مجله مدیریت بیابان
پیاپی 24 (زمستان 1401)

Land degradation is manifested by a significant decrease in biological productivity of land, as a result of natural events or improper human activities. The unfortunate consequences of this degradation are threats to food security, economic well-being and environmental problems caused by the reduction of the exploitation potential of water, soil and plants. The aim of present research is to compare and measure the state of land degradation based on two global GLASOD and Iranian IMDPA models. The great plain of Yazd-Ardakan located in central Iran was selected as the research area. The land unit map of area was prepared. The severity of land degradation was investigated based on the GLASOD and IMDPA models in each of the land units. Accuracy assessment and comparison of both models’ performance were done by calculating overall accuracy and kappa coefficient, as well as non-parametric tests of Spearman and Mann-Kendall, and the significance of the results were confirmed. The comparison of accuracy assessment results showed that the IMDPA production map matched the actual data on the ground by 82%, while this match in the map obtained by GLASOD model was 69%. According to the IMDPA and GLASOD models, desertification was progressing strongly in 33% and 12% of the region, respectively. The intensity of desertification in the moderate class was approaching the severe class, and if there is no proper management to control and prevent the desertification process in the region, in not-so-distant future, the area of land with severe desertification will increase. In general, the lack of soil surface cover is the main factor in increasing the intensity of desertification in the Yazd-Ardakan plain. This issue is result of combination of natural factors and destructive human factors in the region, which has significant effects on increasing the desertification process and soil degradation.

The dust storm is recognized as a global problem which has a large-scale negative impact on the world. Dust strong winds transport them long distances. The dust storm caused a lot of damage to the economy, health and the environment. Therefore, an adequate understanding of the origin and time of dust storms can be effective in reducing dust damage. The purpose of the ongoing research is to identify the source of the dust storm events. For this purpose, the dust events in a period of 11 years were analyzed using the synoptic meteorological data of Kermanshah. The number of 646 dust storms were identified, and their detection operations and identifying of the areas affected by dust storm and areas of origin were performed using MODIS and Deep Blue. The HYSPLIT was used to route the dust storm and the entry routes of dust storm into the Kermanshah city. Based on the dust codes, the highest number of dust storms per year was registered in 2008 and 2009, respectively.  Most dust storms were observed in summer and during May, June and January. The results of DRS, HYSPLIT have shown that the western directions have the largest amount of dust input in Kermanshah, and the MODIS and Deep Blue images also confirm this fact. Overall, the findings showed that most of the routes come from the north and centre of Iraq and the Syrian Desert.  Dust storms originate at the border and arid lands of northern and central Iraq and Syria.

Net primary production is a sensitive index to changes in climatic factors and human activities. The present study was conducted with the aim of quantitatively evaluating the relative role of climate change and human activities on the development of desertification in Torbat Heydarieh and Bojnoord based on the spatio-temporal variations of net primary production. First, primary net production was estimated by ground measurement. Subsequently, it was simulated using the CASA model in statistical period between 1986 and 2017. Six scenarios were designed to determine the relative role of climate change and human activities in the expansion or inversion of desertification. The results of the research showed that net primary production has declined over the 31-year period and that the trend in its changes is negative. An examination of different desertification scenarios showed that the city of Bojnord is under the scenario of expansion of desertification due to climate change, and Torbet Heydarieh city is under the scenario of desertification expansion due to the interaction between climate change and human activities. Based on this, the trend of changes in actual and potential primary net production in Bojnord and Torbat Heydarieh cities was negative and its intensity was classified in the low to medium decline category. Also, the slope trend of changes in primary net production caused by human activities in Torbat Heydarieh city was positive and in the low to medium increase class, and in Bojnord city, it was negative and in the low decrease class.The study of the development or return of desertification scenarios showed that 61.23% of the total area of the study area was affected by the expansion and development of desertification due to the impacts of climatic factors, and 38.77% of those affected by the interaction of climatic factors and human activities in expansion of desertification.

Soil contamination by heavy metals is a significant environmental problem worldwide. Human activities, including mining, are a source of pollution to natural resources. In this study, the phytoremediation potential of rangeland species including, Artemisia sieberi Besser, Zygophyllum atriplicoides Fisch. and C.A. Mey for the absorption of heavy metals of Ni, Co, As, Cr and V was investigated around the bauxite crusher of the Jajarm alumina mine in the direction of the prevailing wind. Soil sampling was performed at the distances of 450-700, 800-1200, 1400-2000 and 2500-5000 meters from the center of the bauxite crusher, and the control site. For this purpose, the seeds were planted in pots with a 3:1:1 ratio of sand, fertilizer and soil. Two-months later, they were transferred to pots with soils sampled from target distances. After completing of a vegetative period, the phytoremediation potential of the species was performed a factorial experiment in a completely randomized block design with three replications in greenhouse conditions. Results indicated that As, Ni, Cr, and Co absorption in above/underground of A. sieberi tissues were higher than Z. atriplicoides. But V absorption in above/underground of Z. atriplicoides tissues were higher than that for A. sieberi and between the vanadium accumulation in the aerial and underground organs of the target species and distances a significant difference was observed at the level of 1%. The amount of heavy metals transfer factor for A. sieberi and Z. atriplicoides was more and less than one in turn. Therefore, in terms of the transfer factor, A. sieberi has a potential for phyto-extraction and Z. atriplicoides has a potential for phyto-stabilization. The results also showed that A. sieberi and Z. atriplicoides were recognized as hyper-accumulating of nickel and cobalt metals. These species can therefore be recommended for the ecological restoration of soils polluted by heavy metals, especially nickel and cobalt in similar regions.

The abundance of agricultural waste and fishing is one of the environmental issues in various regions. Converting these wastes to biochar and using them in the soil is a way to enhance diverse ecosystems and plays a vital role in environmental sustainability. In the present study, the effect of shrimp (Fenneropenaeus merguiensis) and eggplant (Solanum melongena) biochar suspension on certain chemical characteristics of sandy soil was investigated. For this purpose, samples of sandy soil from the agricultural lands around Bandar Abbas were collected intact in PVC columns with a height of 25, and diameter of 20 cm. Then the prepared suspension of shrimp and eggplant biochar was added to the soil in a completely random design in three concentrations of 0, 4, and 8 g/l in three replications. After adding the different soil treatments into columns, they were incubated for 100 days at a humidity range of field capacity and 50% of it was kept in nursery condition. Next, some soil chemical properties including of pH, EC, N, K, Ca, Mg, and Na were measured. Statistical analysis and comparison of means at P<0.05 between various treatments were performed using a one-way analysis of variance and the Duncan’s test in SPSS16. The results of ANOVA showed that the application of both types of biochar had a significant effect on the chemical properties of sandy soil, so that the application of shrimp and eggplant waste biochar caused a significant increase in the amount of K, N, and pH, and a decrease in EC, Na, and Ca compared to the control treatment. The maximum value of K was related to the concentration of 8 g/l of shrimp and eggplant biochar and the maximum value of N was obtained by applying 8 g/l of shrimp biochar. In addition, the increase in the concentration of the two types of biochar indicates an increase in K and N values. The lowest CE value was obtained by applying 8 g/l of eggplant biochar. Based on the results obtained, shrimp and eggplant biochar waste are suggested in the sand soil amendment.

Dust is one of the most important atmospheric phenomena, which has attracted the attention of many scientists as an emergent phenomenon. Current research has studied trend of the number of dust days and its relation to climatic parameters and vegetation index from 2005 to 2017 in the Yazd-Ardakan plain. The DSI was computed for the two meteorological stations at Yazd and Meybod. By classifying the two Landsat 7 and 8 satellite images, the land form/cover maps, including agricultural lands, urban, mantled pediments, covered pediment and erg have been prepared. The NDVI layer was then computed in two classes for the Landsat 7 and 8 satellites. The class area was calculated for all levels of the region and also within two buffers of 10 and 20 km at the center of stations Yazd and Meybod. The relationship between the climatic parameters, including annual average temperature, annual average precipitation and annual average relative humidity, was then calculated. Finally, the relationship between dust index and land form types, NDVI layer and climatic parameters has been investigated. The results showed that the relationship between the DSI and the erg type is direct, but there is an inverse relation with the mantled pediments, covered pediment and agricultural land. Based on the results obtained, urban lands have little effect on the dust storm index. By comparing the DSI with the NDVI, with the increase in the region's dust storm index, the NDVI values for all levels decreased. By comparing the DSI with the climatic parameters, with the decrease in annual average precipitation and relative humidity and the increase in annual average temperature, the dust Storm index increased.