نشریه تحقیقات منابع طبیعی تجدید شونده
سال ششم شماره 3 (پیاپی 21، پاییز 1394)

This paper investigates the influence of closed canopy and canopy gap on soil properties in a pure and mixed beech forest in Alandan forest - Sari. Soil samples were taken from four positions listed in two depths of 0- 10cm and 10-20 cm. Totally 32 soil samples and 16 organic layer samples were taken and transported to the laboratory. Soil texture, pH, EC, bulk density, soil moisture content, organic carbon, total nitrogen, phosphorus and potassium of mineral soil as well as pH, moisture content, nitrogen, phosphorus and potassium of organic layer were measured in laboratory. Results showed that the electrical conductivity of the soil at a depth of 10-20 cm in gaps of pure stand was significantly lower than that of gaps and closed canopy of mixed stand. The gap in pure stand showed significantly lowest percentage of organic carbon. Total N was significantly lower in the gap position comparing with the closed canopy within the pure stand. Difference was significant in the case of Carbon to nitrogen ratio in the second soil depth between gaps and closed canopy in both stands. Soil available K was significantly greater in mixed stand compared to pure one. None of soil properties showed significant differences in depth of 0-10 cm between the various positions in both stands. Relative humidity showed significantly higher percentages in both organic and mineral soil layers in pure compared to mixed stands. The findings suggested that canopy compositions are significantly able to influence some properties of soil n organic and mineral layers.

The aim of this study was to investigate financial feasibility of producing floating paper from rapeseed straw in Mazandaran province. Studies showed increasing attention of farmers to plant rapeseed straw in Mazandaran province. On the other hand, need for paper products are being increased following the growth of cultural, social and economic development plans. Rapeseed straw is one of the best raw materials for construction of new pulp and paper floating factories. Annual production capacity of rapeseed pulp fluting is 2,000 tons for per year. The Industrial accounting principles were used for economic evaluation of project. The total amount of investment was forecasted 36468.4 million Rial. The results of the economic evaluation indices, such as the internal rate of return (17%), payback period (40 months), break-even production (53.2 percent), sales break-even (16494.3 million Rial), capital in the circulation of fixed capital (11.3 percent), capital investment per capita (1091.88 million Rial/ person) and investment income (28.9 percent) and the cost of the product (10,610,350 Rial) indicated that the stablishment of this factory decreases the import of fluting paper, prevents currency waste, and it is financially justified.

The influence of coriolus versicolor on resistance of acetylated fagus orientalis by verjuice was examined in this research. Reducing the common effects of environmental and allergic chemical substances in wood acetylating is the motivation for choosing natural verjuice as the main acetylating material. 90 testing samples that were extracted from three beech trees in Masal woods were applied in 3 groups of 30 in order to study as available, dried and acetylated samples by verjuice. The samples were cultured on Malt Extract Agar medium in 27 °C ambient temperature for 20 days inside incubators in a laboratory environment. The results showed that the level of fungus in acetylated samples has been far less than the available and dried ones, in such way that it has been caused 57 and 65 percent of significant decrease in comparison with other samples respectively. Dry treatment also decreased the level of wood fungus meaningfully at the level of one percent in comparison with the available treatment. Acetylation has lessened thickness swelling behavior in beech trees of the area as well.

In this study the independent effects of moisture content and temperature variation on dynamic properties of beech wood were investigated. According to ISO 3129 standard 10 clear samples were selected. The samples exposing to different moisture content and temperature and then longitudinal vibration test were performed on them. Results showed that the dynamic modulus of elasticity values of water immersed samples were smaller than the samples with lower moisture content, and also in constant moisture content as temperature increased dynamic modulus of elasticity decreased. Increasing temperature from 60 ° C damping factor remained constant, while the damping increased with the increase of moisture content. Maximum values of dynamic modulus of elasticity were observed in completely dried samples and increasing temperature from 60 °C the dynamic modulus of elasticity values in samples were descended.

Punctual assessment of rangeland health is essential for detection of occurred alterations in biotic and abiotic components of rangeland ecosystems. This study aimed to assess rangeland condition in Gremi, Ardabil Province, northern Iran in three methods, i.e., four-factor, six-factor and rangeland health indicators; also it was aimed to designate the best method by analyzing the accuracy and precision of methods. Three exclosures (reference sites) and three range sites under continuous grazing (evaluation sites) adjacent to them were selected. Some attributes of vegetation and soil e.g. canopy cover, bare soil and liter percent were measured on transect lines (50 m) and quadrats (1×1.5m). In rangeland health indicators method, indicators of reference site were firstly evaluated and then the departure degree of evaluation site (grazed rangeland) from reference site was scored. The health of all exclosures and grazed rangelands were categorized ‘good’ and ‘poor’, respectively, by both four-factor and six-factor methods. Departure degree of most indicators from reference site was moderate to extreme in evaluation sites 1 and 2. These sites were marked ‘unhealthy’. The departure degree of evaluation site 3 from reference site was moderate, then, this site was marked ‘at risk’. Accuracy and precision level of four-factor method was greater than those in six-factor method. Consequently, four-factor method was found as appropriate method for assessment of rangeland condition (health) in Gremi. In the case that the aim of rangeland health assessment is to make decision about important issues of management and the reference site is available, we recommend the use of rangeland health indicators method.

This study investigates stress alkalinity on physiological characteristics of the plant Nitraria schoberi in 1391 at the University of Kashan was studied under the greenhouse conditions. In this study the effects of acidity (pH) of water and nutrient availability in the alkaline range of soluble sugars in plant Nitraria schoberi was evaluated in a completely randomized design. Project consists of 5 treatments (each treatment consisted of 4 replicates) control, stress levels: The first level control (Ctrl, pH = 7/2), low alkalinity (LAK, pH = 8/5), moderate alkalinity (MAK, pH = 9), high alkalinity (HAK, pH = 9/5) and extreme alkalinity (SAK, pH = 10) was conducted. In comparison of the was observed parameters Gradient increase in alkalinity, calcium, garlic reduced In both areas of aerial parts and underground and the most calcium in the control group and the lowest amount of stress, alkalinity, calcium is 10, However, the sodium, potassium, chloride, magnesium and alkalinity increase in the slope upward trend in aerial parts and underground are demonstrating, In the control group, in which case the minimum and maximum amount of alkalinity is 10. Soluble sugars in response to changes in alkalinity to the second level of stress is increasing and then decreasing trends in both aerial parts and underground parts of the plant Nitraria schoberi. Maximum amount soluble sugars stress on the second level and the lowest was observed in the control group.