IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2000 | Volume:53 | Issue:2|Papers Count:8

Distribution diagram of tree in diameter classes is needed for access to knowledge about stand condition, preparation of the standing volume tables as well as production of quality product.Besides, prediction of stand future by means of probability distributions (distribution in diameter classes) is of prime importance and can help to plan for proper harvest.This study was carried out in Kheyroudkenar forest. The declining curve of distribution in diameter classes showed that the stand is uneven-aged and irregular. To predict the stand condition, BETA distribution can be used.

Ephedra botanically belongs to Chelamidosperm class and Ephedraceae family with more than 44 species in the world, 10 species in Iran and three species including Ephedra strobilacea, E.intermedia and E.procera in Biarjomand region. Effective ecological factors on Ephedra were investigated in this study. Three vegetation types namely; Ephedra, Ephedra-Artemisia and Artemisia-Ephedr waere shown in vegetation map. In each vegetation type vegetation parameters including density, canopy cover, yield and also stone, bare soil and litter percentage were measured. Effect of rainfall on its production was studied by its production measurement using clipping and weighting method during two years. Soil samples were collected from each vegetation type. Chemical composition of Epheqra was determined in different phonological stages.According to the results, Ephedra propagates by two ways including rhizome and seed. It has horizontal and vertical root systems. Its production is considerable and important for soil conservation. Its production depends on annual rainfall and limits its growth in dry season. Its stems and flowers have no poisonous effect on mature sheep and goats, but its fruit is toxic for sheep, goat, lamb and kids. Its poisonous effect changed during different growth stages.Suitable grazing period of Ephedra in the study area is during autumn and winter. Its palatability was medium. Fat content of whole plant was 4.45% for Ephedra intermedia and 5.6% for Ephedra strobilacea. Percentage of crude protein for mentioned species was 5.34 and 3.91 respectively. There was significant relationship (99% level) between height, canopy cover of Ephedraand its production in Biarjomand region.

Defects in Properties of wood are used as common indicators for grading logs. In this study, the logs of various woody species from ten different forestry projects have been evaluated based on their measured defects.The results of this study showed that the average diameter of acceptable knot for the first 3 meters of the trunks was 2.8 cm for maple (the least value) and 7 cm for hornbeam (the highest value), respectively. Moreover, the knotless portion of the first 10-meter-Iong trunks was 12.2, 32.4 and 20 percent for hornbeam, elm and beech, respectively. As for pith decay of trunk, the least and the highest values were 56 and 84 percent which were associated with maple and elm, respectively. As for trunks with bent defect, oak and basswood showed the lowest value (7 percent), while hornbeam showed the highest value (18 percent). This value for beech was about 10 percent. Bole taper (decrease of bole diameter of less than 2 cm per meter of length) was 65 percent in maple (the lowest value), and 96 percent in oak (the highest value). This value for beech was 75 percent. The lowest and highest values for defect of interlocked fibers were observed in boles of alder (68 percent) and oak (91 percent), respectively. The percentage of boles with interlocked fibers for beech was 89 percent. As for trunk with irregular annual ring, it was shown that hornbeam had the lowest value (82 percent). However, 94 percent of the other woody species didn't show such a defect. Finally, the lowest and highest percentage values for trunks with abnormal annual rings were 16.1 and 24.3 for oak and elm species, respectively.

Four forest sites including three mountain forests and one plateau area were chosen in order to investigate the germination and propagation of the service tree. The purpose of this research was to suggest the most suitable method of seed sowing for the service tree considering variable ecological factors and different treatments.The results of this study indicated that there is a significant difference between eight selected treatments at the level of P=0.001. The result of the Duncan multiple range test presented a significant difference (P=0.05) among four investigated sites using the treatment of A (seed sowing without drupe, exposed in ventilating and forest soil humus cover). Also, the results of this test using the treatment of B (sowing without drupe, with cold stratification and forest soil humus cover) indicated a significant difference between four study areas. The average of frequency in area unit using TB was calculated among four sites. The highest and lowest frequencies were estimated respectively in Kelar Dasht and Shahr Posht sites.It was concluded that Kelar Dasht site using TB (sowing without drupe, with cold stratification and forest soil humus cover) indicated more favorable condition (quantitative and qualitative) for the propagation of service tree in comparison with other sites.

The quality of particleboard, made by used Sleepers from two different regions of Iran (Karaj and Shirgah) was determined. For this purpose, one layer laboratory panels were produced with a density of 750 Kg/m3 and thickness of 16 mm. The effects of two different amounts of resin (8 and 10 weight percent) and three different amounts of hardener (1, 1.5 and 2.5 weight percent) were investigated. The physical and mechanical properties of panels were compared with those reference panels produced from non-impregnated sleepers under the same conditions. The results indicated that static bending strength, modulus of elasticity, shear strength parallel to plane, thickness swelling and water absorption of panels produced from karaj and Shirgah were lower than reference panels and were considerably different. The physical and mechanical properties of panels produced from Karaj sleepers were significantly different from those obtained for Shirgah sleepers in both 8 and 10 weight percent resin. In addition, the amount of hardener had no significant influence on the panel properties. The results showed that the physical and mechanical properties of panels produced from karaj sleepers with 10 weight percent resin and 1.5 weight percent hardener had comparable values with DIN standard and suitable for particleboard industrial applications.

In this study, Mazooge gall flour with high amount of hydrolysable tannin was used as the filler of PF resin. Variable factors in the study were: filler content, assembly time, temperature and press time. In order to evaluate the bond quality, the CBR type of BS standard was used. According to this standard, shear strength together with wood failure were measured. Also independent and interactive effects of variable factors were evaluated.The results have shown that the increase in filler content reduces bond quality of PF resin and in the studied conditions only 15 percent filler content results in a bond quality meeting BS standard, so higher contents are not recommended. Also, better treatments were those of higher assembly time.

Caspian seal is the only known mammal confined to Caspian sea, the largest lake in the world.Twenty five carcasses were collected along Anzali shore (Gilan Province) during 1995-1999. Sex determination in most cases was impossible due to severe scavenging activities of gulls and domestic dogs.Total length, tail length, anterior and posterior flipper lengths were measured on collected specimens. Body length ranged from 69 to 148 cm and mean tail length was 6.64 cm. Anterior and posterior flipper lengths ranged from 13 to 21 and 15 to 27 cm respectively. Fifteen variables were measured on the skulls of collected specimens. The greatest length of skull ranged from 14.8 to 18.4cm and the Mastoid breadth and zygomatic width varied form 7.99 to 9.93 and 7.5 to 10.26cm respectively.Descriptive satistics of all variables are presented in the paper. Also, principal component analysis was carried out on skull variables and results are given. Necropsy of collected specimens showed that seals mostly fed on fishes of cyprinidae and clupeiidae.