فصلنامه جنگل و فرآورده های چوب
سال هفتاد و دوم شماره 4 (زمستان 1398)

The present study aims to investigate the effects of industrial dusts on Zarandin forest covering section 3 of the Neka-Zalemrood Forestry Plan in the northern Hyrcanian forests by analyzing NDVI vegetation indices extracted from Landsat satellite imagery. To this end, in accordance with the position of the MODIS pixels, four 250 m pixels affected by industrial dust were identified near the dust center during field visits. The correlation coefficient between EVI and SPI with a 7 month lag was 0.15 and for NDVI with 8 month lag was 0.13. The p-value was not significant. The NDVI at different distances (from less than 800 m to more than 2000 m) of the pollution center during the years of access to Landsat images (1972-2017) showed a decreasing trend. Simple linear regression results of NDVI and time at different distances from the pollution center showed that the passage of time had an inverse correlation with NDVI in less than 800 m distance from the pollution center and its regression coefficient (R2) was 0.837. By increasing the distance from the pollution center, the NDVI variations decreased over time so that the explanation of the regression coefficient between time and NDVI reached zero in a distance more than 2000 m. Due to the small role of drought and quantitative changes of vegetation in the study area, it strengthened the role of industrial dust due to industrial activities in causing forest vegetation stress.

Forest harvesting operations as heavy and dangerous work requires abnormal, uncomfortable working conditions, exposure to noise and vibration, which has adverse health consequences and may lead to illness and injury. Vascular abnormalities, such as the Rhinoceros or White Hand phenomenon (VWF), are known to be the most important, most dangerous, and most common effects of vibration. The purpose of this study was to determine the permissible time limit for vibration exposure during operator exposure to echomotor vibrations in evacuation of evergreen, poplar and alder trees (VWF) in Kheyrud Nowshahr training and research forest in Mazandaran province. Measurement of the time limit index of the governor indicated that the maximum exposure time (hour) for the operator during vibration was 2.59 hours for the whole tree. Therefore, maximal timing workers can partially prevent diseases and injuries caused by vibration motors. According to the results, since the amount of clock exposure the vibrator worker has in the bibliographic mode is higher and the prediction time of the white-handed disease in the rotor worker is greater, therefore, if one is in the binary phase Working two hours a day, evangelical worker has to work with saw for a maximum of 9.61 hours during the week, which is 14/34 hours for poplar and 18/01 for alder. Accordingly, the more hours an ohmicor worker was exposed to in one day and the more the ohmicorum's total vibration increased, the operator had to wait less time than the saw during the week to prevent white-handed disease (VWF).

The increase in greenhouse gases results in climate changes and global warming and adversely affects the life on earth, while forests play a prominent role in carbon storage. The purpose of this study was to determine the most suitable allometric equations for estimating carbon storage in juniper species. For modeling, after examining the statistical results of quantitative characteristics (diameter at beast height, height and canopy area) of juniper trees and determination of amplitude of changes in breast height diameter, samples of leaf, branch, and trunk were collected from at least 3 trees in each class (total of 35 trees). The amount of carbon storage of leaf, branch, trunk and total trees was calculated in the laboratory. Allometric equations were obtained based on power, exponential and polynomial regression models. Coefficient of determination, standard deviation of fitted model, regression analysis, and normal distribution of residual values were used to validate the models. The results showed that the independent variables, diameter at beast height, crown surface and mean diameter of the crown produced equations with better modeling indices. Also, the power model (R2 = 0.96) and polynomials (R2 = 0.95) was more appropriate than the exponential model. The coefficient of explanation obtained from the regression models showed that these allometric equations are suitable for estimating carbon storage of juniper trees in the study area. The results also showed that each hectare of juniper forest stands was 4.42 tonnes and 13260 tonnes of carbon was stored by underground part of the juniper species in the whole study area. The highest amount of carbon storage is in the trunk and the lowest is in the leaf. The economic value of carbon storage by species was calculated as 25034880 Rials per hectare.

The Zagros forests are one of the most valuable natural ecosystems that are endangered and destroyed every year for various reasons including fires, over-exploitation, grazing, etc. Solution for protecting it lies in the participation of community members in general and rural women in particular. In this regard, one of the related organizations in this field is forest conservation cooperatives, which has not received much attention in this field. Therefore, the present study was conducted with the aim of finding factors affecting rural women's membership in Zagros Forest Conservation Cooperatives in Lorestan province. The statistical population included all rural women over 15 years in Lorestan province (N= 231000). Sample size was calculated using Cochran sampling formula of 235 persons by proportional classification method (based on forest area). The results of the discriminant analysis showed that the seven variables of forest dependence, social trust, environmental concerns, conservation attitudes, self-efficacy, knowledge of forest issues and conservation attitudes had the most power in separating member and non-member groups in cooperatives. In summary, the discriminant function from these seven variables is able to accurately differentiate the studied women with 86.5% accuracy in membership and non-membership of forest conservation cooperatives.

The aim of this study was to investigate flexural strengthening of screwed Glulam made with poplar (Populus alba). Polyurethane adhesive and screw were used for joining layers and applying pressure for manufacturing of three-layer glulam. The variables of this study were types of reinforcing (galvanized steel, aluminum sheet and glass fiber reinforcement polymer) and arrangements of reinforcing: No. 1 (bonded on the bottom (tension) side); No. 2 (bonded on the bottom and top (Tension and compression) side); No. 3 (bonded on the bottom, top and between two bottom layers); No. 4 (bonded on the bottom, top and among layers). Bending test was conducted by Instron according to ASTM D7341. The highest MOR (82.96 MPa) and MOE (1066.33 MPa) were both observed in Glulams reinforced by galvanized steel sheet with arrangement of No. 2 and the lowest MOR (57.82 MPa) and MOE (4397.33 MPa) were both related to Glulams reinforced by GFRP wrapped with arrangement of No. 1. MOR and MOE of control Glulams were 48.1 and 4330 MPa. The increasing percentage of MOR due to reinforcing by galvanized steel, aluminum sheet and GFRP Wrapped were 72.5, 57.8 and 42.6, respectively. The increasing percentages for MOE were 134.2, 57.6 and 28.4, respectively. Failure modes of Glulams changed from brittle to ductile by reinforcing resulted in improving of flexural behavior. The independent effect of types and arrangements of reinforcing on MOR and MOE and also the interaction of types and arrangements of reinforcing on MOE were statistically significant.

This study aims to fabricate an eco-friendly wood plastic composite with poly (lactic acid) biodegradable matrix reinforced by wood flour and pulp fibers. Polylactic acid (PLA) samples were compared to the samples made from one of the most commonly used synthetic plastics, i.e. low density polyethylene to evaluate the results of this study. Besides, in order to achieve the best characteristics of the new composite, some effective factors such as the mixing percentage of the filler and matrix in four levels and the shape of the wood material in two levels of wood flour and pulp fibers were used as variables. Samples made of PLA and low density polyethylene were fabricated by flat press and by injection molding, respectively, according to ASTM standard. In this work, in addition to test the physical and mechanical properties, the morphological properties of the new product were studied by electron scanning microscopy. According to the results, the mechanical properties of all samples made of low density polyethylene and poly lactic acid increased with increasing content of paper fibers and wood flour and the highest mechanical strength was observed for samples containing low density polyethylene. The results of physical properties also showed that in all specimens, with a decrease in the content of wood flour and paper fibers, water absorption and thickness swelling were improved. In addition, samples made of low density polyethylene showed better physical properties than samples containing PLA polymer. Finally, by reviewing the results of this study and comparing the microscopic images of the samples, it can be concluded that the best mechanical and physical resistance are related to specimens made with low density polyethylene and wood flour.

Considering the high cost of the methodical construction of buildings and the use of engineered and safe materials; the structure such as gypsum board has been interested of experts in wood and construction industry. The reason is important features such as low production costs and high earthquake resistance. Moreover, it’s important to determine effective criteria for decision-making for the establishment of industrial units aimed of optimal use of raw materials, the production process and approaches to reduce costs and waste. To achieve this, paired comparative analysis method was selected and after initial studies, field surveys and interviews with experts, 5 main criteria and 32 important sub-criteria were identified. After that, the paired comparisons questionnaires were prepared and filled out by academics and a number of managers and experts in wood and construction industry. The results revealed that among the first level criteria, material and product, economic and financial criteria have the highest priorities, respectively. Besides, sub-criteria of ensuring the sustainable supply of gypsum resources, raw materials costs, background of the mineral composites, background of the construction industry, distance from the gypsum resources, content of the gypsum resources finally the amount of sale had the highest priorities, respectively.

Converting biomass waste such as bagasse as an abundant lignocellulosic resource available for producing biofuels can be a viable alternative to fossil fuel and environmental pollutants. The purpose of the present study was to produce biofuel briquettes from two dimensional classes of shredded bagasse and grinded bagasse. Nanometer lignocellulose binders including nanolignocellulose (LCNF) and nanocellulose (CNF) at three levels of 3, 6 and 9% were used to enhance and improve the thermal and technical parameters. The briquettes were produced by cylinder and piston press at 150 MPa and 100 °C. The results showed a positive effect of nanometer lignocellulosic binders on the thermal and strength properties. Thus, nano-lignocellulose was more effective on the physical and mechanical properties of nanocellulose binder in both dimensional classes. Also, in terms of thermal properties of nano-lignocellulose binder, better results were obtained in biofuel briquettes. Consequently, nanolignocellulose may be a more suitable binder, since its production costs are lower than nanocellulose and the calorific value of briquette is higher due to the low lignin content in the compound. As a result, at 9% level of usage, calorific value and compressive strength of shredded and grinded bagasse were 34.37 N.mm, 19.85 MJ/Kg and 19.85 Nmm 29.45 MJ/Kg, respectively.