Journal of Forest and Wood Products
Year:2019 | Volume:72 | Issue:2|Papers Count:8

The Hyrcanian forests are typical deciduous broadleaf forests characterized by the 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 the FP and water interception in a natural oriental beech (Fagus orientalis Lipsky. ) stand in the Hyrcanian forests, Iran. Event-based measurements were carried out in 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 was found with positive interception (total=25. 5 mm). Maximum FP was measured in September 2016. Results indicated the role of FP on increasing the throughfall and decreasing the interception. Because of the various bioclimatic conditions in the Hyrcanian forests, interception is extremely different in oriental beech stands. Therefore, 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.

This study aims at investigating the possibility of using remote sensing to estimate the woody species diversity which plays an important role in the sustainability of forest ecosystems. For this purpose, Sentinel-2 imagery data was used over a part of the Marivan forests, Iran. The study site with an area of about 500 ha was investigated through field observation. 89 field-plots with a size of 40 m × 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, Fisheralpha, and Dominance were calculated for each sample plot. Satellite imagery of sentinel-2 level 1C product was 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%) were more accurate 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.

Rowan (Sorbus aucuparia L. ) is one of the 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. For this purpose, from 1940 to 2540 m. a. s. l, 34 circular sample plots with an area of 500 m2, in three landforms (ridge, valley, and slope) in four aspects (north, south, east, and west) were selectively established and quantitative characteristics of Rowan were measured. In addition, within each sample plot, a mixture of soil samples was collected from 0 to 40 cm and some of the physical and chemical properties were measured in the laboratory. In order to study the relationship between Rowan distribution and edaphic characteristics, the principal component analysis was applied. The results of two-way analysis of variance along with the interaction between land form and aspect on the mean of quantitative characteristics showed that it has a significant effect on the quantitative characteristics such as the number of tree in hectare, height, collar diameter and crown diameter. The highest mean N/ha (131. 2) in southern aspects and ridge landform, collar diameter (9. 1cm), crown diameter (2. 1m) and height (3. 1m) were measured in southern aspects and slope landform. Soil texture in Rowan habitats is loam to clay-loam with pH (6. 1 to 6. 7), EC (0. 52 to 0. 97 ds/m), N% (0. 30 to 0. 75), OC% (3. 24 to 6. 22) and CaCO3% (5. 21 to 16. 1) were measured. The PCA analysis showed that the presence of this species in slope sites with EC, N%, Silt and CaCO3 and in ridge sites with OC% was more correlated. In general, it can be stated that the number of trees per hectare in the ridges and the increase of the quantitative characteristics of this species in the southern aspects on slopes landform in the range of 1940 to 2540 m. a. s. l. with loam-clay texture have provided more favorable conditions in term of quantitative characteristics for the growth of this species.

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 produce 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 wt%) and cellulose nanofibers at three levels (0, 1 and 2 wt%) and cellulose micro-fibers in three levels (0, 5, and 10 wt%) 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 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. The results obtained from 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 wt% starch and 2 wt% 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 hav the least vessel density and porosity leading to more woody core fiber content. Regarding The 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. In addition, 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, 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 unmodified cases and in three levels of zero, 0. 4 and 1. 5% by weight of glue. Modified carbon nanofibres were used to improve the dispersion of (CNF) into polymeric matrix by surface chemical modification method. The results of the FTIR spectroscopy analysiswere confirmed an oxidation and presence of new functional groups on the surface of modified carbon nanofibers. Mentioned nanocomposites made by solvent molding method and the tensile properties, thermal behavior (TGA) and microstructure were evaluated. Transmission electron microscope (TEM) images indicated better dispersion of modified nanoparticles in 0. 4 wt% than higher values in the polymer matrix. In addition, the tensile esults showed an 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, the best tensile strength observed in nanocomposite specimens containing 0. 4% w/w with modified carbon nanofibers.

The purpose of the present study was to investigate the effect of process variables on the physical and mechanical properties of high-density fiberboard (HDF) and to improve these properties in order to use it in the flooring of buildings. The effect of press factor on three levels (7. 6, 8. 3 and 9. 1 s / mm), the paraffin content in three levels (0, 0. 5 and 1%) and the amount of adhesive in three levels (9, 9. 5 and 10%) were tested on the mechanical properties of the board, such as internal bonding strength (IB), elastic modulus (MOE) and rupture modulus (MOR), and physical properties, such as the percentage of thickness swelling of the resulting boards. The results showed that increasing of press factor improved the flexural strength, modulus of elasticity, internal bonding strength and decreased the thickness swelling of the boards. By adding paraffin, the percentage of the thickness swelling of the boards decreased, while the use of paraffin at higher levels had a negative effect on mechanical strength, in particular internal bonding strength. 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 limit of the board. According to the results of the RSM method and the effect of different variables, the resulting boards with a press factor of 8. 9 s/mm, paraffin and adhesive content of 0. 5 and 9 percent respectively, while maintaining the resistance Mechanical and physical properties in the national standard range, were determined as the optimal level for flooring.

Regarding the increase of the bleaching chemicals usage which caused by aging of the recycled papers and intensifying the negative environmental effects, it is detrimental to investigate the proper methods for decreasing these negative effects. Thus, the present study was aimed to investigate the effect of natural aging on the optical (brightness, yellowness, opacity) and strength properties (tensile, burst and tear indices) of the mixed old newspaper (ONP)/and old magazine (OMG) deinked pulps and also bleached with oxidative and reductive bleaching agents. Local offset-printed ONP and OMG 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 the natural aging decreased the brightness and all strength indices, but the opacity and yellowness increased compared to those of the newly recycled papers without aging. 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. In addition, in two stages bleaching sequences, it was observed to be most appropriate to use FAS as the latter bleaching chemical after H2O2. Therefore, it can be totally concluded that the 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 of woodcontaining recycled papers in terms of the optical and mechanical properties.