فهرست مطالب rostam khalifehzadeh

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.

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.

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.

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.

The production and proper utilization of medicinal plants in natural habitats need to review and identify the natural conditions and climate of the habitat of these plants and separating them from harmful and poisonous plants. The current study was aimed to introduce and determine the distribution of medicinal plants from Lamiaceae family in Mazandaran province as well as the introduction of natural habitats in order to provide information for executive agencies and administrators of land use plan to be used for optimal utilization of potentials of natural resources. In this study, after collecting the documents, the aromatic and medicinal species (wild species) of Mazandaran province were identified and their distribution was investigated. According to the obtained results, the medicinal species of Lamiaceae family in Mazandaran province contain 23 species, belonging to 11 genera among which Stachys spp. with seven species is known as the riches genus in Lamiaceae family, distributed in an area of 16322 km2 in Mazandaran province. As a result of this study, the distribution map of natural habitats, habitat conditions, life form, and utilizable organs of medicinal species belonging to Lamiaceae family in Mazandaran province have been provided. According to the rich flora of Mazandaran province, the results of this study could help in financing, planning, cultivation and production of medicinal plants at industrial levels. In addition, the production of herbal medicines could be used in pharmaceutical, medical and food industries.