IRANIAN JOURNAL OF RANGE AND DESERT RESEARCH
Year:2019 | Volume:26 | Issue:3 (76)|Papers Count:20

Wind erosion and its consequences, such as dust storms and sand movement is one of the environmental problems in arid regions. There are several ways to combat wind erosion, among which biological reclamation using drought-tolerant species and psammophytes is the most sustainable method. The initial establishment of these plants requires the use of sand stabilizers such as mulches. The mulch used in the past was the product of oil refineries and industries, which despite its merits such as strength and flexibility, had many environmental consequences. Therefore, researchers and scientists in the country decided to present an eco-friendly product that would replace the oil mulch. One of these products is polymer-cellulosic mulch, produced by the Department of Chemistry, Malek Ashtar University of Isfahan. This mulch was used in sand dunes of Kashan, during which the mulch resistance to environmental conditions, its effect on plant establishment, and soil moisture uptake and retention were investigated. The results showed that this mulch had no negative effect on plant establishment. Its resistance to wind erosion is very good for the first few months of spraying. However, over time and during the hot summer months, cracks appear that partially overshadow the mulch's stabilizing properties. The soil moisture content was about 4. 5% higher in 10 t/h mulch as compared with control. In general, for the crust and cracks problems, this mulch cannot be a good alternative to petroleum mulch.

Livestock grazing is one of the most important factors effective on soil and vegetation structure and function. This study aimed to investigate the factors affecting the grazing frequency and intensity in the rangeland in autumn 2015. The statistical population was the heads of tribal families in Kuhdasht city (1038 families), among which 310 heads of households were selected by the Cochran formula in stratified random sampling method. Data were collected by questionnaires and direct interview containing seven open questions and 17 closed questions. The validity and reliability of questionnaires were approved by a panel of experts and calculating the Cronbach alpha coefficient (above 0. 85), respectively. Kendal correlation coefficient showed that there was a significant relationship between the grazing frequency with the annual mean income and cost of beneficiaries, annual calving of 10 livestock and distance between summer and winter rangelands. There was also a significant relationship between grazing intensity and the annual calving of 10 livestock. The results of Mann-Whitney test showed that there was a significant difference between the index of grazing frequency and intensity in winter rangeland. The results of the Kruskal-Wallis test also showed that there was no significant difference between index of grazing frequency and intensity with utilization type of rangeland.

A significant area of the country's rangelands is degraded due to various factors and an important part of rangeland species is endangered or their population is severely reduced. Rangeland improvement and reclamation through selecting suitable species and finding the best cultivation methods are of utmost importance in these rangelands. Therefore, according to the results of the research project performed in the Research Institute of Forests and Rangelands, the seeds of Sa. arbuscula were collected from different rangelands of Semnan province along with the existing populations. The study was conducted in a randomized complete block design with three replications at Semnan Research Station since 2011 for five years. The data were analyzed using SAS software and the means were compared with Duncan's test. Our results clearly showed that among the study accessions of Sa. arbuscular, the genotypes 230 and 234 with an establishment percentage of 86. 67% and 84. 02% were superior, respectively. Therefore, the genotypes 230 and 234 could be recommended for rangeland improvement and reclamation.

In order to determine and prioritize the most effective factors on grazing management in Qashqai Nomads’ ecosystem (Shesh Boluki tribe), sampling was done by selecting 405 households (using Cochran formula) from nomad exploiters and 45 individuals from experts with experiences in migration and grazing management in Fars and Bushehr provinces in 2015 and 2016. The survey used descriptive participant observation with questionnaires and interviews. In this study, the viewpoints of two statistical groups were obtained through Likert scale (five-point scale) and then the analysis was done using nonparametric tests including Mann Whitney and Kruskal-Wallis test. he result showed a significant difference between the viewpoints of exploiters and experts regarding prioritization of effective factors on elements and sub elements of grazing management (P<0. 01). The result from integration of exploiters and experts viewpoints showed that effective factors on the element of grazing time were consisted of decreasing in precipitation and frequent drought, early cold weather in summer rangelands, early warm weather in winter rangelands, sufficient foliage in rangeland, water scarcity in winter rangelands; element of spatial distribution of grazing was included of role of shepherd in herd movements and distribution of watering points in rangeland; element of type and composition of herd were consisted of topographical condition, distance from watering point, climate variability and frequent droughts, and also element of livestock number was consisted of exploiter’ s livelihood, drought and climate variability and inter-annual precipitation. In general, a more homogenous answer was observed between expert viewpoints.

One of the problems of most airborne and space-based sensors is the lack of high spatial, radiometric and temporal resolution, due to the high technical and sensor design costs. On the other hand, the identification and monitoring of the factors in natural ecosystems, such as water, soil, and atmosphere requires high spatial, radiometric and temporal resolution. Therefore, it is necessary using merge methods for integrating two or more spatial, radiometric and temporal resolution. Aerosols, especially dust of mines and industries, are part of the contaminate particles that are important in identifying them. Aerosol monitoring requires high spatial, radiometric and temporal resolution sensor, which is practically impossible in a sensor. For this purpose, it is possible to merge images with a high radiometric resolution like Modis and high spatial images like Landsat. One of the most popular indicators for dust detection is the NDDI index, which is obtained using SWIR (2. 1μ m) and blue (0. 47 μ m) wavelengths. In this research, we used several merging algorithms, including Bovery, Gram-Shcmidt, STARFM, ESTARFM, wavelet, PBIM, SIFM and HPF to integrate Modis and Landsat image data of 8 July 2016, and then provided NDDI index maps. The results of the evaluation showed that the best method was STARFM, ESTARFM, and PBIM with correlation coefficient (R2) of 0. 88, 0. 91, and 0. 99, respectively with Landsat image and 0. 51, 0. 5, 0. 57 with Modis image. The mean squared error (RMSE) for all three methods was negligible: 0. 02, 0. 400, and 0. 055 respectively, with the original Landsat images and 0. 004, 0. 6 and 0. 1 with the main images of Modis. Therefore, the STARFM, ESTARFM and PBIM methods could be used to merge Modis and Landsat images to extract data with high precision.

Fire is one of the most important influencing factors on the structure and composition of plant communities, especially in arid and semiarid rangelands. This study was designed to investigate the role of fire on vegetation dynamics in semi-steppe rangelands of Central Zagros. A stratified random sampling was used to collect the data from six sites with one and five years after the last fire. At each rangeland site, 20 plots with four square area meters, 10 plots in the burned sites and 10 plots in the control sites, were used. The cover percentage of each species was accurately recorded. A one-way analysis of variance and Tukey's test were used to compare each of the variables. The results showed that the fire significantly reduced the vegetation cover and litter, and increased the bare soil surface in the region. The composition of the fire region was close to the control area after a period of five years. The fire caused a decrease in the percentage of shrubs and an increase in the proportion of perennial grasses, annual grasses, and annual forbs in the region. The fire also changed the vegetation composition of rangelands, so that the proportion of hemicryptophytes, therophytes, and geophytes were decreased while chamaephytes increased. Fire also increased the proportion of high and moderate palatable species (class I and II) and reduced the proportion of class III species. Based on the results of this study, it can be concluded that the fire reduces litter and increases the bare soil; consequently, the soil erosion is exacerbated, hence this should be considered in rangeland management. Overall, uncontrolled fires in the semi-arid regions of the country will not lead to the restoration of vegetation cover.

Awareness of the nutritional value of different rangeland plants can help animal husbandries to prepare a suitable diet; hence some experiments were conducted to determine the chemical compositions, minerals, gas production and other fermentation parameters of four range plants that can be grown in Torbat-e Jam (including Arctium lappa, Verbascum thapsus, Althaea officinalis and Ferula hermonis), Iran. The above plants were randomly collected before flowering. The range of crude protein (15. 85-22. 87%), ash (8. 27-16. 10%), crude fat (0. 85-5. 75%), neutral detergent fiber (19. 27-37. 53%), acid detergent fiber (15. 53-26. 53%), acid detergent lignin (3. 83-5. 43%), and crude fiber (12. 49-21. 74%) was different among four plant species. The highest amount of calcium (12. 26 g/kg DM) was related to Althaea officinalis. The parameters of gas production and other fermentation parameters were also different among the plants, so that the maximum amount of gas production after 12, 24, and 48 h incubation (47. 32, 61. 64, 71. 21 ml, respectively), potential gas production (75. 70 ml), dry matter and organic matter digestibility (82. 99 and 84. 60 %, respectively), metabolizable energy (10. 66 MJ/kg DM), net energy for lactation (6. 51 MJ/kg DM), and total volatile fatty acids (36. 62 mmol/L) were found in Verbascum olympicum. There was a negative correlation coefficient between the gas produced after 24 h incubation with ether extract, crude protein, and ammonia nitrogen. Comparison of the gas production, fermentation and degradability parameters among studied plants indicated that Verbascum thapsus had higher potential nutritive value.

Species diversity is one of the characteristics indicating changes in rangelands. In this regard, the relationship between range condition as a result of managerial measures and species diversity was investigated. Spearman correlation test and one-way analysis of variance were used for testing the variations of Shannon-Wiener diversity index values of plant types with their conditions. Then, by plotting rank-frequency curves and applying the frequency distribution models, the vegetation types with higher diversity were identified and their relationship with range condition was interpreted. The results showed that Shannon-Wiener diversity index had no significant correlation with range condition. Range condition had no significant effect on the amount of diversity and all three categories of condition (good, average, poor) were classified according to the mentioned index. In general, no significant trend was observed between range condition and amount of diversity. The results suggest that the high values of numerical indices of diversity are not the reason for the improvement of range condition, but their species composition and abundance should also be investigated. Drawing rank-frequency curves and matching the frequency distribution models showed that plant types with good and moderate condition, species with less abundance, were less frequently observed and its curve had a mild slope than those with poor condition, so their diversity was higher. In most plant types, the geometric series model was consistent, indicating low plant diversity and poor range condition. In general, concerning the degree of conformity of the results of the frequency distribution models with the condition of the plant types, the results emphasize the need to pay attention to the parametric indices of species diversity in rangeland health assessment.

Clematis ispahanica Boiss is a rare species of Ranunculaceae family, which has forage and medicinal value. The seeds of this species have a very low germination percentage because of dormancy. Therefore, increasing their germination percentage by laboratory methods can be effective in restoring this plant. In the present study, considering the seed size of C. ispahanica, H2SO4 (96% ) for 5, 10, 20 seconds, hot water (70 and 90 ° C. ) for 15 minutes, ethanol (96%) for 48hours, HCL ( for 2, 4 and 6 minutes), KNO3 (0. 2%) for 48 hours, NaCl (50 milli molar) for 48hours, and scarification using sandpaper were tested to break the seed dormancy. Moreover, the seeds of this species were planted in different depths (1, 1. 5 and 2. 5 cm) and densities (30, 50 and 70 seeds per square meter). Data analysis was performed using SPSS software version 18 and by univariate analysis of variance and the Duncan test. According to the results, the most effective treatments to improve germination percentage and rate were KNO3, NaCl and scarification treatments. The depth of planting had a significant effect (P<0. 05) on the germination percentage, but the density of planting had no significant effect on the germination percentage (P> 0. 05). Due to the lack of use of chemicals in scarification using sandpaper treatment, it has an advantage over other effective treatments, recommended to break seed dormancy and increase its germination percentage. Considering the weight of a thousand seeds (3. 73gr), 1. 12 kg/ha seed (equivalent to 30 seeds per square meter) in the depth of 1. 5 cm is proposed for the planting of this species in the study area.

The main purpose of this study was to analyze the effective factors on farmers' participation in combating desertification plans in Iran. Thus, a number of farmers as a sample population were selected using Cochran’ s formula and multi-stages sampling for selecting samples was done. A questionnaire was used to collect data whose validity was confirmed by advisor and supervisor professors and some experts of desert organization. The reliability of the questionnaire was confirmed by computing Cronbach's alpha that was more than 0. 75. Data were analyzed using SPSS and Expert choice 11 software and results showed that the population of the study had low literacy and income. They also had participated very few in education courses, whereas it was observed a significant positive relationship between variables such as literacy, income, and participation in education courses with the participation variable. Also, the correlation relationship between independent factors such as psychological, cultural, economic, education/extension and institution factors with the dependent variable of participation variable showed that except psychological factor, all of those factors had a significant relationship (sig level of 0. 01) with participation variable. The results of the regression analysis also revealed that social/cultural and economic factors were the most important factors on the participation variable and explained 66% of participation changes. The model output indicated that rural communities showed significant interest in the city.

Haloxylon is a resistant tree naturally found in some desert areas of Iran, which sometimes faces dieback. This research was conducted to investigate the factors affecting the dieback of this species in Hossein Abad Mish-Mast Qom. Growth and yield traits including the density of trees, number of branches, trunk diameter and height, canopy area, tree age, trunk form, pests, and diseases were recorded in the field. Leaf samples were taken from the trees with varying drying and the amount of sodium, potassium, phosphorus, and chlorine was measured. Soil profiles were dug and soil samples were taken from areas with different drought stress of trees to measure physico-chemical characteristics of the soil at different depths. The results showed that there was a direct relationship between the density of trees and their drying. The results of soil analysis showed that soil salinity was an important factor in the establishment of trees since the density of trees decreased by increasing soil salinity. Also, low concentrations of nutrients have been found to be effective in tree growth and yield. The results of leaf analysis showed that the amount of sodium and chlorine in the leaves was very high and in the older trees the amount of these elements was higher in the leaves. The results showed that salinity was not the only cause of drying of the trees but the higher density was more important in causing this problem. Ecological problems and nutritional deficiencies associated with high density and lack of proper planting intervals were the main causes of drying of trees.

Protecting an ecosystem and conserving natural resources requires knowledge of the conditions and land-use changes. The purpose of this study was to monitor land-use changes in the past and evaluate the performance of GEOMOD and LCM models in simulating land-use changes in order to select a more appropriate model for predicting land-use changes in the future. Landsat satellite images were used during the periods of 1990, 2003, and 2016 and land-use changes were monitored by using these images. The simulation of land use status by the LCM model for 2016 was done using the maps of the years 1990 and 2003. Using MLP and Markov chain, the land use map was simulated for 2016. To run the GEOMOD model, the image of the single-user map of 2003 and 2016 were used and the map of "appropriateness of changes" was made by the use of variables affecting land-use change and they were introduced into the model. The results of the accuracy of the simulation map of 2016 showed that LCM and GEOMOD had Kappa coefficients of 81% and 71%, respectively. Therefore, the LCM model was chosen as the most appropriate model and the map of the year 2029 was predicted and prepared.

Dust storm phenomenon is one of the most damaging natural disasters in arid and semi-arid regions of the world especially in Iran caused problem on human health and environment. The main reason of dust storm event can be climate change, destruction of natural ecosystems, deforestation, and destruction of rangelands in Iran and neighbor countries like Iraq. Ilam province due to adjacent to vast deserts such as the Iraq Sahara is exposed to severe dust storm continuously. The aim of this study was to identify the critical points of dust sources in Ilam province. At first step, long-term climate data (8 synoptic weather stations), vegetation cover, and physiography of study area were collected. In the second step, soil sampling was carried out at 0-30 cm soil depths in some places in Ilam province and then these soil samples were transferred to the soil laboratory for chemical and physical analyses. In the third step, by using USEPA model, soil and the maps of climatic parameters were prepared and finally critical and high critical dust source points were mapped through integration of different maps in Ilam province. The results showed that the Bahram Abad area in the central Mehran and Abu-Ghoraib and Abu-Ghovayr areas in Musian part, Dehloran city were selected as high critical sources of dust storm in Ilam province due to the highest corresponding with dust storm identification criteria. This project could be useful for prevention and control of dust storm via identification and dust storm maps.

Iran is frequently exposed to local and synoptically dust storm due to the geographical location of Iran. In recent years, dust storm frequencies and intensities have been increased significantly in Iran and especially in Isfahan Province, seriously disrupting human life and affecting the quality of life. This phenomenon is particularly increased in the spring and summer. Climate factors play an important role in dust storms. In this research, spatiotemporal changes of climate factors and dust storms were studied. Therefore, we analyzed climate factors (precipitation, temperature, wind speed and humidity) and dust storms frequency during 1992 to 2016. Poisson regression model was used for statistical modeling of temporal and spatial variations of dust and climatic parameters. According to the models, there was conformity between the results and the predicted values throughout the months. In addition, the results showed that wind speed played a major role in the occurrence of dust storms and had the highest coefficient. The results also showed that most of the dusty days are in the spring and then in the eastern part of the province, which is related to the local centers in the eastern part of the province and summer winds.

Rangeland vegetation is one of the most important components of arid ecosystems and it is necessary to determine changes in rangeland vegetation under drought and wet years. The present study aimed to investigate the relationship between satellite indices and SPI index in Qom rangelands. For this purpose, the SPI index was calculated in moving averages of 1, 3, 5 and 7 years. In the next step, using Landsat images and after making the necessary adjustments to the images, the vegetation map was prepared using NDVI, MSAVI and EVI indices. Finally, correlation coefficients were used to investigate the relationship between satellite image indices and SPI index. The results showed a moderate and good correlation between MSAVI satellite indices and SPI index at peak vegetation growth months with a one month moving average of SPI index. The results of this study show that to estimate agricultural drought through remote sensing, the MSAVI index is a very suitable method and can be used for estimating drought in areas where meteorological stations are scattered (or nonexistent). Because the number of sampling points in satellite images is far greater than the number of meteorological stations.

This research monitored changes in canopy cover percentage of typical species during a 10-year period in the Ghosheh rangelands to find out the relationship between two important climate variables (precipitation and temperature) and canopy cover changes. Therefore, the canopy cover percentages of six typical species (separately) and annual species (overall) were measured during 10 years at the end of growing season in thirty 2-m2 plots, distributed along two 250– m transect lines. The results demonstrated that the maximum canopy cover percentage for water year 2006-2007 (wet-year) and the minimum value for water year 2012-2013 (drought) were 15% and 5. 5%, respectively. The canopy cover percentage modeling was performed based on linear regression method using precipitation and temperature variables. The precipitation of April explained 65% of changes in canopy cover percentage of A. sieberi at 95% confidence level (RRMSE = 0. 26 & MAE=0. 49). The best simple linear regression model for estimating canopy cover percentage of S. barbata and Z. eurypterum was introduced by total precipitation of March-June and precipitation of March, representing 77% (at 99% confidence level) and 67% (at 95% confidence level) of changes in canopy cover, respectively. Considering the dominant role of A. sieberi, S. barbata and Z. eurypterum in vegetation composition of study areas, it can be concluded that most changes in canopy cover of the studied rangeland are predictable by variability of precipitation during growing seasons.

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).

Correlation between vegetation and environmental variables is the most important issue related to the structure and function of rangeland ecosystems. Environmental factors such as climate, topography, and soil can alter the dynamics of plant communities. In this study, the effects of environmental factors on vegetation of some rangeland sites in Semirom region of Isfahan province were evaluated. Sampling was carried out at 52 rangeland sites in a random-systematic way. At each location, 40 plots of one square meter were placed along four transects, and the percentage of vegetation cover in each plot was measured using ocular-estimate method. The grid layers of bioclimatic and topographic variables were prepared in ArcGIS 10. 1 and values for each range site were extracted. Soil samples were collected from range sites and some physical and chemical properties of the samples were measured. Redundancy Analysis (RDA) was used to evaluate the relationships between environmental factors and the plant species cover. Cluster analysis was also used to group the studied range sites based on environmental factors. According to the results, annual mean temperature, isothermality, mean temperature of wettest quarter, soil texture, pH, organic matter, and elevation were identified as the most important ecological factors affecting plant species cover.

Drought and its effects is one of the world's major concerns. As one of the countries in the dry belt of the earth, Iran has always been and is facing environmental issues and natural hazards caused by drought. Therefore, this study aimed to monitor the aridity in Sistan and Baluchestan using remote sensing data and geographic information system techniques for over a period of 15 years (2015-2000). In this regard, the MODIS satellite images from 2000 to 2015 were analyzed by applying the yearly Precipitation Condition Index (PCI) and Standardized Precipitation Index (SPI). Then, the drought changes were evaluated using supervised classification method and difference images. The results showed that the years 2007 and 2001 with an area of 157383. 06 and 306. 05 km2 had the highest and lowest levels of precipitation, and also with an area of 49511. 1 and 69233. 83 km2 had the minimum and maximum level of drought, respectively. The most severity change of drought has been in time for the 2002-2001 period and the place also belong to parts of Khash, Iranshahr and Sarbaz who takes 194302. 93 km2 of the province. Finally, the general trend of changes in precipitation and drought is decreasing and increasing, respectively, requiring the major planning of resources conservation and risk and crisis management to rehabilitate and maintain the ecosystem of arid regions.

Inappropriate exploitation methods, particularly changes in rangeland use, excessive grazing, and fire have led to sever degradation of rangelands with even worse consequences observed in winter rangelands. The present study, conducted in the poor rangelands of Naftkhane Qasreshirin Plain, aimed to study the effects of practices carried out to improve the conditions of rangelands on vegetation cover and carbon sequestration. The study included four types of treatment including a) furrow and brush-planting, b) pitting and brush-planting, c) managing grazing system, and d) a control treatment with usual exploitation conditions. Details of vegetation cover of the rangelands including condition, trend, biomass, forage production, and rate of carbon sequestration in the four treatments were assessed using transects and quadrates. The highest production rate for biomass and forage, and carbon sequestration in rangelands was 573, 551, and 266 kgha-1, respectively, which belonged to the pitting treatment, and the lowest rates 298, 196, and 137 kgha-1 were for the control treatment. In addition, rangeland condition and trend in studied rangelands were assessed to be positive under pitting and furrow treatments whereas in the control treatment a poor condition and a negative trend were observed. Results of the study indicated that pitting, furrow, and management of the grazing system were respectively the most effective treatments in improving biomass, vegetation cover, forage production, carbon sequestration, and erosion control.