فصلنامه جنگل و فرآورده های چوب
سال هفتاد و دوم شماره 2 (تابستان 1398)

The Hyrcanian forests are typical deciduous broadleaf forests characterized by an important role in providing moisture to vegetation by fog precipitation (FP). The importance of FP on vegetated surfaces as a source of moisture has been acknowledged for a long time. The aim of this study was to quantify FP and water interception in a natural oriental beech (Fagus orientalis) stand in the Hyrcanian forests. Event-based measurements were carried out on 2016 and 2017 during the full leaf period. The rain-collectors used for measuring throughfall and gross-rainfall were n=122 and 10, respectively. During the measurement period 22 rainfall events occurred (total rainfall = 648 mm). The amount of throughfall and interception were 99.4% and 0.2%, respectively. Due to considerable amount of fog (3.5%) throughfall was found to be greater than 100% of GR in 14 rainfall event with negative interception (total=-22.6 mm) and 8 rainfall event were found with positive interception (total=25.5 mm). Maximum of FP was measured in September of 2016. Results indicated the role of FP on increasing of throughfall and decreasing interception. Because of the various bioclimatic condition in the Hyrcanian forests, interception is extremely different in oriental beech stands. Then, Fagus orientalis would have significant influence on the local hydrological processes of the mountain forests of Hyrcanian and its water demand would supply by FP in dry seasons. So, the maintenance of beech stands would help to increase of FP by capturing of fog droplets which would provide groundwater and water demand supply of these ecosystems.

The aim of this study is to investigate the possibility of using remote sensing to estimate woody species diversity that plays an important role in the sustainability of forest ecosystems. To do so, a Sentinel_2 imagery data was used over a part of the Marivan forests. The study site with an area of about 500 ha was investigated through field observation. 89 field-plots with a size of 40 × 40 m were selected over the whole area. Within each plot, tree species and number of each species were recorded. Different woody species diversity indices i.e. Simpson, Shannon-Wiener, Margalef, Fisher-alpha and Dominance were calculated for each plot. Satellite imagery of sentinel-2 level 1C product were provided. Different vegetation indices were generated from the original bands of satellite imagery, and the digital values were extracted from spectral bands, and vegetation indices based on the field sample-plots. In the next step, the correlation between extracted digital values (i.e. spectral data) and species diversity indices was investigated for 66 sample plots, and stepwise multiple regression was applied. The validation procedure based on 23 sample plots showed that the Sentinel-2 data predict Simpson index (R2 = 0.57, RMSEr = 21.39%), Dominant index (R2 = 0.55, RMSEr = 22.63%) and Shannon-Wiener index (R2 = 0.50 RMSEr = 23.16%) more accurately than other species diversity indices. Based on the results of this study, it could be concluded that Sentinel_2 images have a moderate ability to estimate species diversity in Zagros forests.

Effects of Land form and some physical and chemical soil properties on Vegetative Characteristics of Rowan tree (Sorbus aucuparia L.) in Andabil forest, Khalkhal region AbstractEffects of Land form and some physical and chemical soil properties on Vegetative Characteristics of Rowan tree (Sorbus aucuparia L.) in Andabil forest, Khalkhal region Rowan is one of valuable, rare and endangered shrub species in Andabil forest reserve. This study aimed to determine the relationship between vegetation properties of Rowan with soil and physiographic factors in Andabil forest reserve. In three land forms (ridge, valley and slope) and in four aspects (north, south, east and west) sample plots, each 500 m2, were selected. Overall, 34 sample plots were used for measuring vegetative characteristics and soil characteristics including soil texture (clay, silt and sand), pH, Ec, N%, OC% and Caco3%. The results showed that the distribution range of Rowan varies from 1940 to 2540 m.a.s.l. The highest mean height (3.10m), collar diameter (9.12 cm) and crown diameter (2.08 m) were measured on valley form. Soil of Rowan habitats is deep to semi- shallow with pH (6.14 to 6.72), Ec (0.521 to 0.967 ds/m) and with soil texture of loam to clay- loam. In general, Rowan habitats in the southern and western aspects in the forms of slope and edge with light soil texture have more favorable conditions in term of quantitative characteristics for the growth of this species. Key words: Andabil forest, Habitat conditions, Principal component analysis, Rowan, Soil factors.

Regarding the development and application of biocompatible composites in various sectors, including packaging industry and disposable containers, consideration of the methods for improving mechanical properties is essential. the purpose of this study was to make a bio composites with a mixture of polypropylene as a matrix, starch as a filler, and Nano/micro cellulose fibers as reinforcing agent. For this study, polypropylene was used as a matrix, starch as filler in two levels (30 and 40%) and cellulose nanofibers at three levels (0, 1 and 2%) and cellulose micro-fibers in three levels (0.5, And 10%) was used as a reinforcing agent. MAPP was used as a coupling agent and glycerol as a plasticizer. Raw materials were mixed in a co-rotating twin-screw extruder. In this stage, TPS produced and of Nano and micro-fibers of cellulose dispersed in polymeric matrix. Then the granules obtained from the extruder were transferred to the injection device to obtain test specimens. The morphology of the samples was studied by FE-SEM. Data obtained from the results of the experiments were analyzed by using a factorial design in a completely randomized block design with SPSS software; also, Duncan test was used to compare group mean. The results showed that the addition of Nano and micro-fibers of cellulose increased the flexural and tensile strength of the specimens. Samples made with 30% starch and 2% cellulose Nano-fibers had the most flexural and tensile strength.

In order to use alternative sources of fiber such as hemp to supply the paper and wood fiber, the exploration and utilization of abundant hemp variations seems to be necessary. In this study, some hemp populations collected from different part of Iran were evaluated with reference to wood anatomy and fiber biometry characteristics. Vessel characteristics of stems including average vessel lumen area, vessel density and porosity were measured using cross-sectioned tissues of stems. Fiber biometry characteristics of fibers including fiber length, fiber width, fiber cell wall thickness and fiber lumen width were measured and compared using macerated bast and core fibers. In conclusion based on vessel characteristics, Frs, San 02, Mahb, Zah and Mahl, populations, are expected to be putative high potential fiber populations, due to having the least vessel density and porosity leading to more woody core fiber content. Regarding fiber length, populations of Ban, Bsh, Frs and Kash, Bsh and Nhv, showed higher average for bast and woody cores, respectively. Hence these populations are expected to perform better in properties related to fiber length such as textile and paper strength and can be successfully used in paper making, fiberboard and textile industries as well as being used in selective breeding programs. Also all populations were evaluated based on their bast and wood fiber width, fiber cell wall thickness and fiber lumen width as effective factors on final product properties.

Generally speaking, PVAc (polyvinyl acetate) adhesive has weak strength properties with capability of using in wooden products such as wood adhesive. The carbon nanomaterial (CNF) is one of the most influential substances on the strength properties of polymer materials. Thus, the mechanical and thermal properties of polyvinyl acetate glue reinforced with carbon nanofibers were investigated in both modified and virgin cases and three levels of zero, 0.4 and 1.5% by weight of glue. Modified carbon nanofibres were used to improve the dispersion of polymeric matrix by surface chemical modification method. The results of the FTIR spectroscopy test were confirmed oxidation and presence of new functional groups on the surface of modified carbon nanofibers. Mentioned nanocomposites made by solvent molding method and evaluated the tensile properties, thermal behavior (TGA) and microstructure. Transmission electron microscope (TEM) images indicated better dispersion of modified nanoparticles in 0.4% than higher values in the glue matrix. Also analysis data of the tensile test data showed improvement of mechanical behavior of nanocomposites (elasticity modulus, tensile strength, and fracture energy) due to the presence of modified nanoparticles. Improvement of these properties with modified carbon nanofibers was 2.4, 1.6 and 1.8 times, respectively, compared to pure polyvinyl acetate. In addition, two stages of reduction mass relative observed than the pure adhesive in thermal stability of both nanocomposite series. Generally speaking, the best tensile strength observed in nanocomposite specimens containing 0.4% w/w with modified carbon nanofibers.

The aim aim of this study was to investigate the effect of process variables on the dimensional stability of high-density fiber boards (HDF) and improve this feature in order to use it in the flooring of buildings. The effect of speed of press on three levels (350, 375 and 400 mm/s), the amount of paraffin at three levels (0, 0.5 and 1%) and the amount of adhesive in three levels (9, 9.5 and 10%) on the mechanical properties, such as internal bonding strength, elasticity modulus, and rupture modulus, and physical properties, such as thickness swelling, were tested. The results showed that increasing the speed of the press reduced the flexural strength, internal bonding strength and increased thickness swelling of the boards. By adding paraffin, the swelling of the thickness of the boards decreased, while the use of paraffin at higher levels had a negative effect on mechanical strength, especially internal bonding. Also, according to the results, the mechanical and physical properties of the boards improved with increasing adhesive utilization. In this study, the RSM method was used to determine the optimal quality of the board. Regarding the results of the RSM method and the effect of different variables, the resulting boards at 350 mm/s, paraffin and adhesive of 0.5 and 9% respectively, with having mechanical and physical properties in the standard range, were determined as the optimum level for flooring.

The present study was aimed to investigate the effect of natural aging on the optical (brightness, yellowness, opacity) and strength properties (tensile index, burst index, tear index) of the mixed Old Newspaper (ONP)/ Old Magazine (OMG) deinked pulps, bleached with oxidative and reductive bleaching agents. In this research local Offset-printed ONP and OMG (especially derived from Mechanical pulp or Chemical-Mechaical pulp) were naturally aged for five months, then deinked by flotation and bleached with Hydrogen Peroxide (H2O2) and Formamidine Sulfinic acid (FAS) in both single-stage and two-stages bleaching operations. Result showed that natural aging caused the brightness value and all strength indices to decrease and the opacity and yellowness values to increase, compared to those of the newly recycled papers without aging. Therefore, it should be avoided as far as possible. In addition, reductive bleaching (using FAS) was found more effective than oxidative bleaching (using H2O2) in improving all optical and strength properties of the hand-sheets. Also, in two stages bleaching sequences, it was observed to be most appropriate to use FAS as the latter bleaching chemical after H2O2. Thus, it can be totally concluded that application of the reductive bleaching system (by FAS) is apparently more effective and efficient than oxidative bleaching system (by H2O2) in both single-stage and two-stages bleaching operations of the deinked pulps from Offset-printed wood-containing recycled papers in terms of the optical and mechanical properties.