Fatemrh Dargahian; Somayeh Heidarnejad; Samaneh Razavizadeh
Volume 28, Issue 3 , October 2021, , Pages 564-577
Abstract
Today, global warming and climate change are considered to be the greatest challenge of human life that has overshadowed other environmental challenges. In this study, it has been attempted to detect climate change phenomena in Yazd by monitoring the trend of heat wave changes and its relation to temperature ...
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Today, global warming and climate change are considered to be the greatest challenge of human life that has overshadowed other environmental challenges. In this study, it has been attempted to detect climate change phenomena in Yazd by monitoring the trend of heat wave changes and its relation to temperature anomaly. For this purpose, daily temperature data for the time period (1960– 2017) were used. Finally, the characteristics of heat waves such as the number of occurrences of heat waves, frequency of days with heat waves, heat wave continuity, magnitude and intensity of heat waves and average heat wave (hottest day of heat wave) using ClimPACT software in programming environment R 2.10 were calculated. Heat waves are the result of incremental temperature changes. Therefore, temperature anomaly of Yazd station was extracted and compared with the temperature anomaly of the Land's surface. The relationship between heat wave indices and temperature anomalies was investigated. The results showed that the highest number of heat wave events occurred in 2010 and 2016. The number of days associated with the hot wave has increased significantly, with 47 and 42 days in 2010 and 2016, respectively. An increasing trend in the continuity and intensity of heat waves was also observed. The longest continuation for 2013 was estimated to be 13 days. The findings also show that in the last two decades the magnitude of the heat wave has reached more than 31 ° C. Investigation of the relationship between all indices related to heat wave and Yazd temperature anomaly showed good correlation and coefficient of explanation of temperature anomaly and frequency of days with heat wave was higher than other indices and its R2 was approximately 0.6108. In general, the results indicate the intensification, continuity and intensity of heat waves in Yazd city, which can indicate the occurrence of climate change, especially in the last two decades in this region of the country as a representative of the arid regions. Due to the increasing temperature in the coming years on the frequency, intensity and continuity of these waves will increase, knowing how heat waves are processed can help managers and planners make risk management decisions about energy efficiency.
Ali Mirhosseini; Younes Asri; Mohammad Abolghasemi
Volume 27, Issue 2 , June 2020, , Pages 192-203
Abstract
The Bahadoran Kalmand protected area with an area of 255000 hectares is located at about 30 km Yazd township and in the southeastern township of Mehriz with geographical coordinates of 31° 00¢ to 31° 40¢ North latitude and 54° 15¢ to 55° 20¢ East longitude. The ...
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The Bahadoran Kalmand protected area with an area of 255000 hectares is located at about 30 km Yazd township and in the southeastern township of Mehriz with geographical coordinates of 31° 00¢ to 31° 40¢ North latitude and 54° 15¢ to 55° 20¢ East longitude. The vegetation cover was studied using the physiognomic-floristic method. Some soil characteristics were evaluated based on conventional methods and data were analyzed by Principal Component Analysis (PCA) method. The results showed that there was a special relationship between different plant communities and soil characteristics. The most important factors in separating these plant communities were electrical conductivity, acidity, texture, organic carbon, and sodium adsorption ratio. In general, in regard to habitat conditions, each plant community has different ecological needs and tolerance range with environmental factors and soil characteristics.
Naser Baghestani Meybodi; Hosein Arzani; Mohammad Taghi Zare; Jalal Abdollahi
Volume 11, Issue 2 , August 2019, , Pages 137-162
Abbas Zarezadeh; Esmaeel Rahbar; Mohammad Abolghasemi
Volume 11, Issue 2 , August 2019, , Pages 179-190
Kazem Dashtakian; Hamidreza Dashtakian; Mohammad Abolghasemi
Volume 22, Issue 2 , August 2015, , Pages 344-355
Abstract
The source of sandy dunes has been the main question in desert regions. Several theories have been already presented about this question around the world. In addition, several methods have been already invented and applied to find the source of sandy dunes. In this research, the relationship between ...
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The source of sandy dunes has been the main question in desert regions. Several theories have been already presented about this question around the world. In addition, several methods have been already invented and applied to find the source of sandy dunes. In this research, the relationship between playa and sandy area in Yazd province was studied using GIS. At first, the maps of sand dunes and playa in the province as well as neighboring areas were produced. Then, the distance and direction of all sandy polygons to the nearest playa was calculated. Meanwhile, the geographic center of sandy polygons and playa polygons were identified. According to the results, around 60% of sandy polygons had a distance less than 10 kilometers to the playa, and their average distance to the nearest playa was calculated to be 12745 meter. In more than 79% of sandy dunes, the nearest playa was located in the North West. The average angle of playas to the sandy dunes was 332 degree (N), matching with the main windroses and sandroses of province. Therefore, if all sandy dunes and playas are converted to one place, we will have one sandy dune with an average area of 4717 hectares as well as a playa with an average area of 220506 hectares in the northwest of sand dune. Eventually, according to the prevailing wind direction, the hypothesis of the role of playas as the main source of sand dunes in the Yazd province is reinforced.
Elham Fakhimi Abarghouie; Seyed Akbar Javadi
Volume 21, Issue 1 , June 2014, , Pages 109-118
Abstract
From the perspective of rangeland ecology, awareness of the effects of livestock grazing on the changes of structure, plant vegetation and soil characteristics is essential. The aim of this study was to determine the effect of different grazing intensities including heavy (0-200 m distance from water ...
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From the perspective of rangeland ecology, awareness of the effects of livestock grazing on the changes of structure, plant vegetation and soil characteristics is essential. The aim of this study was to determine the effect of different grazing intensities including heavy (0-200 m distance from water point), moderate grazing (200- 800 m) and light grazing (800-1200 m) intensities on vegetation indices and soil characteristics in Nodushan region, Yazd province of Iran. For this purpose, plant vegetation cover and composition were recorded under three grazing intensities. Soil was sampled from depths of 0-30 cm. Data were analyzed by one way ANOVA, t-testandordination method (CCA) to assess the vegetation response in different grazing intensities. Results showed that plant species such as Astragalus achrochlarus, Salsola arbusculata and Tragopogon sp.were found in light grazing area.Allysum minus, Artemisia sieberi, Poa sinacia, Iris songarica, Lactuca glacifolia and Stipa barbata were identified in moderate grazing area. Eryngium sp., Cousinia desertii, Bromus tectorum and Peganum harmala were the major species in heavy grazing area.Soil properties including N, P, K, OC, EC and pH were measured. According to the results, nitrogen and soil organic matter were decreased by increasing grazing intensities but P, K, EC and pH were increased. Since grazing pressure causes damage to vegetation and some soil properties, a moderate grazing is recommended for sustainable utilization of rangelands.
Elham Fakhimi Abarghoie; Mansoor Mesdaghi; Parviz Gholami; Hosein Naderi Nasrabad
Volume 18, Issue 3 , September 2011, , Pages 408-419
Abstract
One of the main objectives of ecosystem managements is preservation of diversity. By measuring the diversity and evenness of the species, the necessary management recommendations will be presented. In this research, the effect of slope, aspect and elevation on richness and evenness of plant species were ...
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One of the main objectives of ecosystem managements is preservation of diversity. By measuring the diversity and evenness of the species, the necessary management recommendations will be presented. In this research, the effect of slope, aspect and elevation on richness and evenness of plant species were evaluated at steppe rangelands of Nodushan, in Yazd province. Systematic random sampling method was applied and the size of plot was determined by minimal area. The results showed that elevation had significant effects on diversity and frequency of species and moderate elevation ranges of 2400- 2600 had higher richness and evenness. Slope range had also significant effects on diversity and frequency and high slopes (30- 50%), had the highest diversity. Aspects had no significant effects on indices of diversity.
Ali Mohammad Ghaeminia; Hamid reza Azimzadeh; Mohammad Hossein Mobin
Volume 18, Issue 1 , May 2011, , Pages 42-57
Abstract
Soil temperature is one of the most important and effective factors influencing the establishment of vegetation in arid regions. Soil temperature is affected by several meteorological parameters. The study of air temperature, rainfall and sunshine hours can be useful ...
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Soil temperature is one of the most important and effective factors influencing the establishment of vegetation in arid regions. Soil temperature is affected by several meteorological parameters. The study of air temperature, rainfall and sunshine hours can be useful to understand the variation of soil temperature. Soil temperature changes and rate of heat transport in soil profile are helpful for evaluating the amount of evaporation, plants water requirements, decomposition rate of materials, biological activities and the time of seed planting. The aim of this study is to evaluate the role of atmospheric factors in determination of the soil temperature. For this purpose, after collecting daily temperatures data of different soil depths (5, 10, 20, 30, 50 and 100 cm) in Yazd synoptic station for 2006, firstly, the effective meteorological parameters were analyzed and then soil temperature at this station was simulated by using sinusoidal changes pattern during the year. Finally, soil temperature variation curve at any depth was plotted and evaluated using the models obtained. Primary results showed that there was a significant relationship between precipitation, air temperature and sunshine hours. Measured and predicted values were evaluated in a coordinate system. The results showed that with increasing depth, the sinusoidal model predicted values underestimate. The results of calculating coefficients of Nash-Sutcliffe model efficiency (RNS2) showed that the estimated values by model for the different depths (5, 10, 20, 30, 50 and 100 cm), compared to the measured ones had efficiency coefficients as 0.92, 0.91, 0.93, 0.92, 0.94 and 0.96, respectively. Since (RNS2) value varies between- ∞ to 1, and when its value is equal to 1, the model has maximum efficiency, so, sinusoidal equations have good capability for predicting temperature variations in soil different depths.
Hamid reza Azimzadeh; Mohammad reza Ekhtesasi; Hossein qoli Refahi; Hassan Rohipour; Manuchehr Gorji; Mohammad hasan Emtehani
Volume 16, Issue 1 , December 2009, , Pages 114-123
Abstract
Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of ...
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Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of sediment transported by wind increases until the wind stream becomes saturated. In the other word the mass transported is limited by the emission rate of materials from the soil surface to the air flow, known as transport limiting. The field length required for the wind to reach its maximum capacity depends on the wind velocity and the components of the soil surface. The field data were collected from 1.9ha fallow lands of Yazd-Ardakan plain. Big Spring No Eight (BSNE) samplers were set up to collect samples of horizontal sediment discharge passing through a point. Twelve events data were collected and analyzed started from May 2006 to may 2007. Two methods were adopted to determine the maximum transport capacity; 1) Fitting the mathematic equation of and 2) Direct measurement of transport capacity. Variance analysis and t-test paired data results showd that, there was no significant difference between the results of these two methods.
Naser Baghestani Maybodi; Mohammad taghi Zare; Mohammad Abolghasemi
Volume 14, Issue 4 , February 2008, , Pages 478-489
Abstract
Wilted and dried up stands of haloxylon aphyllumspecies in afforested areas of Yazd has allways been a focal point of natural resources experts. Using various pruning treatments, the effect of pruning on the wideness of canopy cover and vigor of 12-year-old semi-trees of haloxylon aphyllumhad been evaluated ...
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Wilted and dried up stands of haloxylon aphyllumspecies in afforested areas of Yazd has allways been a focal point of natural resources experts. Using various pruning treatments, the effect of pruning on the wideness of canopy cover and vigor of 12-year-old semi-trees of haloxylon aphyllumhad been evaluated formerly. That study had been conducted in two different sections of the forest in the winter of years 1994. One section had shown a tree-density of 125 semi-trees per hectare, and the other had represented a tree-density of 250 semi-trees per hectare. The treatments included cutting at different heights of 70, 35, 10 cm and also no cutting (control). The results of that previous six-year study (1994-2000) showed that pruning increased vigority and regrowth of plants treated with different levels of pruning. The 35-cm pruning treatment was preferred over other treatments. At the end of growing season of year 2005, eleven years after pruning treatments, the same trees were evaluated for the second time. Results of the new study (in 2005) showed that while non-pruning (control) 23-year-old semi-trees are wilted and almost dried up, the semi-trees with pruning are vigorous and healthy. In terms of canopy cover and height, no significant difference was found between trees with different pruning treatment in the 5 years of 2000-2005. There was a significant reduction in the canopy cover and height of non-pruning (control) semi-trees (p<0.05). For the semi-trees which had been cut at a height of 35 cm, the diameter of canopy and the height were 262 and 164 cm, respectively. This semi-trees showed a good resistance against movement of sands and sand dunes.
Kazem Dashtekian; Mojtabah Pakparvar; Jalal Abdollahi
Volume 15, Issue 2 , January 2008, , Pages 139-157
Abstract
Managing and monitoring of salinity is one of the most important affair in agriculture, specially in arid and semi arid area. For this purpose we have to use new technology like remote sensing and GIS. Most of scientist use maximum likelihood algorithm for mapping soil salinity, but in this method field ...
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Managing and monitoring of salinity is one of the most important affair in agriculture, specially in arid and semi arid area. For this purpose we have to use new technology like remote sensing and GIS. Most of scientist use maximum likelihood algorithm for mapping soil salinity, but in this method field sampling is necessary. In this study several methods were used for producing soil salinity map. These methods are Brightness Index (BI), Normalized Difference Salinity Index (NDSI), Salinity Index (SI), Yazd Salinity Index (YSI), maximum likelihood and average of regression with some Bands. By analyzing and comparing methods with real soil salinity map, suitable method for this region were: 1. Average of regression with standardized band 1,2 and 3. 2. salinity index method.
Mohammad Jankju-Borzelabad; Mahdeyeh Tavakkoli
Volume 15, Issue 2 , January 2008, , Pages 215-226
Abstract
Due to the increasing attentions on multiple uses from rangelands, methods of improving seed germination rates were investigated on 10 arid rangeland species, which have ornamental and/or pharmacological values. 9 dormancy breaking treatments were applied, in a completely randomized design. Seeds ...
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Due to the increasing attentions on multiple uses from rangelands, methods of improving seed germination rates were investigated on 10 arid rangeland species, which have ornamental and/or pharmacological values. 9 dormancy breaking treatments were applied, in a completely randomized design. Seeds were then located in an incubator and daily germination rates were recorded. Between treatments, gibberlic acid caused the greatest influence, on germination of 5 out of 10 species. Low temperature, potassium nitrate, high temperature, sulphuric acid, and water imbibitions also increased germination rates of 3, 3, 3, 2, and 1 species respectively. Lowest effect was found for polyethylene glycol and wet sand treatments. The applied treatments led to high increases in germination rates of Stachys inflata, Pteropyrum aucheri, Capparis spinosa and Fortynia bungei. However, the results for Atraphaxis spinosa, Calligonum polygonoides, Calligonum bungei, Isatis cappadocica, Glaicium oxylobum, and Iris songarica may not be applicable for field workers, because of low (0-5 %) germination rate of these species, while they are valuable for researchers. Further interesting results of this experiment was a logical relationship between treatment that caused the highest increase in germination rate, and phenology stages, habitat conditions of some species.
Naser Baghestani Maybodi; Mohammad taghi Zare; Jalal Abdollahi
Volume 13, Issue 4 , February 2007, , Pages 337-346
Abstract
Study over vegetation on grazed and ungrazed rangelands is significant for range managemen, this the effects of 2-decade exclusion on vegetation of steppic rangelands in Nir range research station were studied. Three 7.5-hectare experimental plots were selected inside and outside of the exclosure. Exclosure ...
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Study over vegetation on grazed and ungrazed rangelands is significant for range managemen, this the effects of 2-decade exclusion on vegetation of steppic rangelands in Nir range research station were studied. Three 7.5-hectare experimental plots were selected inside and outside of the exclosure. Exclosure site had not been grazed from 1986 to 2004. The adjacent site was continuously grazed at the same time. Cover estimated on quadrates and forage yield were measured by clipping and weighting method. Data were analyzed by t-test method. Results showed that cover, density and yield of Salsola rigida and Stipa barbata increased significantly inside exclosure (p<0.01), but it was not significantly different in Artemisia sieberi (p>0.05).Cover, density and yield of Scariola orientalis , Launaea acanthodes and Noaea mucronatawere greater in grazed area, but only the yield of first species, density of second species and cover and density of third species were significantly high (p<0.05). Two-decade protection from grazing showed that vegetation trend is very slow in arid rangelands.