فهرست مطالب

Rangeland Science - Volume:1 Issue: 3, Spring 2011

Journal of Rangeland Science
Volume:1 Issue: 3, Spring 2011

  • تاریخ انتشار: 1390/07/12
  • تعداد عناوین: 9
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  • A. Mirjalili Page 167
    In this investigation, the effects of enclosure, restal delayed grazing and continued grazing treatments on the production rate and vegetation cover were studied. Study area was SadrAbad pasture. After selecting three bands (1+1+1=3 hectare area) as three treatments in the restricted and non restricted area, they were transected to three transects. Then plots (1×2m) were selected to measure the production rate with clipping and weight method and vegetation cover was determined. The data were analyzed using Duncan test in completely randomized block design. As the results showed, the production and vegetation cover percentage in enclosure area, the restal delayed grazing and continued grazing had significant differences(p<0.01).
  • M. Mahdavi, H. Arzani, M. Mesdaghi, Kh. Mahdavi, J. Mahmodi, M. Alizadeh Page 175
    Since Renaissance, the natural ecosystems have fallen into a complete state of disarray due to the rise in the amount of carbon dioxide. Soil, the unsparing stuff, is one of the major sources of carbon storage, and plays a paramount role in the global equilibrium of carbon as well as carbon sequestration. Given that Iran is benefiting from vast steppes, the rate of carbon sequestration in them deserves attention. In order to estimate the soil carbon sequestration, the Saveh Rudshur steppes were selected and placed into three treatments: long-term exclosure, medium-term exclosure and grazing rangelands. The soil sampling was conducted at the depth of 0-30 cm under the plants and between the plants. As many as 60 soil samples on each area and 180 soil samples in total were taken. The sampled soils were dried out in the open air and sifted through a sieve of 2mm meshes in the laboratory. The soil organic carbon was measured using the Walkley-Black method. The findings indicated that there was a significant difference between the amount of the soil organic carbon under the plants and the carbon between the plants on each area separately (P0.05). The results also showed that the amount of organic carbon under the plants is greater than that between them in the treated exclosures while the grazing areas proved a different result. It can be seen from the mean of the total carbon sequestration that there is also a statistically significant difference between the medium-term exclosure with a mean of 22.45 ton/ha and the long-term exclosure with a mean of 17.76 ton/ha and the grazing rangelands with a mean of 18.50 ton/ha.
  • Gh. R. Badjian, Dahlan Ismail, M. Sh. Othman, A.A. Mehrabi Page 183
    The first motive for the determination and evaluation of an energy production system is the need to change. Such system is dynamic in nature and is influenced by many factors such as age and physiological status of individual sheep or goat, quantity and quality of available feed and environment including the management systems. Traditional pastoral resource assessments do not always account for the complex, interrelated nature of land, forage and livestock. Modeling may overcome the limitations of traditional methods by improving the understanding of complex pastoral systems, and makes fast repetitive analyses, spanning time, incorporating variability and representing more realistically complex interactions possible within the system. The estimated values of metabolisable energy for maintenance and production in this study are based on the results of two feeding systems linked together by grazing the energy intake in the Nomadic Production System (NPS) and the dynamic system modeling used to study the assessment of these complex systems. In this study, validation of model relied on the observations of Torki Ghashghaii (TG) sheep (like those in Bakkan) under pen-fed and integrated rangeland-cropland feeding systems, and was carried out mainly by studying the body weight gain of growing animals and also body weight changes of ewes due to pregnancy and lactation. After validation, the study indicated that the mean value of actual data of male and female lambs (weaners) and ewes were in close agreement with the simulated data. These results validate the generalized structure of energy utilization models of grazing sheep under production sub- systems of NPS. These results will enable the prediction of carrying capacities in any given situation under conditions similar to those in Bakkan.
  • Kh. Ebrahimi, S. Feiznia, M. Jannat Rostami, Kh. Ausati Page 193
    Assessing the quality of groundwater is important to ensure the sustainable safe use of these resources. However, describing the overall water quality condition is difficult due to the spatial variability of multiple contaminants and the wide range of indicators (chemical, physical and biological) that could be measured. Therefore, in this case study, some water quality parameters including Na, Mg, Cl, K, and pH, SAR, TDS, Th, Co3, HCo3, So4, Ca and EC of 34 wells and 16 qanats have been monitored and analyzed in a 15 year period. After collecting data, the main affecting factors on water quality of wells and qantas were determined separately by factor analysis test. Zoning maps were generated in Arc GIS on the basis of most important effective factors. Dry and wet years were determined based on rainfall data and 7-year moving average. Finally, the temporal trend of principal factors was depicted and water quality variations of wells and qantas were compared. Believing that sodium and chlorine are the most important parameters for water quality of wells and qanats, water quality of wells during dry years is downgraded as the results show. In initial wet year period, water quality is extremely improved but thereafter it is degraded. Results also show that water quality variation in qanats is negligible.
  • D. Noorollahi, H. Lashkari, M.Amirzade, Gh. Azizi, S. Sharafi Page 203
    The isotopic documents of lake deposition are suitable potential means for studying the intercontinental, environmental and climatic conditions. In order to study the environmental and climatic conditions of Parishan area in Fars province in Holocene, a Core was taken with the length of 2m from the Parishan lake sediment. From this core, kernel time series was provided from documents of carbon and oxygen isotopes. Results show that during the study period, climatic changes because gradual increasing in the value of ∂O18carb. This represents a weak dryness process in the area up to now. Contrary to this, carbon isotope documents during the study period show the more vigorous changes. Variability of ∂C13carb values during the study period is known as the result of changes in the value of evacuation of underground waters to the lake. As it is observed in the process at ∂O18carb throughout the study period, ∂C13carb values have an increasing process, yet the observed changes in ∂C13carb value are more vigorous than ∂O18carb and it seems that variation of underground waters was not in complete harmony with dryness process of the area. It seems that achievement of underground waters around the lake in the form of well and aqueduct is the intensify factor for the reduction of underground inputs to the lake.
  • E. Fakhimi, M. Mesdaghi, Gh.A. Dianati Tilaki, M. Tavan Page 217
    Grazing management plays an important role in the continuous and economic utilization of pastures. Proper grazing management is a main factor for the accumulation of plant litter which reduces soil erosion and increase the soil permeability to keep more moisture in the soil. In current study, the effect of three different grazing intensities (low, moderate and high) along with the grazing gradient on the forage production rate and plant litter percentage was investigated on Nodooshan steppe pastures of Yazd, Iran. A randomized complete block with three replications was used to compare three grazing methods. Data for forage production and litter percent were collected from a 2m2 quadrate in each plot. The results showed significant differences among grazing systems for both traits (P<0.05). The results showed that low grazing had the highest forage production. The regression equation between forage production and litter percentage were logarithmic in both moderate and high grazing intensities. For low grazing intensity, the relationships between two traits showed quadratic egression and therefore, it was concluded that moderate grazing intensity was the best in terms of both forge and litter production.
  • A. Mashayekhan, A. Salman Mahiny Page 225
    For the successful tree establishment, an evaluation of land suitability is necessary. In this paper, we demonstrate how to implement fuzzy classification of land suitability in a GIS environment for afforestation with Juglans regia in Gharnaveh Watershed of Golestan Province in Iran. Juglans regia is one of the most important agro-forestry species in many rural parts of Iran. Relevant criteria for Juglans regia and suitability levels were defined using literature review and expert knowledge and layers were prepared and incorporated into a GIS database. We also defined the fuzzy membership functions for the criteria and assigned some important weights through expert knowledge and Analytical Hierarchy Process. This information was used as input to the weighted linear combination of MCE method. Our results indicate that a low percentage of area is classed as very highly suitable comprising some 645 ha or 11% of area for afforestation with Juglans regia. Results of the study also indicate the usefulness of fuzzy modeling of land suitability which provides some information for optimum land-use planning.
  • G.A. Heshmati Page 235
    There are more than 750 counties in 13 provinces and autonomous regions constituting 30% of China lands which are facing serious problem of desertification. These areas are mainly distributed in arid, semi-arid and dry sub-humid areas in the western part of Northeast China, North central china and most of northwest china. Biological methods are the ultimate way for drift sand stabilization and a fundamental approach for the development and proper utilization of desert. There are 12 deserts in two physiographical situations (hilly and low land situations) where some successful biological methods for combating desertification have been documented. These methods were used on the basis of land use and the best plant species which are suitable for these harsh conditions. The land uses that are suffering most from desertification are agricultural areas, highways, railways, roads, cities, industrial places and mining areas. The important plant species used for combating desertification are Hedysarum laeve, H. scoparium, Amorpha fruticosa, Lespedeza bicolor, Caragara microphylla, C. korshinskii, Artemisia halodendron, A. sphaerocephala, Astragalus adsurgens, Ulmus pumila, Hippophae rhamnoides, Haloxylon ammodendron, Calligonum mongolicum. Transplanted seedlings, direct sowing, use of cutting, and air seeding techniques were used for greening areas degraded by wind and water erosion. Different models have been applied for protecting agricultural areas, cities, highways, railways and roads, industrial or mining and reservoir properties. Some successful models which have been employed are shelter forest system in oases, shelter system for sand fixation in agricultural areas, transportation, industrial or mining and reservoir properties.
  • M. Davodi, A. A. Jafari, G. Assadian, A. Ariapour Page 247
    Seeds of 200 accessions of alfalfa (Medicago sativa L.) were provided from Iranian natural resource gene bank and were sown as drilled plot using alpha designs/unreplicated with 2 repeated entries within all of 10 blocks under dry land farming system in agricultural research center of Hamadan, Iran during 2009 to 2010. The data were collected and analyzed for plant height, stem number, leaf stem ratio (LSR), node number, vegetation score, forage dry matter yield (DM yield), crude protein (CP), dry matter digestibility (DMD), water soluble carbohydrates (WSC), crude fiber (CF), acid detergent fiber (ADF), and total ash. DM yield was positively correlated with node number, plant height, stem number, vegetation score and negatively correlated with leaf/stem ratio, DMD(%), CP(%)and WSC(%). The factorial analysis was based on the principal component extraction and varimax rotation method. Results of factor analysis were accounted for 81% of total variance for first six factors. Factor 1 which was accounted for 19% of variation was associated with DMD, WSC and ADF. This factor was regarded as quality factors. Factor 2 accounted for 17% of variation was named as the productivity factor since it included DM yield, vegetation score and leaf/stem ratio. Since the third (CP and CF) and forth factors (plant height and node number) were important. Based on ward cluster analysis, 200 entries were divided into 7 groups. Accessions in 4 clusters were calculated well above the overall mean for DMD, CP, WSC and total ash. The accessions in cluster 7 had higher values for DM yield and morphological traits. The results of this study indicate that selection of variables in productivity factor (factor2) could enable breeders to release the desirable increment in forage yield of alfalfa.