optimal ecological characteristics of site situation of the identified old trees, it can be considered as the reasons for the sustainability of old trees along with their long life.