Showing 16 results for Iran.
Y. Asri,
Volume 7, Issue 4 (1-2004)
Abstract
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Kavir Biosphere Reserve covers an area of 686598 hectares situated in the northwest of Dasht-e-Kavir and east of Daryach-e-Namak. The Biosphere Reserve presents a variety of habitats, including cliffs and rocky outcrops, piedmont plains, gravelly, deserts and sand dunes, saline plains and salt marshes, and seasonal rivers and springs. The main aim of this research is to identify the plant species and to introduce of the flora in Kavir biosphere reserve. For this purpose, plant samples were collected from different habitats of the area in three growing seasons between 1994-1999. The life forms of species were determined and the biological spectrum of the area was plotted. The position of the area concerning phytogeographical classification was studied based on geographical data and references. A total number of 359 species and subspecific taxa was identified. These include 3 gymnosperms, 312 dicotyledones and 44 monocotyledones. Altogether, 43 families and 224 genera are known from the area. The following families have the highest number of species: Chenopodiaceae, Asteraceae, Brassicaceae, Poaceae, Boraginaceae, and Fabaceae. Therophytes with 198 species (55.1%) are the most frequent life forms in the area. The distribution of 245 species (68.3%) is restricted to Irano-Turanian region. Of these, 30 species (12.2 %) are endemics of Iran. . |
B. Ghahraman, H. Abkhezr,
Volume 8, Issue 2 (7-2004)
Abstract
Rainfall intensity with different frequencies is needed for many hydrologic models. Rainfall intensity–duration–frequency relationships (IDF) have been investigated for different regions using previously recorded data. Iran Meteorological Organization has prepared IDF curves for 66 stations in Iran since which are the most updated data. Comprehensive IDF relationships were developed for these data. The results showed remarkable changes when compared with previous studies of Iran. This may be due to a change in parameters of probability distribution function as a result of increased record length of stations. Some relationships were also developed for ten year-hourly ( P6010) rainfall estimation from some parameters such as average annual rainfall and average maximum daily rainfall. Such a relationship was made for all stations and also for different classifications of regions (based on average annual rainfall and apparent climatically divisions). The validity of all relations was analyzed for eight independent stations with suitable spatial distribution. It was shown that all relationships are nearly valid as far as a suitable region is choosen. The previous relationship for Iran is not useful at present.
A. A. Barati, J. Mir Mohammad Sadeghi, A. Khatoonabadi,
Volume 8, Issue 2 (7-2004)
Abstract
Considering the population growth and limitation of expansion in cultivation areas, employment in non-agricultural jobs in rural areas is inevitable. The purpose of this study is to investigate the factors affecting the supply of labor of the rural families on non-agricultural jobs in the rural areas. A sample of 300 families from rural areas of the Ghoochan Township in 2000-2001 was studied. The data were collected through interviews and questionnaires. The analysis used a multivariable regression equation.
The results showed that: 1. The wage level of the non-agricultural experience of the person had positive effect on the supply of labors to non-agricultural jobs. 2. However, this effect was negative for the number of days the person worked on farm. Finally, since wages earned from non-agricultural jobs was higher than that of agricultural jobs. Therefore, it is suggested that for the purpose of increasing the income of rural people, non-agricultural jobs in rural areas be facilitated and encouraged
F. Shahryari, G. Khodakaramian, A. Heydari,
Volume 8, Issue 4 (1-2005)
Abstract
Representatives of fluorescent pseudomonad strains were assessed for their antagonistic activity against the blackleg of potato pathogen, Pectobacterium carotovorum subsp. atrosepticum. Tested strains belonged mainly to Pseudomonas fluorescens Biovars III, IV and V and they could produce inhibition zone on PDA medium against P. c. subsp. atrosepticum ranging from 1.5-5.5cm. Six selected strains were used in two concentrations 107-109 and 1010-1012 colony forming units to control potato blackleg disease caused by P. c. subsp. atrosepticum under greenhouse conditions. Results showed that all strains applied could reduce the disease ranging from 46 to 71 percent. There was no significant difference among strains and their two concentrations under greenhouse conditions. Most of the strains applied increased potato fresh weight and all of them produced antibiotic and siderophore compounds in vitro.
H. Arzani, M. Jangjo, H. Shams, S. Mohtashamnia, M. A. Fashami, H. Ahmadi, M. Jafari, A. A. Darvishsefat, E. Shahriary,
Volume 10, Issue 1 (4-2006)
Abstract
Range suitability and its grazing capability are the most important criteria in rangeland analysis and monitoring. Determination and monitoring of factors affecting on range suitability and diagnosis of them are important .All range ecosystem components affect range suitability. Which among them physical and vegetational factors, forage production, water resources and sensitivity to erosion were considered. The objective of this research was to determine range suitability of Lar, Dasht bakan, Ardestan, Siahrood rangelands to design a model for sheep grazing. This study was carried out in four regions, two of them (Siahrood and Lar) located in Alborz mountain chain, Ardestan in center of Iran and Dashtbakan in Zagros mountain chain. According to the results among physical factors, slope remoteness of watering points and sensitivity to erosion had more effect on grazing capability than vegetation factors. In Siahrood watershed aboundancy of poisonous plants, high slope, transient watering points and non resistant formations were limiting factors. High slope, sensitivity of soils and stones to erosion, kind of exploitation in Lar watershed affected range suitability. In Ardestan watershed, low range productivity, presence of invader plants, erosion, remoteness of watering points are major limitation of range suitability. In Dasht Bakan factors including slope, elevation, dispersion of water resources and transient water resources were limited grazing capability. In land evaluation each land utilization type has certain land use requirement and each land unit has certain land qualities. Utilization of rangeland based on grazing capacity, range readiness and recreation of degraded rangeland can improve suitability of rangelands in the studied areas.
E. Mahdikhani Moghadam, A. Kheiri, M. Mohammadi,
Volume 10, Issue 4 (1-2007)
Abstract
To carry out this study, total DNA was extracted from eggs and from second stage juveniles of several populations of Meloidogyne javanica and Meloidogyne incognita, using phenol / chloroform method. Following extraction, DNA was electrophoresed on 1% agarose gel to determine its quality and quantity. A specific primer pair (C2F3 / 1108 23 and 20 nucleotides, respectively) was used to discriminate M. javanica from M. incognita populations using polymerase chain reaction (PCR). Primer annealing sites were located in the 3′ portion of mitochondrial gene encoding cytochrome oxidase subunit II (COII) and in the 16S rRNA gene. Following PCR amplification, electrophoresis of amplified DNA showed 1.7 kb fragment in populations of both species. Digestion of 1.7 kb amplified product with HinfI restriction endonuclease resulted in the generation of two DNA fragments of 0.7 and 1.0 kb in M. javanica and three DNA fragments of 0.3, 0.4 and 1.0 kb in M. incognita. There were no differences in the digestion patterns among various populations of each species examined.
R. Sepehri, Gh. Tahmasebi, M. J. Jalali Zonoz,
Volume 11, Issue 41 (10-2007)
Abstract
During the honeybee breeding project in central Iran, sex alleles homozygoty and sex alleles number in the third generation of 364 colonies were studied in 2003. Sex alleles homozygoty was measured based on Ruttner (1988) and Tarpy and Page (2002) methods. The total area of worker brood area, stored pollen, and drone brood area were measured on the combs. The whole extracted honey weight and remaining honey in the combs were evaluated as honey production of colonies. Adult population was evaluated based on the number of full combs of adult honeybees. The results showed that sex alleles, average homozygoty and number in the colonies were 18.83% and 5.32 respectively. The results showed no significant correlation between homozygoty of sex alleles or sex alleles number and stored pollen ( P > 0.05 ) , but significant negative correlation between sex alleles homozygoty and colony population, total brood area and honey yield ( P < 0.01 ) was observed. So introduction of new sire colonies in the mating Isolated area is essential to prevent sex alleles homozygoty and also performance of honeybee colonies from decreasing.
H. Mehrabi Basharabadi,
Volume 12, Issue 44 (7-2008)
Abstract
Kerman province is the largest producer of greenhouse cucumber and tomato in Iran. This paper calculates the interest rate of return (IRR) and return period of investment (RPI) in vegetable, cut flowers and strawberry in greenhouse and compares them with vegetable grown outdoors. To do the study, a random sample of 309 farmers was selected in the province of Kerman in 2005. Results showed that IRR for vegetable, cut flowers and strawberry in greenhouse was about 20, 14 and 23 respectively, and it was 45/8 percentage per year for vegetable outdoors. RPI for vegetable, cut flowers and strawberry in greenhouse was about 8, 29, and 7 years, respectively. Vegetables Production under greenhouse produces more employment opportunities, has better yields, higher price and efficient use of factors, but it has lower IRR, higher production cost, higher pesticide residue and is more capital intensive in comparison with outdoor production. Improvement of greenhouse credits, enlargement of metal greenhouses, research on yield and development of greenhouses at region 5 are the important policy-making implications of this paper.
A. Taghavi, Gh. Tahmasbi, A. A. Talebi, A. Zarnegar, A. Monfared, H. Nazarian,
Volume 12, Issue 45 (10-2008)
Abstract
The species diversity of bumblebees was investigated in two provinces, Tehran (Fasham, Zayegan) and Qazvin (Alamut, Wikan) in central Alborz during 2005-2006. Three casts of queen, worker and male bumblebees were collected during spring and summer in six dates in the two mentioned regions. Sampling of adult bees in Wikan was done from 26 July 2006 until 19 September 2006, and in Zayegan from 24 May 2006 to 17 September 2006. In sum, eleven species were collected of which eight species were common in the two regions. Data of different species casts at two regions were analyzed by Excel ver. 6 and Ecological Methodology ver. 6. 1. 2 soft wares. Species diversity of two regions was determined and compared with three indices of Simpson, Shannon-Weiner and Brillion, and evenness was calculated with indices of Simpson, Camargo and Esmit-Willson. Species richness of two regions was compared in research. The obtained results showed species diversity, evenness and species richness were more observable in Wikan compared with Zayegan. Consequently, Wikan in comparison with Zayegan was more sustainable. Similarity of two regions was 0/46, showing many differences in terms of the kinds. Also, there were 8 similar species in the two areas.
A Vaezi, H Bahrami, H Sadeghi, M Mahdian,
Volume 13, Issue 49 (10-2009)
Abstract
Proper evaluation of soil erodibility factor is very important in assessment of soil erosion. In this study, soil erodibility factor (K) was assessed in a zone, 900 km2 in area in Hashtrood, located in a semi-arid region in north west of Iran. Soil erodibility factor was measured at the unit plots under natural rainfall events in 36 different lands in the study area from March 2005 to March 2007. Results indicated that the measured soil erodibility factor K is on average 8.77 times lower than the nomograph-based values in the study area. To achieve a new nomograph, correlation between measured soil erodibility and soil physicochemical properties was studied. Based on the results, soil erodibility factor negatively correlated with coarse sand, clay, organic matter, lime, aggregate stability and permeability, while its correlation with very fine sand and silt was positive. Results of principal component analysis of soil properties and multi-regression analysis showed that the soil erodibility factor is significantly (R2 = 0.92, P < 0.001) related to soil permeability, aggregate stability, lime and coarse sand. A new nomograph with a R2 of 92% was developed based on these properties to easily estimate soil erodibility factor in the study area. The soil erodibility factor can be reliably estimated using the nomograph in all regions with the soil and rain properties similar to those in the study area.
Sh Ghergherechi, F Khormali, Sh Ayoubi,
Volume 14, Issue 51 (4-2010)
Abstract
Gypsum is the most common sulfate mineral in soils of arid and semi-arid regions. Two hundred million hectares of the earth’s surface and about 28 million hectares of Iranian arid soils are covered by gypsiferous soils. The studied soils consist of alluvial plane and eolian plains in northern Iran. Soils were classified as Haplocambids, Aquisalids and Endoaquepts. In this study, genesis, formation and development of gypsum in soils were investigated. Study area includes different geomorphic surfaces from the upper watershed to alluvial plains. Gypsum crystals without considering their size, shape, arrangement are determined as pedogenic. In the weakly-developed horizons, in aridic moisture regimes, formation of euhedral pedogenic gypsum crystals and incomplete infilling of voids was dominant. In the well-developed soils, in xeric moisture regime, gypsum crystals are oriented and the perpendicular in arrangement of crystals along pores is dominants. Gypsum crystals occur in different shapes such as lenticular, tabular, and rosette-like and fan arrangement. Origin of gypsum in weakly-developed soils was weathered gypsiferous marls in upper Atrak basin. The source of gypsum in the soils with shallow ground water is high content of sulfate dissolved in soil solutions. In horizons affected by fluctuation of ground water contaning sulphur, euhedral tabular shape is dominant. In well-developed soils, based on Snowball morphology, gypsum is classified as stage II nodule. Results showed that there is no relationship between formation of the snowball morphology, b-fabric and kind of diagnostic horizons (A, B and C).
M. R. Shoaibi Nobariyan, H. Torabi Golsefidi, Sabereh Darbandi,
Volume 18, Issue 70 (3-2015)
Abstract
CEC of the soil is the exchange sites of organic and inorganic soil colloids. Modeling and Estimation of CEC is a useful indicator for fertility. The new alternative approaches for estimating CEC are indirect methods based on intelligent models. In this research in order to estimate CEC, 485 soil samples were prepared from two regions, chaparsar (Mazandaran in northern Iran) and Bostanabad (North of West Azarbaijan, Iran).In this paper introduces the application of genetic programming. Input parameters that are percent Clay, Organic Carbon and Silt, evaluate using genetic programming, neural network and Neural Inference Systems-Fuzzy models. The results indicate a good ability to intelligent models for CEC Estimation According to indices used in this study. Genetic programming model with a root mean square error of 1.78 and coefficient of determination 0.95 compared to other models have been more efficient and is able to provide satisfactory results, Also are the explicit solutions that reflect the relationship between input an output variable, was presented based on genetic programming. This preferred the genetic programming model adds the other models. Stepwise regression analysis to determine the contribution of each of the parameters indicated in the CEC that organic materials having Most coefficient of variation of 84% is justified CEC and clay and silt, respectively, with a correlation coefficient of 10% and 6% respectively.
H. Fathizad, M. Tavakoli, M. A. Hakimzadeh Ardakani, R. Taghizadehmehrjardi, H. Sodaiezadeh,
Volume 24, Issue 4 (2-2021)
Abstract
The purpose of this research was to investigate the trend of annual changes in Yazd station's meteorological parameters including minimum and maximum average daily temperature and average daily precipitation (1961-2005), as well as the predicted annual mean of these parameters in the three upcoming thirty years of the 2040s, 2070s and 2100s, by the SDSM model, under RCP2.6, RCP4.5, RCP8.5, A2, and B2 scenarios. Accordingly, by using the coefficient of determination and the MAE, R2, RMSE indicators, we evaluated the data generated by the SDSM model in comparison with the observed data in the base period. The lowest value of R2 based on the calibration and validation of the mean values of observed and simulated SRES was obtained for precipitation (86 and 80%). In terms of the R2 evaluation index, the accuracy of the small-scaled results of the minimum and maximum average temperature values was more than that of the average precipitation; however, in terms of the MAE and RMSE evaluation indicators, the accuracy of the small-scaled results of the average precipitation was higher than that of the minimum and maximum average temperature values. Subsequently, HadCM3 large-scale climatological data was used to predict the future periods (2010-2100). The results indicated that the temperature was raised in all months and seasons and the precipitation was decreasing in most of them, thereby confirming that the climate was changing in the studied region.
F. Soroush, F. Fathian,
Volume 25, Issue 1 (5-2021)
Abstract
In the present study, the spatial and temporal changes of climate variables such as pan evaporation (Ep), temperature (T), relative humidity (RH), sunshine duration (SD), wind speed (W) and precipitation (P), as well as their relationship with altitude, were investigated. For this purpose, 68 meteorological stations with 30 years of data (1987-2016) throughout Iran on both seasonal and annual time scales were selected. Trend analysis of climate variables showed that over the past 30 years, most areas of Iran have become warmer and drier although all trends have not been significant. Investigation of the relationship between the trend slope of climate variables and altitude illustrated that there was no significant relationship between them during the study period on the annual time scale (p>0.1). However, in winter, the rate of increase in T (minimum, maximum and mean temperatures) and SD (p<0.1), as well as the rate of decrease in P (p<0.01), was significantly enhanced by increasing the altitude. The increase in mean and maximum T (p<0.1) and SD rates (p<0.001) in summer were significantly lower in the highlands than in the lowlands. In autumn, the trend slopes of minimum and mean T (p<0.05) were negatively correlated with altitude; in addition, the rates of increase in P and RH (p<0.05) in the highlands demonstrated a sharper increase. It seems, therefore, that most changes in climate variables have occurred in both autumn and winter. The results also showed that in winter, the highest rates of increase in Ts were related to the altitude of 1500-2000 m; however, the highest decrease in P belonged to the altitude of 2000-2500 m. In autumn, the highest rates of decrease in minimum and mean Ts had occurred in the altitude of 2000-2500 m; as well, he highest rate of increase in P was observed in the altitudes of both 0-500 m and 2000-2500 m.
A. Shahbaee Kotenaee, H. Asakereh,
Volume 26, Issue 4 (3-2023)
Abstract
Precipitation is one of the most significant climatic parameters; its distribution and values in different areas is the result of complex linear and nonlinear relationships between atmospheric elements-climatic processes and the spatial structure of the earth's surface environment. Classification of data and placing them in small and homogeneous zones can be effective in improving the understanding of these complex relationships and their results. In the present study, zoning and analyzing the distribution of rainfall in Iran concerning environmental factors was performed using the annual precipitation data of 3423 synoptic, climatological, and gauge stations in the country during the period from 1961 to 2015 and the altitude, slope, aspect, and station density data. After standardization and preparation of the data matrix, the optimal number of clusters was determined and the data set was entered into the neural-fuzzy network model (ANFIS-FCM). The results showed that the values of R2 and MAE indices were 0.76 and 0.23, respectively which indicate the appropriate accuracy of the model. It was also found that in the four output zones of the model, environmental factors have a high impact on the spatial distribution of precipitation. In the first and third zones, the combination of high altitude and slope factors along with geographical proximity to precipitation systems has caused the average annual rainfall in these zones to be 318 and 181 mm, respectively. The mean annual rainfall has decreased to about 100 mm by the weakening of the role of environmental factors in the second and fourth clusters.
F. Fathian, M. Ghadami, Z. Dehghan,
Volume 26, Issue 4 (3-2023)
Abstract
In this research, the trend of spatial changes in extreme indices of temperature related to the health and agriculture sectors such as the number of frost days, number of summer days, number of icing days, number of tropical nights, growing season length, diurnal temperature range, cold spell duration index, and warm spell duration index were investigated for 54 synoptic stations throughout Iran for observational (1976-2005) and future (2025-2054) periods. Daily maximum and minimum temperature data of three regional climate models namely, CCSM4, MPI-ESM-MR, and NORESM1-ME from the CORDEX project under RCP4.5 and RCP8.5 scenarios were downscaled for each station using a developed multiscale bias correction method. Then, trends and changes of extreme temperature indices were investigated using Mann-Kendall and Sen’s trend line slope methods. The results indicated that the warm indices such as the number of summer days and tropical nights indices have had a positive trend at most stations in both observational and future periods. In contrast, cold indices like the number of frost days have had a decreasing trend in most stations. The results of cold and warm spell duration indices showed that most stations have had no trend for both periods. The growing season length has increased in more than 60% of stations (45% having a significant trend) mainly located in the northern, northwestern, and western regions of the country. Based on the results, it can be concluded that without considering thoughtful climate adaptation measures, some parts of the country may face health risks and limited habitability and agriculture in the future.
