فصلنامه تحقیقات مرتع و بیابان ایران
سال بیستم شماره 4 (پیاپی 53، زمستان 1392)

If the occurrence of some climatic elements especially rainfall at a given time is less than normal and long term condition, the region will encounter drought. The evaluation of drought in each region needs the quantification of drought. Although none of the indices is superior compared to the others some indices could be more suitable for some users. For this reason, the results of all indices could be different. Main indices investigated in this research were as follows: SIAP, DPI, Z index, PNPI, SPI. The mentioned indices were evaluated using the data of 15 synoptic stations of Hamedan during 20 years, and the best methods were determined. Then, based on that, the map of drought and wet conditions of the province was produced. According to the results, SIAP and Z SCORE were identified as the best compared to the other methods and they could be considered as main indices in the evaluation of drought in Hamedan province.

According to the important role of water in livestock growth, and on the other hand, the loss of rangeland forage in the absence of sufficient water for drinking, the necessity of considering the water resources suitability is highly emphasized. Therefore, for optimal use of existing potentials of livestock and rangeland, the quantity, quality and distribution of water resources need to be taken into consideration. Given that several factors are involved in determining the suitability of water resources, this research was aimed to identify the most important factors affecting the suitability of water resources, limiting factors, and the classification of southwestern rangelands of Sabzevar on the basis of water resources suitability for sheep grazing, as the dominant livestock in these rangelands. This research was conducted using FAO (1990) method in GIS. First, DGN maps of the study area were prepared and the boundary of the region was determined. Then, water resources of the region were investigated in terms of quantity and quality (TDS, EC, and Mg+2). Finally, the layers of quantity, quality and equidistant points from water resources (prepared for four slopes of 0-10, 10-30, 30-60, and >60%) were integrated to produce the water resources suitability model. Results showed that the water resources of the study area had no limitation in terms of quantity so that all were classified as S1 suitability class, but in terms of quality, all water resources except one were classified as S2 suitability class. The final model of water resources suitability showed that 62.7, 2.4, and 34.9% of the rangelands in the study area had the suitability class of S2, S3, and N, respectively. Accordingly, slope, inappropriate distribution of water resources and salinity were identified as the most important limiting factors.

Due to the human activities and natural phenomena, the face of the earth is constantly changing. The use of remote sensing technology is considered as the best tool for change detection and evaluation. With advances in this technology and satellite images with high spatial and spectral resolution as well as a variety of image processing techniques, the changes in land-use could be estimated and managed. In the present study, the land use changes of Kashan Salt Lake were investigated in a 12-year period. Landsat TM images of 1990 and Landsat ETM+ images of 2002 were used in this study and after carrying out the required actions in the preprocessing stage the map of change detection was produced by supervised classification. Results showed that 35.18% of the study area has changed and the highest percentage of the changes is related to the mulching land class. Although, several considerations, including spatial resolution changes and spectral power changes should be taken into account in interpretation and comparison, significant changes in the study area indicate the necessity of further studies to achieve more accurate results.

Knowing that if the forage supply during grazing periods in a rangelands is sufficient for daily requirements of animal units, is one of the important factors affecting the balance between forage supply and livestock requirements in rangelands. In this regard, a study was performed and 25 range species were sampled at two growth stages (flowering and seeding) during two years. At each stage, 3 samples were collected and for each sample 5 stands were cut, and amount of crude protein (CP), dry matter digestibility (DMD) and metabolisable energy (ME) were measured in the samples in order to know the extent of critical level for daily requirements of animal units in the rangelands of Nazlo Chai Basin. For statistical analysis of the data, GLM test was applied to compare the measured factors in two years, and the sources of variations within groups were determined by Duncan test. According to the obtained results, the average amount of crud protein per unit of vegetation cover at both flowering and seeding stages was 11.5 and 9.02 percent, respectively, and these amounts were higher than critical amount of crude protein (7 percent) for maintenance requirement of one animal unit. Average amounts of forage digestibility at the growth stages were %59.86 and %54.55 respectively, and these amounts were higher than the critical amount of 50% for this factor in order to supply maintenance requirement of one animal unit. Average amount of metabolisable energy at the growth stages were 8.18 and 7.27 Mj/Kg DM which was higher at flowering stage, and lower at seeding stage than the critical amount of metabolisable energy (8MJ) for supplying maintenance requirement of one animal unit. The highest amount of crude protein (%11.33), digestibility (%60.14) and metabolisable energy (8.22Mj/Kg DM) were related to forbs, and the lowest amount of these parameters were %8.64, %52.75 and 6.97(Mj/Kg DM), respectively for crud protein, digestibility and metabolisable energy, related to grass species. Also, shrubby species contained intermediate amount of investigated forage quality factors, and the measured amounts of crude protein, digestibility and metabolisable energy in these species were %10.34, %56.72 and 7.64 (Mj/Kg DM), respectively. The results of this study are provided as basic information for the management of livestock and rangelands in the studied area and similar regions all around the country. Also this information can be useful for classification of forge quality and the methods for determination of condition, grazing capacity and trend of the rangelands.

Desertification is a phenomenon occurring in arid, semi-arid, and dry sub-humid regions and leads to potential loss of land. The Sistan plain is mainly affected by desertification so that no parts of the land, economic resources and social facilities are secure from the development of desertification. In the present study, the desertification condition of the southwest of Hirmand was investigated by ICD method. To achieve this goal, the map of land units was produced by combining the maps of geomorphology, plant communities and satellite images, and it was used as the basic map for scoring the factors and indices. According to the obtained results, the current status of desertification in most of the land units is classified as average, high and very high, including 58.3, 15, and 26.7% of a 6418 ha- surface area of the region.

Natural resources are considered as a national wealth, having an essential role in the independence and life sustainability of each country. The role of human and how to deal with natural resources is one of the factors threatening these valuable and god-given resources. Therefore, the knowledge of the human needs, problems and socio economic issues could be useful in recognizing the reasons of non-peaceful behavior with the surrounding nature. In the present study, it was attempted to study the socio economic issues, problems, and the needs of Hamoon residents in order to identify effective human factors on degradation of the natural resources of the study area. For this purpose, after carrying out necessary studies, interview and questionnaires, uncontrolled harvesting of firewood and forage was identified as destructive factors, leading to desertification. In order to identify human factors affecting the aforementioned destructive factors, the questionnaires were completed by experts and exploiters and the obtained data were analyzed by linear regression test in SPSS software. Our results showed that the age of exploiters, the history of exploitation and the size of family had direct effects on the amount of firewood and forage harvesting while an inverse effect was found for the surface area of agricultural lands. In addition, the number of animal unit had an inverse effect on the amount of harvested firewood while it affected the amount of harvested forage directly. It can be concluded that a few of socio economic factors have a close relationship with land degradation and desertification of the study area. A high correlation was found between the studied factors and the amount of harvested firewood and forage.

In this study, the preference value of four rangeland species of semi steppe regions of Iran including were measured preference index of different species in three stages of vegetative, flowering and seed ripening Poa bulbosa, Bromus tomentellus, Noaea mucronata and Stachys inflate were investigated. The study was conducted during vegetative growth, flowering, and seeding stages in semi steppe rangelands of Cheshmeh Anjir, Karsanak, and Jashloobar. One-way ANOVA was applied to analyze the data. The results of combined analysis of variance showed that the preference value of the mentioned species differed significantly among the studied sites as well as studied species, while no significant differences were obtained among phenological stages. Interaction effects of region×species (R×S), species×phonological stage (S×PS) and species×phonological stage×region(S×PS×R) were significant, indicating multiplicative diversity of data. According to the results of Duncan's Multiple Range Test at 5% level of probability the highest preference value was recorded for Poa pulbosa and Bromus tomentellus. The lowest preference value was obtained for Stachys inflate and Noaea mucronata. The comparison of preference value in three studied sites showed that Poa bulbosa in Cheshmeh Angir site and Stachys inflata in Karsank site had the highest and lowest preference value, respectively. It is due to the different species composition and climatic conditions of the sites. Generally, the obtained results of this study showed that the preference value changes of Poa bulbosa did not differ significantly during different months.

Destruction and manipulation in the desert pavement due to changes in land use is one of the serious problems in arid and hyper-arid regions throughout the world. Desert pavement is one of the important geomorphologic properties, providing natural safety mulch in central plain of Iran. In other words, desert pavement in arid regions plays the role of vegetation in humid area. In recent paper, desert pavement coverage was measured by random sampling in 20×20 (cm×cm) plots in the faces of coarse, medium and fine glacial plains of Yazd-Ardakan. Soil Wind Erodibility (SWE) and Wind Threshold Velocity (WTV) were determined in wind erosion-meter tunnel and in two natural and disturbed conditions. Results showed that the percentage of desert pavement coverage varied in the range of 83.3±5.1 in coarse glacial. SWE and WTV varied at about 19±3.1kg/ha.hr and 9.4±0.4 m/s at a height of 2m, respectively. In medium glacial plain, desert pavement coverage varied in the range of 70±14%. SWE and WTV were determined at about 34±19.9 kg/ha.hr and WTV varied in the range of 8.5±0.8 m/s. Fine glacial plain was bare and without desert pavement coverage. SWE and WTV varied at about 1300.9±1087 kg/ha.hr and 5.2±0.5 m/s, respectively. According to the results, soil erosion resulted in increased potential for wind erodibility at about 25 times greater than natural conditions. Also, with removing desert pavement, WTV decreased by about half. Our results indicate the necessity of attention to the desert pavement as a natural safety factor so that human manipulation and intervention in fragile and sensitive conditions of arid regions will not result in severe and irreversible damage.

Poa genus has important role for livestock grazing and forage production. To evaluate the effects of both drought and cold treatments on seed germination and seedling growth, 6 genotypes of Poa pratensis and Poa trivialis were examined in laboratory and greenhouse using a factorial experiment based on completely randomized design in three replications. Drought levels (0, -0.3, -0.6, -0.9 and -1.2 MPa), made by PEG 6000 solution, were related to the germinator experiment. For green house experiment, five drought levels of 20, 40, 60, 80, 100% field capacity (FC) were made by weighting of wet and dried soil. Data were collected and analyzed for seed germination percent, speed of germination, root/shoot length ratio, seedling length, vigor index and seedling weight. Results showed significant differences between drought treatments, species, genotypes within species and interaction effects between drought and species for most of traits. No seeds were germinated in -0.9, -1.2Mpa, indicating low to moderate resistance of two species to drought stress. Seed germination traits were decreased by increasing drought stress. In contrast, the shoot/root length ratios (R/S) and dry/fresh seedling weight ratio (D/F) were increased. For -0.3MPa stress, the means of seed germination percent, root and shoot length were 11, 10 and 16% lower than those for control, respectively. In greenhouse, for 20% FC, the average values of root and shoot lengths were decreased by 34 and 23% than those for control. The R/S values were increased to maximum values by increasing drought stress. Therefore, it was suggested as a good indicator for screening of drought resistant genotypes. In comparison between control and cold pre treatment (4°C), results showed significant effects of cold treatments for some of seed germination characteristics in laboratory. It was concluded that genotype Astaneh (24066), belonging to Poa pratensis, had higher values for most of seed characteristics and vigor index than those for other five genotypes in both environments and it was recognized as superior genotype for breeding improved varieties.

Soil, plant and livestock are the main and active components of rangeland ecosystems and have close relationship with each other so that changes in the characteristics and composition of each component affect other components directly and indirectly. This research was conducted in order to survey the effect of various grazing intensities on soil organic matter and nutrient elements in mountain rangelands of Chaharbagh in Golestan province. Thus, five rangeland sites including exclusion site (reference), key site, critical sites such as watering site, vicinity of village and resting site were selected and soil sampling was conducted in two depths of 0-20 and 20-40 cm, with regard to the depth of rooting, using random-systematic method in the end of grazing season. Then, soil properties such as organic matter (OM), total nitrogen percent (TN%), absorbable phosphorous (P), potassium (K), sodium (Na), calcium (Ca) and magnesium (Mg) of each soil sample were determined in laboratory. Data analysis and mean comparisons were performed by two-way analysis of variance and Duncan test, respectively. Results showed that site, depth and interaction effects were significant in various sites in all parameters with the exception of Na and Mg, and various grazing intensities had significant difference in study parameters. In general, with increasing grazing intensity, the amount of OM, N, P and K decreased with the exception of resting site. Meanwhile, the mean of nutrient elements and organic matter in reference and key sites were similar and highest, indicating the necessity of considering the balance between livestock and rangeland, suitable distribution of livestock and consequently preventing intensive grazing in order to maintaining the sustainability of rangeland ecosystems.

In arid and semi-arid areas, drought damages are more than other regions due to the fragility of environment. Parts of central, eastern and southern Iran with arid and semi- arid climate are include these regions. The object of this study was to investigate the relationship between hydrological and climatological drought in Sabzevar Plain. In this study, SPI and SWI indices were used for the zonation of hydrological and climatological droughts in Sabzevar plain. Precipitation and groundwater data were collected from 1999 to 2007 and from 2001 to 2007, respectively and then were analyzed by the mentioned indices. After calculating SPI and SWI, drought zonation was performed for each year using Kriging method in ArcGIS. Results showed that climatological and hydrological droughts did not follow a certain order and the highest intensity and frequency of droughts were west Sabzevar plain. In other hand, the east region has enjoyed normal and wet condition. According to the results, a significant relationship was found between climatological and hydrological drought in the study area as hydrological drought occurred one year later compared to climatological drought.

Biodiversity assessment is important for better understanding of ecosystem structure and function, gene bank conservation and evaluating and controlling environmental changes. Knowledge of the effect of grazing on standing vegetation structure and soil seed bank is essential for better management. This research was conducted to compare the diversity and richness indices under exclosure and grazing in Mahoor Mamasani rangelands. Sampling of standing vegetation and soil seed bank was carried out in these two areas. Canopy cover percentage was measured in plots of 1m2 and soil seed bank samples were taken from two depths (0-5 and 5-10). Standing vegetation and soil seed bank data were analyzed to evaluate the response of individual species diversity and richness indices and soil seed bank to grazing. Also, multivariate analyses were applied to assess the response of plant communities in both standing vegetation and soil seed bank. Results showed that grazing and exclosure affected species diversity and richness indices, significantly. Exclosure area showed the highest species richness and diversity while the lowest was recorded for grazing area. Also, aboveground vegetation significantly had greater species richness and diversity. Due to the damage of some standing vegetation and soil seed bank indices of biodiversity under overgrazing, it is recommended to make some changes in current rangeland management and utilization in order to restore vegetation.

Forage quality and palatability of plant species for Baluchi camel were evaluated in the south of Fars province rangelands. Forage quality was measured in two phenological stages (the initiation of vegetative growth and flowering) and their palatability indices were calculated in both stages by free grazing system and timing method. The one-way ANOVA was used to compare the palatability of plant species and factors affecting forage quality (ADF, CP, ME, and DMD) in each phenological stage. The comparison of forage quality factors as well as palatability of each plant species between two phenological stages was performed by paired t-test. Linear regression was used to examine the relationship between forage quality factors and palatability. Results showed that, depending on the kind of species and phenological stage, the quality and palatability of plant species had significant differences. Overall, our results showed that there was no significant relationship between quality and palatability of plant species. Consequently, this study indicated that the Baluchi camel don’t choose plant species for grazing based on forage quality, and other factors such as companion species and the height of plant species might determine their palatability.

In this research, the coverage of Amygdalus eburnea and Calligonum comosum was evaluated by three quadrat, visual estimation in quadrat and line-interception on rangelands of Shahr-e babak (Kerman province) in summer season of 2009. The goal was determination of the accuracy and effectiveness (speed of sampling) of these methods. The methods were compared by t-test. Coverage estimation of A. eburnea with quadrat and line-interception methods (except for the habitat with moderate density) showed no significant difference to control method, but visual estimation in quadrat method showed significant difference with control method in three habitats. Also, coverage estimation of C. comosum with quadrat method, visual estimation in quadrat method (except of moderate density habitat) and line-interception method (except for the habitat with high density) showed no significant difference to control method. In the case of A. eburnean, the highest and lowest accuracy were recorded for quadrat method and line-interception method in all three habitats, respectively. In the case of C. comosum, line-interception method and visual estimation method had the highest and lowest degree of accuracy in all three habitats, respectively. Therefore, quadrat method and line-interception method are suggested for coverage estimation of A. eburnean and C. comosum, respectively.

The determination of nutritional value of range plants is essential to assess the available energy for animals at different growth stages, recognition of correct grazing time and increasing animal yield without damage to range plants. In this study, four species including; Alopecurus textilis, Festuca sulcata, Poa trivialis, Bromus tomentellus were sampled in three phenological stages (initial growth, flowering & seeding) in 2008. Quality parameters such as crude protein, acid detergent fiber, dry matter digestibility and metabolisable energy were calculated based on AOAC (2000) instruction. A one-way ANOVA was used for comparing the quality parameters of species and phenological stages, and Duncan’s Multiple Range Test was used to determine the source of variations within groups. Results showed that the mean amounts of crude protein at different growth stages were 9.96, 8.18 and 6.09 percent, respectively that in initial growth and flowering stages were higher and at final growth stages were lower than the approximate amount of critical level (7%) for supplying the daily requirement of animal unit (50 Kg sheep). The mean amounts of digestibility at different growth stages were 51.34, 46.86 and 41.69 percent, respectively which were higher at vegetative growth stage and lower at flowering and seeding stages than the critical level (50%) for one animal unit maintenance. The amounts of metabolizable energy at different growth stages were calculated to be 6.73, 5.97 and 5.09 Mj/KgDM respectively that their amounts at all growth stages were lower than the approximate critical level (8 Mj) for supplying the requirement for one animal unit. These results represent that the favorability of rangeland forage quality is not same in different growth stages and determining the daily animal unit requirement on the basis of forage quality is needed. Overall, studied species in terms of crude protein supplying, especially at initial growth stages, were evaluated as favorite but in terms of supplying the daily metabolizable energy requirements of grazing animal in region, had less favorability.

One of the most important problems of agriculture soil science and natural resources in Iran is the lack of information of ecosystems so that the degradation of water, soil and vegetation potential leads to desertification. The main purpose of this study was to investigate the possibility of using satellite data to determine soil texture by using regression-modeling approach. The images were geometrically corrected and used to determine the best band combination to make the false-color composite images. This combination was used to applying unsupervised classifications. Field data gathering was conducted with a stratified random sampling. Points were located by using GPS and 80 surface soil samples were taken. The percentage of sand, silt, clay, and soil saturation humidity of each sample was determined. Some analysis such as PCA and making the various soil indices were done on the images. Multivariate, linear regression was applied to produce some models to develop the results of sample analysis to the entire surface of the study area. Produced maps were re-grouped in the classes considered for the soil parameters. By combination of three maps of sand, silt and clay, soil texture map was developed in four major classes with the logic of Boolean algebra. The accuracy table was prepared in accordance of the produced maps with the ground realities. High Kappa coefficient indicates a high potential of satellite data to produce maps of soil science with a high precision. This method can be fast and useful, in studies of desertification, combat desertification and controlling methods.

There are a variety of rangeland habitats with different plant species composition in Iran. Range and livestock management will require an understanding of different phenological and vegetative characteristics of plants as well as continuous changes in palatability of plants during the growing season. Grazing behavior of Yazdi native goat was evaluated in Nodushan rangelands of Yazd within a 4-year period (2007-2001). A 3-yaer old goat was selected as the representative of the whole flock for investigations at the beginning of each year. The timing method was applied to determine the palatability of plants. Experiment was repeated with three 20-minute periods in each stage. Results indicated that the grazing was found to be mainly concentrated on Artemisia siaberi, stipa barbata, stipa causasica, Iris songarica, Eurotia ceratoides and annual plants based on spending more than 85% of the grazing time by the goat on these species. The preference value for annual plants was higher than perennial plants at the beginning of the growing season on normal and favorable conditions. According to the results of this research, the conservation and restoration of these native species in steppe range management should be considered.