Journal of Forest and Wood Products
Year:2018 | Volume:71 | Issue:3|Papers Count:8

This research was carried out with the aim of studying the status of natural regeneration and biodiversity (plants and soil invertebrates) of beech forest in three development stages including initial, optimal and decay. After identifying the development stages, one 1 ha sample plot was established in each development stage. Within each sample plot, 10 100 m2 micro-sample plots were laid out as random-systematically. The values of natural regeneration, plant and soil invertebrates diversity in optimal, initial and decay stages have been recorded and eastimated in 30 micro-sample plots. The results of this research showed that natural regeneration in the optimal stage was significantly greater than other stages (7. 5 seedlings per 100 m2), while the differences of natural regenerations between the stages of initial (2. 9 seedlings per 100 m2) and decay (2. 8 seedlings per 100 m2) were not statistically significant. The plant diversity (Shannon-Wiener index) in the optimal stage had the highest values (2. 375), whereas the decay stage had the lowest value (1. 929). But the differences in the initial stage with other stages were not statistically significant. Also the differences of soil invertebrates diversity (Shannon-Wiener and Simpson indices) were not statistically significant in the studied stages. The decreasing of soil invertebrates diversity (Shannon-Wiener index) in these treatments was respectively as optimal, initial and decay. This research emphasizes the values of natural regeneration, plant and soil invertebrates diversity in optimal stage is better than initial and decay stages.

Quantifying the mechanical properties of roots is one of the most important issues in stabilizing slopes and modeling soil reinforcement. The aim of this study was to estimate the mechanical properties of hornbeam trees in three stem diameter classes include small, medium, and large trees in Patom district of Kheyrud forest. For this purpose, number of five trees in small (7. 5-32. 5 cm), medium (32. 5-57. 5 cm) and large (57. 5-82. 5 cm) diameter classes were selected and roots on both up and down sides (slope of 20-30 percent) of the trees were collected, then placed between two jaws of the Instron machine. Tensile strength test and tensile force were performed. The results showed that there is a positive power relationship between root diameter and tensile force. In all stem diameter classes at both sides of trees, tensile strength decreases by increasing root diameter based on negative power function. The results of covariance analysis showed that tensile force and tensile strength were significantly different among three stem diameter classes. Tensile force was higher in medium and small trees at up and down sides, respectively. While, in large trees tensile force in downside was more than upside. In medium trees, tensile strength were significantly higher in upside and downside (F=12. 9, P<0. 05) than small and large trees. Covariate factor (root diameter) was significant in all cases. The results of this study showed that stem diameter of trees and up and down sides of the trees affect the tensile force and tensile strength of hornbeam trees and it is possible to change the amount of tensile strength with age. Therefore, it is necessary to investigate changes in roots mechanical properties in different ages of trees in order to modeling the slope stability.

Runoff generated by rain in forest areas and its flow on the roads can cause road damage and disrupt the operation and transportation. This research aims at minimizing the runoff damage to the road due to the flood by determining the optimal culverts diameter on the path of Tuska Kalam-Lyre Sar, Tonekabon, basin 35 in 23 forest sub-basins. Using the Curve Number method with different return periods, the maximum runoff flow of each sub-basin was calculated in cubic meters per second. Then, the optimal culvert diameter of the sub-basins was determined by using the Nomograph for determination of the diameter of concrete pipes. The results showed that on the B3 sub-basin, the maximum runoff for the return periods of 5, 10, 25, 50 and 100 years is 3. 37, 4. 48, 6. 04, 7. 29 and 8. 63 cubic meter per second, respectively, in which the culverts diameter is not suitable for the maximum passage runoff above the 5-year return period. On the B23 sub-basin, the maximum runoff for the return periods of 5, 10, 25, 50 and 100 years is 2. 24, 2. 98, 4. 02, 4. 86 and 5. 75 cubic meters per second, respectively, in which the culverts diameter, for the maximum passage runoff different return periods, is more than optimal. On the B9 sub-basin, the maximum runoff for the return periods of 5, 10, 25, 50 and 100 years is 2. 8, 3. 73, 5. 02, 6. 06 and 7. 17 cubic meters per second, respectively, in which the culverts diameter, for the maximum passage runoff different return periods, is optimal.

The aim of this study was to evaluate the changes of chemical (calcium, (Ca2+), sodium (Na+) and potassium (K+)) of the canopy and litter leaching of Velvet maple (Acer velutinum Boiss) during a year against those nutrients in rainfall (RF). Measurements were carried out in mixed stands, located in district one of forest research station of Gorgan University, the eastern Caspian forests of Iran. In order to perform the research, three Velvet maple trees were selected in 0. 5 ha stand and throughfall (TF) (405 samples) and litterflow (LF) (243 samples) were sampled after each RF within a year from (2012/02/03) to (2013/02/03). The nutrients amounts in TF, LF and RF as well as monthly nutrient dynamics of TF and LF, were compared using t-test analysis and one way variance analysis at the 95 of confidence level. Results showed that the amounts of K+ and Ca2+ in TF were 134. 83 and 0. 19 kg ha-1 year-1, respectively, significantly higher than those in RF, however, the amount of Na+ was 52. 27 kg ha-1 year-1, significantly lower than RF (p<0. 05). Also, amounts of Na+ and Ca2+ in LF were 91. 9 and 1. 68 kg ha-1 year-1, respectively, significantly lower than those in RF. We found out that nutrient leaching of TF and LF was significantly different in several months. Velvet maple trees can usefully improve the potassium contained in the soils. In order to select suitable species for afforestation, soil fertility improvement and forest management, we need to know more about leaching process information along with other characteristics of trees.

The main objective of this study was to replace the chemical polymers with natural and renewable polymer and subsequently reducing environmental concerns. In addition, the physical and mechanical properties of composites reinforced with tobacco stalk flour, were studied. For this purpose, the tobacco stalks flour and poly lactic acid contains30: 70; 40: 60, 50: 50 and maleic anhydride grafted polypropylene as a coupling agent, in two levels of 4 wt% and 6 wt% were used as variable factors. The results showed that by increasing the amount of the tobacco stalk flour and reducing the content of PLA, the dimensional stability of the boards was decreased but the dimensional stability of boards made with PLA improved significantly compared to the polypropylene composites. In many cases, the mechanical properties of the composite were increased and even doubled than mechanical properties of the composite made with polypropylene. That's mean; the PLA's natural polymer did not damage the physical and mechanical properties of the wood-plastic composites, but also in some cases improves its properties up to 50% compared with chemical polymers. This natural and renewable polymer is environmentally friendly and the composite can be placed in a group of green composites.

Annually huge amount of un-used rice straw after rice harvesting were burned due to no specific utilization. Whereas, based on the biorefinery concept there is possibility to use these agricultural residues for production of high value added products. So, this study was aimed to extract the silica from the rice straw (Oryza Sativa var Indica) as one of the important agro-industrial residues in the country and its capabilities for production of silica nanostructures based on the mentioned concept. After washing, drying and grinding of rice straw samples, some of them were separately leached with a hydrochloric acid and some ones with a sulphuric acid at concentration of 0. 5 M for 30 min with constant stirring. Afterwards, the silica content of acid-leached and un-leached rice straw samples was measured in a muffle furnace with varying temperatures at 500, 600, 700, 800 and 900° C for 2 h. The results were obtained from Energy Dispersive X-ray (EDX) and X-ray Fluorescence (XRF) demonstrated the maximum presence of silica into the rice straw ash. Two of aforementioned spectroscopy methods explored the higher content and purity of acid-leached rice straw samples in comparison to un-leached rice straw ones. The Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the prepared silica nanostructures had a spherical shape and their average particle sizes were 30 nanometer for un-leached rice straw samples and less than 12 nanometer for acid-leached ones.

Recently, paper recycling has been significantly increased for several reasons such as environmental concerns and coast-saving. Ultrasound is used in the paper industry at various stages. Deinking has an important and determinant role in the recycling of newspapers. The aim of this study was to conduct the process of deinking in order to improve the optical properties of newspaper as a cellulosic material by using ultrasonic pretreatment combined with chemical method. The hydrogen peroxide, sodium hydroxide, sodium silicate, poly sorbent 80, and Diethylenetriaminepentaacetic acid were utilized for chemical deinking. Effect of important parameters of ultrasonic pretreatments such as ultrasonic bath temperature and sonication time on deinking efficiency was investigated by using response surface methodology based on central composite design. After chemical treatment of obtained recycled pulps, maximum and minimum efficiency of deinking for hand sheet papers with 60 gsm grammage according to standard T 205om-88 were calculated about 88 and 45% respectively. Surface and 3D curves were created to show the interactions of the independent variables with response one (deinking efficiency). Based on the ANOVA test, the quadratic model presented the best explanation of variables interaction. Ultrasonic pretreatments increased brightness and decreased opacity of obtained recycled newspaper compared to the control ones. According to the statistical analysis, the effect of each variable on deinking efficiency was significant and sonication time was introduced as the most effective factor. In addition, 47 oC ultrasonic bath temperature and 31 min sonication time were determined as the optimal conditions for maximum deinking efficiency (86. 95%).

The aim of this study was to enhance the physical and mechanical properties of deinked recycled paper by using the cellulose nanofibers (CNFs) and obtained fine fibers from pulp refining. The process was conducted in the presence of a cationic additive including cationic starch (group A), poly aluminum chloride (group B), or cationic polyacrylamide (group C). The Design Expert software was used to prepare the experimental design and analyzed the results. The results showed that by using fine fraction up to 16 wt% and cellulose nanofibers up to 7 wt%) with cationic starch (group A) the tensile strength was increased almost 44%, burst strength 53%, and water retention value of pulp (WRV) 35%. These values for treated pulp with group B were 41%, 48%, and 22% while, , for treated pulp with group C were 40%, 42% and 27%, respectively. However, those treatments increased the dewatering time from pulp and the highest increase in dewatering time was 47% when 16 wt% fine and 7 wt% cellulose nanofibers were used along with cationic starch. In addition, increasing of dewatering time for treated pulp with group B and group C were 41% and 30%, respectively. The evaluation and comparison between different treatments indicated that the treatment of deinked recycled pulp with group C would be a suitable treatment, due to minimum adverse effect on pulp drainage time and considerable improvement of dry strengths.