Jalal Abdolahi; Mohammad hasan Rahimian; Mohammad hosein Savaqebi
Volume 14, Issue 3 , January 2007, Pages 289-301
Abstract
Today, various indices have been developed for monitoring of vegetation cover in different climatic condition, which cause variation in aspect and spectral reflectance. Therefore, an index can give different values in different conditions. In addition, sparse vegetation and soil background are the other ...
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Today, various indices have been developed for monitoring of vegetation cover in different climatic condition, which cause variation in aspect and spectral reflectance. Therefore, an index can give different values in different conditions. In addition, sparse vegetation and soil background are the other limitations. Hence, combination of some indices can provide sufficient real information in such areas. Contribution of each parameter can be obtained from a statistical method. However, there is no guarantee that the high correlation coefficients would get a good vegetation cover map. It depends on the originality of each predictor variable. The main objective of this study was to identify some probable limitations of Landsat ETM+ images for mapping of vegetation cover in arid and semi-arid zones, especially in drought conditions. In addition, it suggests a method for mapping of sparse vegetation cover in such areas. For this purpose, vegetation cover percentages were measured in two dry and rainy years (2000 and 2002) in the Nodoushan basin, Yazd, Iran. Afterwards, Landsat ETM+ images of two mentioned dates were acquired and different indices were derived. In addition, some environmental factor maps were generated and aligned with other variables (e.g. DEM, Slope and Aspect maps). These data were analyzed using a multiple linear regression method and built regression equations of the form: vegetation cover (%) =1X1+2X2+…+ for each year. Xi’s are independent variables (Satellite data bands, different indices and environmental factors) and’s are regression coefficients and is a constant. According to the equations, vegetation cover maps were generated using ILWIS software capabilities. Then, their accuracies were determined. Results show that the 2002 map (rainy year) is more reliable than the 2000 map (dry year). It was also found that if a drought was occurred in the arid zones, soil background would be dominant and therefore, vegetation indices would not be able to estimate vegetation cover confidently
Shaban Shafizadeh; Ahmad reza Seifalahi; Zabih Eskandari
Volume 14, Issue 3 , January 2007, Pages 302-312
Abstract
The defficiency of Nitrogen in soil causes low growth of plant. Gas nitrogen is comprised of 80% of the atmosphere and is converted to nitrogen ion by different methods that are used by plants. Symbiosis of Rhizobium bacteria with legumes is the most effective methods to fix nitrogen. Isolation, identification ...
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The defficiency of Nitrogen in soil causes low growth of plant. Gas nitrogen is comprised of 80% of the atmosphere and is converted to nitrogen ion by different methods that are used by plants. Symbiosis of Rhizobium bacteria with legumes is the most effective methods to fix nitrogen. Isolation, identification and introduction of rhizobium in each area causes more production of foliage, improve soil texture and nitrogen ion in soil. Use of chemical nitrogen is very expensive, collapse soil texture and cause infection of soil and water.This experiment was carried out to isolate, identify and introduce rhizobium strain from the most important pasture legumes in Esfahan. A total of 200 samples of legumes and soils were collected and transferred to laboratory, to check and examine root nodules. Shape and size of nodules were recorded and rhizobium bacteria were isolated from nodules on YMA medium. Pure cultures of bacteria were made on YMA tube and were maintained at 4°C in the Refrigerator. These bacteria were identified as Rhizobium meliloti from Medicago sativa and Onobrychis viciaefolia. Seven strains of rhizobia were examined to induce nodule in legumes in free nitrogen media and they produced nodule on Medicago sativa and Onobrychis viciaefolia seedlings.
Mohammad javad Ahmadian yazdi; Esmaeil Rahbar; Orujali Karimi
Volume 14, Issue 3 , January 2007, Pages 313-322
Abstract
A general model was developed to explain the interrelationships between soil saturation percentage, mean annual precipitation, and population density on growth and vigority of planted Haloxylon trees. Based on the model, estimated number of population density for 7 years old Haloxylon plantation in Sabzevar ...
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A general model was developed to explain the interrelationships between soil saturation percentage, mean annual precipitation, and population density on growth and vigority of planted Haloxylon trees. Based on the model, estimated number of population density for 7 years old Haloxylon plantation in Sabzevar was 309 trees per hectar; therefore, six density treatments were selected around the estimated density; two density treatments over estimated number, two under it, and existing density as the control treatment. The treatments consisted of T1=247, T2=278, T3=309, T4=340, T5=371, and existing density(control) T6=500 trees per hectar. The treatments have been compared in a Randomized Complete Block Design, with four replications, since winter of 1994. After thinning practices, height(H) and crown diameters(CD) of the remained trees were measured. This measurement was repeated during the growth period in ten years. Since the CD increment between the first and the 10th measurement was 3 times more than H increment; therefore, a size index(SI) model of the form H×(CD)2, which was constructed by trial and error, was found to distinguish the best among the 6 treatments. The growth percentage of H, CD, and SI between first and the last measurement were calculated. The analysis of variance of the growth percents showed that there is significant differences between treatments for H, CD, and SI. The highest growth belonged to T2 and lowest belonged to T6(control). The results show that optimized population density of seven years old Haloxylon stands in Sabzevar is 10% less than the estimated number based on the general model.
Ahmad Tobeh; Amir Ghalavand; Eslam Majidi; Mahdi Panahian
Volume 14, Issue 3 , January 2007, Pages 323-335
Abstract
This experiment carried out in order to compare morphological and physiological characteristics of drought and chilling resistance of alfalfa cultivar in 1379. Garghologh with four varieties Hamedani, Yazdi, Bami and Baqdadi using field (based on Latin Square Design), pot and in vitro culture. According ...
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This experiment carried out in order to compare morphological and physiological characteristics of drought and chilling resistance of alfalfa cultivar in 1379. Garghologh with four varieties Hamedani, Yazdi, Bami and Baqdadi using field (based on Latin Square Design), pot and in vitro culture. According to results, indigenous var. "Garghologh" was superior in many aspects. Under gradual drought, root length, auxiliary roots no. and root fresh and dry weight of Garghologh was higher than those of other varieties. Garghologh had the greatest cell membrane resistance and from the viewpoint of relative water content (RWC) in the probability level of 1%, Garghologh and Baqdadi stood in lst group and the other varieties stood in 2nd group. From the viewpoint of chlorophyll stability, there was no significant difference between varieties. Germination percentage of Hamedani and gargolog in mannitol solution with the increase in density was higher than that of other varieties. Germination percentage of Garghologh and Bami in NaCl solution with the increase in density was higher than that of others and Hamedani had the lowest germination percentage under this condition. Garghologh had the highest auxiliary root no. and internodes no. the lowest branch no./unit area and leaf area. Under chilling stress, viable plant percentage of Garghologh was the highest and of Baqdadi and Bami was the lowest. Under growth in low temperature in pot culture, the root length of Gargologh was higher than that of other varieties.
Majid Ghorbani javid; Gholamabbas Akbari; Foad Moradi; Eraj Allahdadi
Volume 14, Issue 3 , January 2007, Pages 336-351
Abstract
In order to study the yield and water relations and osmotic adjustment in sensitive and tolerant genotypes of cutleaf medic (Medicago laciniata(L.) Mill) under drought stress, a greenhouse experiment was conducted in 2004, using a factorial arrangement in RCBD with three replications. Two genotypes of ...
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In order to study the yield and water relations and osmotic adjustment in sensitive and tolerant genotypes of cutleaf medic (Medicago laciniata(L.) Mill) under drought stress, a greenhouse experiment was conducted in 2004, using a factorial arrangement in RCBD with three replications. Two genotypes of cutleaf medic, were treated in four levels of water stress include -0.1, -0.2, -1 MPa as low, medium and high stress levels respectively and Field Capacity (FC = -0.03 MPa). Results indicated that tolerant genotype had a significant superiority to sensitive genotype in most studied characteristics such as yield, Shoot and Root dry matter, Relative Water Content (RWC), Water Potential (ψw), Osmotic Potential (ψs), Turgor Potential (ψt) and Osmotic Adjustment during medium and high water stress levels. This experiment showed that tolerant genotype had important traits; that might be possible to use these characteristics for selection of tolerant medics and recognition of mechanisms of drought resistance.
Hosein Azarnivand; Mahdi Ghorbani; Hamed Joneidi jafari
Volume 14, Issue 3 , January 2007, Pages 352-358
Abstract
In this study, effect of salinity stress on germination of Artemisia scoparia and Artemisia vulgaris were investigated.Five salinity treatments included distilled water, 100,200,300 and 400 mM NaCl . Experimental design was factorial with CRD arrangement and 4 Replication. Result showed, Artemisia Scoparia ...
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In this study, effect of salinity stress on germination of Artemisia scoparia and Artemisia vulgaris were investigated.Five salinity treatments included distilled water, 100,200,300 and 400 mM NaCl . Experimental design was factorial with CRD arrangement and 4 Replication. Result showed, Artemisia Scoparia is more resistant than Artemisia Vulgaris and in both species germination decreased with increasing salinity.
Farhad Azhir; Amrali Shahmoradi
Volume 14, Issue 3 , January 2007, Pages 359-367
Abstract
Accessibility to a major portion of information about vegetation cover function of rangeland ecosystem is provided by the way of autecological study of range plant species. Autecological study of a range plant named Ferula ovina was accomplished in Tehran province. Topographic, edaphic, and climatic ...
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Accessibility to a major portion of information about vegetation cover function of rangeland ecosystem is provided by the way of autecological study of range plant species. Autecological study of a range plant named Ferula ovina was accomplished in Tehran province. Topographic, edaphic, and climatic characteristics of the species's habitat were determined. The canopy cover, density, frequency, and preference value of the plant were measured. Names of other species which are accompanied with Ferula ovina in its major ecosystem were listed. The results showed that habitat elevation for this species is 2000 to 3200 meters above sea level. Topographic aspect is not a major limitation for its growth. At its habitats, average annual precipitation is about 400 mm. Mean annual temperature is 8 centigrade. Its major ecosystem includes geological layers of tuff, limestone, shale, conglomerate, sandstone, siltstone and clay stone. This plant prefers loamy and/or sandy-loamy soils. Electrical conductivity of soil at different parts of the habitat indicates less than 1.0 ds/m. A range of 7.0 – 7.5 was observed for soil pH. In rangelands in which vegetation is dominated by this species, its percent canopy cover, frequency, and density are 12.35% , 81.62%, and 16750 plants per hectare, respectively. Its root system includes a main root and a few distributed roots. Vegetation growth of this plant starts in early May. Its flowering stage is in 5th to 20th of June, and seed ripening stage is in the fourth week of June. The plant propagates only by seeds. When plant is green, it is not grazed by livestock such as sheep and goat. However, it is harvested and stored as livestock fodder in fall and winter. The main insect seen on the plant is a butterfly named Malocosma sp.
Gholam reza Ghahari; Mojtabah Pakparvar
Volume 14, Issue 3 , January 2007, Pages 368-390
Abstract
The artificial recharge of groundwater (ARG) is a proven method of increasing the water level in unconfined aquifers. Although the ARG activities at the Kowsar Station have been proven successful due to an 8 fold increase in the area of irrigated farm fields, quantitative studies are lacking. We have ...
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The artificial recharge of groundwater (ARG) is a proven method of increasing the water level in unconfined aquifers. Although the ARG activities at the Kowsar Station have been proven successful due to an 8 fold increase in the area of irrigated farm fields, quantitative studies are lacking. We have been monitoring floodwater discharge and diversion to our ARG system and the piezometric level since 1992. These data were used to establish a relationship between the ARG events and the water table variations at the study site. Firstly, the water tables (WTL) at the time of recharge, and for 3 months after it, were grouped and the equipotential lines for the aquifer were constructed. Then the same data were grouped according to the months corresponding with the minimum and maximum pumping. It was observed that all piezometer, showed a rise in WTL for 3 months during the Oct. - Feb. period if there was an ARG event. The trend was reversed when there was heavy pumping during the irrigation season; thus the aquifer was sinking. The general trend in the area indicates an overdraft from the aquifer. It is interesting to note that the WTL in piezometer No. 2, which is located in the center of the ARG systems, shows a gradual rise, in spite of the opposite observation in other 3 piezometers. The lowest WTL is observed in piezometer No. 4, which is located at the center of irrigated fields.
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.
Ebrahim khalifeh; Mojtabah Pakparvar; Mohammad reza Kaviyanpoor
Volume 14, Issue 3 , January 2007, Pages 403-420
Abstract
Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. ...
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Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. Edges and borders are evident characteristics of wind deposits and sand dunes. Inactive (old) dunes are more voluminous and smooth. Furthermore active dunes have distinct feature. Also temperature, humidity and plant cover variation lead to change surface and feature of inactive dunes. These changes can’t be observed in one band images. Therefore making uses of filters particularly non directional edges enhancement and band ratio techniques are main ideas to process the images of these dunes especially about their activity and displacement. In present research filter and band ratio techniques have been used and consequently, third band in Profile Testing and Spectral Analysis method (in this case study b5 of Landsat ETM+) and ratio of first and second bands (in this case study b62/b4) have been introduced respectively as appropriate band and ratio for these techniques to identify and separate active (new) and inactive (old) sand dunes.
Ghasem ali Abarsaji; Amr ali Shahmoradi; Sadegheh Zare kia
Volume 14, Issue 3 , January 2007, Pages 421-431
Abstract
Autecology of plant species is an important portion of ecological studies in natural resources science. This study was conducted to investigate on autecology of Hedysarum kopetdaghi. This range plant species is a perennial plant from Papilionaceae family that grows mostly in range ecosystems of ...
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Autecology of plant species is an important portion of ecological studies in natural resources science. This study was conducted to investigate on autecology of Hedysarum kopetdaghi. This range plant species is a perennial plant from Papilionaceae family that grows mostly in range ecosystems of Golestan National Park. Ecological characteristics such as climate, topography, soil, phenology, regeneration, chemical compounds, and preference value of the plant were studied. Precipitation and temperature data were collected from Khan Cheshmeh Climatology Station which is located near the study area. The results showed that this species grows at scattered spots in rangeland ecosystems of the area. Based on data collected in several years, annual rainfall of the study area is 249.5 mm and means annual temperature is 11.9 degree Centigrade. Soil studies showed that Hedysarum kopetdaghi appears on soils with silt–loam texture and pH of 7.5–7.9. No sign of salinity was found in the soil. The plant has a vertical tap root system. The major root penetrates soil more than 2 meters. In its major ecosystem, canopy cover of this species is about 0.2-1/16%. The density and frequency of this species are 70-1500 plant/ha and 3-15%, respectively. Vegetative growth stage of Hedysarum kopetdaghi species usually starts in late march. Flowering is completed in late May and early June. Seed ripening occurs in late June and early July. Above ground materials of Hedysarum kopetdaghi contains 27.13% crude protein at the vegetative growth stage. Preference value of this plant is 75% for sheep and goats. Grazing the related rangeland ecosystems in inappropriate season, as well as overgrazing, are the major causes of biological degradation creating endangering conditions for this range plant. This species has a high level of resistance to grazing and relatively harsh natural conditions. This plant is a suitable range species to be used in range seeding programs for degraded ranglands of the study area or similar rangeland ecosystems.
mahmood Goudarzi; Mahdi Farahpour
Volume 14, Issue 3 , January 2007, Pages 432-446
Abstract
According to reports, the problem range managers face is impossibility of distinguish between dry land farming and the rangeland, as the reflectance between dry land farming and rangeland are the same. One solution is usage of temporal images, i.e. times that reflectance between these two features is ...
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According to reports, the problem range managers face is impossibility of distinguish between dry land farming and the rangeland, as the reflectance between dry land farming and rangeland are the same. One solution is usage of temporal images, i.e. times that reflectance between these two features is high. For the experiment rainfed cereal farms and rangelands in Taham region of Zanjan province, characterized as a semi arid area, was selected. Crop calendar (seeding, sowing, harvesting) of rainfed crop was drawn. Outstanding dates, over which differences between natural vegetation and crops was high, were distinguished. Corresponding Landsat ETM images, 8 August 2002, and IRS images (multi-spectral and panchromatic), 16 October 2002, were used. Images were georeferenced using available topographic map to a Universal Transverse Mercator projection using control points. For preparation of base map (ground true) IRS panchromatic images were interpreted and land use map was made through digit screen checking boundaries of the map lead to preparation of the final map. Via Image Classification Techniques, supervised (maximum likelihood and Box classification), unsupervised and principal components analysis were used to create a map. The maps were overlaid on base map (ground true) and accuracy of classified map was assessed. The result showed that it is not possible to distinguish between dry land farms and rangeland with the assistance of image classification technique, in panchromatic images however dry lands could be easily distinguished through the pattern, shape and texture found on images.