مجله مرتع
سال هفتم شماره 1 (پیاپی 25، بهار 1392)

Vegetation evaluation in order to introduce important range forage species with high potential of growth and reproduction is essential for proper rangeland management. Given that the remarkable areas of saline and alkaline rangelands in Gorgan region and the problem of forage production in rangelands of this area, the present research aimed at studying effect of enclosure on sexual biomass production of halophyte species Puccinella distans. Inside and outside enclosures, two 50 meters transects were located at two directions. In each transect, 10 study points were selected systematically, and in each point, forage of nearest individual was gathered. Different plant organs were separated in the laboratory and were dried in the oven at 60° C for 24 hours. Then, dry weight of different organs from samples was measured, Independent t-test was used to compare different means. The results showed that total weight of vegetative and reproductive organs and total plant biomass production were significantly different between grazed and ungrazed individuals (P<0/05). Also, the plant height significantly differed between grazed and ungrazed individulas (P<0/05). Total Biomass of above ground organs and average weight of roots were also significantly different in grazed and ungrazed individuals. The average biomass production of ungrazed individuals of P. distans was 264.1 kg ha-1 in which 13/19 % of total biomass was allocated to reproductive organs. Also, 5/9% of the total biomass production of grazed individuals was allocated to reproductive organs. The results demonstrated that sexual biomass production is higher in ungrazed than grazed individuals.

Vegetation characteristics, climatic conditions, type and availability of water resources and slope are the most important factors influencing grazing behavior of herbivores in rangelands. In other words, grazing behavior of herbivore species is specific to each rangeland site. Understanding grazing behavior of herbivore species is important for grazing management and optimum utilization of rangelands. Therefore, grazing behavior of Yazdi native goat (Capra aegarus hicus) was studied for a 4 years period (2007-2001) in Nodushan rangelands of Yazd province. At the beginning of each grazing season, a 3-years old goat was selected as representative of the whole flock. daily grazing and rest period as well as daily movement distance and average speed were recorded for 4 years during 6 months of grazing season and were analyzed using a randomized complete block design. Maximum speed and distance traveled in each of the slope classes were also studied. Results indicated that the minimum distance traveled (14 km/day) was recorded in September that was not significantly different from July and August (P≤0.05). The maximum distance traveled (19.3 km/day) was recorded in April that was not significantly different from May and June (P≤0.05). The minimum and maximum rest period were 2:43 and 1:18 hrs, respectively. The highest and the least travel speed and the least that were 1.5 and 1.2 km/hour, respectively. Changes in travel speed was not related to the slope percentage of rangeland site.

This study was performed to clarify the effects of growth season and different harvesting intensities on changes in soluble carbohydrate reserves of Stipa hohenackeriana and Salsola laricina. The study was conducted in National Plan Site of Institute of Forests and Rangelands in Khoshkeh Rud-e-Saveh. Fourty individuals (bases) from each species were selected and various harvesting intensities (treatments) including No harvesting (as control) and 25, 50 and 75 percent harvesting were applied from 2007 to 2010 growth seasons. Forage sampling from treated individuals was conducted in autumn and spring. Soluble carbohydrates were measured using the Phenol - Sulfuric Acid method. Data two-ways ANOVA followed by Duncan multiple comparison tests was performed to compare significant differences between treatments. Results showed that a significant effect of species and growth season on carbohydrate reserves. In both species, spring samples had higher carbohydrate reserves. Meanwhile soluble carbohydrates in organs of Stipa hohenackeriana was more than that of Salsola laricina in both seasons. Effects of harvesting intensity on soluble carbohydrate reserves of two species showed three different groups of treatment effects: no harvesting with the highest carbohydrate reserves, 25 and 50% harvesting levels with medium carbohydrate reserves, and 75% harvesting level with the lowest carbohydrate reserves. Considering the obtained results and range management issues, more than 50% harvesting level must be avoided as it damages the soluble carbohydrate reserves of the species.

This research was followed after few introductory surveys of heavy metals distribution in the mining zone of the Central Iran. The research was carried out in the territory of Kushk Mining Company, located at45km northeast from Bafgh city and 145 km from Yazd city. The morphology of the area is mountainous. The major desert shrubs in the polluted area are Artemisia siberia and Salsola vermiculata. The surface soils (depth:0-25cm) and 10 samples from each plant species with root, juicy stems and second years old stems were randomly collected to a distance of about 8 km (where metal concentrations in soil were decreased to a minimum amounts) from mining waste dam. Because of the lead and zinc mining operation in Kushk, the lead, zinc and cadmium in soil and plant samples were measured. Also due to secondary formation of gypsum in mine formations, calcium in the samples was measures as an essential element for plants. Desert shrubs in despite the impressions have an special living pattern and so different behaviors in uptake and excretion of heavy metals. The accumulation of metals (lead, zinc, cadmium and calcium) in juicy and fresh shoot organs were increased about 2.5 times more than roots and were decreased from a mean concentration of 85.82 ppm in juicy stems to a minimum mean concentration in dry stems with the mean of 0.0 ppm in A. sieberi less accumulation of heavy metals in fresh shoots relative to root with a more accumulation of Ca have been shown in A. sieberi and S. vermiculata showed any significant difference in means of metals in its organs but the mean of heavy metals were increased in its shoots (from 4.6 ppm in root to 12.91ppm in shoot) and the mean of metals were decreased in shoots (from 153.52ppm in root to 134.69ppm in shoot).

This study aimed to generate potential distribution map of Astragalus verus Olivier, in Fereydounshahr rangelands in Isfahan province with 1000 square kilometers area approximately. Potential distribution map of the species in the study area was produced using Ecological Niche Factor Analysis (ENFA) methods, applying presence data of the species and some environmental variable maps (topography, climate and soil maps). Vegetation types dominated by A. verus was checked in the study area and 50 sites with presence of the species were recorded using a stratified- random sampling approach. Soil maps were obtained from seventy soil profiles and climatic maps were produced using data from 10 climatic stations. 9 maps of different soil properties, 19 maps of various climatic parameters and 3 maps of different topoghraphic variables (from a 90 by 90 meters DEM) were generated using geostatistic method.. These maps were used as input layers for ENFA model. Results showed that soil EC, caco3 and organic carbon content, and pH together with slope percentage and monthly mean temperature were respectively the most important environmental factors influencing the species ecological niche. The produced species distribution model showed high accuracy (calculated Kappa coefficient, ROC area under curve plots and cross validation were 0.69, 0.85 and 95 %, respectively. given that industrial and medicinal value of A. verus, the produced potential map can be used for conservation and habitat improvement programs of the species.

Eighteen forage samples of Kochia prostrata [L.] Schrad at three phenological stages of vegetative growth, flowering and seeding were collected to determine the quality and digestibility of the species. Forage samples were collected from 2 regions of Neour (Ardabil province) with 1900 to 2000 meter above sea level and MeshginShahr with 1300 to 1400 meter above sea level. Chemical composition and lab digestible capability of the samples were determined, and gas test was performed at the time of 0, 2, 4, 8, 12, 24, 48, 72 and 96 hrs. The amount of produced gas and related parameters were measured and estimated using P=a+b(1-ect) formula. The Dunkan test was used tocompare a, b and c values in various treatments. According to the results, the amount of crude protein was significantly higher in the vegetative growth stagecompared to other two phonological stages. The amount of produced gas of forage samples was relatively high in vegetative stage. The produced gas from soluble and insoluble sections of forage samples collected from MeshginShahr and Neour rangelands were 64.97 and 63.69 ml, respectively. Metabolizable energy per kg dry matter of forage samples at the vegetative growing stage collected from MeshginShahr and Neour were 2.20 and 2.18 M cal, respectively. By development of phenological stages, the mean amount of dry matter, crude protein, ash, and crude fiber were decreased, significantly (P<0.01), however the mean amount of ADF, NDF and OM were increased. Overall, there were no significant differences between the amount of metalizoble energy, digestibility and gas production of forage samples from two study regions. Metalizoble energy was higher in vegetative growth stage in comparison with other two stages due to, higher crude protein and soluble carbohydrate content at this stage. In conclusion, the best time for the studied species to begin grazing in semi-steppic rangelands of the Ardabil province is toward end of vegetative growth of the species.

The aim of this study was to determine similarity between established vegetation and soil seed bank of several halophytic plant communities in rangelands of the Sorkh-Deh, Damghan in Semnan province. Vegetation sampling in each vegetation homogenous unite was carried our based on Random-systematic sampling using 100 one square meters plots. In each plot, cover percentage of all species were estimated, separately. In order to assess soils seed bank, soil samples were also collected from two soil depths (0-5 and 5-10 cm) in each vegetation plot. The seed bank size and composition of collected samples were then studied in a seed germination experiment in glasshouse for a period of 10 months. According to the results, the highest number of seed species was recorded in soil samples of Salsola dendroides community with 14 species and the lowest number in Halocnemum strobilaceum community with 3 species. Comparison between species composition of vegetation and soil seed bank showed that only few species (8 species) were common in both while many species were either unique to vegetation (31 species) or soil seed bank (9 species). Dominant species in established vegetation were absent from soil seed bank. Therefore, soil seed bank has low potential for vegetation restoration in such a saline rangeland.

Rangeland co-management emphasizes on rangeland stakeholders and analysis of social relationsamong them. Trust and collaboration relations, are two important social factors influencing rangelandco-management. This study aimed to analyze the trust and collaboration networks among rangeland stakeholders in Nariyan village, located in Taleghan Region Qualitative methods such as participatory observation and interview techniques were used to detect the target groups and evaluate the structure of livestock management in the study area. The structure of trust and collaboration networks among rangeland stakeholders were studied using some quantitative method such as network analysis approach. Three main indicators of social networks including density, centralization and reciprocity of all rangeland stakeholders network were evaluated. Also, Jacard correlation coefficient between trust and collaboration network was calculated based on QAP index and then a linear regression was produced between these two variables Results show the density level of bonding ties, social capital and social cohesion of sub-group No.1 was more than other studied groups. The centralization indicator of trust and collaboration networks based on ingoing and outgoing ties shows a scatter structure in these networks. Moreover, the reciprocity and sustainability level of sub- group No. 1 was more than other groups. The bonding of mutual trust and collaboration is more than bridging of them. The coefficient of determination results revealed that, 87 % of the collaboration changes may related to trust variable. In conclusion, the social network analysis enables rangeland managers to detect the challenges of rangeland co-management and assist them to achieve a comprehensive policy to overcome the challenges.

To separate main ecological sites based on environmental factors 16 different soil properties (13 parameters) and topographic variables (3 variables) were investigated in Taleghan rangelands, Alborz Mountains. Sampling was done in 5 land units extracted from integration of geology, slope and elevation maps. Vegetation was studied using a random-systematic method along a100 meters transect in 5 meters length sampling unit that were located 20 meters from each other. Soil samples were taken from 0-30 cm depth at starting and ending points of each transect. To investigate similarity and difference between ecological sites, cluster analysis was done based on Euclidian distance and Wards method. ANOVA analysis followed by Duncan test was used to compare the environmental factors. Principle Component Analysis was used to determine the most important environmental factors partitioning ecological sites. Results of cluster analysis, showed 5 different plant groups in 57% dissimilarity. ANOVA results showed significant difference in soil organic carbon, nitrogen, lime, pH, potassium contents and soil depth between ecological sites. Principal component analysis also showed that soil nitrogen, potassium, organic carbon, calcium and clay contents as well as slope percentage are the most important factors separating different ecological sites.