جستجوی مقالات مرتبط با کلیدواژه « desertification » در نشریات گروه « محیط زیست »

Biological rehabilitation is an effective way in preventing desertification process. Saxaul trees have distributed in Central Asia including Iran. It is a psammophyte species, and grows in sandy deserts, on sand dunes. This species is drought resistance, wind, salinity and limited nitrogen. So, it is widely planted to rehabilitate the arid areas in Iran since 1955. Water scarcity is going to be the major global issue. Supplying water in arid climates is the first step in tree planting. Therefore, different irrigation techniques were considered to invent new water supplying methods for Haloxylon. Ammodendron seedlings. The average annual rainfall in the study area (Sejzi Plain) is about 99 mm and annual evaporation is 1675 mm. The wind speed varies from 1 to 16 m/s. The experimental treatments were considered in a completely randomized design with five replications. Suitable water supplying techniques for saxaul sapling in these arid conditions based on the results are; pitcher irrigation, aquasorb usage, surface stone coverage and Plastic isolation of the planting pits, respectively, as compared with the normal planting and watering. The saplings irrigated with the pitcher technique as the most efficient way show 84 % higher length and 88% greater canopy diameter.

More than 75 percent of Iran is located in arid and semi-arid then land degradation and desertification are one of the crises ecological. We require a proper understanding of causes and processes of desertification to control the huge phenomenon on the global and regional situation. Because southeast of Iran located in arid land then assessment of desertification is very importance for planning of project.

In this study, using GIS techniques to assess desertification with IMDPA model in 27.020 Ha of Chah-hashm Plain.

Result show vegetation criteria (2.97) is more effective than climate criteria (2.68) and other hand aridity index (3.92) is most effective index and continuing drought (1.6) index is less effective index in this area. Result indicated intensity of desertification is in high class with 2.82 numerical value. In this area some limitations such as lack of rainfall, high temperatures, high evaporation, the instability and sensitivity to soil erosion is a natural limits of the area and cannot be control but with improved irrigation methods, education and extension service for the optimization use of agricultural land can be move to improve the situation and to assist in slowing desertification

Today one of the ecological crisis is the phenomenon of desertification that affecting the world. Desertification is more related to social and anthropogenic issues than natural causes and it becomes more important over the time. Monitoringis the systematic collection and analysis of information as a project progresses. In this study, using AHP method and GIS techniques has been to assess desertification process with IMDPA model in 5.7864 acres of Southeast region in the Iran. The results of the analysis showed that desertification benchmarks and indicators in the three periods had a nonlinear trend of desertification process in the region so that the numerical value is equal to 2.73 in the period 2001-2004 but In the period 2004-2007 the figure has decreased that is show decreasing trend of desertification in recent years and In the period 2007-2010 the numerical value is 2.55 that observed a increasing trend of desertification. Among the indicators studied, aridity and annual precipitation indicators were maximum effect with values 3.81 and 3.4 And SAR values ​​has 1.17 that the least impact on desertification. After analysis of data we understanding that in the many years we had in warning about indicators but we located in not warning years in 2007 and 2008 with climate benchmark. We find that region is not in warning about SAR indicator in all years of study and we are in warning about precipitation indicator in all years except 2007 in region

Desertification could be traced back to one or many factors. Thus, to cope with such a phenomenon, there exists a need for a profound understanding of the processes and the causes. The study area of the current paper is the extent of Shahrekord’s Marghzar as an important case amongst the important ones of the province. In order to evaluate the roots of desertification in the area, the Iranian model of desertification potential assessment (IMDPA) was used. Three criteria included are water resources status, soil and vegetation. These criteria were scored against the defined set of scores provided in the tables. According to the fact that in the model, each criterion is summed up by applying geometric average of the indices, the final map of the corresponding criterion was prepared by superimposing all the maps of the indices.  Next, the criteria were combined by applying geometric average and the final map was created. Based on the criteria, the severity of desertification in the region according to the IMDPA model is 1.61 which falls into the medium class. Results indicate that the vegetation utilization and water table drawdown indices, as the two most influential indices, are averaged around 4 and 3.23, respectively. The vegetation index acts as the most critical case defining the lion share of the desertification severity of the area. Of the total area, 3.1% is classified as low and 96.9% as medium severity classes. From the major causes of desertification in the region, one could point out to over utilization of the rangelands and intense livestock grazing which have imposed a downgrading force over the vegetation cover. Of the rest, over withdrawal from the underground reservoirs and the multiplicity of wells could be mentioned. These latter causes have the Marghzar dried and water tables drawn