نشریه تحقیقات منابع طبیعی تجدید شونده
سال هفتم شماره 1 (پیاپی 23، بهار 1395)

Beech is one of the richest, most important, and most economical forest types of Iran. Total height variable is one of the main forest morphometric variables. The height variable of trees is used in forest biometrics: determining volume, height curve drawing, and computation Slenderness coefficient of trees. One of the crucial factors in calculating the diameter at breast height is the size of tree. The forest of 90 trees of Hajikola Mazandaran forest was selected for this research; five samples per class were randomly chosen to evaluate Slenderness coefficient beech. Accelerators increase the height of beech trees until they reach 40 cm in diameter, higher. The minimum average height of 19.20 meters in diameter classes 30-50 cm & maximum average 27.55 meters a height diameter classes 100-120 cm. The average Slenderness coefficient 34.58 stability was witnessed as accepted. Slenderness coefficient in the increase of tree diameter shows a decreasing trend. Reducing the Slenderness coefficient of beech tree at a young age is because of the competition for crown which results in height growth and low diameter growth. And thereafter, the increased diameter growth and decreased height growth occur. Age and diameter growth increase the stability of the tree.

This study was carried out to assess the effects of pre-heat treatment on the wood particle Carpinus betulus marked one-layer particleboard and to increase the dimensional stability, to decrease water absorption and to improve mechanical properties. For this purpose horn beam wood-particle were with the steaming system of temperature 160° C time of 20, 40 pre-heat treatment the steam. Then the one-layer particleboard that was by 6% phenol formaldehyde was introduced by hot press one laboratory. After particleboards production, physical and mechanical properties in water absorption, thickness swelling, MOR, MOE, internal bonding (IB) panels were measured and analyzed. The results showed that physical property, thickness swelling, and the water absorption, pre-heat treatment panels in 2 and 24 hours immersing in water, effect per- heat treatment on the 2 hours water absorption was not significant. But water absorption in 24 hours was decreased to 65.65 to 77.60% then (92.31%) untreatment. The results indicated effect pre-heat treatment on the MOR was significant. So, at the time of 20 min MOE 2221.40 MPa was increased. But treatment the time 40 min 2046 MPa was decreased not significant. Pre-heat treatment was increase internal bond (IB) 0.618, 0.514 MPa significant.

This study aimed at investigating the effect of Nano clay and compatibilizer of maleic anhydride polypropylene on the long term water absorption, moisture diffusion coefficient and morphology of wood plastic composite. For this purpose, wood flour with 50% ratio was mixed with polypropylene and Nano clay particles with 0, 2 and 4% ratio by dry weight of wood flour and compatibilizer material with 0 and 3% ratio by weight of plastic were used. Mixing process of materials into the extruding machine was done and test samples were fabricated through injection molding technique. Fourier Transfer Infrared spectroscopy (FTIR) was used to study the effect of anhydrate compatibilizer. Then, long term water absorption of Nano wood plastic composite for 1560 hours was done. Also moisture diffusion coefficient was calculated to determine the speed of water absorption in Nano wood plastic composite. X-ray diffraction and scanning electron microscopy was utilized to study morphology of Nano composites. The result showed that by increasing Nano clay and compatibilizer material, water absorption and moisture diffusion coefficient in wood plastic Nano composite were decreased. The obtained results of Infrared spectroscopy showed that on the effect of increase the anhydrate compatibilizer, amount of absorption of hydroxyl groups (OH) were decreased. Determining the type of crystallographic structure of Nano composites by using the XRD showed that the fabricated structure in Nano composite was intercalation and with increasing Nano clay and compatibilizer material, the distance between the silicate layers of clay were increased. The results of scanning electron microscopy also showed that the improvement in interface between wood and plastic was in effect of increasing the anhydride compatibilizer.

In order to introduce a non-wood raw material to particleboard manufacturing, this study was performed on the feasibility of using rice husk mixed with wood particles. The percentage of rice husk in mixture (0, 15, 30 and 50%) amount of urea formaldehyde resin (9, 11 and 13%) and press time (5 and 7 min) were selected as variables, other factors being constant. Data were statistically analyzed with SPSS software and the assessment was made on the data obtained from Duncan test. Results indicated that adding rice husk to wood particles as much as 15% not only has no negative effect, but causes an increase in modulus of rupture and that of elasticity, as well as an increase in internal bonds of boards as compared with boards made of only wood particles. Grouping the experimental data while using Duncan test was indicative of the fact that an optimum condition for manufacturing particleboard while using a mixture of rice husk and wood particles is to add 15% rice husk the mixture, use 11% urea formaldehyde resin and employ a pressing time of 7 minutes.

There are some reasons that have made natural resources conservation plans unsuccessful. Lack of cooperation of local communities, passive approach in natural resources management, paucity of local base of plans, lack of participation of beneficiaries and lobbies in decision-making, are the reasons that have made these plans frustrated. The aim of this effort is to find out “Why some of graze exploiters in Malekshahi are enthusiastic in participating in grazing management plans while some of them are not?” This study was scrolling from supervision and field control but descriptive – scrolling from data collection point of views. Statistical society is including all graze exploiters of Malekshahi that are 251person. Data gathering was done using questionnaire and the sample size was simple-random based on Morgan-Takman table. Factor analysis showed that managerial, economic, information – communicative, education – promulgating and cultural are the most effective factors respectively.

This study was carried to examine the composition, characteristics and diversity in species Prangos uloptera DC site. In each control and homogenous area, homogenized units in 3 sites were selected for sampling. After observation of plant species in the area during the growth season, plant taxonomy was collected by conventional methods and various flora and other resources to identify families, genera and species of each were determined. Diversity, richness and evenness, dominance was determined in the habitat presence species and control by using plant diversity indices. Different indicators studied were tested by t-test using SPSS software. The results showed that the largest families in terms of number of species, the Lamiaceae with 14 species (19.18%) and Poaceae with 13 species (17.81%), the Fabaceae and Asteraceae each with 10 species (13.70%) and Apiaceae with 6 species (6.85%) have the highest species. The habitat presence species, 61 species belonged to the 15 families and 48 genera and the control sites, 50 species belonging to 34 genera and 13 families collected and identified. Life forms of plants include 26.32% hemi-cryptophyte, 13.82% therophyte, 4.61% chamephyte, 2.63% geophyte and 0.66% phanerophyte. From the view point of regional elements, plants of this region include 67.12% Irano-Touranian, 12.33% Irano-Touranian, Mediterranean and Euro-Siberian, 9.59% Irano-Touranian and Euro-Siberian, 5.48% Irano-Touranian and Mediterranean and 5.48% is related to other elements. The results showed that there was no significant difference between evenness index in the presence and absence of species -at the level of 95 percent. But there was significant difference in dominance and richness differences in the two regions’ comparison of the diversity index.