مقالات رزومه رستم خلیفه زاده

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.

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.

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.