hadi Eskandari Damaneh; Hamed Eskandari Damaneh; Zahra Sayadi; Asadollah Khoorani
Volume 28, Issue 4 , November 2021, , Pages 772-786
Abstract
Due to the prevailing arid and semi-arid climate, Iran has always suffered from the production and spread of airborne substances, especially dust. This phenomenon is very destructive due to its direct impact on the environment and human health. Therefore, this study aimed to investigate ...
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Due to the prevailing arid and semi-arid climate, Iran has always suffered from the production and spread of airborne substances, especially dust. This phenomenon is very destructive due to its direct impact on the environment and human health. Therefore, this study aimed to investigate the variation trend of aerosol optical depth (AOD), normalized difference vegetation index (NDVI), rainfall, temperature, wind speed, and correlation between AOD and climatic parameters in Iran. Data on AOD and NDVI were collected from Modis sensor images and other data from the ECMWF climate site over 2000-2019 with a spatial resolution of 10 km. The Mann-Kendall trend analysis was used to investigate the trend of changes in these parameters, and the linear correlation model was used to check the correlation between AOD and climatic data. The results of the variations trend of AOD, NDVI, and climate data showed that the trend of these parameters was different in different regions of Iran so that NDVI and rainfall had decreased by 85.13% and 67.57%, respectively, while AOD, wind speed, and the temperature had increased by 71.43%, 71.86%, and 99.37% across the country, respectively. The correlation of AOD, NDVI, rainfall, temperature and wind speed revealed that AOD had a negative correlation with NDVI and rainfall in 50.94% and 51.31% of the country, respectively, while its correlation was positive with temperature and wind speed over 68.42% and 50.36% of the country, respectively. Therefore, the increase in airborne suspended particles strongly depends on the trend of variations in vegetation cover and climatic factors, including rainfall, temperature, and wind speed, which can be well studied using satellite and climatic data with appropriate spatial and temporal resolution.
Golmohammad garivani
Volume 10, Issue 3 , September 2019, , Pages 263-288
Ahmad Ahmadi; Karim Javanshir; Hasan Ahmadi; Valiolah Mozafarian
Volume 10, Issue 2 , September 2019, , Pages 169-192
Hosein Tavakoli Nekou; Abbas Pourmeydani; Seyed Mehdi Adnani; Hosin Bagheri; Mahmoud bayat
Volume 26, Issue 3 , September 2019, , Pages 650-659
Abstract
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, ...
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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.
Kamal Omidvar; Reza Ebrahimi; Fatemeh Taghavinia; Nezam Tani
Volume 25, Issue 1 , April 2018, , Pages 89-101
Abstract
The aim of this study was to analyze the effects of global warming on plant growth degree day in the future decades. To this aim, simulated daily temperature data were drawn from EHOM database and under A1B scenario during 2015-2050 from Germany Plank Max. Then, daily degree data were downscaled with ...
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The aim of this study was to analyze the effects of global warming on plant growth degree day in the future decades. To this aim, simulated daily temperature data were drawn from EHOM database and under A1B scenario during 2015-2050 from Germany Plank Max. Then, daily degree data were downscaled with a separation of 0.27*.027 degrees longitude and latitude, covering around 30*30 km of Iran, by regional climate model designed at the Abdul Salam Center for Theoretical Physics, Italy. Finally, a matrix with dimensions of 13140*2140 was obtained that rows represent degree day and columns represent stations (cells). The threshold of 5 ° was selected to calculate the growth degree day. Finally, the monthly average of growth degree day was calculated in a matrix with dimensions of 12*2140 in MATLAB software. Then, the map of average of growth degree day was designed through Surfer software. The results showed that June and July had the highest average monthly growth rate in the 100-1000 degree-day. In summer months, the highest degree day was observed in Khozestan plain. With regard to the degree day in spring and summer, Iran can be divided into three areas of mountains and interior foothills, internal pits and external foothills, and plains and southern coast.
Hamidreza Mirdavoudi; Vahid Etemad; Mohammadreza Mohajer; Ghavamoddin Zahedi Amiri
Volume 25, Issue 1 , April 2018, , Pages 116-128
Abstract
Grazing is one of the most important factors in providing environmental conditions for change in species composition, structure and function of ecosystems. West oak woodlands of Iran as a valuable ecosystem are not immune from this threat. Therefore, it is essential to study the various ...
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Grazing is one of the most important factors in providing environmental conditions for change in species composition, structure and function of ecosystems. West oak woodlands of Iran as a valuable ecosystem are not immune from this threat. Therefore, it is essential to study the various aspects of this phenomenon in these ecosystems. The aim of this study was to examine the effects of relative grazing intensity on vegetation characteristics in an oak forest dominated by Quercus brantii. The research was conducted in Dalab Park, located in Ilam province, west of Iran. Information of vegetation, soil and other environmental variables were collected from 53 sample plots (16×16 m) using the random sampling method in various disturbances classes. Two-way indicator species analysis was used for classification of the ecological groups. Indicator species analysis was used to determine indicator species in each class and canonical correspondence analysis to identify the relationship between factors and the plant groups studied. The results showed that the grazing as well as soil, topographic factors and the light reaching to the forest floor was identified as the most influential factors on plant composition. Grazing explained the highest percentage of variance (11.2%) in floristic composition and caused an increased frequency of non-palatable species and resistant species to grazing and soil compaction as well as increasing of annuals including Bromus tectorum, Picnomon acarna, Minuartia picta, Rochelia disperma, Holesteum umbellatum, Lophocloa phlorides, and Valerianella vesicaria. These species were identified as invasive species based on density, abundance, and available resources. On the other hand, it seems that the spread of palatable species such as Vicia sativa,Trifolium physodes, Lens cyanea, and Lathyrus inconspicaus in the moderate grazing site indicates the role of balanced livestock grazing in maintaining the proper species composition in rangelands.
Jaber Sharifi; Amrali Shahmoradi; Allahvirdi Noori; Farzaneh Azimi Motam
Volume 24, Issue 4 , January 2018, , Pages 719-729
Abstract
The major portion of our rangelands are located in arid and semi-arid regions. In this climate, variability of vegetation under climate change impact of balanced energy flow in ecosystems ranges vegetation is that the generally composition and structure of vegetation typically occurs over time. on the ...
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The major portion of our rangelands are located in arid and semi-arid regions. In this climate, variability of vegetation under climate change impact of balanced energy flow in ecosystems ranges vegetation is that the generally composition and structure of vegetation typically occurs over time. on the other hand, human factors and grassland management, especially crucial in maintaining its stability or degradation plays. Accordinglymonitoring vegetation winter pasture areas was conducted in Ardabil Province from 1387 to 1391. In each community a key area was determined to establish a permanent site, In each key area of the canopy cover, density and abundance during the three transects 500 m in 30 plots (1/20 × 1/20 meter) as well as soil moisture and organic carbon were measured. The results showed that a four-year period, proportional to changes in rainfall and temperature, Under local management conditions, In Moqan sites of Artemisia fragrans with absolute dominance and renewed growth. In direct response to the seasonal and annual rainfall and vegetation cover has a decisive role the results of the survey year to year changes in vegetation,climate changes from year to year and soil moisture also how the soil erosion condition can as an appropriate guide to the correct current methods used for management of rangeland ecosystems.
Mostafa Taleshi; Esmaeil Aliakbari; Mostafa Jafari; Seyed Jafar Seyed Akhlaghi
Volume 24, Issue 4 , January 2018, , Pages 881-896
Abstract
Resilience indicators against environmental hazards are one of the basic criteria in planning and evaluating adaptation programs with the effects of natural hazards in rural areas. The present paper seeks to identify, formulate and validating of resilience indicators in rural areas to drought so ...
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Resilience indicators against environmental hazards are one of the basic criteria in planning and evaluating adaptation programs with the effects of natural hazards in rural areas. The present paper seeks to identify, formulate and validating of resilience indicators in rural areas to drought so that planners and researchers can study these resiliency, drought and water crisis indicators, which are confirmed by and the agreement of experts and experts has come to the fore. The research method is descriptive-analytic, using questionnaires of experts and experts. In this research, different criteria and indices of theoretical literature were extracted and 35 questionnaires were subject to arbitration by experts and expert experts. In this research, 25 suitable indicators approved by experts, executive experts and local experts have been introduced. The most suitable indicators and the most consensus can be indicators such as: livelihoods of the household, the growth trend or decrease in the natural resources of the village, the probability of immigration from the village, access to various agricultural water resources, the level of agricultural land (ownership), the state of insurance coverage and Emergency services, agricultural development, household saving potential, and the prospects for non-farm business in the future. The results of this research can be the beginning for the development of a national model of rural resilience assessment indicators, the establishment of resilience index data banks and their quantitative reduction in order to achieve sustainable development and also reduce the effects of climate change and drought in rural areas of the country.
Mohammad Khosroshahi; Morteza Abtahi; Mohammadtaghi Kashki; Sakine Lotfinasab; Fateme dargahian; Zohre Ebrahimi
Volume 24, Issue 2 , July 2017, , Pages 404-417
Abstract
So far, different statistics have been presented for the area of deserts in the world and Iran by individuals and organizations. The reason for this difference is mainly due to the disagreement among experts in providing a comprehensive definition of desert and factors affecting its formation. In this ...
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So far, different statistics have been presented for the area of deserts in the world and Iran by individuals and organizations. The reason for this difference is mainly due to the disagreement among experts in providing a comprehensive definition of desert and factors affecting its formation. In this paper, the factors of natural environment, such as climate, vegetation, geomorphology, soil, geology and hydrology, whose effects are directly or indirectly involved in the emergence and general appearance of the desert, were investigated. Therefore, to identify and define the desert ranges in terms of the study factors, a number of indicators were defined, based on which desert zones were identified for each factor individually. Then, digital maps were produced by overlaying the layers. Results showed that the largest area of desert regions in Iran with a surface of 693690 and 567711 square kilometers is influenced by climatic and vegetation factors, respectively, and the least area of desert regions with a surface area of 208041 and 272,258 km is affected by the geological and geomorphologic factors, respectively. From the aspect of soil science, the area of desert regions in Iran covers a surface of 514930 km2. The total area of deserts was calculated to be 9007293 square kilometers, which accounts for 55 percent of the total area of Iran.
sahar sabaghzade; Mohammad Zare; Mohamad Hosein Mokhtari; Mohamadreza Afkham olshoara
Volume 23, Issue 4 , March 2017, , Pages 843-855
Abstract
Arid land degradation is the biggest environmental challenges in 21st century. Saxaul (Haloxylon spp) is one of the most important species for sand dunes fixation, widely used in reclamation of arid lands. One of the applications of satellite data is to estimate the biomass of plants. In this study, ...
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Arid land degradation is the biggest environmental challenges in 21st century. Saxaul (Haloxylon spp) is one of the most important species for sand dunes fixation, widely used in reclamation of arid lands. One of the applications of satellite data is to estimate the biomass of plants. In this study, Landsat 8 satellite images were used for mapping the biomass of Haloxylon plants in the South Khorasan province. Then, 11 vvegetation indices (DVI, IPVI, NDVI, PVI, RVI, SAVI, TSAVI, WDVI, Brightness, Wetness, Greenness) were calculated. To determine the correlation between biomass and satellite data, 30 plots of 30*30 m 2 were used in the region and vegetation parameters were measured. Principal component analysis and cluster analysis were used to classify the indices. Finally, the effective indices were selected and the regression models were fitted. Results showed that the regression model obtained from the TSAVI index with RMSE of 14.9 and R 2 =0.43 had the best estimation for the above ground biomass of Haloxylon.
Behnam Hamze
Volume 23, Issue 4 , March 2017, , Pages 876-892
Abstract
In this study, vegetation of the Bisotun Protected Area with an area of ca. 50,000 hectares in west of Iran, Kermanshah province, was studied. Samples of vegetation were collected using the Braun-Blanquet method where 66 réléves were taken from different habitats. To express the phytosociological ...
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In this study, vegetation of the Bisotun Protected Area with an area of ca. 50,000 hectares in west of Iran, Kermanshah province, was studied. Samples of vegetation were collected using the Braun-Blanquet method where 66 réléves were taken from different habitats. To express the phytosociological status of the site, data were analyzed by employing Analyse Factorielle des Correspondence (AFC) and Classification Ascendante Hiérarchique (CAH) methods using Anaphyto software. The results of phytosociological data analysis showed that there were 10 associations, three sub- associations and two communities in the area as follows: Lonicero nummulariifoliae-Aceretum cinerascentis (pistacietosum khinjuki, vicietosum variabilis, amygdaletosum orientalis), Trigonosciadio tuberosi-Feruletum haussknechtii, Prangetum pabulariae, Ferulago phialocarpae-Cruciatetum persicae, Pimpinello deverroidi-Astragaletum compacti, Astragaletum geminani, Quercetum persicae, Trifolietum scabro-pilularae, Trifolietum scabro-stdellati, Trifolio scabri-Avenetum fatuae, Trifolio scabri-Avenetum ludovicianae, Crataegetum aroniae, Amygdaletum arabicae, Bupleurum kurdicum community and Triticum boeoticum–Festuca ovina community. The establishment of the syntaxa is affected by altitude, exposure, slopes, and edaphic factors.
Fatemeh Hadian; Seyed Zeinolabedin Hoseini; Mansoureh Seyed Hoseini
Volume 21, Issue 4 , March 2015, , Pages 756-768
Abstract
Precipitation is one of the factors affecting vegetation. Nowadays, satellite images are broadly used for monitoring the effects of precipitation variations on the vegetation changes. The aim of this study was to investigate the relationship between vegetation dynamic and precipitation variations using ...
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Precipitation is one of the factors affecting vegetation. Nowadays, satellite images are broadly used for monitoring the effects of precipitation variations on the vegetation changes. The aim of this study was to investigate the relationship between vegetation dynamic and precipitation variations using NOAA AVHRR images during the period of 1982-2006. Precipitation maps were created using the inverse distance weighting interpolation (IDW) method and time intervals of precipitation data. The study area was a forestland beside Caspian Sea, four rangeland vegetation types with grasses and shrubs, farmland areas and urban areas, located in Ardabil and Guilan provinces. To monitor the relationship between the precipitation and vegetation changes, the linear regression (NDVI, Y & Rainfall, X) method was employed. Based on the results, depending on the precipitation time, plant species, and growth form, the effect of precipitation on vegetation was different so that no significant relationship was observed between vegetation and precipitation in forestlands, farmlands, and urban areas. The highest correlation coefficient between spring precipitation and vegetation was related to the rangelands. In grassland areas, the correlation coefficient was higher than that of shrublands, whereas the reaction of grasslands to precipitation in various parts was different.
Razieh Mohammadi; Kamaladdin Naseri; Gholamali Heshmati
Volume 21, Issue 1 , June 2014, , Pages 119-127
Abstract
This study was conducted to investigate the effects of Haloxylon aphyllum plantation on natural plant communities and soil properties of Abbas-Abad area in Khorasan Razavi Province. For this purpose, Haloxylon plantation and control areas were selected to compare with each other. In each area, fifty- ...
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This study was conducted to investigate the effects of Haloxylon aphyllum plantation on natural plant communities and soil properties of Abbas-Abad area in Khorasan Razavi Province. For this purpose, Haloxylon plantation and control areas were selected to compare with each other. In each area, fifty- meter transects were located by random-systematic method. Measurements were done by point sampling method. Eighteen soil samples were collected from Haloxylon plantation and control areas to determine EC and pH values in the laboratory. Data were analyzed by t-test. According to the results, although higher species diversity was significant in Haloxylon plantation area (P<0/05), Haloxylon caused the replacement of non-native communities, so that only 64.28% of species composition in Haloxylon plantation area was similar to the control area. On the other hand, higher soil pH and EC in Haloxylon plantation area was significant (P<0/01) and probably in the long term, Haloxylon causes the salinity and alkalinity of the soil surface.
Mostafa Jafari
Volume 21, Issue 1 , June 2014, , Pages 139-153
Abstract
Iran faced with climate and environmental changes in past years and it is projected that some climatic changes will occur in the future. Net Primary Production (NPP) is an important index to evaluate production in natural ecosystems including forest, rangeland and desert. Climate change impact will cause ...
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Iran faced with climate and environmental changes in past years and it is projected that some climatic changes will occur in the future. Net Primary Production (NPP) is an important index to evaluate production in natural ecosystems including forest, rangeland and desert. Climate change impact will cause changes in biomass production in natural ecosystems. In this research, the vulnerability of NPP in Iranian forest, rangeland and desert ecosystem has been considered. Results of this consideration presented here in six selected climatic zones in Gilan, Mazandaran, East Azerbyjan, Kermanshah, Khorasan and Systan and Baluchestan provinces. According to the result outcomes, total NPP of forest, rangeland and desert ecosystem in Gilan, East Azerbyjan, and Khorasan provinces, under temperature and precipitation changes, has been increased in the year ended 2039. While, the amount of NPP in Mazandaran, Kermanshah, and Systan and Baluchestan provinces would have been decreased. These changes in Khorasan provinces (including North, South and Razavi) will show highest increase, indicating suitable increase of precipitation and temperature in the region. Quantitative changes in NPP depend on total biomass and changes of precipitation and temperature. As an example, these changes in forest ecosystems of Gilan, and Khorasan provinces, will increase and in Mazandaran, and Kermanshah provinces, will decrease. Also, these changes in range ecosystems of East Azerbyjan, and Khorasan provinces, will increase and in Kermanshah, and Systan and Baluchestan provinces, will decrease. While, changes in desert ecosystems of Khorasan provinces mainly will increase and in Systan and Baluchestan provinces, will decrease.
Ahmad Ahmadi; AmrAli Shahmoradi; Sedigheh Zarekia; Elahe Ahmadi; Saeedeh Nateghi
Volume 20, Issue 1 , June 2013, , Pages 172-181
Abstract
In this research, Astragalus effusus was considered for autecological study in West Azarbaijan’s catchments. This palatable range species belongs to Papilionaceae. In this study, the ecological characteristics (climatic, topographic, edaphic), distribution in the catchments, phenology, root system, ...
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In this research, Astragalus effusus was considered for autecological study in West Azarbaijan’s catchments. This palatable range species belongs to Papilionaceae. In this study, the ecological characteristics (climatic, topographic, edaphic), distribution in the catchments, phenology, root system, and preference value of Astragalus effuses were investigated. The main part of the study was conducted in study sites of Poldasht (at the elevation of 900 m asl and mean annual rainfall of 120 mm), Shahidan valley (at the elevation of 1700 m asl and mean annual rainfall of 500 mm) and Salmas (at the elevation of 2000 m asl and mean annual rainfall of 338 mm) at different time intervals. The results showed that Astragalus effusus grew in all West Azarbaijan’s catchments from an elevation of approximately 800 to 3575 meters above sea level in all geographic aspects. It grew best on medium-textured soils, from sandy loams to clay loams. Some of the main companion species of Astragalus effusus were Onobrychis cornuta, Bromus tomentellus, Achillea millefolium, and Stachys schetschegleevii. In Salmas study site, the time of initial growth, vegetative growth, flowering, seed ripening and seed dispersion of this species were late March, late April, mid May, mid June and late July, respectively. Astragalus effusus was a tap-rooted species and its roots penetrated to the depths up to 2 meters in sandy loam soils of Salmas region. The geologic studies indicated that the main habitats of the Astragalus effusus were areas with lithologic characteristics of dark gray limestone and red marly limestone with shale in the upper part. This species had no toxic substances and was proper spring forage for livestock.
Mohammad Khosroshahi; Ahdei Kali rad; Hamid Hossaini Marandy
Volume 18, Issue 2 , September 2011, , Pages 336-352
Abstract
In this research, deserts domain of Iran was studied and compared in view of the geological and climatological specifications.Geological deserts domain was made as digital maps with considering saline and evaporate formations which have been effective in their development. To determine climatological ...
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In this research, deserts domain of Iran was studied and compared in view of the geological and climatological specifications.Geological deserts domain was made as digital maps with considering saline and evaporate formations which have been effective in their development. To determine climatological deserts domain, climatological factors including amount of precipitation, rainfall coefficient variation, rainfall irregularity coefficient, the average intensity of daily precipitation, annual average temperature and amount of evaporation were calculated for all studied stations. Using Geographical Information System (GIS), the isohyets digital maps were prepared for each factor. With overlaying layers, a transitional boundary was made through which non-desert areas were separeted from deserts. All (geological and climatological) desert units were set up on the country map with utilization of the coordinate system and georeference. According to the results, climatological and geological deserts respectively encompassed 42.5 % (700991 km2) and 12.6% (208041 km2) of Iran map. Each individual layer covered different desert area on the map. Crossing and matching of two layers (common parts of overlaying) was 22.6% of the geo-climatological deserts of Iran which indicates differences between spatial distribution of geological and climatological deserts.
Naser Ansari; Mohammad Fayaz; Mohammad hassan Gasemi
Volume 16, Issue 3 , December 2009, , Pages 293-304
Abstract
Rangelands degradation is the most important problem of Iran natural resources, especially in these decade .In this research for determination of the quality and quantity of rangelands degradation,9 provinces distributed within 3 main zones of Henry Pabbot’s climatic zones map of Iran territory, ...
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Rangelands degradation is the most important problem of Iran natural resources, especially in these decade .In this research for determination of the quality and quantity of rangelands degradation,9 provinces distributed within 3 main zones of Henry Pabbot’s climatic zones map of Iran territory, were selected. In these provinces, sample areas in each climatic zone were bounded on topographic maps. In the sample areas, converted rangelands to other usages, from 1955 to 1995(40 years) and then, lost and converted rangelands clarified. Considerable decline in forage production of the rangelands were also well described by comparing dry matter yield in an enclosure and the fenced area. Results showed that 9.1% of the rangelands areas, during 40 years between 1955-1995 periods, had been disappeared. Rangelands degradation in semi-desert zone with degradation index of 28.4% is lowest and in high-mountain zone with degradation index of 60.5% is the highest one. Degradation intensity in high-mountain zone is as twice as semi-desert zones. Average of degradation index for all the country zones, is 49.4% that revealed, about half of the production potential of the rangelands has been lost.
Mohammad Khosroshahi; Mohammad taghi khashki; Tahereh Ensafi Moghaddam
Volume 16, Issue 1 , December 2009, , Pages 96-113
Abstract
Many climatology scientist adopted temperature and precipitation among all climatic parameters to identify desert regions from non-desert areas. There is no one definition of a desert that is accepted by all. The boundaries of a desert change radically depend on the variance in the range of proposed ...
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Many climatology scientist adopted temperature and precipitation among all climatic parameters to identify desert regions from non-desert areas. There is no one definition of a desert that is accepted by all. The boundaries of a desert change radically depend on the variance in the range of proposed criteria definition accepted. Thus this study was carried out to identify the boundaries of a desert territory from non-desert regions using climatic data such as total precipitation, average intensity of daily precipitation, annual average temperature and evaporation together with the coefficient of variance and seasonal concentration. For each climatic factor a digital map was produced for all studied provinces using Geographical Information System (GIS). By overlaying all digitized climatic factors a transitional strip of boundary was recognized and then its accuracy was checked with field data and topographic map. Based on this boundary strip, three zones were recognized as 1- true desert zone located inside the strip of boundary.2- non-desert area, outside of the boundary and 3-Semi-true desert zone located in the boundary strip itself. It was concluded that true or natural desert that known as climatology desert are 700991 km2 or 42.5 % of the Iran map.
Hamid reza Moradi; Mohammad reza Fazel puor; Hamid reza Sadeghi; Zeinalabedein Hoseini
Volume 15, Issue 1 , January 2008, , Pages 1-12
Abstract
More than one-third of land in the world is located in the areas with arid and semiarid climate and desertification has increased in these areas during recent decades. Around 80% of Iran is located in arid and semiarid areas. Sand dunes as an indicator of desert land cover an area about 32 million hectare. ...
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More than one-third of land in the world is located in the areas with arid and semiarid climate and desertification has increased in these areas during recent decades. Around 80% of Iran is located in arid and semiarid areas. Sand dunes as an indicator of desert land cover an area about 32 million hectare. Among which 12-mil hectare has not been stabilized yet. Advancing moving sand dunes has resulted in much damage to agricultural products and urban areas. In this survey satellite images and aerial photos are used to evaluate the role of land use changes on desertification in 1955, 1997 and 2002. To do so, IRS image of 2002 and available aerials photos of 1955 and 1997 are used. Following making the aerial photos mosaic processing was done using ILWIS software and needed data completed by field surveying and the land use map was produced for two years. To produce the land use map using digital processing methods 10 sample set (training points) were selected uniformly in the area. After preprocessing including geometric corrections, image enhancement and band composition, image classification was done by maximum likelihood method and the land use map was produced. In this phase, obtained land use map was corresponded to the ground truth map which was achieved by field surveying and recording coordinate of points with GPS pixel to pixel and accuracy obtained from numerical classification estimated to be 45.3%. Then due to obtained low accuracy, the visual method used to produce the land use map so the accuracy of 78.5% achieved. Finally, the area of each land use and the rate of changes were calculated. The results indicate a decrease of 2000 ha in the area of the desert land from 1955 to 1997 and of 160 ha from 1997 to 2002 and an increase in the area of the other land uses. Results show no desertification in the study area, even though land degradation can obviously be identified in the area, which is resulted from the changes of gardens, and agricultural land uses to industrial and urban areas.
Gholam reza Shadnoush
Volume 13, Issue 4 , February 2007, , Pages 285-295
Abstract
In order to comprehend magnesium, calcium, sodium, potassium, phosphorous, chloride, copper, iron, manganese and zinc content of dominant range plants (Agropyron intermedium, Bromus tomentellus, Hordeum bulbosum, Cousinia bakhtiarica andScariolla orientalis) speciesin Chaharmahal ...
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In order to comprehend magnesium, calcium, sodium, potassium, phosphorous, chloride, copper, iron, manganese and zinc content of dominant range plants (Agropyron intermedium, Bromus tomentellus, Hordeum bulbosum, Cousinia bakhtiarica andScariolla orientalis) speciesin Chaharmahal and Bakhtiari province was investigated. Samples were taken from five ungrazed areas during three stages of plant growth including growing, blooming, and seedling between 1997-2000 years. Concentrations of all above ions were determined by standard methods. The result showed that maximum concentration of magnesium and calcium in Scariolla orientalis, which amounts of means were 2.8 and 11.6 gr/kg, respectively. The highest concentration of sodium and potassium were found in Bromus tomentellus and Hordeum bulbosum respectively, with amount of 0.4 and 22.4 gr/kg. Maximum of phosphorus and chloride were observed in Hordeum bulbosum with amounts of3.1 and 5.4 gr/kg, respectively. Highest of copper and iron were 9.5 and 368 mg/kg, which belonged to Cousinia bakhtiarica and Scariolla orientalis respectively. Speciesof Agropyron intermedium contained39.3 mg/kg manganese and concentration of zinc in Scariolla orientalis was 18.6 mg/kg, which the amounts were the highest between species. This study showed which phosphorous, sodium, copper and zinc were insufficient for sheep grazing requirement in all species, but magnesium was insufficient only in Agropyron intermediumand Bromus tomentellus, also calcium concentration was lower than sheep requirement in Hordeum bulbosum. Therefore, mineral supplementation required to provide these mineral for grazing sheep and goats in spring and summer in range plants. Hence, potassium, chloride, iron and manganese provide the requirement of grazing sheep and goats, but chloride was over loaded and it was in the level of toxicity and unsafe for sheep and goats. Also different phenological stage showed that assessment factors were significantly different at growing, blooming and seedling stage of species. These factors must be considered when sheep and goats are grazing on natural pasture.
Farhad Fakhri; Seyid Moh... Jafari; Mohammad Khosroshahi
Volume 14, Issue 3 , January 2007, , Pages 391-402
Abstract
Since geological formation is very important in the process of desert and desertification, in this article lithology, stratigraphy of the Boushehr province was studied with the help of 1:100000, 1:250000 scale maps of G.S.I and N.I.O.C using GIS methodology. Quaternary formations and most ...
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Since geological formation is very important in the process of desert and desertification, in this article lithology, stratigraphy of the Boushehr province was studied with the help of 1:100000, 1:250000 scale maps of G.S.I and N.I.O.C using GIS methodology. Quaternary formations and most of the evaporatic formations in the province were recognized. Saline and evaporatic formations were introduce as “Primary deserts”. Then with the help through overlaying the drainage network on the basic map of Quaternary formations, the secondary deserts was then recognized this kind of desert possess the evaporative material such as gypsum and salt. Both of these processes (The primary and secondary deserts) have formed Boushehr province deserts. final Results showed that 47% of Boushehr province area is classified as desert including 592041 ha “Primary deserts” and 574579 ha as ‘secondary deserts”. It was concluded that most important geological formation effective in deserts formation in Boushehr province comes from Hormoz series, Gachsaran, Mishan and Aghajari formations.