فصلنامه جنگل و فرآورده های چوب
سال شصت و هفتم شماره 2 (تابستان 1393)

In order to achieve a sustainable management and development of natural resources، a set of technical، eco-social، environmental and ecological criteria must be considered in the planning process. An appropriate model is therefore needed to address all the criteria mentioned above، in the decision making process and finally provide a reliable result. In the last few years، analytical hierarchical processes were used increasingly in natural resources research. The question is، can the method be used in such research and would the output be applicable? Delphi and AHP methods were used to conduct a multi-criteria based forest road planning. The order of ranked criteria in both methods were investigated and compared. According to the obtained data from participants different ratings for the criteria in the two different methods were recognized. However، average rating (overall weight of each criterion) showed that the four most important criteria out of the eight criteria were ranked in the same order in these two methods، but the priority levels 5، 6، 7، and 8 were ranked differently in the two methods. According to the results، variances among the experts during the Delphi process were noticeably reduced because it is performed in three rounds so that it can lead to a consensus within the panel of experts. However، results of performing AHP showed that this method is so sensitive to the experts’ responses، thus the output cannot be easily used in practice. Therefore، researcher should care more when using this method or its output and، similarly، experts when rating criteria by this method.

Tree felling، delimbing and bucking includes all activities undertaken to fell standing trees and prepare them for extraction. The study was conducted in Gorazbon district in the Hyrcanian forests. In this study، the objectives were to discover the special characteristics in the time consumption of manual tree delimbing and bucking، productivity and costs، and develop regression model. The continuous time study was conducted with professional operators for chain-saw delimbing and bucking and the cycles were broken down into time elements. Tree delimbing time of working crew is the most time-consuming element in delimbing and bucking، followed by bucking and rest and meal time. The operational and personal delay is the most time-consuming delay time in tree delimbing and bucking. Result showed that time consumption for delimbing and bucking was increased with increasing diameter. Labor costs accounted for 37% of the hourly cost while only 1. 5% was related to machine cost. A significant linear relationship was found between delimbing and bucking cycle time and diameter. Productivity of chainsaw delimbing and bucking was increasing related to tree DBH as power. The costs of chainsaw delimbing and bucking with and without delay time were 203710 and 179796 Rial/m3، respectively. The cost of delimbing and bucking was increased as simple exponential equation when DBH of harvested tree was decreased. However، the unit delimbing and bucking cost for chainsaw operation decreased as tree size increased. Total delimbing and bucking cycle time without delay averaged 25. 31 minutes and with delay time were averaged 22. 34 minutes.

Moderate Resolution Imaging Spectroradiometer (MODIS) have been widely used for active fire detection in the world as the specific channels used for the fire detection have made the MODIS images applicable. The main objective was to explore the capability of MODIS images for active fire detection in the Zagross forests using the MODIS contextual algorithm. The study was performed in the Marivan forests located in the Zagross forests، west of Iran. Details of 20 reference fires occurred in the study areas were acquired and imported to GIS. MODIS images of fire days as well as the previous and past days of fires were collected. The Aqua images were obtained from the L1B level، which was suitable for using in this algorithm whereas Terra images were obtained from PDS format and then preprocessed to the L1B. MODIS images were processed for active fire detections using MODIS contextual algorithm. MODIS active fire detections were compared with reference fires. The results revealed that six reference fires were found. In addition، four fires were detected by images not included in the 20 reference fires. Finding the location of these four fires on the 1:25000 topographic maps showed that they have happened in urban areas. The shorter duration and lower temperature of fires during the data acquisition was probably the main reason in failing fire detection. Thirty percent of all reference fires were detected which may help to prevent more losses. It can be concluded that MODIS images provide a valuable source of information concerning the fire activity in the Zagross forests; however، the contextual algorithm was not successful in the detection of forest fires. We recommend that MODIS contextual algorithm can be used in the Zagross forests، however، complementary research، should be carried out for development a regional fire detection algorithm in this area.

The aim of this research is to classification of soil seed bank in Populus Caspica Protected Area. The study of above ground vegetation and soil seed bank were carried out with Braun-Blanquet and seedling emergence method respectively. Results showed that size of soil seed bank in upper layer (713 seeds per m2) were significantly lower than depth layer (1163 per m2) but species richness from 42 to 28 species were reduced with increasing the soil depth. The result also showed that based on the whole plants from the region (65 species) only 35 species were classified in the persistent soil seed bank. Generally، we are concluded main، late-successional، species have not the ability to producing persistent soil seed bank، so the restoration of extant vegetation cannot rely on the soil seed bank in case of the overall habitat is destroyed.

In order to study the qualitative، quantitative characteristics of a pure common Populus alba stand in Polkalleh & a mixed stand of Populus alba & Populus nigra in Karchegan، two 30-year-old stands were selected with a plantation interval (spacing) of 2. 5 × 1. 5 m in each of which 30 pcs of 2 are samples were randomly selected. In each sample pc all the trees diameters were measured using a diameter gage tape and relevant heights were measured using a Sonto gradiometer. The measurement results of quantitative variables showed that average diameter for the pure Populus alba stand 26. 36 cm، for the mixed stand of Populus alba & Populus nigra 22. 02 cm، for the Populus alba trees in the mixed stand 22. 44 cm and for the Populus nigra trees in the mixed stand 20. 98 cm obtained. Also the average height for the pure Populus alba stand 23. 09 m، for the mixed stand of Populus alba & Populus nigra 21. 05 m، for the Populus alba trees in the mixed stand 21. 31 m and for the Populus nigra in the mixed stand 20. 42 m calculated. Average volume for the pure Populus alba stand 679. 06 m3/hectare and for the mixed stand of Populus alba & Populus nigra 679. 06 m3/hectare obtained of which 323/81 m3/hectare for the Populus alba trees and 106. 24 m3/hectare for the Populus nigra trees respectively. According to the results، quantitative and qualitative characteristics of pure Populus alba stand is in a better situation than than the mixed stand of Populus alba & Populus nigra.

In order to study the effect of elevation on quantitative and qualitative characteristics of the humid forests of Guilan Shafaroud، series 17، 16 and 7 were selected that fall in to three height classes; class 1 (less than 500 m)، class 2 (500 – 1000 m) and class 3 (1000 – 1600 m). In height class 1، 2 and 3 sample plots were determined as 4، 15 and 20 respectively and each sample plot was 0. 1 ha and characteristics of species، total height، crown symmetry، crown diameter، canopy cover، and diameter at breast height، regeneration status of the species and percent of species mixture in each site were calculated. The results showed that there are maximum density of lime in the elevation range of 600 - 1000 m from Height above sea level and extends to the northern and eastern slopes. Also، symmetry of the crown، regeneration status and canopy cover survey of trees showed that broad and symmetrical crowns ranged from 400 - 800 m، utmost regeneration density belong to height class 1، 2 and the height class 2 with %85 have maximum canopy cover. The distribution of trees in diameter classes revealed that forest under study has irregular uneven-aged structure and the irregularity of the curve also shows the ravages during different stages of growth. The overall، habitat of class 1 in Shafaroud forests، determine the most suitable habitat for lime trees.

Today، determination of the ecological species groups for current and future situation of forest and its relationship with environmental factors is necessary for forest management. For this purpose، 50 plots were established in altitude range of 2091- 2811 meters above sea level and 600 hectare in protected area of western Dena. Four ecological groups was identified Using Twinspan analysis that altitude، slope and EC were effective in separation of groups. The second group with most grass cover located in low slope that soil conditions of it was best. But fourth group with Juniperus polycarpos، Ferulago angulata indicator species had unsuitable environmental conditions. In the first group، Pistacia atlantica was indicator species and this group had lowest altitude and highest lime and tree cover of oak. Also، results showed that classification of vegetation can up to 80 percent separately habitats accurately. So، these researches can help to identify of ecological niche of species and to understand of habitats situation.

Polylactic acid based Biodegradable nanocomposites reinforced with acetylated nanocellulose were fabricated with solution casting procedure. The nanocomposites were prepared by adding 1، 3 and 5% nanofiber loadings. The microstructure، physical، mechanical and thermal properties of the prepared nanocomposites were investigated. Scanning electronic microscope (SEM) analysis of the composites confirmed the uniform distribution of nanoparticles within the matrix at low percentages. According to water vapor barrier test results، acetylated fibers did not improve the permeability of the prepared composites. Tensile strength (elongation) of nanocomposites had improved significantly by reinforcing with nanofibers due to the good dispersion of nanofibers at 1 and 3 percent، while the increase of nanofiber led to an aggregation and a brittle film with increased modulus of elasticity. Reinforcing effect of nanocellulose caused an increase in glass transition and melting temperature of the composites. However، the thermal behavior of nanocomposite and pure PLA films showed a very similar pattern.

In the present study، development of new asbestos-free brake pad using lingo-cellulosic fibers and nano aluminum oxide particles was investigated. Variable factors were the type of lignocellulosic materials (Jute، bagass and rice husk) and the size of aluminum particles (nano and micron). These newly formulated brake pads have been tested under the grey cast iron disc. Friction coefficient and wear rate and thermal expansion were examined. Results showed that brake pads made from jute fibers and nano alumina have the best shear strength properties and the highest shear strength was obtained by using of rice husk and micro alumina. Also the best friction coefficient was about the manufactured linings by bagass fhbers and nano alumina and the lowest wear rate was observed in the linings made of rice husk and micro alumina. Results showed that brake pads made from Lignocellulosic fibers have desirable properties in comparison with standard values. Therefore using of this material in manufacture of brake lining is possible and properties of the linings made of nanoaumina were improved.

Cellulose nanofibers (CNF) which isolated from wood and non woody plants have attractive advantages comparing with the synthetic fibers، some of the most relevant being the following: low density، renewable sources، biodegradability، availability، and high specific mechanical properties. Recently، the use of CNF in green materials، especially as reinforcement in different polymers has been increased greatly. However، the existence of the hydroxyl groups on the CNF surface leads to high hydrophilicity and limited dispersibility of CNF in non- polar polymers. In this study، the chemical modification has been used to enhance the hydrophobicity and dispersibility of CNF in non-aqueous mediums. Therefore، isolated CNF from Kenaf bast fibers was acetylated with acetic anhydride to obtain acetylated cellulose nanofibers (ACNF). The properties of both acetylated and non-acetylated nanofibers were studied. FTIR analysis was used to confirm the replacement of hydroxyl groups with acetyl groups. The degree of substitution was calculated by using titration method and it was found to be 0. 22. XRD analysis indicated crystalinty index of ACNF decreased compared to untreated CNF. The dynamic contact angle measurement showed that the hydrophilic surfaces of CNF become more hydrophobic due to the partial acetylation. In addition، TGA results clearly demonstrated an increase in thermal stability of acetylated nanofibers. The study of the dispersion illustrated that acetylated cellulose nanofibers formed stable، well-dispersed suspensions in both acetone and ethanol.

The MOE and MOR are controlled by production variables of particleboard process. Now، the basic question is which of the particleboard variables is effective on bending strength property? 13 variables of internal scientific resources were measured with 100 repeats. The study steps include the following; liner regression or stepwise، Genetic algorithm، and Artificial Neural Network. The number of effective variables was selected from the output of the stepwise procedure and then modeling of these variables using WinGamma and Mathlab. The number of effective variables in the modulus of elasticity and modulus of rupture are equal to 10 and 9، respectively. As the results of Gamma test shows، effective variables of bending strength are as following: 1. Type of wooden raw material، 2. specific gravity of raw material by simple averaging، 3. specific gravity of raw material by weighted averaging، 4. UF percent، 5. particleboard density، 6،7، and 8. Time، tempreture، and pressure of press. In the other hand، particleboard thickness of MOR and also، percent mixture of wood and non-wood lignocellulosic materials and NH4CL percent for MOE are important. Results of Genetic algorithm and Neural Network were showed that some variables can be kept constant and particleboard properties are controlled by these effective variables، but specific gravity of raw material by weighted averaging for MOR and UF percent of MOE have the strongest effect. Result of BFGS Neural Network has shown that mean absolute percent error of MOR and MOE are equal 5. 644% and 4. 91%، respectively.

Upgrading recycled fiber properties has been a constant concern in pulp and paper industry. In this respect many researches has been applied. The present paper has been considered the effect of Amylase enzyme in pulping stage of old corrugated container (OCC). Also، pre-soaking of OCC (first step of pre-soaking for 6 hours in 3% consistency in different pH(s) and second step of pre-soaking at 60˚C for 18 hours with constant pH) in acid، neutral and alkaline pH on physical and mechanical properties (air resistence، tensile index، burst index، tear index and fold) of recycled paper and its effect on Amylase performance was investigated. Soaking itself improved mechanical properties. Alkaline pH pre-soaking had the most efficient effect on the mechanical properties. The results indicated that α-Amylase treatment improved the mechanical properties (except tear index) in the non-soaked samples but Amylase treatment had no significant effect on the soaked samples in the experimented pH ranges. The results showed that independent effects of soaking and alkaline treatments had superior effect on mechanical properties compared to enzymatic treatment. Statistically، none of treatments had significant effects on air resistence.

The objective of this study was to investigate the relationships between 16 process variables of the CMP tower chemi-mechanical pulp، and 17 newsprint quality properties at Mazandaran Wood and Paper Industries and to develop predictive models. After preparation of suitable data series considering the time needed for pulp to paper، the relations between process dependant and newsprint independent variables were determined using partial least squares (PLS) regression. In result، 4 calculated latent vectors could categorize and relate variables. The first vector as the most important factor، determined about 50 percent changes of 7 newsprint properties including; Caliper، Bulk، Breaking Length MD، Elongation MD، Burst، Opacity and Air Resistance. The amount of fibers remained on the +48 mesh screens including long fiber fractions، was the most influencing variable on the above 7 newsprint properties. To predict the newsprint properties، after reduction of model dimensions، reduced rank regression method were used that in result the changes in paper caliper، bulk، breaking length MD، burst and، opacity were determined as much as 48. 7، 49. 2، 45. 3، 51. 5 and، 52. 4 percent respectively by CMP tower process variables.

In this research، creep behavior of medium density fiber board (MDF) under different conditions (different relative humidity and different temperature) was investigated. For this purpose، flexural creep tests at 15% and 30% of ultimate bending load were performed by using flexural creep equipment. The samples underwent under load at relative humidity of 45، 65 and 85% and temperatures of 15، 23 and 30°C for 72 hours. The results showed that relative creep and total creep of the samples increase with increasing temperature and relative humidity، while the creep modulus decreases with increasing temperature and relative humidity. The greater changes were obtained at higher relative humidity and temperature an also at higher load level. The results also showed that the relative creep is more sensitive to relative humidity compared to temperature. Conversely creep modulus is more sensitive to temperature compared to relative humidity that greater changes have been observed in higher load level.