Witches’ broom disease has led to major losses in lime and alfalfa production in Oman. This paper identifies bioclimatic variables that contribute to the prediction of distribution of witches’ broom disease in current and future climatic scenarios. It also explores the expansion, reduction, or shift in the climatic niche of the distribution of the disease across the different geographical areas of the entire country (309,501 km²). The maximum entropy model (MaxEnt) and geographical information system were used to investigate the potential suitability of habitats for the phytoplasma disease. This study used current (1970–2000) and future projected climatic scenarios (2021-2040, 2041–2060, 2061–2080, and 2081–2100) to model the distribution of phytoplasma for lime trees and alfalfa in Oman. Bioclimatic variables were downloaded from WorldClim with ± 60 occurrence points for lime trees and alfalfa. The area under the curve (AUC) was used to evaluate the model’s performance. Quantitatively, the results showed that the mean of the AUC values for lime (16SrII-B) and alfalfa (16SrII-D) future distribution for the periods of 2021-2040, 2041–2060, 2061–2080, and 2081–2100 were rated as “excellent”, with the values for the specified time periods being 0.859, 0.900, 0.931, and 0.913 for 16SrII-B; and 0.826, 0.837, 08.58, and 0.894 for 16SrII-D respectively. In addition, this study identified the hotspots and proportions of the areas that are vulnerable under the projected climate-change scenarios. The area of current (2021–2040) highly suitable distribution within the entire country for 16SrII-D was 19474.2 km2 (7.1%), while for 16SrII-B, an area of 8835 km2 (3.2%) was also highly suitable for the disease distribution. The proportions of these suitable areas are very significant from the available arable land standpoint. Therefore, the results from this study will be of immense benefit and will also bring significant contributions in mapping the areas of witches’ broom diseases in Oman. The results will equally aid the development of new strategies and the formulation of agricultural policies and practices in controlling the spread of the disease across Oman.
This paper studies the shoreline alterations occurring along the Al Batinah region in the Sultanate of Oman and the impacts of Cyclone Kyarr on its shoreline. The methods used in this research employed Sentinel images and the Digital Shoreline Analysis System within the GIS environment to measure changes of the shoreline and explore Kyarr's impacts from 2017 to 2020. The results showed that from 2017 to 2020, the Al Batinah coast experienced erosion at a rate of 9 m/year. In addition, the Shoreline Change Envelop showed that the maximum shoreline change was reported from 2018 to 2019, with a 1145 m advancement that coincided with Kyarr in 2019. Further, data from the period between 2017 and 2018 showed that 73 % of the coastline was dominated by soil deposition at an average rate of 10 m/year, while the period between 2018 and 2019 showed erosion at an average rate of -40 m/year. The results of this study will be of interest to decision-makers involved in monitoring shoreline changes and would also be of immence importance in ensuring sustainable coastal zone management and development, especially in areas prone to extreme events such as tropical cyclones.
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