فصلنامه پژوهشهای علوم و فناوری چوب و جنگل
سال بیست و هفتم شماره 2 (تابستان 1399)

Nitrogen dynamics is one of the factors that may change under silviculture practices. Regarding the importance of total nitrogen content and its seasonal variation, the present research studies these changes in the mixed beech-hornbeam stands located in district one of Shast-Kalateh forest, Golestan province, Iran.

To study the total nitrogen variation in an average altitude of 850 meters and northeast direction with two-stage and middle-aged structure, 20 samples were randomly collected at the depth of 20 cm in four stands (1 ha) as treatments including non-managed stand and 3 managed stands (selection system) in 10 (Parcell 30), 7 (Parcell 33), and 1 (Parcell 31) years rotation from January 2014 to January 2015. The data and seasonal variation were compared by repeated measure design (p≤0.05).

The results showed that there was a significant differences between managed treatments and control (p < 0.05). The highest (61.37 gr kg-1) amount of total nitrogen was observed in control treatment (Parcell 32) while lowest (41.78 gr kg-1) was in managed treatment (Parcell 31). The total nitrogen content in managed treatment (Parcell 30) (4.80 gr kg-1) was close to the control. Also, seasonal comparison of total nitrogen showed significant differences in all treatments. Among all managed and control treatments, summer (4.31, 3.05, 2.4 and 4. 31 gr kg-1) and winter (5.52, 5.96, 4.55 and 4.77 gr kg-1) had the lowest and highest total nitrogen, respectively.

Single tree selection system creates positive changes in above ground section of forest stand, compared to others. It cans also changes in above and below gound sections of forests and cause to reduce total nitrogen in ecosystem in early years. Decreasing in total nitrogen content is not permanent and due to the self-regulation and self-sustainbality of ecosystem, the amount of nitrogen is driven to equilibrium through time. According to the results, single-tree selection system has lead to a decrease in total nitrogen content, therefore, to help restore ecosystem to balance situation, the rotation period should be calculated with respect to the amount of growth, the capacity to restore stand and the habitat to restore the ecosystem to a perfect balance. Regarding the difference of 0.32 gr kg-1 nitrogen in managed treatment (Parcell 30) with 10 year rotation compared to the control treatment, it is advisable to increase the rotation period 3 to 5 years in selection system to improve stand physiognomy (crown cover, etc.) and edaphic conditions.

Rural communities in developing countries are facing challenges for their livelihood due to various reasons such as resources limitations, low income and job opportunities. In forested areas, wood and non-wood forest products have created an opportunity for self-consumption and have become a source of income for local residents. In this regard, the present study seeks to identify the type and rate of forest product utilization and its impact on livelihoods of local communities in the Jaji Aryub forests of Paktia province, Afghanistan.

This study was an applied study that was conducted as a survey in Jaji Aryub forests of Paktia province in Afghanistan. The statistical population of the study consisted of 1404 household heads in 14 villages, of which 303 were selected based on Krejcie Morgan table. The main research instrument was a researcher-made questionnaire consisting of 20 items related to the type of forest products use in five sections: 4 items fuel consumptions, 3 items construction consumptions, 7 items food and nutrition uses, 2 medication uses, 4 items outdoor recreational services. Livelihood level of the local communities were studied in three dimensions of employment and income with 12 items, nutrition and health with 5 items, and support and housing with 6 items. Expert opinion was used to determine the content validity of the questionnaire and calculated Cronbach's alpha coefficient was used to estimate its reliability. After data collection, analysis was performed using SPSS 21 software in two parts: descriptive and inferential statistics.

According to the respondents' viewpoints, in average, fuel consumption with 3.94 and outdoor recreation with 2.57 (from 5 point), had the highest and the lowest using rates by local communities, respectively. Livelihood of rural families was correlated to usage of wood and non-wood forest products with medium rate (approximately 3 from 5) in three dimensions of nutrition and health, support and housing, and employment and income. The results indicated that, there is a significant positive correlation between the using rate of forest products by local communities and their total livelihood (99% confidence level). The results also showed that there was a positive significant relationship (99% confidence level) between respondents' use of forest products and their age and number of household members with correlation coefficients of 0.163 and 0.148, respectively. While a negative significant correlation with their education level were distinguished.

livelihoods of local communities in the Jaji Aryub forests of Paktia province, Afghanistan are, highly, depended to the forest resources due to various reasons such as environmental limitations, individual characteristics, lack of welfare, and limited income and job opportunities. Providing new energies (solar radiation, wind and oil), new job opportunities, creating local and regional markets and supplying processed products, as well as conducting training workshops based on participatory and social forestry were recommended.

Nowadays the nanoscale fillers and cellulose nanofiber (CNF) have been extensively developed in food industry, particularly food packaging systems. The incorporation of nanoscale fillers in the packaging material can play a useful role in improving the mechanical, barrier and thermal properties of the packaging material. Cellulose nanofiber have received much attention as reinforcement in polymer nanocomposites due to their renewability, low cost, biodegradability, high aspect ratio and having good mechanical properties. The main aim of this study was to fabricate and to evaluate the properties of nanocomposite films made from (CNF) and low-density poly (ethylene) (LDPE). Here, styrene maleic anhydride (SMA) was added as a coupling agent.

The nanocomposites with different cellulose nanofibers (0, 3, 5, 10 wt %) were prepared by freeze drying of CNF gel and melt compounding of dried CNF with LDPE in an internal mixer and then the composites were manufactured by compression molding method. Water absorption, fourier transform infrared spectroscopy (FTIR), and mechanical test (modulus of elasticity, strain-to-break and tensile strength) and atomic force microscopy (AFM) of the prepared nanocomposites were evaluated. Also the dispersion of nanoparticles in polymeric matrix was evaluated by scanning electron microscopy (SEM).

AFM micrograph confirmed the nanoscale size of CNF, averagely obtained 35±10 nm. The morphology of fracture surface evaluated by scanning electron microscopy confirmed the uniform dispersion of CNF. The results of mechanical tests indicated that the presence of CNF in the polymer matrix increased the tensile strength and modulus of elasticity of nanocomposite compared to those of pure LDPE. The nanocomposite with 10 w % CNF had the highest tensile strength and modulus of elasticity. The results indicated that the strain-to-break of LDPE decreased with the introduction of CNF into-polymer matrix. The effect of CNF in the water absorption of the film was investigated. The water absorption was increased from 0.46% to 0.90% as the CNF percentage increased from 0 to 10 wt %.

The results achieved from these investigations were indicating appropriate effects of nanofibers cellulose for the strong interaction with LDPE polymer which caused high mechanical properties (at 10 wt% of cellulose nanofibers) in nanocomposites. The modulus of elasticity of nanocomposite films was significantly increased. Weight percentage of CNF is the most effective parameter on specific tensile strength and modulus of elasticity properties of nanocomposite samples. The presence of CNF in the nanocomposites increased the water absorption.

Quantitative and qualitative characteristics of forests can provide valuable information on the impact of forests on the environment. Quantitative and qualitative characteristics of forests can provide valuable information on the impact of forests on the environment. Detailed information from forest areas can be obtained by sampling or sampling. Although it is desirable to have complete censuses, sampling methods are preferred in many cases because of the cost and time savings involved. One of the sampling methods is the multi-tree method. In the present study, the performance of 3 to 10 tree sampling method was evaluated in estimating the number of trees per hectare, chest area and canopy cover and its results were compared with full inventory.

In the present study, the performance of 3 to 10 tree sampling method was evaluated in estimating the number of hectares per hectare, chest area and canopy cover .For this purpose, 30 hectares of one hectare of forests of watershed Oladghobad in west of Lorestan province were selected and data on all trees within these plots were recorded. In the next step, using tree simulation in Geographic Information System (GIS) environment, sampling was done using multi-tree method within one hectare plots.

Results of comparing the number of trees per hectareand canopy characteristics showed no significant difference between different polycrystalline methods with full inventory. Also, the results of comparing the mean rank of three characteristics Number of trees per hectare, basal area and canopy cover of each tree in different multi-tree methods with full inventory showed the nearest estimation in nine-tree, four-tree and five-tree methods, respectively. The results showed that the spatial pattern of the trees was due to the clustering of the species and the higher density of the branching species than the clustering species. The most precision for these characteristics was obtained for the three (9.27), four (3.65) and seven (2.67) tree methods, respectively. Finally, three characteristics were tested using E%2×T index. The results showed that three (14139.45), four (2393.16) and six (1678.87) tree methods, respectively, are suitable for sampling in the region's forests. O-ring function was also used to study the spatial pattern of Iranian oak trees.

Also according to the characteristics of the bream cross section, the four tree method, given the smallest distance with the real mean of the community, also has the lowest value (2393.16) according to the E%2×T index, as an appropriate sampling method for watershed forests Oladghobad is recommended.

One of the major problems in the pulp and paper industry is the presence of activated sludge. The Mazandaran Wood and Paper industries factory about 14 tones of activated sludge daily, which results in high environmental pollution. Therefore, the necessity of using this material in different paper industries is very important.Chemical treatment with furfural is one of the methods for removal of environmental pollution and heavy metals. This study aimed to scrutinize chemical treatment of activated sludge with furfural of 3% and its effect on the physical and mechanical properties of recycled paper pulp.

Initiallyfor the preparation of test specimens, the activated sludge were mixed and refined with waste newsprint paper pulp at ratios of 0, 10, 15 and 20%.The activated sludge was treated in a beaker for 30 min in 3% furfural and then in a water bath at 100 ° C for 90 min.After that, the treated activated sludge was mixed and refined with waste newsprint paper pulp at ratios of 0, 5, 10, 15 and 20%. And again, the samples with the above ratios were prepared with newsprint paper pulp according to TAPPI standard.Finally, water absorption and their mechanical properties, especially tensile strength, tear, RCT, burst and folding strength were measured.

The results of statistical analysis showed that activated sludge had a significant effect on the mechanical strength and water absorption of specimens. Significant differences in tear strength and water absorption were observed between the treated and untreated samples. The results showed that by increasing the untreated activated sludge in the samples the mechanical properties decreased and the water absorption increased. Chemical treatment with furfural activated sludge showed an increase in the mechanical properties and a decrease in the amount of water absorption. FT-IR spectrum results of the treated samples showed that treatment with furfural to strengthen and activate the functional groups on the surface of activated sludge fibers.Degradable of furfural treated samples was also lower than samples that of untreated activated sludge and samples made of waste newsprint paper pulp so that the treated samples had 26% degradation over 120 days. Samples from waste newsprint paper pulp and untreated sludge samples showed a 83% and 75% weight loss over 120 days, respectively.

According to the results, mixing ratio of 5% of furfural treated sludge was better in terms of strength and water absorption properties. Use of activated sludge at higher ratio for the product made is not recommended due to reduced mechanical strength and increased water absorption.

Information on forest types and their spatial distribution are valuable for sustainable forest management and planning. The use of remote sensing technology and geographic information system for providing such fundamental information specially in mountainous and remote areas, has been considered by many researchers and forest managers. The current study aims to investigate the capability of Landsat-8 and Sentinel-2 satellite data to generate forest type map in the Kojur watershed of Hyrcanian forests. The performance of some parametric and non-parametric classification methods was also compared.

Following quality assessment, some preprocessing techniques including vegetation indices (VI) extraction, tasseled cap transformation (TCT), principal component analysis (PCA) and fusion were applied on the satellite imagery. Field information collected in September 2018 plus available field data from September 2013 and May 2014, in total 60 sample plots, were used to produce a ground truth map. Forest type was determined through Gorji Bahri approach in each plot. Based on forest types separability, six types were identified (pure beech, mixed beech, beech-hornbeam, mixed hornbeam, pure eastern hornbeam, and eastern hornbeam-Persian oak) to be classified using satellite data. The performance of some classifiers like support vector machine (SVM), random forest (RF), artificial neural network (ANN) and maximum likelihood (ML) was analyzed using two different training datasets.

The results indicated that the sentinel-2 dataset performed better than Landsat-8 for producing forest type map specially when the number of classes increases. It was also found that image fusion methods on sentinel-2 and landsat-8, appropriately improved the result of classifications. This research confirms the effectiveness of number of training samples on the performance of classifiers. Respecting the accuracy assessment criterion, the SVM and RF algorithms showed better result while only 22% of field data was used as training samples. By increasing the number of training samples to 50% of field measurements, the highest accuracy was obtained using RF algorithm applying on all datasets from two satellites.

The Landsat-8 and Sentinel-2 satellite data have moderate capability (overall accuracy around 75% for four-class classification) for mapping forest types in the Hyrcanian forest. The SVM and RF produced more stable and accurate results in comparison with two other algorithms, ANN and ML. Complementary studies are recommended in different forest sites while considering phenology of species and topographic attributes.

One of the the challenges of lumber traffic is adulteration in wood kind which is widely spread due to the difficulty or impossibility of wood identification –especially exotic hardwoods- at macroscopic level. The other concern regarding luxury and aesthetic wood market in Iran is trading the colorful wood of some endangered and protected trees species like wild Pistachio in the name of imported tropical wood. The aim of this study was to identify different types of luxury hardwoods in the wood market of Iran and validate their corresponding commercial names.

39 different hardwood pieces were collected from Ports and Maritime Organization of Guilan as well as lumberyards, marquetry and wood mosaic workshops in Tehran and Karaj. First, the scientific names of samples corresponding to commercial names were recorded. Cross-sections of woods were sanded and scanned and microscopic slides were prepared. After extracting the anatomical features of samples, genus or species of wood was identified and compared with those claimed by the seller or handicraftsman.

The results showed that 80 percent of hardwood samples were dealt and used in industry by the correct name. Imported hardwoods were mainly of tropical woods which shared many common features (arrangement of axial parenchyma, presence of banded parenchyma, crystals, and storied structure). According to the similarity of key features, the process of discrimination and identification was not easy and fast. Well-known tropical timbers like okoumé, rosewood, African padauk, and sapele were correctly traded. Almost all timers in warehouses were named correctly; however, in retails and small workshops, discrepancy increased. Among collected samples, the most discrepancy was observed in the case of teak and a wood called "fofel". Teak is one of the few tropical woods in the market that has distinct growth ring boundaries and hence, its identification is comparatively easy. Therefore, we conclude that the incorrect naming of teak woods is partly due to the dishonesty of wood sellers. On the other hand, "fofel" is a wrong labeling of Indian rosewood and there are some cheatings regarding this wood due to its popularity in Iran wood market.

The main conclusion of this study is that due to the similarities, distinguishing common decorative woods in Iran market is impossible in terms of macroscopy and merely based on texture and color. Even on the microscopic level, the wood identification is laborious and can be accomplished only by cautiousness. Having said that, the exotic hardwoods in Iran market –especially at wholesales- are relatively in good accordance with their English commercial names and hence, Iran wood market is relatively verified in this aspect. However, due to the existing discrepancies in the case of some popular luxury woods, it is recommended to trade these exotic hardwoods with certificate or verification of wood anatomists.

Hygroscopic nature of wood is one of the limiting factors for some outdoor applications. Coating, impregnation with various hydrophobic chemicals or modification methods can be applied to protect the wood against moisture absorption. In this study, the effect of chemical modification of wood by substituting hydroxyl groups with long and cyclic functional group (phthalate) and short group (acetyl) on its hygroscopic properties was investigated.

Sapwood specimens of poplar (Populus deltoides) and Norway spruce (Picea abies) with 48 mm in diameter and 5 mm in thickness were cut. The specimens were extracted for 8 hours prior to modification using acetone/ethanol (2:1, v/v) solution. The specimens were then pressure treated with acetic anhydride and phthalic anhydride at 120 °C for 1, 2, 4 and 24 hours. After modification, the specimens were first washed with acetone for 48 hours and then washed with distilled water for 48 hours. After leaching, the specimens were dried in an oven at 103 ±2 °C for 24 h and weighed. Weight percent gain (WPG), physical properties of the modified wood including reduced equilibrium moisture content (EMC R), moisture exclusion efficiency (MEE) and wettability by Sessile Drop method were measured and the chemical changes were also evaluated by infrared spectroscopy test (ATR-FTIR).

ATR-FTIR studies showed that the peak observed at 1732-1746 cm-1 which is related to the stretching vibration of carbonyl group (C=O) confirms the formation of ester bonds within both types of modified woods. The results showed that modification with acetic anhydride in comparison with phthalic anhydride at the same reaction time led to a higher WPG and lower MEE. Less WPG obtained by modification with phthalic anhydride can be due to the larger size and more non-polarity of the phthalate group compared to the acetyl group, as well as the hydrolysis of the ester bond between the phthalate and hydroxyl groups caused by leaching. However, there was no difference between the anti-moisture exclusion efficiencies of the woods modified by two types of anhydrides at the same WPG. In the acetylation process, modification of Norway spruce was more successful than that of poplar, whereas the wood species showed no difference in the modification with phthalic anhydride. The results of the wettability test showed that the contact angle of the Norway spruce increased after modification by both types of the anhydrides. However, in poplar wood, only the specimen modified by phthalic anhydride at high WPG had a higher contact angle than the control specimen. Results also showed that compared to the acetylation process, WPG of the wood modified by phthalic anhydride was less affected by increasing the reaction time. This may be due to the lower reactivity of the phthalic group with wood compared to the acetyl group.

There was no difference between the anti-moisture exclusion efficiencies of woods modified by short-chain anhydride (acetic anhydride) and the cyclic anhydride (phthalic anhydride) at the same WPG, which indicates that the type of anhydride does not affect this physical property of wood. Our results showed that wettability of the modified woods can be a function of other factors such as surface quality and permeability in addition to the amount of hydroxyl group substitution.