فهرست مطالب

  • Volume:1 Issue:2, 2013
  • تاریخ انتشار: 1392/03/18
  • تعداد عناوین: 8
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  • Hamid Reza Kamyab, Abdolrassoul Salman Mahiny Pages 99-112
    Logistic regression (LR) was used to model urban growth between the years 1987 and 2001 in Gorgan city, north east of Iran. Three groups of variables including economic-social, land use and biophysical variables were used in the modeling practice. Using covariance of the independent variables, distance to administrative and sporting centers plus distance to cities were removed. ROC (Relative Operating Characteristic) value for LR was 0.87 that confirmed success of the modeling method. Using maps of urban growth probability predicted by the LR model, urban distribution patterns for the years 2010, 2020, 2030, 2040 and 2050 were created. Land use maps for the years 2001-2050 were created using urban probability pattern maps and the base land use map of the year 1987. We used landscape metrics at class and landscape levels to compare the urban growth effects on other land use types present in the area. The comparison showed that urban development influences agriculture and pasture land use types more than other land uses. Also, we found that the landscape in the study area has undergone fragmentation and will become more fragmented and heterogeneous over time. Urban growth creates higher urban patchiness and increases the number of pasture and agricultural patches. The information thus obtained is helpful in more effective management of the area.
    Keywords: Fragmentation, Gorgan, Landscape Metrics, Logistic Regression, Urban Growth
  • Reza Ghazavi, Abbasali Vali Pages 113-122
    Re-vegetation of bare soil is believed to increase, or at least maintain the organic matter levels of soil. The aim of this study was to investigate the soil characteristics changes, nutrient pool sizes and their availability under mid canopy, and canopy gap positions of saltbush in an area re-vegetated with Atriplex lentiformis. Some of the physical and chemical soil characteristics (the particle size distribution, soil bulk density, EC, pH, Na, K, organic C, N, P, C/N ratio and C/P ratio) were measured in two different soil depths at both planted shrublands and control area. The results from samples analysis showed that the soil of the control area is significantly different from the Atriplex shrublands area. Maximum of K and Na proportion were measured in 0 to 20 cm under mid canopy in the planted sites. K and Na in different soil layer showed a significant difference between ungrazed area, grazing area and control area (P)
    Keywords: Atriplex lentiformis, Re, vegetation, Saltbush, Soil characteristics, Soil nutrient
  • Ali Reza Nafarzadegan, Hossein Ahani, Vijay P. Singh, Mehrzad Kherad Pages 123-144
    Evapotranspiration is one of the most important components of the hydrological cycle which is directly influenced by atmospheric conditions. This study investigated annual and seasonal trends in reference evapotranspiration (ET0) and its key influencing climatic variables during 1966-2005 at 10 stations in southern Iran (with centrality of Fars province). First, multivariate regression analysis was performed to identify the major meteorological variables affecting ET0. Second, annual and seasonal trends in climatic variables as well as ET0 were assessed using the Mann-Kendall test, Spearman''s rho, the Pearson correlation and linear regression to evaluate their contribution to the temporal trend in ET0. Results suggested that the more effective variables for ET0 were wind speed (U2), relative humidity (RH) and sunshine hours (n). Also, the majority of trends in seasonal and annual ET0 were non-significant and after that decreasing and increasing trends had higher frequencies. In addition, distributions of relative frequencies of trend types at all considered time-scales were similar for both parametric and non-parametric techniques. Hence, the disagreement between parametric and non-parametric trend results did not depend on the degree of normality in the annual and seasonal ET0 distributions in the study area.
    Keywords: Climate variables, Lilliefors test, Normality degree, Trend analysis
  • Abbas Farshad Pages 145-158
    Global warming is claimed to be the cause of climate change, which is often held responsible for water shortage. Let geopedology represents the complex process of soil formation, out of which much can be learnt about paleoecology; soil formation being a dynamic interaction between the atmosphere, biosphere, lithosphere, and the hydrosphere. In a multidisciplinary sustainability-oriented study in northwestern Iran, geopedologic data were analyzed and cross-referenced with some historic and archaeological information to reconstruct paleoecologic conditions in several time periods, through which the changes both in climate since upper Pleistocene, and in landuse and their consequences in terms of land degradation could be concluded. The occurrence of a (sub-) surface layer of travertine, dated 27,000 y BP that is coated by a thin organic layer with traces of rancienite (mineral), dated 13,000 y BP, implies a humid environment, corresponding with the pluvial uppermost Würm. The geopedologic survey, supported by soil micromorphology, revealed that between 6,000 and 2,600 years ago the area was subject to cycles of erosion and sedimentation that have led to glacis formation. A type of climate that is characterized by the alternation of wet and dry periods is also supported by the occurrence of Petrocalcic and Argillic horizons in the soils. Cultivating rice, tobacco and cotton, which was practiced until over a century ago, also implies relatively wetter conditions. The study concludes that aridification has never been as degrading as it is today, due to the over-exploiting of the non-renewable fossil groundwater.
    Keywords: Aridification, Geopedology, Global warming, Hamadan, Iran, Soil micromorphology
  • Mohammad Reza Kalbassi, Esmail Abdollahzadeh, Hamid Salari-Joo Pages 159-178
    Global aquaculture production has more than tripled during the last 15 years, and aquaculture is expected to account an increasing share in global seafood production. There are large differences among countries in the rate of growth and development of aquaculture. This review tries to explain the progress and problems of aquaculture during three last decades in Iran. The total production of Iran from aquaculture was 25,800 tons in 1994, approximately 8 percent of the total fisheries production. However, by 2008 it increased to more than 154,000 tons; 27% of total fisheries production. During the last decade, production share of different species in Iran has been variable. In the years 1998 and 2008 the highest percentage of aquaculture production was belonged to silver carp Hypophthalmichthys molitrix (50%) and rainbow trout (Oncorhynchus mykiss; 40%), respectively. The results showed that culture of rainbow trout has grown noticeably in the past two decades. At present, Iran has been acquired the first rank of rainbow trout culture in fresh water of the world. But in contrast, in recent decade shrimp aquaculture industry has failed due to white spot syndrome. Coastal and inland waters of Iran have more potential for aquaculture development. Recently, great sturgeon Huso huso and some species of barbus family have aroused interest from government and private enterprises for potential aquaculture use. Although aquaculture of Iran has shown a significant growth in the last decade, but it is concluded by introducing new species and overcome to present aquaculture problems in the country, the aquaculture production will be increased to several times.
    Keywords: Aquaculture development, Aquaculture statistics, Freshwater, Iran, Rainbow trout
  • Hasan Fazli, Gholam Reza Daryanabard, Shahram Abdolmaleki, Gholamali Bandani Pages 179-190
    Recently the previous Caspian ecosystem is in a catastrophic condition which caused changes in the absolute and relative abundance of the commercially important Caspian kutum (Rutilus frisii kutum) in Iranian waters. The paper presents estimates of yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of Fmax, F0.1, F30%. It proposes a method for estimating acceptable biological catch (ABC) that accounts for large differences in the quality and quantity of information and available data. The current average Y/R (with F=0.61/y, and tc=3.2 y) was 218.3 g per recruit, which indicates that the fishery is operating below the maximum Y/R at 236.9 g when tc = 3.5 y. The Y/R was the highest at Fmax and F0.1, when tc = 4 y (244.8 g and 214.2 g), respectively. The F30% value was 0.85/y at tc of 4 y with the SB/R of 338.3 g. The Fcurrent (0.61/y at current tc is 3.2 y) is higher than the corresponding reference points, F0.1 (0.47/y) and F30% (0.46/y). The ABC of kutum was estimated at 7,850 mt in 2009-2010.
    Keywords: Acceptable biological catch, Reference point, Rutilus frisii kutum, Spawning biomass per recruit, Yield per recruit
  • Ali Kazemi, Alireza Riyahi Bakhtiari, Nabiallah Kheirabadi, Asma Mohammad Karimi Pages 191-198
    Concentrations of lead (Pb) were found in the shells of the oyster Saccostrea cucullata and sediments in May 2010. Samples were obtained at four sites on Qeshm Island, at three sites on Hormoz Island, and at three sites in Lengeh Port along the intertidal coast of the Persian Gulf of Iran. The levels of Pb in sediments and shells were analyzed by graphite furnace atomic absorption spectrophotometer. Mean Pb concentrations in the different sampling stations varied between 613.94 and 0.06 µg g-1 in the shells of S. cucullata and 180.78 and 0.86µg g-1 in sediments. Biological effects criteria suggest that Pb concentrations in sediments in three sites from Lengeh Port were higher than ERL (effects range low), but at the all sites were lower than ERM (effects range medium). The present results support the significant differences in shell and sediments’ accumulated concentrations of Pb among sites attributed to input sources of human activities including urban, domestic, industrial, agricultural, shipping and transport, mining activities, and ports and harbors
    Keywords: Biomonitoring, Hormoz Island, Human activities, Lengeh Port, Qeshm Island, Saccostrea cucullata
  • Seyyed Morteza Hoseini, Ali Jafar Nodeh, Seyyed Abbas Hosseini Pages 199-206
    Formalin is a common disinfectant and therapeutic agent in fisheries-related activities. Considering large variation in susceptibility of different species to formalin toxicity, it is necessary to determine its toxicity and safety margins in different species, separately. Therefore, to investigate formalin acute toxicity and safety margins on Caspian roach, an experiment was conducted in 1g Caspian roachs Rutilus rutilus caspicus. Fish were exposed to 0, 30, 40, 45, 50, 55, 60, 70, 100, 150, 200, 250, 300 and 400 ppm formalin and mortality was recorded after 0.5, 1, 12, 24, 48, 72 and 96h. 0.5-96 h LC50 values were 49-246 ppm. The lowest observed effect concentrations (LOEC) were found to be 40-150 ppm at different periods. No observed effect concentrations (NOEC) were 30-100 ppm at different periods. According to regression model for NOEC versus time, concentrations of 88.4, 80.3, 51.2 and 40.1 ppm are suggested as the maximum concentrations for 0.5, 1, 12 and 24 h bath treatment, respectively. Results showed the recommendations for formalin safety in the literatures are not applicable and valid for Caspian roach. Such differences could be due to species or experimental differences which should be taken into account before treating.
    Keywords: Caspian roach, Disinfectant, LOEC, NOEC, Toxicity