فهرست مطالب رستم خلیفه زاده

Climate change has been a serious issue in the last two decades and many studies have focused on its various aspects. Therefore, it is necessary to determine the future habitat of rangeland species present and future years, under climate warning models. In this regard, it should be investigated whether the increase in temperature will have a positive effect on the presence of species in the habitats of the distribution site or a negative effect?.

For this purpose, from 19 bioclimatic variables and three physiographic variables and logistic regression model, to quantify climate change in the next three decades (2050) and to examine its effects on the current change of Ferula ovina species and the future, was used. Output maps were also grouped into four categories with a probability of occurrence between zero and one. These groups, unsuitable habitat, (0-0.25); Habitat almost suitable, (0.25-0.5); It shows a high proportion habitat (0.5-0.75) and a very high proportion habitat (0.75-1). Finally, by referring to the coefficients of climatic variables and topography in regression relations, effective variables for the current and future range of F.ovina were introduced.

Based on results; among the climatic and topographic variables, only the indicators related to the average temperature of the warmest season (BIO10) and the average temperature of the coldest season (BIO11) were identified as effective on the distribution of F.ovina species in present and future Alborz rangeland habitats. The characteristics increase as the climatic conditions become more difficult. Average annual temperature in places with a probability of more than 75%; over the next three decades, under milder (Rcp 4.5) and pessimistic (Rcp 8.5) scenarios, it will rise from 2.6 to 0.3 ° C. The height of suitable habitats will be 60 to 162 meters. As a result, adequate habitat levels (greater than 75% probability) decrease in response to climate change. Under climate scenarios, 15% of suitable habitat habitats will be lost by 2050 and current unsuitable habitats will increase by 48%. Overall; climate change and increasing temperature characteristics will cause the vertical expansion of F.ovina species to higher latitudes along the altitude gradient. This indicates that over the next three decades, the presence of F.ovina species in the habitats of the region will decrease and the risk of its removal from the southern Alborz ecosystems is evident.

According to the results obtained in this study, large changes in the distribution of this species are expected to occur along with climate change. These changes are such that they can limit the suitable climatic conditions for the life of this important and effective species in the southern Alborz rangeland habitats. Therefore, in order to improve the conditions, the least that can be recommended in such conditions is to control the degradation of F.ovina species habitat, by managing livestock grazing and preventing rangeland use change, and in general, to apply a conservation approach in these habitats. If a protective approach is applied; It is to be hoped that climate change, by itself, will not be able to remove, undermine, or even completely eliminate this valuable species from the flora of the region, and perhaps the physiological, phenological, and morphological adaptations of this species will help combat climate change. Therefore, while protecting it inside the habitat, it is necessary to think of measures to protect it outside the habitat with an approach close to nature. In this regard, collecting seeds and storing them in the gene bank of natural resources, introducing superior and drought-tolerant ecotypes with better structural and functional traits and preparing strong seeds from them, cultivating them in small one-hectare plots in botanical gardens and plant collections And finally their rangeland in habitats with poor and very poor status class; One of the basic requirements is its protection outside the habitat with an approach close to nature.

The knowledge of rangelands suitability is a requirement for the exploitation of medicinal plants of those rangelands. Accordingly, the present study was conducted to evaluate the exploitability of MPs in 12 representative habitats of semi-steppe regions based on the ecological and economic (E&E) indices. For this purpose, after measuring the vegetation and estimating the production of MPs, the E&E indices related to the exploitation of MPs in each habitat were calculated. Finally, based on the indices, the suitability class of each habitat was determined according to the FAO guidelines by the limiting factor method. The results showed that the forage available of habitats varied from 90 to 591 kg.ha-1. Also, the share of MPs production in habitats was obtained between 5 and 58%. In other words, the production of MPs in the habitats varied from 27 to more than 383 kg.ha-1. Accordingly, the expected value of each hectare of habitats from the exploitation of MPs, taking into account the discount rate of 5.4% in September 2020, varied from 3 to 41 $.ha-1. Overall, the suitability of the habitats varied between good to unsuitable (25% good, 17% moderate, 25% low, and 33% unsuitable) in terms of production and exploitation of MPs, but all the habitats had good suitability in terms of forage production for grazing. Therefore, the exploitation of all the habitats cannot play an important and equal role in improving the livelihood of pastoralists and with the approach of preserving the plant genetic resources, the exploitation of MPs in all the rangeland habitats could not be recommended. In addition, the permitted exploitation limit in each habitat varies according to the conditions and trend of the rangeland and the sensitivity of the soil to erosion. This issue should be considered in the policy of paying attention to MPs, and it should be emphasized in the multi-purpose rangeland management plans.

Detection of climate parameters indicates that climate change has begun in Iran and it is necessary to identify the potential habitat of the indicator species, present and future years, under climate warning models. In this regard, it should be examined whether the increase in incident temperature in the country, will have a positive effect on the presence of species in the habitats of the distribution site, or a negative effect? For this purpose, the current and future range of Stipa barbata species for the next three decades (year-2050) was predicted under two climate warning models (scenario RCP4.5 and RCP8.5) using the logistic regression model. Output maps, with probability of occurrence between zero and one, to four categories unsuitable habitat (0-0.25), almost suitable habitat (0.25-0.5), habitat with high suitability (0.5-0.75) and habitat with very high suitability (0.75-1), were grouped. Finally, based on the coefficients of the variables in regression relationships, effective variables for the current and future range of S. barbata species were introduced. Based on the results; only temperature-related indices (BIO7 and BIO10) were found to be effective on the distribution of S. barbata species, present and future. The values of the indices increase with increasing climatic conditions. As a result, the range of S. barbata species decreases in response to climate change. This indicates during the next three decades, the presence of S. barbata species will decrease in the habitats of the region and there is a risk of its removal from the ecosystems of the region. In total, climate change and consequently increase in temperature characteristics causing the vertical spresd of S. barbata species, and it will move towards higher latitudes along the altitude gradient of the region.

The detection of changes in climate parameters indicates that climate change has begun in Iran and it is necessary to identify the habitats of potential species, present and future years, under climate warning models. In this regard, it should be examined whether the increase in temperature in the country will have a positive effect on the presence of species in rangeland habitats, or a negative effect?. For this purpose, the current and potential future range of Artemisia Aucheri for the next three decades (2050) were predicted under two climate warning models (Rcp4.5 and Rcp8.5).

In this connection; First, the event map (presence and absence) of A. Aucheri species was prepared at the level of rangeland habitats. Then, the values of predictive environmental variables were calculated at the species occurrence site. For this purpose, 19 bioclimatic variables and three physiographic variables (slope, direction, height) with a pixel size of 4.9× 4.9 km were used to model the distribution. The points of presence were marked with the number one and the absence with the number zero. Then, considering the values of each of the climatic and physiographic variables as independent variables and the amount of presence and absence of the species as a dependent variable; a regression relationship between species occurrence and environmental variables was calculated. In the next step; based on the resulting regression relationship, prediction maps of the current (present) range and the potential future range of A. Aucheri species for the next three decades (2050) were prepared. In this regard, data related to monthly temperature and precipitation for the base time period (current) and the future time period, with a resolution of 30 seconds, in small scale from the WorldClim.org database, under two climate warning models (milder scenario and The more severe scenario) (Rcp4.5 and Rcp8.5) was downloaded from the General Atmospheric Circulation Model (CCSM4) and the maps were modified using temperature and rainfall data from synoptic meteorological stations. Then, by modifying the temperature and rainfall layers, layers of 19 bioclimatic variables were generated in DIVA-GIS software. From the digital elevation model map in the GIS environment, slope percentage and slope direction maps were generated and used as physiographic variables. All peripheral layers were standardized in Arc-GIS software in terms of area, number of pixels and image system. Next, the calculated environmental variables were placed in the regression relationship presented in the previous step, which was obtained between species occurrence with climatic and physiographic variables. Then, in the context of the Biomod package in the R program; the statistical model was transformed into a species distribution map, and in accordance with the fitted values, in Arc GIS software, a map was generated with a value between zero and one, and values close to one indicate areas with high probability of occurrence of the species. To better map the current range and future potential range; output maps, with a probability of occurrence between zero and one, to four floors; Inadequate habitat (0-0.25), almost suitable habitat (0.25-0.5), highly suitable habitat (0.5-0.75) and very high fitness habitat (0.75-1), The grouping was intense and by referring to the coefficients of variables in regression relations, effective variables for the current range and potential future range were introduced. In this regard, the extent of conformity of the presence range of A. Aucheri species with the current range (present) and their potential range in the future was evaluated using kappa statistical coefficient.

Global warming due to increased greenhouse gas emissions; it has caused obvious changes in Iran's climate, including rising temperatures, increasing climatic hazards and decreasing rainfall, in the last two decades. In this regard, most scientific sources emphasize that the increase in temperature has reduced the coefficient of bioclimatic comfort, and some plant and animal species that are not able to adapt to climate change, they migrate from their permanent habitat or gradually disappear. In this study, this aspect of the issue, namely climate change and the distribution of plant species, was emphasized. Based on the results; among the climatic and topographic variables, only the temperature-related indicators, in order of importance, include; BIO9, BIO10, BIO5 and BIO1 were identified as effective on the distribution of A. Aucheri species. The values of the characteristics increase as the climatic conditions worsen and as a result, the suitable habitat level (more than 75% probability) of A. Aucheri species will decrease for the following decades. In other words, it is shrinking in response to climate change. In this regard, the suitable habitat area of this species (probability of occurrence more than 75%) according to the current forecast map is 274505 hectares, which is about 18% of the total rangeland habitats in the southern Alborz. Also, the suitable habitat area of this species according to the forecast maps for 2050, under two scenarios of Rcp4.5 and Rcp8.5, is 208175 and 131964 hectares, respectively, which has about 13 and 8% of the total rangeland habitats. Overall; the area belonging to the classes in which A. Aucheri is more likely to be present has decreased in 2050 than at present. This indicates that in the future, the presence of A. Aucheri species in the habitats of the region will decrease and the risk of its removal from the ecosystems is evident. In sum, climate change and the consequent increase in temperature characteristics will cause the vertical expansion of A. Aucheri species and its movement towards higher latitudes along the altitude gradient of the region. Hence, the lower (1100 m) and upper (2500 m) expected range of vegetation range and altitude range in which A. Aucheri was observed (3400-1800 m); it will change over the next three decades. In this regard, the expansion of plants to higher altitudes during recent periods, an example of species displacement under the influence of climate change, has been mentioned. Also, one of the most important effects of climate change is the displacement of the geographical area of plant species. Based on the results of the present study and similar studies, by determining the degree of overlap of the current range event with the potential future range (for the next decade) of plant species, according to two climate warning models (milder scenario and more severe scenario); The changes that will occur as a result of climate change over the next decade in the distribution of species can be examined. Also, the results will be applicable in conservation and vegetation restoration programs, and based on the results, it is possible to identify suitable climatically and topographically sites for species conservation and rangeland.

In this study, regarding to the diversity of rangeland services, we tried to explain structure of alpine/subalpine ecosystem habitats using a brief review on current data and determine their dominant vegetation types in Iran. In this regard, different vegetation characteristics were determined using the data of the previous project of “Recognition of ecological zones of Iran”. On the basis of the information of mentioned project, the regions above 2700 m a.s.l., equal to 2.2 m ha were considered as alpine/subalpine vegetation zones. These zones, have been categorized according to their vegetation formations (growth forms and plant genus) and the area occupied by bushes and cushion plants, grasses, forbs and Junipers, respectively. The final report of the project of recognition of ecological zones of Iran, has lack of data for vegetation types of the peak areas, wetlands and meadows. According to diversity in vegetation types and structures, selecting the area above 2700 m a.s.l, is not a valid criteria for the alpine vegetation in the whole country’s area, so, it required a up to date and precise criteria to identify and distinguish this areas within different vegetation zones. Therefore, it need further studies according to challenges and opportunities of these areas, which among them, detailed monitoring and conservation, are the most important plans. The complexity and vulnerability of these ecosystems emphasize the priority of eco-restoration plans for these vegetation zones.

Multipurpose use of rangelands is one of the new challenges facing rangeland users, according to which grazing pressure in rangelands can be reduced and an important step can be taken to increase the welfare and empowerment of rangelands, preserve ecosystems and improve ecosystem services related to them. Therefore, the present study aims to evaluate the potential of rangelands in the semi-steppe region, for the use of medicinal plants and forage production, in 12 habitats of the country (including: Arshad Chamanof Sahand, Shiveh Soor of Marghavar of Urmia, DoshKharat of Golestankooh, Derakhtak of Friedan, Aliabad Moshiri of Koohrang, Freeze heights of Binalood, Khoraklat of Razavi Khorsan, Joladak of Alamut, Sar Ali Abad of Gorgan, Rineh of Larijan, Otaghsara of Larijan and Kaboudcheshmeh of Savadkuh) were performed. For this purpose, after measuring the vegetation and estimating the production of medicinal plants; based on ecological, economic and social criteria and indicators; the suitability of each habitat for the use of medicinal plants was determined. Then, by comparing the suitability class of habitats for the use of medicinal plants and their suitability class for livestock grazing, a decision was made regarding the priority of the type of rangeland use. Overall; 17% of habitats, by all criteria, are unsuitable for the use of medicinal plants. 33% have good suitable, 25% have medium suitable and 25% have low suitable. The results suggest that not all rangeland habitats are suitable for the use of medicinal plants, and not all of them are suitable for the use of medicinal plants. This issue should be considered in the policies related to the harvest of medicinal plants from the rangelands, and the use of medicinal plants should be allowed, taking into account the suitability of the rangeland. In rangelands with potential for medicinal plants, it is possible to reduce the number of livestock and grazing livestock in accordance with ecological principles; he used medicinal plants along with livestock. This, in addition to compensating for the economic problems caused by reducing the number of livestock, will also restore vegetation and enhance the richness of medicinal plants.

Background and Objective:

Soil organic carbon in rangeland ecosystems has a variety of functions such as increasing soil fertility, controlling erosion, increasing soil water permeability and, reducing the effects of greenhouse gases. Therefore, it is a key indicator in determining soil health that affects all physical, chemical, and biological properties of soil. The large area of the country's rangelands causes a serious challenge to the use of traditional methods in estimating soil organic carbon. In such situations, the use of remote sensing capabilities can be considered as a suitable option for monitoring the organic carbon of the country's rangeland soils.  The aim of this study was to determine the most important spectral factors affecting topsoil organic carbon in two summer rangelands.

Materials and Methods:

 This research was carried out in two summer rangelands of Lazour and Asaran. The first rangeland (Lazour) with an area of 8150 hectares and an average height of 2875 meters is located in the range of eastern longitudes 52.514 to 52.694 degrees and northern latitudes 35.855 to 35.934 degrees in Tehran province. The second Rangeland (Asaran) with an area of 5642 hectares and an average height of 2465 meters is located in the range of eastern longitudes 53.265 to 53.392 degrees and northern latitudes 35.804 to 35.882 degrees in Semnan province. In this research, the data of the OLI sensor of the Landsat 8 satellite were used. After pre-processing satellite imagery of the studied areas, Top of Atmosphere (TOA) reflectance layers of bands 2 to 7 along with the variables of surface albedo, Clay index, Carbonate index, Grain Size index, NDVI, brightness, greenness, and wetness index of Tasseled cap transformation were calculated. In each of the target areas, using Digital Elevation Model (DEM) maps, the slope, aspect, and hypsometric maps were prepared and by combining the last three layers with each other, a map of homogeneous sampling units was obtained. Soil sampling was performed using the stratified-random sampling pattern. In this way, in each of the homogeneous units, according to its area, several soil samples were randomly taken from a depth of zero to 20 cm and the amount of organic carbon of the samples was measured using the Walkley-Black method.

Results and Discussion:

 The results of this study showed that the spectral variables of Top of Atmosphere (TOA) reflectance layers of bands 2 to 7 along with the variables of surface albedo, Clay index, NDVI, brightness, greenness, and wetness index of Tasseled cap transformation have a significant correlation with topsoil organic carbon (p < 0.01). Also, the results of factor analysis by principal component analysis (PCA) with eigenvalues greater than one showed that the total cumulative variance explained by the 12 variables is 91.74%, which was explained by two factors. The first factor (soil color) explained 76.6% of the variance and the second factor (vegetation and soil texture) explained 15.14% of the variance.

Conclusion:

 The results of this study confirm the existence of a significant relationship between topsoil organic carbon and spectral factors extracted from Landsat 8 OLI sensor data in semi-steppe rangelands. Because of the large area of rangelands in Iran, the use of traditional methods in estimating soil organic carbon is not possible due to the need to spend a lot of time and money. And in such situations, the use of Remote sensing (RS) capabilities can be considered as a suitable option for monitoring the topsoil organic carbon in the rangelands.

Gross primary production is one of the key factors for understanding growing grassland conditions and rangeland monitoring. The present study aims to introduce an improved index based on the primary GDP and NDVI vegetation index of MODIS. In this regard, field operations were carried out in May, simultaneously with the growth of vegetation in the Rasin basin of Kermanshah province. In each of the types, reference areas were determined, and six (100-meter) transects were deployed in each of the representative points. Along each transect, five plots were placed at a distance of 20 meters, and a total of 84 transects and 420 plots were used in the field. Information such as rangeland type and actual fresh forage (AFY, kg/ha) were determined in the Rasin basin. In general, three types were identified in the field. Modified primary GDP data were calculated and validated with the measured data in the Rasin basin of Kermanshah province. The results showed that, in type 1, with R2 equal to 0.77 Ss index of gross primary production of NDVI as an improved index, in type 2, Ss index of primary production of NDVI with R2 0.73, in type 3, Ss index of gross primary production NDVI with R2 equal to 0.71, and finally, for the whole rangeland type, Ss index of gross primary production of NDVI with R2 equal to 0.51 was determined as the improved index. The results also showed that the modified primary GDP data is an acceptable indicator for monitoring grasslands. The accuracy of estimating rangeland production based on the Ss index of gross primary production of NDVI was 80%. The statistical results of comparing the estimated values with field observations indicate the acceptable accuracy of statistical models in estimating production. Also, since MODIS data is available twice a day, the improved index can supply the real need for rangeland monitoring on a regional scale.

Soil organic carbon is one of the most important indicators of soil quality. The purpose of this study is to study the spectral and non-spectral behaviors of soil in order to estimate the organic carbon of topsoil using factor analysis and multiple regression methods in the semi-steppe rangelands of Asuran, Semnan province. Soil sampling was performed using stratified random sampling method. After creating a map of homogeneous units in the area, in each homogeneous unit according to its area, several sampling points were selected completely randomly. A total of 145 sampling points were collected. At each sampling point, a composite soil sample (a mixture of 9 observations) was taken. Soil organic carbon was measured using Valkyli-Block titration method. Data of 114 samples were used to calibrate the model and data of 31 samples were used to validate it. The results showed that the correlation of spectral variables obtained from Landsat OLI sensor with surface soil organic carbon is higher than non-spectral variables obtained from 1: 25000 topographic maps. Also, the results of factor analysis by principal component analysis with eigenvalues greater than one showed that the total cumulative variance explained by 14 variables was equal to 90.2%, which was explained by three factors. The regression equation generated by the three extracted factors had suitable potential for predicting surface soil organic carbon (R2 = 0.59). The root mean square error (RMSE) of the proposed model was calculated to be 0.3.

Determining the distribution range and habitat conditions of indicator species of plant communities in rangeland ecosystems is the basic information needed for these ecosystems' management. Different species of the Astragalus genus have diverse functions in natural ecosystems. Therefore, in this article, the distribution area of the Astragalus species in Iran and their relationship with the altitude factor were evaluated. According to the obtained results, the total area of Iran's Astragalus habitats in those rangelands where Astragalus species are present in the main composition of the plant types is higher than 20.94 million hectares (13% of the country's area). The most area of Astragalus habitat and the most species richness of the Astragalus genus are located at 1000 to 3000 m.s.l. A. fasciculifolius, A. arbusculinus, A. spinosus, and A. squarrosus arethe most frequent of the Astragalus genus at altitudes of less than 1000 meters. A. fasciculifolius, A. microcephalus, and A. gossypinus are the most frequent species of the Astragalus genus at altitudes of 1000 to 2000 meters. A. adscendens, A. microcephalus, A. susianus, and A. gossypinus are the most frequent species of the Astragalus genus at altitudes of 2000 to 3000 meters.  A. adscendens, A. gossypinus, and A. microcephalus are the most frequent of the Astragalus genus in areas with altitudes of more than 3000 meters.

Determining the preference value of rangeland species by grazing livestock is one of the factors in rangeland management. In this study, the preference value of rangeland plants of Polour site in mountainous rangelands of Mazandaran in the months of grazing season (July to September) and different years (2007-2010) was investigated. The species selection index was used to determine the preference value of species. Species Production and consumption inside and outside the exclosure in the months of the grazing season and for four years were collected to calculate the species selection index. Duncan's multiple range test was applied to compare the means of traits. The results show that the species preference index, as well as the species preference index in different months of the grazing season, was significantly different at (p<0.01) Elymus hispidus var hispidus, Arenaria gypsophiloides, Bromus tomentellus, Dactylis glomerata, Festuca ovina, Taraxacum montanum, Tragopogon graminifolius, Falcaria vulgaris were classified in palatable class I. Astragalus aegobromus and Ferula galbaniflua were in palatable class II. Dianthus orientalis, Stipa hohenackeriana, Papaver bracteatum, Thymus pubescens, Verbascum Thapsus, Gagea lutea, Goebelia alopecuroides, and Euphorbia helioscopia were classified in palatable class III. Therefore, in the study of preference value, in addition to the taste of the studied livestock, factors such as the amount of production and the percentage of available plants, the distribution, and the amount of livestock access to them play a role in this area.

The study of  vegetation dynamics under grazed and non-grazed rangelands is one of the most important prerequisites for range improvement. In this research, vegetation composition and the vegetation functional groups were compared in an exclosure site (livestock excluded for six years) and grazed area in semi-steppe rangelands in Tehran province. Systematic random sampling technique through the use of transects and quadrats was employed to collect vegetation data. Results showed that there were 23 species common in both areas of exclosure and grazing while 4 and 8 species were restricted to exclosure and grazing areas, respectively. Results of t-test showed that exclosure significantly increased the percentage of canopy cover of some desirable species such as Agropyron intermedium, Bromus tomentellus, Festuca ovina, and Thymus Fedtschenkoi (p<0.01) Also, the rate of canopy cover of grasses, perennials and hemicryptophytes  significantly increased in exclosure area (p<0.01). Moreover, exclosure significantly increased the canopy cover percentage of some vegetation families such as Gramineae, Lamiaceae, and Rubiaceae. However, it significantly decreased the canopy cover percentage of Apiaceae family. The results of this study showed that grazing performance for six years had produced favourable changes in vegetation composition of the area. Another result of this study is the use of hemicryptophyte and trophyte functional groups to detect grazing rate in summer rangelands. So that, the predominance of hemicryptophytes and the reduction of trophytes indicate the grazing intensity of the low to medium, and the increase of trophytes and decrease of hemicryptophytes in the plant composition indicates a high grazing intensity of the livestock.

Knowledge of preference value of plant species is one of the essential requirements for determining forage available and consequently, calculation of grazing capacity for rangeland habitats. This project was investigated in 36 species including of 21 perennials and 15 annuals species. For this purpose, during four-years period (2007-2010) in each month of the growing season (spring and summer) film was taken from a non-pregnant and non -lactating unit adult ewes (Lori)for at least 1800 seconds with an average weight of 50 kg inside the flock which were grazing in rangeland. Results indicated that annual grasses such as Boissiera squarrosa, Bromus danthonia, Bromus tectorum, Heteranthelium piliferum had the highest grazing time with a total duration of 3083 seconds compared to other species. Subsequent species including of Agropyron trichophorum with 2594 seconds, Bromus tomentellus with 1232 seconds, Onobrychis melanotricha with 681 seconds, broadleaf herbaceous annual such as Helianthemum ledifolhum, Viciea peregerina, Diplotaxis erucoides, talaspi perfoliatum, Minuartia obtusiloba with 670 second and Hordeum bulbosum with 565 second were ranked in the next. Finally, it was found that annual grasses and shrubs in May, perennial grasses in June, and broadleaf herbaceous annual in July have quite palatable and located in Class I. Also, total grasses and perennial forbs in July, annual forbs and shrubs in May and June have fairly palatable respectively which have located in class (II) and vegetative forms have palatable class III in other months.

The present study was conducted to compare the parameters of vegetation in two sites grazed by livestock and wildlife (whole and goat) in Arasbaran rangelands of East Azarbaijan. After determining the key vegetation type, sampling of vegetation parameters was carried out on both sites using a systematic random sampling. Within each region, five transects of 100 m were established and ten plots of two square meters were systematically sampled on each transect. In each plot, along with each transect, the palatability class of the existing species, vegetative form, cover percentage, density, and production were measured. Results showed that canopy cover percentage, density and production were higher in wild life grazing site than in livestock grazing site and were statistically significant. On the other hand, because of their agility and mobility, wildlife has greater selectivity and a wider range of grazing than livestock. The results also showed that the canopy cover percentage, density and amount of forbs production were lower in the livestock grazing site as compared with the shrubs, due to the concentration of sheep grazing on forbs (generally legume family plants).

Fire in rangelands has significant effects on plant and soil factors. In this research, the effects of fire on plant factors were investigated in semi-steppe rangelands of Sirachal for three years (2015-2017). The two selected rangelands were similar in terms of vegetation type (before the fire) were next to each other. The treatments included control rangelands and burned rangelands, and sampling was performed using transects and quadrates (30 plots) for three consecutive years. Vegetation factors included canopy cover, production, density, species richness, and life form. The statistical analysis of the treatments was carried out using the independent t-test. Comparison of different years, in each of the burned or control rangelands, was done using analysis of variance and the means were compared with Duncan's test. The results showed that fire during the years of the project did not have a significant effect on the canopy percentage and the production of all rangeland species, but it had a positive and significant effect on the density of all rangeland species. High difference in density compared to the cover and production could be due to the low canopy cover and production of new seedlings. In other words, new seedlings of plants had a low canopy cover, low production, and a high density. In terms of species richness, the highest difference is related to the absence of shrub species in the burned rangeland; however, according to the Sorenson index, the two treatments were similar in terms of plant species. Also, in terms of life form, fire had a positive and significant effect on the cover percentage, density and production of forbs, a positive and significant effect on the cover percentage and density of grasses, and a significant negative effect on the shrubs.

   Organic carbon is one of the most important soil quality indices, affecting almost all physical, chemical and biological properties of the soil. The purpose of this study was to investigate soil spectral and morphometric factors to estimate the organic carbon of topsoil, using factor analysis and multiple regression methods in semi-steppe rangelands of Lazour. Soil samples were taken with a stratified random method. For this purpose, 157 training sites were selected in homogeneous units. Of these, 127 sites were used to calibrate the model and 30 sites were used to validate the model. In each of the training site in a random manner, a soil sample including nine observations was taken from a depth of 0 to 20 cm of soil surface. Soil Organic Carbon (SOC) was measured using Walkley-Black titration method. The results showed that the variables of Albedo, Clay Index (CI), NDVI, Relative Relief and Tasseled-Cap's Brightness and Greenness indices had a significant correlation with the SOC (p<0.05). Also, the result of factor analysis by Principal Component Analysis (PCA) method with eigen-values greater than one indicated that the total cumulative variance, explained by the six variables, was equal to 81.1%.This variance was explained by two components. Using multiple regression model, an appropriate regression equation was calculated to predict SOC (R2=0.789). The Root Mean Square Error and the Mean Absolute Relative Error of the proposed model were calculated as 0.24 and 0.10, respectively. Due to the direct relationship between the SOC and the factors such as soil fertility and sustainability against erosion, a spatial distribution model of SOC could be an important sub-model to design other complex models such as the terrestrial ecosystems biomass and soil erosion models.

The current research was performed in Homand Absard Research Station to investigate the yield of Vicia villosa under different sowing and establishment methods. Initially, the seeds of this species were collected from similar natural habitats. Afterward, seed characteristics including germination percentage, viability, seed vigor, etc., were examined. The study area is a semi-steppe region with an average rainfall of 333 mm. Two sowing methods including seeding and seeding together with rainfall storage, and spring and autumn sowing dates were considered in a split plot design with three replications. Data analysis was performed with SPSS software, and mean comparisons were done by Duncan's multiple range test. According to the obtained results, no significant differences were obtained for the yield of the seeds cultivated in autumn and spring between two sowing methods at 5% level of probability. However, the interaction between methods and season was significant and higher yield was recorded for the seeding with rainfall storage method in autumn season.

Determining of utilization factor is one of the most important factors which used to evaluation of equality between livestock and rangeland. Water points are one of the effective factors that effect on the grazing distribution in rangelands. While some factors such as slope، height and soil factors have no limitation، distance from watering points is limited the use of forages. In this research، the percentage of use factor of Artemisia sieberi Besser was calculated around watering points using ocular estimate method. The aptest regression equations were determined for each of watering points. Before grazing of livestock، 10 pair plots of 4m2 were established with pegs. The dry weights of forage at 10 plots were calculated randomly. After grazing، the factor of use in the other 10 plots was estimated and the real utilization of them was calculated by clipping and weighting method. The estimated and real data were used to calculate of regression equation. And the estimated data modified with it. In this stage، after grazing، two transects of 1. 7 km were established around each of watering points randomly. In each of 100 m of one transect، the utilization rate of A. si. was estimated by establishing of a plot of 4 m2. All of the estimated data were modified by regression equation that calculated in previous stage. The regression coefficients of two equations were compared each other using group regression method. And final regression equation was calculated. The results show that the utilization factor of A. si، and distance from watering point have a high correlation each other (R-sq = 85%). As well as، with increasing of distance from watering point، the utilization factor decreases.

In this research, species richness, life forms and platability of plant species in the key and critical areas was investigated. Two Whittaker, plots of 0.1-ha were established in each of mentioned areas. In each of Whittaker, plots from 0.1 to 1000 m2 respectively, species name as well as life forms, the number of each species and their palatability classes were recorded. By using linear regression models, two appropriate equations were calculated for species richness in critical and key areas. In order to compare the regression equetions of species richness, the group regression model was used. The results show that the species richness in key area is significantly different from critical area (P<0.05) so the species richness in key area is higher than the critical area. To find the relationships of the life forms and palatability of plant species in the key and critical areas, biplots were provided by using Principal Component Analysis (PCA). The correlation between palatability of species in key and critical areas are positive and negative respectively. Also the phanerophyts and chamaphyts have a positive correlation in key area but the geophytes has a negative correlation in it. This issue in the critical area is vice versa.

watering points are from the most effective factors that influence grazing distribution in rangelands. Where other limiting factors such as slope, height and soil have no variation, forages utilization by livestock is limited by distance from watering points. In this research, the effects of livestock overgrazing on vegetation of a critical area around livestock watering point were investigated in a flat and arid rangelands in Chahe-Nou of Damghan, Iran. In ordet to determine of degraded area around watering points, the importance value of two species of Peganum harmala and Artemisia sieberi in 8 geographic directions were analysed by using ANOVA and Duncan's multiple range test. The association of two species of Pe.ha and Ar.si was studied using Chi-squer test. Transects of 1.5 km were laid out in 8 geographic directions around watering point and samples were taken systematically. Each 100 m of one transect was considered as block. In each block, four quadrats of 4 m2 were plotted to measure canopy cover percentage, density and frequency of both species. Results showed that importance value of Pe.ha was not significant for all transects (P>0.05) but the importance value of Ar.si was significant (P<0.05). There were negative association between the two important species of Pe.ha and Ar.si. It can be concluded that the intensity of grazing was concentrated within 500 meters around watering point which can be considered as critical zone. The results also showed negative impact of overgrazing on vegetation structure, which may indicate the necessity for a monitoring program livestock grazing and watering points in these rangelands.