فصلنامه تحقیقات مرتع و بیابان ایران
سال بیست و نهم شماره 4 (پیاپی 89، زمستان 1401)

One of the important factors in determining the grazing capacity of rangelands is determining the preferred value of rangeland plants according to the type of livestock using the rangeland and its changes during the grazing season. In this study, the preference value of rangeland species in Zaminsang rangeland in Hormozgan province in the months of grazing season (January to May) and different years (2007-2010) was investigated. To determine the preference value, the method of utilization percentage of plant species and determination of preference index were used. The results were analyzed in a split plot statistical design in time in a randomized complete block design in SAS software and the statistical mean of the studied trait was compared with LSD test. The results showed that the most preferred livestock is primarily Aeluropus lagopoides and Atriplex leucoclada and Alhagi graecorum. The lowest percentage of exploitation was from Halocnemum strobilaceum and Desmostachya bipinnata. Based on the preference value index classification, Aeluropus lagopoides and Atriplex leucoclada species are relatively palatable species (relative preference), Alhagi graecorum and Halocnemum strobilaceum species are moderately palatable species (moderate preference) and Desmostachya bipinnata was one of the almost non-palatable (relative avoidance) species.

Atriplex canescens James is one of the successful non-native species in improving and rehabilitating the desert rangelands of Markazi province, which has been cultivated in a large area of saline habitats along the Meyghan playa (about 12,000 ha) since 1981. This species after a few years of growth becomes woody and the density of green aerial organs, survival and forage production decrease. Increasing forage production, vitality and viability of this plant are the requirements for the management of these habitats and pruning is one of the necessities to achieve this. In this study, pruning and census operations have been carried out in three study sites with an average area of one hectare located in the Meyghan playa for four years to determine the appropriate level or height of pruning. At each site, four levels of pruning, including pruning from the ground and pruning from heights of 20, 40, 60 cm and control (without pruning) have been applied. Each treatment was performed on 16 A.canescens stands with an average diameter of canopy and height of 160 and 115 cm, an average production of 530 g per stand and an average of 34 years of age. Pruning was done in March of the first year of study and vitality, forage yield, height, canopy diameter and survival rate factors were inventory in three years later. Data collected and analysed using two way ANOVA (Sits and treatments) based on completely randomized design. Based on the results, in two sites located in the northern and western regions of Meyghan playa with an approximate number of 400 stands per hectare and an age of 38 years of rangeland planting, pruning treatments from heights of 60, 40, 20 cm and pruning from the ground from A.canescens had more favorable effects in terms of increasing vitality and forage production. On the site located in the southern part of the Meyghan playa, with an approximate number of 350 stands per hectare and an age of 30 years of rangeland planting, pruning from ground surface and pruning treatments from heights of 20, 40, 60 cm respectively have been useful in terms of vitality and forage production. In total, after three years used of pruning from ground surface and pruning treatments from heights of 20, 40 and 60 cm, the average yield of A.canescens respectively were 690, 679, 658 and 818 g per plant rootstock. To improve the characteristics of A.canescens species in terms of positive plant factors such as vitality, survival and forage yield, in Atriplex cultivation areas of the northern and western margins of Meyghan playa with an age of 38 years of rangeland planting, pruning operations from a height of 60 cm and for southern areas of Meyghan playa with an age of 30 years of rangeland planting, pruning from the ground is determined and proposed.

Understanding the ecological characteristics of plant species and how they respond to environmental factors provides information necessary for vegetation management and rangeland management. Therefore, in the present study, the ecological needs of the species Salsola kerneri (Wol) Botsch with emphasis on determining the ecological factors affecting vegetation changes and investigating the response of these species to ecological factors changes using Canonical Correspondona Analysis (CCA) and Generalized Additive Models (GAM) in Mazandaran province were discussed. Data were analyzed using SPSS17 and CANOC 4.5 software. The results showed that S.kerneri showed a significant response to some of environmental factors in its habitat. The response pattern of S.kerneri along the Ec, pH and Tnv (Lime) followed the monotonic increase model and increased with increasing values, abundance and percentage of vegetation. Therefore, with the increase of these factors in a certain range, the coverage percentage of this species increases. The response of this species along the pH of soil followed the monotonic increase model and by increasing this factor, the presence and percentage of vegetation decreased. The response of this species along the organic matter (%) of organic carbon (%), nitrogen (%) and litter%) followed the monotonic decrease model and by increasing this factor, the presence and percentage of vegetation decreased. The response pattern of S.kerneri along the clay (%),soil specific gravity, Altitude of sea, mean annual temperature, potassium (ppm) and phosphorus (ppm) followed the unimodal model and its optimum growth rate for these factors were 11%, 1.1 g/cm3,13C°,1700m,12.5°C, 700 ppm and 5 ppm respectively. It grows in lands with low to relatively high slopes, but it has more abundance in slopes of 40-50%. The highest cover percentage of this species in the eastern slopes and the lowest in the northeastern slopes. The stone (%), sand (%) and silt (%) response also followed the bimodal model. The study of this species response curve along the slope of topographic and soil factors provided valuable information to determine the ecological needs of this species that can be considered in rangeland improvement operations in similar areas.

Understanding the environmental factors affecting the establishment of vegetation, can help in the proper management of rangeland ecosystems. Optimal habitat has a beneficial effect on the survival and reproduction of species. With the advancement of statistical science and GIS, it has become possible to predict the habitat of plant species using modeling methods. Therefore, the present study was conducted with the aim of preparing a forecast map of B. tomentellus habitats based on the climate forecast model in South Zagros (Fars province). First, using 29 synoptic stations inside and adjacent areas, a database including variables of precipitation, night temperature, daily temperature and average temperature was formed and 19 climatic measures were calculated. Also, using a digital height model with an accuracy of 30 meters, three physiographic variables including slope, direction and height were prepared. Then, using updated maps of ecological zones and field visits, the presence and absence points of B. tomentellus were identified. Using logistic regression, the growth behavior of this species in the South Zagros region was determined and the model map and the corresponding equations were calculated in the current conditions. Using current equations and placement of data extracted from the Worldclime database, the future distribution map of B. tomentellus for 2050 was generated under the RCP4.5 and RCP8.5 climate scenarios. The results showed that B. tomentellus species will migrate to higher altitudes of 170 and 260 m, respectively, in the RCP4.5 and RCP8.5 scenarios. Also, the area of ​suitable habitat areas, from 26.8% of the area of ​South Zagros rangeland habitats in the current conditions, to 8.5% under the RCP4.5 scenario and 1.7% under the pessimistic scenario (RCP8.5) in 2050 Will be reduced.

Drought is an unpleasant climatic phenomenon that directly affects different dimensions of human societies. In order to know and choose the right management decision, it is necessary to design and develop an integrated approach to more effectively control this phenomenon and provide early warnings.In this study, twelve various remotely sensed indices of the Moderate Resolution Imaging Spectroradiometer (MODIS) and digital elevation model (DEM) were used to monitor drought during 2000–2018 growing season. Standardized Precipitation Index (SPI) with time scales of 1 to 12 months was used as reference data. The relations between thirteen indices and SPI with different time scales were modulated using machine learning approach. The random forest technique was used to construct a comprehensive drought monitoring model in Ilam Province. Validation data were provided based on relative soil moisture, Standardized Precipitation Evapotranspiration Index (SPEI), and crop yield data. It was observed that random forest produced good applicability (R2 = 0.88) for SPI prediction. In the next step, the Drought Hazard Index (DHI) was generated based on the probability occurrences of drought using the comprehensive drought model which was made in the previous step. The Drought Vulnerability Index (DVI) was calculated by using 7 socioeconomic indices. Finally, the Drought Risk Index (DRI) was obtained by multiplying DHI and DVI for Ilam province. The result of the DRI map showed that 2 Counties are at very high risk of drought, 4 Counties are at high risk and 4 Counties are at moderate and low risk of drought. Overall, the result of our study provides a comprehensive method for assessment of regional drought. Also based on this model, Counties with high vulnerability can be identified to provide timely management programs to help improve the situation.

To evaluate the genetic diversity and relationships among traits of herbaceous milkvetch, 10 genotypes belong to five species including Astragalus vegetus. A. brevidens, A. brachyodontus, A. effusus and A. cyclophyllus in Sanandaj in a randomized complete block design with three replications were studied. Seed sowing was done in November 2018 and morphological traits of plant in spring 2020 were measured. Analysis of variance released significnant (p≤0.01 and 0.05) difference for milkvetch populations (G) for all studied traits. In 2020 (two years old plants), the mean of plant establishment was about 26%, the number of primary branches was 3.2, plant height, the tallest stem length and crown diameter were 16.9, 19.2 and 15.4 cm respectively, the length and width of the root were 17.4 and 6.2 cm, respectively, the average of fresh weights of the whole plant, arial and root parts were 2.3, 1.9 and 0.4 g and the average of dry weights of the whole plant, arial and root parts were were 0.9, 0.7 and 0.2 g respectively, average dry to fresh weight ratio was 0.38. Average of leaflet per leaf was 7.7, so mean of length and width of leaf and leaflet were 7.5, 3.7, 2.3 and 0.5 cm respectively. Up to this stage, the accession of A. effusus Darreh Shohada (West Azerbaijan) and three accession of A. vegetus (Zereshk of Qazvin, Saral of Kurdistan and Qarehbagh of West Azerbaijan) were superior ones in terms of forage production and other studied traits. The weight of the plant was positively correlated with plant vigor, length and width of leaf (p≤0.05) and with plant height, crown diameter, number of primary branches, length and width of root, arial and root weight at 1% probality level. The results of stepwise regression of forage yield on other traits showed that plant weight, establishment percentage, plant height and crown diameter at 1% and the length of leaf and root at 5% probality level (R2adj = 91.1%) were forage yield components. Therefore, in order to achieve higher forage, the genotypes with larger aerial parts and deeper roots should be selected.

The establishment and growth of vegetation on marly lands is usually difficult because of mineralogical properties of marls especially clay minerals aggregation as impermeable fraction in these rocks and sediments. This research aims to systematically investigate relatively densely grown plant species and determine their habitat needs as well as their protective role in the soils resulting from the erosion of the Gurpi marly belonging to the Cretaceous period with a thickness of more than 100 meters in two regions as Vastegan and Dorahan areas in Borujen Township, Chaharmahal & Bakhtiari province.  For this purpose, 65 marl soil samples were taken and physical and chemical tests were performed on 31 samples. Botanical surveys performed using repeated field visits and plat made up on the 180 plots and plant samples were identified after moving to plant museum (Herbarium) of agricultural and natural resources research and education center. In general, more than 400 plant species growing in the region and on different formations. A collection of rangeland species Astragalusbrachycalyx-Daphnemucronata- Cirsiumbracteosum with a density of more than 50% can be present in the lands resulting from the erosion of neutral marl lands(PH =7-8) with moderate  lime amount and without Na+ and Cl- presence can  established and go through its growth stages. In addition, a collection and colony of rangeland species with the combination of Astragalus susianus-Daphne mucronata-Amygdalus elaeagnifolia) can be established in alkaline marl (pH>8) with high amount of lime fraction and cl- and should be presented as a biological solution to control the erosion of the soils affected by the erosion of alkaline marls.

Early establishment of rangeland plant species, especially in arid and semi-arid regions, is a considerable issue to increase their yield. In order to investigate the effects of seed priming on changes in yield of the Astragalus brachyodontus pasture species, the present study was carried out in the greenhouse with factorial design. Three treatments of hydro-priming (distilled water), osmopriming (Polyethylene Glycol with two levels of -0.4 and -0.8 MPa) and hormone priming (gibberellic acid) as the first factor, and three levels of deficit irrigation stress (100% field capacity, 75% field capacity and 50% field capacity) were considered as the second factor and 3 populations (Zanjan, Qom and Khalkhal) as the Third factor with 3 replications. The results showed that seed priming, deficit irrigation stress, populations and their interactions had a significant effect at the 1% probability level on all investigated traits. The soil water reduction caused a significant decrease in seedling germination percentage, stem length and weight, but the root length increased and the root weight first increased and then decreased intensively. The maximum yield of height (11.0267 cm), root length (30.6467 cm), stem weight (1.1700 g) and root weight (1.3664 g) was related to Zanjan population in normal irrigation. The treatment of -0.4 MPa osmopriming had the highest values in root length (33.1556 cm), stem weight (1.2144 g) and root weight (1.4800 g). Generally, according to the present research, -0.4 MPa osmo-priming and hormone priming with gibberellic acid were introduced as treatments to improve the Astragalus brachyodontus species performance in the greenhouse under the severe deficit irrigation stress condition. This results can be considered to improving the establishment and performance of this native valuable forage, in breeding programs and rangeland development, to improve its initial establishment in deficit irrigation conditions.

One of the most important methods of extracting information from satellite data is various image classification techniques. The current research was conducted to separate and classify plant ecological units by classification tree analysis algorithm on satellite images and also visual interpretation of Google Earth images in one of the semi-steppe rangelands of Chaharmahal and Bakhtiari province. After applying the classification algorithm in Idrisi TerrSet software, the software generated the error matrix, and then based on the values inside this matrix, the extracted statistics were evaluated. The results of visual interpretation showed that finally, seven types of plant ecological units that were different in terms of structural features were identified and expressed as descriptive statistics, including Astragalus verus, Bromus tomentellus, Scariola orientalis, Astragalus verus-Bromus tomentellus, Astragalus verus -Stipa hohenikeriana, Bromus tomentellus-Stipa hohenikeriana, and Stipa hohenikeriana. The results also showed that the overall accuracy and kappa coefficients of 0.92% and 0.89 for Landsat 8 images and 0.94% and 0.92 for sentinel 2 images were achieved. Based on the obtained results, it was found that satellite images and aerial images have a suitable separation capability to prepare a map of plant ecological units. Since the visual interpretation of Google Earth images is a time-consuming and expensive method, it can be concluded that satellite images, especially Centile 2, can be used as a tool due to their high resolution and high-resolution images, Practical and usable, provide accurate information and details of the earth's surface phenomena and be used as a suitable source for preparing a map of plant ecological units.

In the rural society, various factors play a role in the participation of local communities in the conservation of natural resources. Among them stakeholders have the central role as participation plays an important role. Natural resources are considered as one of the main economical sources and their restoration and conservation are considered as the base for human activities for the current and future generations. These factors include social factors, economical factors and cultural factors, which are known as norms. Most experts believe that participation is the main and determining factor in the process of growth and development in developed and developing societies. Therefore, in order to prevent the degradation of rangelands, a comprehensive plan must be designed by various organizations and departments to monitor the exploitation and utilization of rangelands and this depends on the participation of the stakeholders. In order to protect and restore rangelands, organizations must be aware of the norms that affect local collaborative behaviors. The aim of this study is to identify the norms that influence the pastoralists participation and to determine the contribution of each of their components in the conservation of Nodushan rangelands, Yazd province. In this study we assessed the impact of norms including social, economical and cultural factors as independent variables on the amount of pastoralists participation as a dependent variable. The method was descriptive-analytical in the form of a questionnaire based on a five-option Likert scale. The sample size included 104 pastoralists and random sampling. After checking the reliability and validity of the questionnaire, the path analysis method was used to rank the independent variables. The results showed that the social factor with 0.857, the economic factor with 0.633 and the cultural factor with 0.144 had the greatest total impact and also the direct and indirect impact on the pastoralists' participation. The method of exploitation in rangelands, the amount of income of pastoralists, and the awareness and experience of pastoralists had the first priority. Spearman's correlation coefficient between independent variables and pastoralists' participation showed that the social factor and the economical factor have a positive and significant correlation coefficient with the dependent variable of pastoralists' participation. Therefore, it was suggested that the social and economical factors should be considered as the most important indicators of attracting pastoralists participation in planning for restoration of rangelands.