نشریه تخریب و احیاء اراضی طبیعی
پیاپی 2 (پاییز و زمستان 1399)

Since the desertification is increases, providing the appropriate management strategies will decreased the desertification intensity and its expansions. For this, understanding of desertification process as well as its driving forces seems to be necessary to study in a research project. The main purpose of this study is to assess the desertification by using, IMDPA model in three periods those of 2000-2004, 2005-2009, 2010-2014 on Dehloran plain, Ilam province having 543.52 Km2areas. For this purpose, three affective criteria of climate, water and geomorphology-geology have been used for assessment of desertification. Each criterion was also evaluated by using a number of indices. The results of the desertification process in the first period of 2000-2004 showed that the criteria of climate geomorphology and geology and water, respectively, with weighted average 1.38, 1.30 and 1.19 were the most affective criteria in this period. Differently, in the second period of 2005-2009 the criteria of water, climate and geomorphology and geology, respectively, with weighted average 1.80, 1.50 and 1.30, had the most impact on increasing desertification. In the third period of 2010-2014 the criteria of climate geomorphology and geology and water, respectively, with weighted average 1.88, 1.30 and 1.20, were the most effective criteria in the intensity of desertification. Salinity index was recognized as the most affective indices in desertification process in all periods of time. This index hadthe greatest impact in the second period due to the indiscriminate use of farmers from exploitation wells which resulted in both decreasing groundwater levels and increasing salinity index. Overall, in study area the salinity index had an increasing trend which could be because of low rainfall, decreasing groundwater levels, and the special geology conditions.

Different decision-making models are applied for assessing the combating desertification alternatives and providing optimal alternatives through taking into account the total effective measures that sometimes the results of the prioritization of these models are not consistent. This issue depends on the nature of the model, the considered criteria, and the way of weighing the criteria as a group by the experts. So, there is need for presenting some functions in some groups to prioritize the alternatives offered in each region by the different models on the basis of logic and strong principles and theoretical foundations. In this paper, it has been tried to do so by using the social welfare functions. The function of Group Ranking Value (GRV) was used in this study and the combating desertification alternatives resulted from the 13 decision-making models in the Khezrabad Region of Yazd were analyzed. In this regard, after the formation of coordinated and uncoordinated sets, different solutions were estimated in each set and finally, the objective function (Tobj) was calculated for any of the resulted solutions in order to achieve the final solution. The solution with the highest T value was presented as the final and collective alternative. The obtained results indicated that the first solution or in other words, the alternative order of A18>A23>A31>A20>A23 is the best order for the presented alternatives.

Severe deforestation in the forests of northern Iran has caused soil degradation and erosion, reduced carbon storage and altered the natural state of forest stands. Therefore, this study aims to investigate the effect of tree species fusion on physical and chemical properties and soil carbon storage in two degraded and un degraded stands, three different forest types and two soil depths in Aliabad forestry plan Done. In this study, ten specimens in the degraded massif and 15 specimens in the undamaged massif were selected for sampling according to the typology of the dominant tree species. Soil samples were collected by mixed method at two shallow depths and physical and chemical factors of soil (bulk density, moisture content, acidity, nitrogen, potassium, calcium, magnesium and organic carbon) were measured and analyzed for variable Soil-related SAS statistical software was used. According to the results of the types in terms of potassium, acidity and electrical conductivity in the two masses are significantly different from each other  (P <0.01) two soil depths in terms of organic matter and electrical conductivity were significantly different (P <0.01). Also, two habitats in terms of potassium content and interaction (habitat Î soil depth) also showed a significant difference in terms of acidity (P <0.05). In addition, according to the results, the amount of storage Carbon in undegraded mass (30/97 kg / ha) was more than degraded mass (29/95 kg / ha) and in two depths, 10-20 had the highest amount of carbon sequestration compared to 0-10, on the other hand, comparison The average carbon storage in the three forest types also showed that the hornbeam type has the highest amount of carbon storage compared to the oak-hornbeam and hornbeam-maple types, and it seems that the hornbeam species is a moderator in element decomposition and sedimentation Carbon is in the soil.

Tillage operations have the most effective role in increasing soil yield economically. Therefore, the purpose of this study is to compare the effect of conservation tillage operations (No tillage e and Low tillage) and conventional tillage system on physical and chemical properties of topsoil in different time sequences in Aqqala region. The experiments were performed in a completely randomized design at a depth of 0-25 cm in three treatments without tillage, low tillage and conventional tillage. In this study, data analysis is performed by comparing the mean of the data in the three treatments. Data normality test was performed using Kolmogorov-Smirnov test. The difference between the means was calculated using Duncan's test at the confidence level of 0.05 and 0.01. In this study, the parameters of organic carbon, organic matter, bulk density, carbon sequestration, percentage of clay, silt and soil sand were evaluated in three treatments. The results showed the difference between the performance of conservation tillage and conventional tillage and the low yield of conservation tillage at the beginning and then its increase in the long run. Therefore, changing the way crops are grown from the previous conventional system to modern tillage methods can be a good solution to improve soil cultivation conditions and increase crop production efficiency in these lands.

One of the factors changing the quality and pollution of groundwater resources in plain areas is the presence of nitrate ions. Sari plain is also prone to vulnerability due to the existence of various agricultural, residential, industrial and proximity to the sea. Groundwater quality assessment is costly; But it is possible to save money by using methods to assess the vulnerability of the aquifer. Vulnerability assessment is a low-cost method in identifying areas prone to pollution that plays a key role in water resources management. Therefore, in the present study, two methods, DRASTIC and SI, have been used due to the existence of land use parameter in the SI model and its comparison with the DRASTIC model and the use of the final map to determine the vulnerability of the Sari plain aquifer. For this purpose, first the amounts of nitrate during the years 1393-1397 were zoned and mapped. Then the parameters of both models such as depth to water table, net nutrition, aquifer constituents, soil type, topography, unsaturated zone constituents, hydraulic guidance and land use, which were prepared as a layer in ArcGIS software and weighted and rated Classification and integration of these layers, the final map of paternal damage to contamination was prepared. Based on the results, the two methods were classified into four groups: very low, low, medium and high risk. Medium vulnerability class in DRASTIC and SI methods with 39.75 and 39.56, respectively, have the highest percentage of area in the northern and plain areas with agricultural use. According to the obtained results, the two models showed the same results in terms of vulnerability in the region, but the percentage of area with very low risk in the SI method is higher than DRASTIC.

The ecosystem of arid and desert areas has difficult conditions for plant growth and development, due to lack of moisture, high temperature, strong winds, soil erosion and land degradation caused by human activity, as a limited number of plant species are able to survive. Wind erosion is one of the problems in these areas due to lack of vegetation. There is a need to increase vegetation to prevent this erosion. In such areas, native plants with the ability to adapt to hard environmental conditions are valuable species that are important to be identified. To conduct this research, two random transects with a length of 250 m were first placed to measure the vegetation status and at a distance of 50 meters from each other, plots were thrown 3×3  meters according to the condition of the cover.Also, 1×1m plots were used to measure the percentage of canopy, bare soil, rocks, density and litter. Three soil samples were taken and some of its characteristics were measured. To estimate the amount of eroded soil, the remnants of erosion-resistant areas as well as the depth of degraded soil around the stems and roots of shrub and shrub species were measured at 10 points. The protective performance of plant species against wind erosion was estimated using the difference in the height of the stabilized soil under each canopy relative to the surrounding soil.The results showed that the species of Tamarix sp, Alhagi camelorum, Aeluropus littoralis, Suaeda fruticosa have good adaptation to areas subject to wind erosion in the study area. The predominant species in the region is the Tamarix shrub. Each turmeric shrub has an average canopy cover of 2 square meters in this area, which stabilizes an average of 3.3 square meters of soil. On average, during the droughts of the last 10 years, about 102 tons of soil per hectare of the area has been eroded annually. Therefore, it is suggested that in order to improve the environment of the region, a suitable conditions should be provided for the establishment of species compatible with the region.

The present research aims to study vegetation cover degradation in Isfahan province, Iran using the MODIS sensor data. So, the 16-day images of the DNVI vegetation cover index of MODIS were used for 2010, 2015, and 2020. To precisely analyze vegetation, cover in Isfahan province and the counties of Khour va Biabanak, Aran va Bidgol, Isfahan, Semirom, and Fereydun Shahr, NDVI was categorized into four classes (0-0.1, 0.0-1.2, 0.0-2.3, and >0.3). Then, the variation trend of these classes was explored over a 10-year period. The results revealed an ascending trend of the 0-0.1 and 0.2-0.2 classes so that they reached from 62.93% and 32.65% in 2010 to 69.69% and 27.63% in 2020, respectively, whereas the 0.0-2.3 and >0.3 classes descended in the same period, changing from 3.69% and 0.74% in 2010 to 2.19% and 0.49% in 2020, respectively. The results of NDVI in the counties of Fereydun Shahr, Isfahan, Semirom and Khour va Biabanak showed the rising trend of the 0-0.1 and 0.1-0.2 classes and the falling trend of the 0.2-0.3 and >0.3 classes. The opposite was observed in Aran va Bidgol, i.e., an ascending trend in the 0.0-2.3 and >0.3 classes but a descending trend in the 0-0.1 and 0.1-0.2 classes. This can be ascribed to the expansion of arable lands. Vegetation cover degradation was fiercer in Semirom and Fereydun Shahr, possible due to the degradation of rangelands and forests by land-use change and excessive exploitation. Using the results of this study, it is possible to study the trend of vegetation changes in different regions of Isfahan province and adopt appropriate plans and policies on vegetation cover use.

Land use identification and determination of their spreading level in the region is one of important factors in the natural resources and environmental studies. Preparing land use map from satellite data is one of the fastest and most cost-effective methods. This study’s aim is to determine the best algorithm for TM satellite images classification between 6 supervised classification methods including maximum likelihood, mahalanovis distance, minimum distance, parallel pipe, support vector machines and binary codes to extract land use map of Zenouz Chai watershed.For grassland, wasteland and abandoned and agricultural land use, 30 training samples and for badland land use 45 training samples were prepared separately using ground control points. Results were assessed for satellite image classified using by overall accuracy index, kappa coefficient, producer accuracy and user accuracy. Investigation of TM image classification accuracies showed that the maximum likelihood algorithm with overall accuracy coefficient (84/73 %) and kappa coefficient 65/0, have the higher efficiency for image classification into four land use classes. The results showed that maximum likelihood method has more capabilities than other methods for land use map preparing. Therefore, the results of this study can be used to provide land use maps with higher accuracy using maximum likelihood method to assessing the environment and natural resources works in the areas with the same situations.

Changes in land uses are of the human interventions influencing ecosystem processes. In this study, some soil properties and clay mineralogy have been studied in three land uses including a combination of oak forest and dry farming, dry farming and 20-years-old abandoned dry farming in Karezan region. Soil samples were taken from control profiles of each land use and the soils were classified based on key soil taxonomy 2014. The results of soil properties showed that the highest ρb is 1.59 gr/cm3 in surface horizon belonged to 20 year- old abandoned farming. The lowest soil pH in surface horizon belonged to combination of oak forest and dry farming usage with amount of 7.28 and the highest belonged to 20 year- old abandoned farming usage with amount of 7.61. OM in combination of oak forests and dry farming usage was 1.15 % which was higher than other usages. The highest percentage of lime in surface horizon belonged to 20 year- old abandoned dry farming usage .The highest CEC in surface horizon belonged to a combination of oak forest and dry farming usage with amount of 24.56 cmol+/kg. In all land uses, all measured metal oxides except calcium oxides were decreased from surface to the depth of soil. Also, except calcium and magnesium oxides, the rest of metal oxides had a decreasing trend from the top of slope downwards. Clay mineralogy by X-ray indicated that Vermiculite, Kaolinite, Illite and Chlorite composed the main parts of clay minerals and different usages did not affect the type of identified clay minerals.

Soil erosion is one of the most important environmental issues in the world, because it affects soil resources. Using crop or garden residues is an approach to prevent soil loss that acts as a protective layer, in addition to absorbing the kinetic energy of raindrops that can increase the shear strength of the soil surface and reduce erosion. Accordingly, the present study was planned with aims to compare the tree litter effect on the hydrological variables of sheet erosion in a parallel hillslope with linear, concave and convex profiles. This study was performed in laboratory conditions using a rainfall simulator. Then, the desired hillslopes were designed with different profile in the plot and filled with a sandy soil. Finally, under the 30 mm/h rainfall intensity, the amount of runoff volume and soil loss was measured in each storm event. The results showed that the total amount of runoff volume in the protected plot decreased by 34.74% and 2.79%, compared to the controlled plot of parallel-linear and parallel- concave hillslopes, respectively. Also, runoff volume in the protection plot increased by 4.29% compared to the control plot in parallel- convex hillslope. The amount of soil loss for parallel-linear, parallel-concave and parallel-convex hillslopes had 70.14%, 87.65% and 61.90% reduction in protection treatment compared to the control plot, respectively. Based on the results, the convex hillslopes have the maximum soil loss.

The goal of this study is to prepare the potential map of subsidence in Abarkouh plain. For this purpose, data of 34 piezometer wells and 77 logs were used. Five factors affecting the subsidence include groundwater level, lithology of the aquifer, land use, aquifer thickness, and the thickness of the clay layer were selected and with Point Count System Model (PCSM) using, each study points leveled and their raster layers prepared with using Kriging interpolation. According to the importance and effect of each studied parameters in the occurrence of the subsidence, the weight of each layer was calculated using the Shannon’s entropy theory. Then, the raster layers multiplied by weight of each parameter and combined together, and the potential map of the land subsidence was obtained. Finally, in order to investigate the accuracy and validation of the produced map, the results compared with the land subsidence map that obtained from Sentinel -1 radar image. The results of the land subsidence potential map (PCSM method) showed that the eastern, northern and northeastern regions of the study area had the highest potential of subsidence. Besides the groundwater table drawdown, these areas contain clay with considerable thickness. According to the Shannon entropy theory, the thickness of the clay layer had a maximum effect on the subsidence occurrence. The comparison of subsidence potential map with the subsidence map that extracted from radar images showed the high efficiency (R=0.87) of the method that used in the present study.

This study was conducted to identify the site demands of Rhus coriaria whit the aim of conservation, rehabilitation and development in Sumac Forest reserve area in Shazand city from Markazi province. For this purpose, 14 square-shaped sample plots were established by random-systematic sampling method with a grid size of 200×300 meters. Quantitative characteristics such as the height, mean Tree Crown Diameter and Mean collar diameter of the thickest tree in addition to ecological characteristics were recorded in each plot. To study the physicochemical properties of soil (such as texture, electrical conductivity, pH, organic carbon, nitrogen, phosphorus and potassium), 28 samples were taken at two depths of 0 to 15 and 15 to 30 cm. Canonical correlation analysis (CCA) was used to determine the relationship between site conditions and soil properties whit ecological characteristics of R. coriaria. Kruskal - wallis test was used to compare the effect of geographical aspects on the height and crown diameter. The results showed a significant effect of geographical aspect on height and crown diameter. The largest crown diameter (100.25cm) and the maximum height (112.30cm) were observed in the northern aspect. The results of CCA analysis for vegetation and first soil depth were able to appropriately distinguished R. coriaria plots from others and showed that R. coriaria site had the most positive relationship with soil pH (44%). Also, the results of CCA analysis for vegetation and second depth of soil showed that R. coriaria site had the most positive correlation with soil EC and Potassium (60% and57%, respectively). In general, the results showed that the sample plots containing R. coriaria had higher pH, phosphorus, nitrogen, potassium, organic matter, silt and electrical conductivity. Since that, having knowledge of specific characteristics of each habitat (site) is necessary for the regeneration and development strategies, according to the obtained results, it is suggested that soil fertility be strengthened in the central core of this forest reserve.