محمد ابوالقاسمی

Rangelands are composed of different plant species with different vegetative characteristics that have a certain grazing value. Hence, the grazing livestock also shows a special grazing behavior according to it. Without knowing these behaviors, planning and managing rangelands and livestock is not possible. This research was carried out on camel herds in the rangelands of the Tabas desert from 2015 to 2017. Parameters such as grazing time, rest time, livestock movement time, distance traveled, and livestock movement speed were examined by GPS. The results showed that in spring, summer, fall, and winter, grazing time, livestock movement time, distance traveled, livestock movement speed at (p < /em><0.01), and rest time at (p < /em><0.05) were significantly different. The highest grazing time (342 minutes), rest time (119 minutes), and distance traveled (21.66 km) by camels in the studied rangelands were in summer and the lowest in winter. The highest speed (2.12 km/h) and travel time (359 minutes) were in spring and the lowest in winter. Therefore, knowing the mentioned parameters will help the rangeland management in determining the appropriate time for the camel to move in the rangeland and will increase the livestock performance.

The electric initiator is an important component of the explosive train which provides requiered energy to initiate a chemical reaction by converting the electric current to the heat via a bridgewire. This initiator is widely used in the field of aerospace industry in the solid rocket propellant motors, separation systems and etc due to its low weight and high reliability. In this research, a mathematical model has been introduced to investigate the effective parameters on the electric initiator performance. Comparison of numerical simulation results by finite difference method and experimental data showed that this model has the ability of the prediction of the ignition time and determine the transient temperature profile in axial and radial direction. The model showed that the reduction of the contact heat transfer coefficient between the bridgewire and the primer compared to its increase has a greater effect on the heat transfer rate. It was also found that with increasing the current, the temperature changes decreased along the axial direction and increased in radial direction.

This study was conducted in the central plateau of Iran to examine the income, cost, and profitability of conventional systems, in which camel is common during the years 2015 to 2017. For this purpose, by selecting 28 conventional systems with an average of 126 camels, the amount of income and cost per camel during the regular period of each year (spring) was completed and calculated by the operators with a questionnaire. The type of research is practical, and the statistical population included 28 camel herders. Random sampling was performed. Variables included income factors and camel costs. Using the analysis of engineering economics, the current value of income (PV income) and the present value of costs (PV cost) were calculated for the studied years, and then the net present value (NPV) and the benefit-to-cost ratio (BCR) was calculated with Excel software. The results showed that in all conventional systems, the net present value was positive, and the benefit-to-cost ratio was greater than one (BCR≥1). The highest gross income in each of the conventional systems was related to the sale of live camels (male camels, 6-month-old camels, elimination camels) and the highest cost was related to camel driver’s wages and the purchase of manual forage. However, by calculating gross income from expenses, the amount of profitability was determined, so it is suggested that due to the appropriate profitability of this profession, the relevant agencies have a plan to expand the cultivation of this industry along with the tourism industry and considering that forage of these habitats will not be able to supply the nutritional needs of camels in traditional areas, and the continuation of this situation will endanger the vegetation; therefore, it should be done with caution.

The Bahadoran Kalmand protected area with an area of 255000 hectares is located at about 30 km Yazd township and in the southeastern township of Mehriz with geographical coordinates of 31° 00′ to 31° 40′ North latitude and 54° 15′ to 55° 20′ East longitude. The vegetation cover was studied using the physiognomic-floristic method. Some soil characteristics were evaluated based on conventional methods and data were analyzed by Principal Component Analysis (PCA) method. The results showed that there was a special relationship between different plant communities and soil characteristics. The most important factors in separating these plant communities were electrical conductivity, acidity, texture, organic carbon, and sodium adsorption ratio. In general, in regard to habitat conditions, each plant community has different ecological needs and tolerance range with environmental factors and soil characteristics.

The genus Salsola is the largest species of the Salsoloideae with a population of 130 species, widely distributed in arid and semi-arid regions of the world. The superiority of this genus over other genera is high seed production and high forage yield. Tolerance to severe climatic conditions such as high temperatures and prolonged droughts indicates the importance of this species in semiarid and arid environments. Species such as S. rigida, S. laricina, S. imbricata, S. richteri are used as livestock forage in arid and semi-arid regions. The relatively high forage production of species of this genus (150 to 700 kg/ha) with good nutritional value (protein content more than 10%) makes these species important for steppe and desert rangelands. In addition, some species of this genus, including S. imbricata and S. richteri have medicinal value. Rangelands rehabilitation using Salsola species is possible through seeds and potted seedlings. For better propagation, seeds should be used every year for the same year. Here, the important species of Salsola along with its applications for the development and extension of these valuable plants for various purposes are presented.

Rainfall storage with plant species planting is used for rehabilitation and improvement of rangelands, especially in arid areas. In this study the effect of rainfall storage treatments furrow, pitting and crescent pond on the establishment of Ferula tabasensis in Kalmand Bahadoran area of Yazd province was evaluated. This area is one of the habitats of the species studied. Seeds were planted at two season, early fall as autumn sowing and late winter as spring sowing. The research was a split plot design, based on randomized complete blocks with three replications. The main plot was planting time (spring and autumn) and sub plot was planting method (farrow, pitting and crescent pond). The seeds were planted in 2013 and 2014. The results showed that seed emergence rate in autumn were significantly higher than spring planting. Among the planting methods, the impact of the crescent pond method was slightly more than the other two methods. In general, planting methods caused more than 50% seed emergence. Although some of these seedlings were destroyed for various reasons, however, the establishment of about 30% of seedlings shows that the methods of rainwater harvesting in the establishment of cultivated plants have had a positive effect.