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Abstract:  
Introduction
Desertification phenomenon as one of the manifestations of land degradation is one of the natural hazards that are spreading rapidly due to human interference in nature and the misuse of it. There are many challenges affected by this phenomenon such as loss of fertile lands, reduction in forest, rangeland and fertile plain biomass, decreasing in aquifer water level, decreasing in water quality and poverty and migration in most regions of Iran in recent years.

Materials and methods
North Khorasan Province with an area of 28182 square kilometers is located in northeast of Iran. A considerable part of the province has been suffering from reduced tolerance due to significant land use changes, plant cover degradation and deforestation. It has faced of high level of vulnerability to desertification because of environmental pressure and extreme equilibrium changes. 
Few studies have been conducted on desertification mapping and identification of its main factors in the province. The purpose of this study was to provide a map and assessment of the hazard of desertification with two Iranian MICD and IMDPA models and identifying the main destruction criteria in the province. For this, the required data including aerial photos, topographic maps, etc. was collected firstly and the data were converted to the appropriate format and initial maps of slope, aspect, DEM, land use and land units were prepared. Two IMDPA and MICD models were used to assess the desertification hazards. In each model, the desertification criteria were identified and scored. Severity of desertification of each land unit and the whole area was determined for two models. Finally, the present desertification map of the area was obtained by the above methods.

Results
According to the intensity map of desertification hazard based on the IMDPA model, the average numerical value of desertification intensity in North Khorasan province was 2.67 indicating that the moderate to severe desertification hazard class in most parts of the province. Effective criteria in desertification include climate (3.2), erosion (2.76), agriculture (2.9), geology (2.2) vegetation (2.8) and soil (2.3) respectively Based on the model. To evaluate the desertification status using the MICD model. The results showed that the severity of desertification hazard based on the MICD model is more than 80 percent of the province's regions in the moderate to severe class.
 
Conclusion and Discussion
Northern Khorasan province includes several species affected by special environmental conditions and two vegetative regions of Iran i.e. Turanian and Hirkani Land Use Intensive changes and vegetation destruction cause desertification more rapidly in this region. It results increasing risk of flood, decreasing groundwater levels, salinization, poverty and migration of inhabitants. Desertification criteria were classified in the following order: climate (3.2), agriculture (2.9), vegetation (2.8), erosion (2.76), soil (2.3) and geology (2/2) based on the results of this study. Therefore, the climate factor with the value of 3.2 with low rainfall and potential evapotranspiration indicators (more than 70%) is the main factor in increasing the desertification intensity of the region. The destruction of agriculture and vegetation, which shows direct human communication with the environment and resources, has the highest impact on the severity of desertification of the region after the climate. That’s reason is excessive exploitation especially in rangelands (in the form of excessive gravel and picking plants). In general, they are located in the rangeland landscape based on the results of both of the major models of vulnerable ecosystems in the province. These ecosystems, which are subject to overgrazing, consecutive land use change, exploitation and degradation of rangelands, are highly vulnerable and in addition to reduce the production of forage and medicinal plants, they will become desert landscapes. Land use changes in forest ecosystems and their transformation into agricultural lands have played a significant role in changing the face of these ecosystems in recent years. These changes have increased flood conditions at different levels and the risk of flooding the inhabitants of the area after every rainfall. In desert ecosystems, due to the inherent potential of these areas, high erosion, which reflects the low soil capacity against erosion, accelerates salinity, drought and, consequently, degradation of vegetation. Maintaining balance of livestock and pasture and turning to other methods of exploiting pasture, such as medicinal herbs, beekeeping, ecotourism development, flood spreading that maintains the economic conditions of local communities, as preserves vegetation and controls flood are the management priorities in the province. Therefore, considering the importance and extent of the multi-dimensional phenomenon of desertification in the region, it is suggested to prepare the strategic plan for risk management of desertification of the province and by introducing appropriate, conservative, aggressive and competitive strategies in various conditions, an important step would be taken to improve the vegetation of rangelands and increase forage production, control water and soil erosion and control water and soil, control flood and damages, feed and strengthen  groundwater resources, improve environmental conditions of the areas and adjust drought effects.
     
Type of Study: Research | Subject: Evaluation desert
Received: 2019/05/8 | Accepted: 2019/09/14

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