فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال بیست و هشتم شماره 1 (بهار 1400)

Canopy gaps are the most important environments for many species regenerations. Studying regeneration in natural and Man-made canopy gaps provides practical information to enhance the quantity and quality of tree species regeneration. This study aimed to investigate the relation between geometrical characteristics of canopy gaps with diversity and density of tree species regeneration in natural and Man-made canopy gaps.

Two 16 ha plots were selected with relatively similar site conditions in part of series one and two of Dr. Bahram-nia 's forestry plan, Shastkalateh, Gorgan. The position of 56 canopy gaps was recorded using a differential positioning system (DGPS). The main indices of the gap’s geometry including area (A), perimeter (P), and perimeter to area ratio (P/A) were measured and then the circular index (C) and the Gap shape complexity Index (GSCI) were calculated. Also, the frequency and diversity of tree species regeneration were recorded within 25 m2 plots centered on each gap. Gaps were classified into three small (20-150 m2), medium (150-300 m2), and large (more than 300 m2) area classes, and indices of species diversity were calculated for each gap using PAST software environment. Statistical analysis was performed to determine the significance of differences and relationships between geometric indices and diversity of regenerative species.

The average area of natural and Man-made canopy gaps were 206 and 176 m2, respectively. The mean circular index of Man-made canopy gaps (C = 0.72) was higher than natural ones (C = 0.66); although, their difference was not significant. Increasing the area, the shape of the natural gaps shifted away from the circular, elongated, and the complexity of their shape increased. The shape complexity index of Man-made gaps did not show a significant difference with increasing the area. Perimeter to area ratio of large gaps was smaller than other classes in both types of gaps. Regeneration density of Velvet maple and Ironwood species were significantly higher in medium Man-made gaps than other species, other classes, and natural mediums gaps. As a result, richness, total individual regeneration, diversity, dominance, and evenness in the medium gaps (300-150 m2) showed the maximum value and significantly different from the large gaps (greater than 300 m2). In natural gaps, with increasing area regeneration density of Velvet maple and Date-plum species, species richness, total individual regeneration, and species diversity of regeneration decreased significantly. A positive correlation was observed between the gap’s P/A with the regeneration density of maple and hornbeam species in natural gaps (r = 0.480 and r = 0.356, respectively). The richness index had a negative correlation with the perimeter (r = -0.337) and with area of natural gaps (r = -0.103). In Man-made gaps, the evenness index showed an inverse correlation and the species richness showed a direct correlation with P / A (r = -0.553 and r = 0.578, respectively).

Man-made gaps were more regular and rounder than natural gaps. As the shape of the Man-made gaps shifts away from the circle form, it was elongated and increased in fractures and complexities, and also the density of maple’s regeneration increased. Medium-sized Man-made gaps (150-300 m2) showed the highest value of richness, diversity, and regeneration density compared to other categories of gap area. Therefore, this range of gap size could be considered as the optimum range.

Salinity stress is one of the most important factors limiting the growth and expansion of plants on the planet. In the world, an area of about 800 million hectares, in Iran about 44 million hectares and in Golestan province more than 75000 hectares of its lands are affected by salinity and has poor vegetation, sparse and exclusively salinity-resistant species. The use of salinity stress-resistant tree species and increasing their yield by adding the required nutrients from different sources to the soil can be effective in establishing vegetation and optimal use of saline soils.

For this purpose, the present study was performed on one-year-old bitter olive seedlings (Melia azedarach) in a factorial experiment with two-factor as a completely randomized design. Salinity stress with irrigation water once every five days in five levels including 0, 5, 10, 15 and 20ds/m and fertilization in four levels including 0, 50, 75 and 100 g of Herbban mineral fertilizer it was applied for each seedling with five replications for 120 days. In order to reduce the adverse effects of displacement and repair of damaged roots, fertilization was performed 50 days before salinity stress. During the period of salinity stress, the rate of vitality quality and survival percentage were measured every five days and at the end of the period, 15 vegetative traits were measured. Data analysis of variance was performed using SPSS software and Duncan test was used to compare the means. Rank data were also analyzed by Kruskal and Ellis tests.

The results showed that salinity stress caused a significant decrease in vitality quality, survival, longitudinal growth, leaf area, number of leaves, average individual leaf area, specific leaf area, leaf fresh weight, leaf dry weight, fresh weight Root and leaf specific gravity increased at 5% probability level. The effect of fertilization caused a significant increase in longitudinal growth and a significant decrease in leaf specific gravity. The highest vitality quality and survival were observed in conditions without salinity stress and fertilizer application. The lowest vitality quality and survival were obtained at 20ds/m and 100 g of fertilizer. Significant increase in longitudinal growth and significant decrease in leaf specific gravity were the only significant effects of fertilization. Comparison of means did not show any difference between the mentioned traits at the control level and 5ds/m. The highest survival percentage at the end of the period at the levels of 10 and 15 ds/m were equal to 100 and 75%, respectively.

Therefore, according to the results, bitter olive easily tolerates salinity of 5ds/m and if suitable fertilizers are used with short stabilization time and high absorption percentage, it can be grown in areas with salinity of 10-15ds/m acted with different goals.

Study of slenderness coefficient and crown ratio of trees in forest parks to determine the stability of the stands against the wind is one of the important issues in the park management. The most important reason is the intensive presence of families and vehicles in these areas, which can cause irreparable damage if trees fall. Therefore, this study was conducted to investigate the sensitivity of Eldar pine trees in different parts of Sorkheh Hesar Forest Park to wind throw. Attempts have also been made to evaluate the suitability of diameter at breast height, as a variable that is simple and inexpensive to measure, to predict the crown ratio and slenderness coefficient as two important indicators for determining the susceptibility of trees to wind throw.

After a field survey, 14 patches were selected for sampling so that sampling sites were well distributed throughout the park. A total of 151 trees were randomly selected and their diameter at breast height, total height, trunk height, slenderness index and canopy ratio were calculated. Independent t-test was used to examine differences between tree lines and patches. Regression analysis was also performed to model the relationship between diameter-slenderness index as well as diameter-crown ratio.

Based on the results, the average basal area of the measured trees was 0.034 m2 and their average volume was 0.208 m3. Considering the variety of planting spaces, basal area and volume of pine stands were calculated 9.45-54.4 m2. ha-1 and 57.8-332.8 m3. ha-1 respectively. The results showed that the average slenderness index was 57.29% and that 0.7% of the trees were in unstable conditions. The average crown ratio was 0.557 and based on this index, 2.6% of trees were unstable. There was a significant difference between the forest patches and the tree lines along the streets in terms of crown length, canopy ratio, trunk height, and slenderness index. The linear model had a significant fitting to the data of diameter-slenderness index as well as diameter-crown ratio, with error percentage of 13 and 11.7% and coefficient of determination of 0.28 and 0.17, respectively.

In general, pine trees in Sorkheh Hesar National Park are in a stable condition and a small percentage of them need biomechanical study of wood tissues in order to determine the maximum tolerable wind speed and take precautions such as pruning. Also, diameter at the breast height in various plantings in terms of density, alone is not enough to predict the slenderness coefficient and the crown ratio of the trees. It is necessary to measure the total height and crown height of the trees to determine the slenderness coefficient and crown ratio. Due to the effect of the area and shape of tree patches in the incidence and severity of wind throw, it is necessary to consider the shape of the spots as a teardrop that is directed towards the prevailing winds in the region to minimize the risk of falling in busy places.

The semi-arid vegetation area of Zagros is the second source of forest biomass in Iran and has a special environmental importance. Over the past decades, the ecological potential of this region has degraded due to severe human pressure, and its forest trees have declined in the last two decades due to drought stress and attacks by wood-eating pests and charcoal fungi. Since chemical control further disturbs the natural conditions in ecosystems and biological control requires long-term research, so the application of sanitary cuttings is the most important way to control the degradation of Zagros forests in the current situation. Numerous scientific references have reported the positive role of branching and pruning of forest and garden trees in controlling pests and diseases. This article is the results of the second phase of a study that investigated the proper method of sanitary cutting in the forests of the Zagros vegetation area in the next four years. The aim was to investigate the role of five cuttings treatments in two forms of high and coppice to control the dieback of Persian Oak trees in the Zagros area.

In this study, the effects of vegetative form and sanitary cuttings on the survival and vitality of Persian oak after eight years was tested and compared with the project results in the four-year period of the first phase. Vegetative form was studied at two levels of high and coppice and cutting type in five levels including removal of infected parts of trees, complete removal of crown, cutting from height 10 cm and cutting from 10 cm depth and control treatment (without sanitary cutting). The researches treatments were compared with non-parametric tests due to the quality of the vitality data and the lack of parametric statistics assumptions in the survival treatments. Pair of two-phase research treatments were compared with Wilcoxon test, two vegetative form treatments with Mann-Whitney test and group cutting treatments with Kruskal-Wallis test and in pairs with Dunn-Bonferroni test.

The results showed that the difference in survival and vitality of the two vegetative forms in the two phases of the study was not significant at the 5% probability level. The difference of survival of cutting treatments in the two phases of the study was significant in all treatments at the level of 1% probability, except in the treatment of cutting infected sections. The difference of viability of cutting treatments in the two phases of the study was significant only in the control treatment at the level of 1% probability, in contrast to survival. The results of survival and vitality after eight years from the start of the experiment in the second phase showed a significant difference (α=1%) in the cutting treatments and no significance (α=5%) in the two vegetative form treatments. Also, the results of pairwise comparisons showed that the difference in the vitality percentage of the two treatments cut from the depth and from a height of 10 cm with the control treatment and the difference between the two treatments of cutting infected parts and complete cutting of the crown were not significant (α=1%).

In general, the targeted cutting treatment of infected parts in terms of survival (88.8%) which was the main factor of the study showed the best result alone and in terms of vitality (87.4%) with complete crown cutting treatment. Therefore, this sanitary cut is recommended to control the dieback of Persian oak trees in similar forest areas in the Zagros.

Roads and other linear structures are the most important examples of human activities, and it can be mentioned that they have the most critical environmental effects on the natural habitats and ecosystems of the world. One of the most obvious of these adverse effects is environmental pollution, which has received more attention in the last three decades.The purpose of this study was to investigate the sound level of a heavy vehicle engine with a high engine volume in two different longitudinal slopes of a forest road and to identify the type of relationship between decreasing sound intensity and increasing distance from the road.

In order to measure the sound intensity, eight stations were used as acoustic measurement points along 20 km of the main one-way forest road of Teaching and Research Forest from Tehran University ,with low (2-5%) and high (8-11%) longitudinal slopes and Zero (roadside), 25 meters, 50 meters, 75 meters, 100 meters distances into the mass and downstream of the road and the axis of the road (closest situation to the car engine) were selected.The average sound level emitted from the Benztruck was 2624. This research was performed by the SL-4023SD digital audiometer with an accuracy of 1.5 dB and a resolution of 0.1 dB. The factors such as ,mean car sound level for a vehicle with constant engine volume, longitudinal slope in two levels, distance from the road in five levels were measured and analysis of variance was performed by GLM procedure whith using SPSS software.

In stations with longitudinal slope of the lower class by 58.7% and in stations with longitudinal slope of the upper class by 56.6%, a decrease in sound intensity was observed compared to the roadside. In all stations, the greatest decrease in sound intensity was recorded at distances of 0-25 meters from the roadside. In general, the type of relationship between decreasing sound intensity with increasing distance in longitudinal slope stations of the lower and upper class is logarithmic.

According to the results, it can be seen that the longitudinal slope of the road did not have much effect on the intensity of sound emitted from the road. In this study, all variables, both independently and dependently, significantly affected sound penetration. The results of this study showed that the sound intensity decreased by moving away from the sound source. Careful design of road technical specifications such as longitudinal slope, maintenance of road pavement, the presence of vegetations on the roadside and prevent its destruction, maintaining and restoring the density of trees in the roadside mass, combined planting of broadleaf and coniferous species can be Somewhat reduce the intensity of sound emitted from the road.

Self-assembly engineering of cellulose nanocrystals in polymer substrates to expand the application range of these bio-nanostructures has become one of the hot topics of research. Mashkour et al. (2013 and 2019) introduced a method based on surface tension torque (STT) to control cellulose nanocrystals' self-assembly in polymer solutions to print birefringent nanocomposites. In this paper, the effect of solvent evaporation rate and concentration of polyvinyl alcohol/cellulose nanocrystal solution as polarizing printing ink on the quality of 3D nanocomposite printing was investigated.

Aqueous polyvinyl alcohol (PVA) solutions were prepared at three concentrations of 2.5, 5, and 10 percent, containing 5 percent of cellulose nanocrystal (CNC) by weight extracted from cotton fibers as printing ink. An embossed copper mold was used for the printing of polarizing nanocomposite films. The conventional oven and vacuum oven were used to regulate the rate of ink solvent evaporation. Evaluation and comparison of polarizing print quality were performed by microscopic imaging and quantitative analysis of the resulting micrographs.

Analysis of microscopic images revealed that by increasing the ink carrier (PVA) ratio in the ink formulation, the ink viscosity increased significantly, whereas by adding CNC nanoparticles to the composition, the increase in viscosity was significantly reduced. Three indicators were defined and used to assess and compare the quality of printing: Interference Color Contrast (ICC) Index, Pattern Match Index (PMI) and Pattern Symmetry Index (PSI). The increased concentration of ink due to an increase in the weight fraction of the ink carrier increased the ICC index, and the effect of this factor on the PMI and PSI indices showed a similar pattern; The highest and lowest values of the PMI and PSI for three-component inks were obtained at concentrations of 10% and 5% PVA, respectively. Increasing the solvent phase's evaporation rate did not significantly affect the ICC index, while PMI and PSI values significantly affected and reduced print quality.

In summary, based on the findings of this study, it can be stated that the use of three-part printing ink takes precedence over two-part printing ink. Reducing the evaporation rate of the solvent phase was also found to have a significant positive effect on print quality. With regard to the ink composition used in this study, a concentration level of 5% is recommended for the ink carrier to achieve the desired print quality.With regard to the ink composition used in this study, a concentration level of 5% is recommended for the ink carrier to achieve the desired print quality.

formaldehyde was used as a cellulose tissue resistor and important in textiles and is technically feasible. Also in this search, pulp of paper has applied inside to yarn because to more effect elucidation of crosslink reaction.

The conditions under which these studies have been made simulate those which have been found useful in the textile industry for the application of formaldehyde and relative Compounds such as polyvinyl alcohol (PVA) was attempted to apply for the improvement of fabrics made of regenerated cellulose fibers. The main challenge:In usual Formaldehyde is combined with urea to strengthen cellulose tissue But Cellulose- formaldehyde application has two problems. the first problem is hard and brittle of this compound so it is Not suitable for textile industry and second problem is that , gradually compound releases formaldehyde and formaldehyde is smelly and toxic.

To solve these problems of emission of formaldehid and stiffness , 3 solutions were done In this study, polyvinyl alcohol was used instead of water Borax catalyst was used in the formaldehyde-cellulose reaction and the unreacted formaldehyde was neutralized with solution of sodium hydroxide50%Wt/Wt.

In this study Formaldehyde-cellulose reaction conditions were optimized , 3 Phenomenons was examined as a goal and proved: 1.Formaldehyde evaporates at 30 ° C without reaction, and at higher temperatures (150 ° C) the reaction of formaldehid-cellulose takes place over a wide range of conditions. But it can be done with borax catalyst at 95oC 2. Reaction is not possible under mildly acidic conditions and the medium must be acidified with HCl or a NH4Clcatalyst must be used. 3. The cellulose-formaldehyde reaction before the addition of urea and the synthesis of cellulose methylene ether reduces the evaporation of formaldehyde. Reducing the evaporation and degradation of formaldehyde makes the product suitable and safe for the textile industry. 4. Treatment of cellulose fibers with formaldehyde in severe acidic conditions causes significant changes in their physical and mechanical properties. The properties of such treatment increase Improved elasticity and stiffness (Young modulus) in cotton fabric. In this study, formaldehyde emission (FE) and content (FC) from different types sample; were measured using head-space test method namely Gas Cromarography(GC) and NaHSO4 method. there was no significant effect from the moisture content. approximately the same indication of formaldehyde values, as well as similar behavior, were seen for each method.Moreover, the results indicate surprisingly that there was a good correlation between Values of the emittable formaldehyde concentrations from most of the products investigated . Values of the emittable formaldehyde concentrations from most of the products investigated in the present study were below the limits that are in the usual urea-formaldehid method.

Product of this paper can be use to cellulose coating of soft plastic such as polyvinyl chloride leather and polypropylene yarn. Because it is softer and more elastic than the usual urea-formaldehyde method and releases less formaldehyde.

One of the most effective methods to protect wood against weathering is the use of coating. Among different coatings, light-curing ones have been attracted much attention due to less investment, low energy consumption, low cost, high solid content and solvent-free, high speed curing and yield, etc. In this study, the effect of two transparent UV-curing coatings, including epoxy acrylate and urethane acrylate on the weathering resistance of spruce wood was investigated.

200 mm-thick coating layers were applied on the surface of wood using a film applicator followed by UV-curing process of epoxy acrylate and urethane acrylate each for 5 and 40 seconds, respectively. Then, the coated specimens and control one were exposed to 6 months weathering. Finally, the effect of weathering on the specimens were tested using ATR-FTIR, stereo microscope, SEM, calorimetry, roughness, water-droplet contact angle and cross-cut adhesion.

Results showed that the color of uncoated wood specimens changed and their roughness increased due to weathering. Many surface cracks occurred in the uncoated wood after weathering. Many cracks were also developed on the surface of urethane-acrylate coating, while no surface cracks were observed in the epoxy-acrylate coating. The discoloration level caused by weathering was higher in the control sample compared to that of the coated samples. The most resistant coating to the weathering discoloration was epoxy acrylate. The contact angle of weathered samples was affected by the surface cracks and roughness values in addition to changes on the surface chemistry. ATR-FTIR results showed a reduction in the intensity of peaks at wavenumbers of 1740 cm-1 (vibration of C=O) and 1504 and 1595 cm-1 (vibration of C=C in aromatic ring of lignin) which indicates the degradation of hemicelluloses and formation of new carbonyl compounds and lignin degradation in specimens due to the weathering. Reduction in the intensity of peaks at wavenumbers of 1510 cm-1 (vibration of CO-NH) and 1248 cm-1 (vibration of C-O-C) in wood samples coated by urethane acrylate showed the cleavage of urethane chains due to UV radiation. Results also showed that urethane acrylate had lower adhesion strength than epoxy acrylate, and the strength was reduced for both coatings as the result of weathering.

In general, both epoxy-acrylate and urethane acrylate coatings increased the resistance of wood against weathering. However, epoxy acrylate had much better performance compared to urethane acrylate. The adhesion strength and color of the epoxy-acrylate coating with no surface cracks were less affected by the weathering.