مجله مدیریت بیابان
پیاپی 17 (بهار 1400)

Wind erosion and its control has always been one of the important topics in arid regions. Therefore, this study aimed to assess the potential of remote sensing data in mapping this phenomenon based on the wind erosion indicators of IRIFR model in Isfahan province. For this purpose, different parameters including land topography, wind speed, desert pavement, vegetation cover, soil moisture, aeolian sediments, land use and land management were extracted from MODIS, Landsat and SRTM space shuttle, and combined using fuzzy logic. Then, the accuracy of produced map was assessed with 200 random points and error matrix against field-based wind erosion map which was obtained from IRIFR model. Results showed that wind erosion is more dominant in Naein, Aran and Bidgol, Ardestan and Isfahan counties. According to the produced wind erosion map, 26.3% of the study area was classified as low, 56.9% as moderate, 11.8% as high and 5% as very high. The overall accuracy of more than 73% between produced and field-based maps indicated the high performance of remote sensing data in mapping of wind erosion. Therefore, due to many advantages of these data, the presented method can be used to map and report wind erosion condition at different spatial and temporal scales.

Temperature is one of the most important physical parameters that control the transfer and exchange of energy between different layers of the earth and the atmosphere. LST estimation methods based on satellite images require surface and atmospheric parameters such as surface emissivity, average air temperature, atmospheric transfer coefficient, and water vapor as input. Uncertainty in these parameters causes errors in the retrieval of land surface temperature. This study aimed to compare the accuracy of different methods for estimating atmospheric water vapor in estimating land surface temperature using Landsat 8 images. In this study, atmospheric water vapor was estimated using FLAASH atmospheric correction methods, MODIS sensor images, and SWCVR method. Then, the impact of atmospheric water vapor on land surface temperature accuracy was investigated using the split window and single-channel methods. Validation of Land surface temperature images was performed using cross-validation and ground measurement methods. Therefore, 20 Landsat 8 images related to 2018 and 2019 were used to estimate atmospheric water vapor by the FLAASH atmospheric correction and SWCVR methods, and land surface temperature estimation. MODIS radiance images were used to estimate atmospheric water vapor and the land surface temperature product of this sensor was used for cross-validation. The surface temperature was measured using a thermometer in places with homogeneous cover, for ground-based validation. Results showed that among water vapor estimation methods, the SWCVR method is more suitable for estimating land surface temperature and the split-window method based on the SWCVR method shows the lowest RMSE and MADE at 3.47 and 3.18. Results of RMSE image classification of split-window algorithm based on the SWCVR showed that 1.67% of the area has an error of more than 4 °C and 98% of the study area has less than 4 °C error.

The present study was conducted to improve root, shoots growth, and seedling quality index of milkweed (Calotropis procera) using biopriming bacteria Pseudomonas putida (Trevisan) strain 169. An experiment was performed with two levels of inoculum including control and rhizospheric bacteria and three growth periods of one, two, and three months, using a factorial experiment in a completely randomized design with five replications. Biopriming results showed that seedlings obtained from bacterial priming in one-month, two-month, and three-month periods compared to the control, increased 707.5, 1823.1 and 47.6% in root volume; 654.6, 1798.6 and 40.3% in root area; 270.6, 38.5, and 6.6% in fresh weight of stem and 58.5, 19.3 and 2.5% in seedling height, respectively. The highest value of the quality index was observed in seedlings inoculated with the bacterium in the third month. The results of Pearson correlation showed that the parameters of aerial parts such as height, collar diameter, and stem weight were significantly correlated with each other, except root length and root dry weight. Results revealed that the priming of rhizosphere bacteria used in this study had a positive effect on improving the growth parameters of milkweed seedlings. Therefore, it is suggested that more research be done on the coexistence of rhizosphere bacteria in different plants and the interaction of their effects so that this technique can be used more for plant production and desertification.

Due to the intense and unprincipled changes in land use, it is necessary to detect land cover/use change over time using satellite imageries for sustainable land management. This study aims to monitor land use and land cover changes, model and predict their status in the next 15 years in Jagin plain, Jask coastal desert. In this study, Landsat satellite images of 1987, 2003 and 2018 were used to detect changes. After applying geometric and atmospheric corrections on the images, land use maps  of each year at 11 land use /land cover classes including farmlands, aquaculture, erg, halophyte, mangrove, habitable zones, nebka, vegetation affected by water flow vegetation (rangeland), bare lands, were prepared using hybrid classification method. The Markov chain forecasting model was used to validate the model in the first stage, and was used in the second stage to predict land cover/land change in 2033. Comparison of the simulated map of 2018 and the real map with the Kappa coefficient of 83% confirmed the capability of the Cellular Automata Markov Chain in predicting of land cover/land changes. According to the results, in 2032, agriculture lands in the region will have an upward trend and grow by 74% compared to 2018. Habitable zones, marine access network and aquaculture lands will also increase during the study period. In the study area, vegetation and riverbed vegetation areas show a downward trend and will mainly converted to agricultural lands. Sand dunes, which are among the main threats to people and mangrove forests, will be extended by 2032, threatening the southern part of Sorglam village and the eastern part of the mangrove forest.

Haloxylonplanting and developing artificial forests in arid lands is one of the important actions to combat desertification. In this research, tree planting (by Haloxylon  aphyllum Iljin) in Dosangi Meybod in different methods including repairing, runoff control, pitting and planting in owed have been compared with control area. For this purpose, in each area, four 300 m transects were considered randomly - systematically, and 15 plots (10 m2) were randomly collected on each transect. In each plot, vegetation characteristics including total vegetation percentage, density, canopy cover, freshness and depth of root and soil characteristics including moisture, permeability and soil carbon storage were measured. The Shapiro-Wilk test were used to test of normality of the collected data,  and were analyzed using one-way analysis of variance and Duncan's test. According to the results of analysis of variance, the effect of planting with different methods on crown cover, density, freshness and deep rooting of Haloxylon shrubs and the percentage of vegetation is significant at 1% level. However, its effect on permeability and soil moisture in May is significant at 1% level and on carbon storage is significant at 5% level. Increase of vegetation cover by 5.1%, density of 249.7 number per hectare, Haloxylon cover of 3.7%, freshness class 1.5, soil moisture in spring 38.1% rooting more than 3 m and permeability 8.03 cm/h was related to the planting in dry river, which had a relative success in vegetation development in this region.

One of the effective methods to increase crop production in arid and desert regions of the country are some mechanisms increasing plant resistance such as seed priming. A field experiment was conducted on a farm located in Jolgeh Shah Hashem, Dalgan, with a desert climate, in 2017-2018. This research was carried out as a split-plot experiment in a randomized complete block design with three replications. Experimental treatments consisted of four drought stress levels of irrigation at field capacity "no stress"; irrigation at 75 % of field capacity "moderate stress"; and irrigation at 50 % of field capacity "severe stress"; as main plots, and four seeds priming levels of no priming; hydropriming; Osmopriming with polyethylene glycol; and hormonal priming with salicylic acid as subplots. Results showed that seed priming reduced the number of days to plant germination compared to non-priming treatment. Among prime treatments, hydroprim had the fastest seed germination time after sowing. On the other hand, stress and prime treatments caused early maturity of the plant and among the above treatments, the shortest day to ripening was obtained from severe stress and hydroprime treatment. The highest values of the fresh and dry weight of the plant, fresh and dry sepals of roselle were obtained from no stress treatment and seed priming at all levels of hydropriming, osmopriming, and hormonal priming. Comparing the above three treatments, it can be concluded that the seed priming with salicylic acid achieved better results than other treatments in no stress conditions. It was also observed for the traits of anthocyanin and sepal phenolic compounds that with increasing stress intensity, the content of these compounds increased in sepals.