فصلنامه جنگل و فرآورده های چوب
سال شصت و هفتم شماره 3 (پاییز 1393)

Estimation and mapping of forest resources is a precondition for management, planning and research. This research was conducted to investigate the spatial structure and estimation of crown cover and density of an oak forest in the west of Iran (Loristan province) using kriging interpolation method of geostatistics. Field sampling was performed based on a 100 m×100 m systematic grid using 2000 m2 circular samples. Overall, 80 sample plots were measured in 80 hectare. Experimental variograms for forest stem density and crown cover were calculated and plotted using the geo referenced inventory plots. The calculated variogram of stem density and crown cover showed strong spatial autocorrelation, which fitted by Gaussian model. Estimations were made by ordinary block (45 m×45 m) kriging. Cross-validation results showed that all the estimations are unbiased. Therefore, kriging have the potential to more accurately estimate and map the crown cover and density of this kind of coppice forests, accurately.

The relationship between altitude, slope and tree age with the red heartwood of Beech (Fagus orientalis Lipsky) were investigated. Transect sampling method was used to collect the data. The results showed that in the 476 sampled trees, 132 trees were suffering the phenomenon of red hearts with deferent shape and size. The results indicate that the tree with red heartwoods in Shafa-roud forest area, with 95% confidence intervals were 27.7 ± 4.6 percent. The mean values (Ki) of the red heartwood were significantly different in three altitude forest areas. The relationship between altitude variations and red heartwood were significantly different. The relationship between slope variations and red heartwood were not significant (ˆr = 0.271, p- value = 0.097). The results of this study indicate that the frequency of the red heartwood was increased in older stands and was extended when the stands become older than 150 years. The ratio of red heartwood in older and young stands was 2.74.

Diameter is such a notable characteristic in forest inventory that it is important to have a suitable method of its measurement, especially in coppice trees. This seems more important in Zagros forests that most of them are covered with coppice trees. So this research was aimed to find an efficient method in studying the diameter at root collar (DRC) of Persian Oak coppice trees as the most important species in Zagros forests. For this purpose, DRC by two methods, crown area and height and tree height were measured in 235 Persian Oak coppice trees. The results showed that the average of DRC by the first method (24.06±12.69 cm) was significantly different from the second method (13.03±7.22 cm) and it had higher significant correlation with other characteristics. Also the linear relation between DRC by two methods and other characteristics showed the higher significant correlation of the DRC measured with the first method. So it is concluded that the first method applied in this research is an efficient method in DRC studies in Persian Oak coppice trees of the study area. Also it can be recommended to assess this method in other coppice trees of Zagros forests and if proved, it can be applied to all coppice trees in Zagros forests.

Spatio-temporal variability of throughfall (TF) has an important role on the biogeochemical processes, soil, watershed hydrology as well as the nutrient cycle in forests. Spatial distribution and temporal stability of TF patterns by five individual Persian oak trees (Quercus brantii var. Persica) in the Zagros forests of western Iran, Ilam, was quantified. Sixteen TF manual gauges were placed beneath the five selected tree canopies in the eight geographic directions and the gross rainfall (GR) was measured by the mean of six homemade gauges records placed in an open area adjacent to the study site. Rainfall interception (I) was indirectly estimated as the difference between GR and TF. The measurements were recorded during three months from end of December 2010 to beginning of April 2011. During this period, 24 rainfall events with cumulative depth of 302.4 mm was collected, of which on average 14.3% evaporated as I or expended as canopy storage by individual Persian oak trees. Less than 6% of sampling points in the time stability plots deviated consistently (α= 0.05) from the mean normalized TF, meaning lower heterogeneity of TF compared to other studies on the forest stands. Moreover, generally ranking of TF collectors of time stability plots confirmed lower TF concentrations near the tree trunks for individual Persian oak trees. Time stability plots in the current study were appeared a useful tool to quantify TF distribution of individual Persian oak trees.

Anatomical changes of the exposed roots in Cupressus sempervirens L. var horizontalis were used to estimate soil erosion in Hassan Abad valley, Chaloos, Iran. A total of 30 exposed roots, for five trees, were used to estimate erosion. Cross-sections of 20 μm were papered and the first year of exposure by erosion was identified. We finally estimated the mean annual erosion. The statistical relationship of the mean annual erosion with the percentage of the plant coverage, geographical aspects and slopes were investigated. The mean erosion of the study area has been estimated around 0.5 mm per year. There was negative relationship between the annual erosion and slope as well as the percentage of the plant coverage. The samples obtained in southern and western aspects showed higher annual erosions. We concluded that anatomical changes of exposed roots of C. sempervirens are valuable tools to date erosion events, however, the responses of diverse species under different types of erosion remains to be studied in future.

The oriental beech constitute one third of northern forests area and stocking volume in the north of Iran. These stands obseve in pure and mixed. In order to properly management which guarantee sustained yield, it is crucial to collect basic information including stocking (volume and stem number), tree growth, diameter distribution pattern, diameter-height relationship, diameter-volume relationship and models estimating wood production. This study carried out in the Gorazbon district in Kheirud forest with an area around 934.24 ha.Volume increment and stem number were measured directly using permanent sample plots. A steady state variable of DBH used for estimation of tree height and volume. Wood production was estimated by wood production models. Results showed that, with a fraction of 31% of all individuals, beech allocated 57% of standing volume in the Gorazbon district. The total stem number of beech trees were 70777 and 71567 in the years 2003 and 2012 respectively. Mean stem number of beech was 9203 and 9308 tree per ha in the years 2003 and 201 respectively. Standing volume of the species was increased from 192 sylv per ha in 2003 to 197 sylv per ha in 2012. Total stem number increment and total volume increment were 116203 stem and 115301 sylv,respectively. Analysis showed the Prodan model as a best fit to DBH-height.

To understand the compatibility of xylem with dry climates, wood anatomy similarities and differences of four shrubs were investigated in dry and cold region of Sarab (Azarbaijan sharghi province). These shrubs were: Pteropyrum olivieri, Rosa canina, Tamarix gallica, and Rhamnus pallasii, while the wood anatomy of Pteropyrum sp. is reported for the first time, in this research. After preparing microscopic sections of mature xylem and staining them, wood anatomy of studied species were reported and compared. The results showed that Pteropyrum olivieri and Rosa canina are the most similar in terms of wood anatomy while Rhamnus pallasii and Tamarix gallica have the least similarities with each other. Those anatomical features which compensate the drought stress were different in these shrubs according to local distribution of studied species; among them was the occurrence and intensity of spiral thickenings in vessels, the presence of vascular / vasicentric tracheids, and the size and grouping of vessels. Tamarix gallica which were grown only near the lake had the least adaptation to drought in its stem while Rhamnus pallasii which could distribute in the harshest conditions were equipped with the best adaptive traits.

Dutch elm disease is one of the most destructive and common plant vascular diseases now which is known as a global problem. The aim of this study was comparison of early- and late-wood vessels diameter and ray dimensions. In 4 species: Ulmus carpinifolia, Zelkova carpinifolia, Ulmus glabra and Celtis australis from Ulmaceae. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The data of xylem vessel and ray attributes measurement among disease and healthy species analysis via one-way at level of 0.01. The compare means was done with Duncan test. The results showed that the maximum and minimum frequency of disease belong to English elm and Hackberry respectively. There is significant difference between xylem vessels and ray attributes of species. The results of light and electron microscopy showed that there is a change and destruction in xylem vessels and ray structure in affected trees.

In this research, cellulose-silk composites production in liquid phase was studied. In this respect, BMIMCl ionic liquid was synthesized in the laboratory and was used for dissolution purpose. After dissolution of the biopolymers and mixing them in the liquid phase, obtained suspension was spread in a Petri dish. Then, the composite gel was washed with running methanol to remove the IL, cellulose and cellulose-silk composite films were prepared and after processing, their transparency, water absorption and thickness swelling, water vapor permeability and tensile strength were determined. Also, further characterization of structure was performed using XRD technique. Results showed that both polymers were appropriately dissolved in Ionic liquid and the cellulose-silk composite was prepared in the liquid phase homogeneously. Water absorption, thickness swelling and water vapor permeability of the composites were increased but its transparency decreased comparing to pure cellulosic film.Original cellulose (cellulose I) was deformed to Cellulose IIcrystalline structure, during dissolution and regeneration. Also, tensile strength and Young's modulus of the composite were less than cellulosic film although the strain at break point was increased.

Partial replacement of formaldehyde with furfural in the urea-formaldehyde resin on the formaldehyde emission, physical and mechanical properties of particleboard was investigated. The modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), water absorption (WA), thickness swelling (TS) and formaldehyde emission (FE) of Poplar particleboards made with the modified resins were measured and were compared with the conventional UF resin. Also, chemical structures of the synthesized Resins were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The results indicated that modulus of rupture (MOR), modulus of elasticity (MOE) and formaldehyde emission (FE) from boards was decreased by partial replacement of formaldehyde. Boards prepared with modified resin with 50% furfural showed the highest internal bond (IB). Two and 2 hours water uptake test of the boards prepared with modified resin unlike thickness swelling was decreased compared to the conventional resin. Boards prepared with industrial urea-formaldehyde resin presented the least thickness swelling. Best treatment and condition of preparing boards in terms of MOR, MOE and stableness of dimensions, it can be introduced using urea-formaldehyde resin (except formaldehyde emission), also in terms of IB and water absorption, using resin modified with 50% furfural. Boards cured with conventional UF resin presented the least formaldehyde emission.

The effect of fiber surface modification on physical and mechanical properties of Kraft pulp was studied with and without Chitosan. First, the amount of carboxyl groups of Kraft pulp at different addition levels (0, 2, 3, 4 and 6%) of hydrogen peroxide was determined by means of methylene blue test. Then, the samples containing the highest carboxyl groups were treated at pH=8.5 with Chitosan at 0.75% addition level (based on oven dry pulp). Results showed that individual surface modification of fibers increased the strength properties of paper. It was also indicated that alone application of Chitosan can act as a dry strength agent due to its ability to produce Hydrogen, Ionic and Covalent bonding. Also, surface modification of fibers by H2O2 lead to increase of Carboxyl groups followed by increasing anionic charge with together with Chitosan formed a dual system. The effect of Chitosan on apparent density, tensile index and burst index of Kraft paper were significant and on the tear index of paper was not significant. In the current study, the best results obtained at level of 3% hydrogen peroxide.

In the present research, the effect of different peroxide charges and reaction times were investigated in hydrogen peroxide bleaching of mixed old newsprint and old magazine deinked pulp. In the beginning, mixed recycled papers were pulped using conventional method and then deinked by flotation. In addition, deinked pulps (mixture ratio of 70% ONP and 30% OMG) were bleached with hydrogen peroxide at different charges of 0.5, 0.75 and 1% from peroxide and times of 30, 60 and 90 min under constant process conditions. The bleached pulps refined with laboratory PFI mill to freeness of 300 ml, CSF and then standard handsheets (60gm-2) were made from them. The residual peroxide existing in bleaching liquor, chemical oxygen demand (COD) of bleaching effluent and also the paper quality properties (optical, physical and strength properties) were measured according to respected standards. Obtained results indicated that with increase in bleaching times, the residual peroxide in liquor was decreased but the differences of them was insignificant (P<0.01) with increase in peroxide charge. Also effluent COD was enhanced significantly with increase in the both peroxide charges and bleaching times. When the peroxide charge and also the bleaching time were added, the paper brightness had increased significantly but opacity was not significantly changed (P<0.01). Increasing the bleaching agent of peroxide has not been shown any significant influence on the paper strength properties. However increasing the bleaching time led to significant improve in these properties.

The aim of this study was to investigate the barrier properties of cellulose nanocrystals PVA nanocomposites. Nanocomposite films with different filler loading levels (3, 6, 9 and 12% by wt) were developed by solvent casting method. The effect of cellulose nanocrystals on the barrier properties of the nanocomposites was studied. To this end, moisture absorption, water vapor permeability (WVP), oxygen transmission rate (OTR) and chemical vapor transmission rate (CVTR) of nanocomposite films were measured. The results showed that adding cellulose nanocrystals improve barrier properties, by reduction of the moisture absorption, WVP, OTR and CVTR of nanocomposites. These improvements in the barrier properties of nanocomposites were attributed to the high crystallinity and the strong interactions between the hydroxyl groups of cellulose nanocrystals and PVA chains, indicating that the cellulose nanocrystals were well dispersed and adherent to the PVA matrix. Furthermore, cellulose nanocrystals provide tortuous path for diffusing molecules to pass through the film. Barrier properties improvement in fully hydrolyzed matrices was more significant than partially hydrolyzed matrices.

The properties of alkaline sulfite anthraquinone (AS/AQ) pulp from old corrugated container (OCC) was studied. In each trial 100 grams (based on dry weigth) of OCC and 18% active alkali was used. Three levels of anthraquinone (0.0.1 and 0.2% based on dry weigth of the OCC) and two pulping times (120 and 150 minutes at maximum pulping temperature) were applied. Pulping temperature, Na2So3/NaOH ratio and liquor to OCC ratio at 170ºC,30/70 and 8/1 respectively were constant in all pulping trials. The results showed that the effect of pulping temperature on pulp kappa number, AQ on pulping yield and kappa number and the interactive effect of time and AQ on pulp yield and kappa number were statistically significant at 99% level. The highest yield was reached applying pulping condition of 18% active alkali,pulping time of 150 minutes pulping time without the addition of AQ and the lowest kappa number was related to pulps produced applying 18% active alkali, 0.2% AQ and 150 minutes pulping time. The results of pulp strength measurements revealed that pulp produced applying 18% active alkali, 150 minutes pulping time without AQ exhibited the highest tensile strength index at 24.6 N.m/g and the highest tear strength index at 10.54 mN.m2/g was related to pulp produced applying 18% active alkali, 150 minutes time and 0.2% AQ. Pulps produced applying 18% active alkali, 150 minutes pulping time and 0.1% AQ was selected for elemental chlorine free (ECF) bleaching applying D0EPD1 bleaching sequence and kappa factor of 0.35. The brightness, opacity and yellowness of the bleached pulp were determined as 82.6%, 80.22% and 5.64% respectively. The bleaching yield was measured as 92.1% (based in the dry weigth of unbleached pulp) and the tensile strength and tear strength indices of bleached pulp were 17.88 N.m/g and 10.48 mN.m /g respectively.