نشریه تحقیقات منابع طبیعی تجدید شونده
سال ششم شماره 4 (پیاپی 22، زمستان 1394)

Ziziphus numularia is drought-resistance plant species. This study aims at identifying the best irrigation and seedbed treatments before planting for Ziziphus numularia seedling production. This study was carried out in Masjedsoleiman nursery as factorial experimental design with three treatments i.e. the planting bed in four levels, irrigation in three levels and scratching the seeds in three levels, as unbalanced completely random design. The results demonstrated that the main effects of all planting bed treatments and their interaction with irrigation effects on all traits (except length of stem) were significant. In different methods of seed scratching, for all traits were not significant. Also for traits including the dried weight of root, survival percentage and length of the root had the most importance respectively. As for the treatment effects, the treatment combination of every day watering in soaking seeds for 48 hours in general soil had the most survival percentage.

This study was carried out in order to evaluate the effect of nano SiO2 solation on physical, mechanical and morphological properties of popular (Populus deltoids). Test samples for physical and mechanical properties by using Immersion method in nano SiO2 solation in laboratory temperature were saturated. Then, physical tests including basic density, volumetric shrinkage and swelling and water absorption according to ASTM standard and mechanical properties including impact strength, compression strength parallel to the grain, bending strength, modulus of elasticity and hardness were done on the treated and untreated samples respectively according to ISO, ASTM, B.S and DIN. The result showed that Treatment of the Populus deltoids with nano SiO2 increased the basic density, water absorption, hardness, bending strength, modulus of elasticity and compression strength parallel to the grain. So that volumetric shrinkage and swelling and impact strength of treated samples was less than untreated samples. The results of statistical analyzes showed that between treated samples and without treatment for bending resistance, modulus of elasticity, hardness, impact strength, density and shrinkage and swelling tests there are significant differences at 95% confidence level but for compression strength parallel to the grain and water absorption tests there is not a significant difference.

In this research the impact of the type of finger joints layout (no connection, surface connect, connect on all levels) and the number of layers (three layer, five layer) on the modulus of elasticity and modulus of rupture of layer beam made of Populus Nigra have been studied. Dimensions of the samples were 130 × 12/5 × 7/5 cm. By combining these factors, there were six treatments with four repetitions totally 24 beams has been made and the bending strength was measured using a mechanical testing machine. By increasing the number of layers in the layer beam, modulus of elasticity and modulus of rupture beams increases. Maximum modulus of elasticity and modulus of rupture was related to beams with 5 layers. Maximum modulus of elasticity and modulus of rupture was related to Beams which coupling in the surface layer. Maximum modulus of elasticity and modulus of rupture were related to beams with 5 layer and coupling in the surface layer. And minimum modulus of elasticity and modulus of rupture were related to the beams with 3 layers and connect on all levels. The effect of alignment on modulus of elasticity and modulus of rupture of finger joints were not significant but the influence of layer on modulus of elasticity and modulus of rupture on layer beams is significant.

To evaluate and compare the properties of White Mulberry wood to some other wood, acoustical and musical features of the free vibration on free-free bars in longitudinal-radial and longitudinal-tangential planes were investigated. Ten pieces of each species of White Mulberry, Maple, Beech, Poplar, Caucasian oak, Pine Silvestris, Walnut and Japanese Zelkova with dimensions 20 (tangential) × 20 (radial) ×360 (length) mm devoid of any appearance defects such as cracks, knots, rots, etc. according to ISO 3129 standard were selected and values of dynamic modulus of elasticity, damping factor, acoustic coefficient and sound velocity were measured and compared with each other. The results showed that the acoustic properties of White Mulberry were of inferior quality to other species of the research, especially for Tar construction. While according to criteria of investigation in this research Maple wood and Pine Silvestris species have the best properties in the construction of Tar. It can be claimed, in general, that if the ignoring the timbre of White Mulberry wood, the other investigated species of this study have more suitable acoustic properties than White Mulberry in musical instruments’ construct.

The study was conducted to investigate effects of enclosure on restoration of vegetation cover and soil properties in the rangelands of Taftan. Therefore, three enclosure areas (Neron, Koteh, Naroon) were selected. Next to every enclosure site, a site was selected as controlled ones. Vegetation sampling was done with plots of 8m2 (regarding vegetation cover of the area) and soil sampling was taken from depth of 0-30 cm. Vegetation (production, vegetation cover, density, richness, diversity) and soil data (soil texture, pH, EC, organic carbon, total nitrogen, available phosphorus, available potassium, CaCO3, Mg, Na) were analyzed using analysis of variance in completely randomized design. In total, 14 species from 8 families and 11 genera were observed. Koteh enclosure area exhibited the highest numbers of plant species, of which approximately 90% were perennials with high conservative value. Rangeland enclosure exhibited the highest vegetation cover, plant production, plant density of class II and III. The maximum and minimum values of production, vegetation cover were related to Neron enclosure area and the Neron control treatment. The highest and lowest species richness and diversity were measured in Naroon and Koteh enclosures. Results of soil parameters showed that the amounts of phosphorus, potassium and calcium carbonate in Naroon enclosure and also concentration of potassium in Neroon showed significant increase in comparison to control areas. Analysis of variance showed the highest organic carbon, nitrogen, and potassium in Naroon enclosures. The lowest nitrogen was measured in Naroon, Koteh and related controls. Neron control treatment had the least value of potassium. In total, results of study showed that rangeland enclosure had positive effect on vegetation cover and soil specification in the rangelands of Taftan region.

In order to analyze density measurement methods, a study site with four replicates in Fereydoonshahr characterized with vegetation type Astragalus verus-Bromus tomentellus was selected. In each site (an area with 5000 m2 in dimension 50*100m), real density was calculated by counting all individuals of Astragalus verus. Samples were taken in random-systematic manner. Within each replication, five transects 100 m in length were established and given sample size for each method, some points were selected in randomized manner and density measurement methods(Closest Individual Method, Nearest Neighbor Method, Random Pairs Method, Point Centered Quarter Method, Wandering Quarter Method, Angle Order Method, Corrected Point Distance Method) were implemented. Difference between density measurement methods by control method counting was evaluated using LSD method. According to the results, the closest estimation to control is nearest neighbor one. Point Centered Quarter Method, Wandering Quarter Method, Angle Order Method, and Corrected Point Distance Method showed significant difference to control. The largest and lowest sample size was attributed to Angle Order (33) and Wandering Quarter Methods(125) among others. The regular and T square had longest and shortest measurement times. The nearest neighbor showed the highest accuracy and Wandering Quarter as well as Point Centered Quarter had the least accuracy.