مکانیابی رویشگاه‎های دارای بازده اسانس گیاه خوشاریزه با استفاده از مدل حداکثر بی‌نظمی

Abstract
Background and objectives: A systematic and scientific study of the subject of medicinal plants in the present era and the presentation of a scientific program for their proper and optimal exploitation require the initial identification of habitats, the preparation of a distribution map, and the identification of these plants in their original habitat. Each plant species is related to some environmental factors of its habitat, considering its habitat characteristics, ecological needs, and tolerance range. The suitability of a variable alone cannot be a sufficient reason for the development of a habitat, but rather its potential habitat must be determined by considering all the ecological needs of a species and its adaptation to environmental conditions.The presence of plant species in a region is influenced by environmental factors and interspecies relationships, and some environmental factors have the more effect on the establishment of plant species. Determining effective factors and studying response of species to environmental factors helps to obtain species distribution prediction models. Therefore, the aim of this study is to find the most suitable habitat for Echinophora platyloba DC. where they have the more amount of essential oil.
Materials and methods: This plant belongs to the genus Echinophora. This genus has four species of aromatic perennial herbaceous plants in Iran. In this study, using the maximum disorder method, first, suitable places for the growth of the medicinal species Echinophora in Torbat Heydariyeh County were determined. The growth type of Echinophora platyloba was identified in the area by a field survey and its range was determined using natural features. The locations of the species were determined using the experience of local people, especially shepherds. Through a field survey in late May, June, and early July 1401, 43 locations of Echinophora presence were recorded and plant samples were collected. The minimum distance between the points of presence of the species was recorded as 600 meters. After the vegetative stage and before the flowering stage, the amount of essential oil in Echinophora is at its highest level, so plant samples were collected during this period. According to the study objectives, 29 environmental factors including 19 bioclimatic factors, 7 soil factors and 3 topographic factors were used in modeling. Bioclimatic factors were extracted from the international database and topographic factors from the digital elevation model of the city. In order to prepare soil layers, information related to 159 soil profiles was received from the Research Center and Natural Resources Departments of Khorasan Razavi Province. Soil variables include sand percentage, silt percentage, clay percentage, electrical conductivity, soil alkalinity, soil water saturation percentage and organic matter content. Then, a map related to each soil variable was prepared using interpolation methods. Three indices of mean absolute error (MAE), mean deviation error (MBE) and root mean square error (RMSE) were used to select the most appropriate interpolation method. 43 points of presence of euphorbia plants in the study area were recorded through field surveys and plant samples were collected and after drying, essential oil extraction was performed using water distillation method. 50% of the points with suitable essential oil yield were selected to rerun the model.
Results: Based on the topographic maps prepared, the altitude class of 1800-2200 meters above sea level covers the largest area of about 55% of the total area of the county, and the altitude class of 1000-1400 meters above sea level has the smallest area. The slope class of 0-5 covers the largest area of about 81% of the total area of the county, and the class <20 has the smallest area. The largest area related to the southern slope with 34.8% of the area of the region covers the largest area. The results showed that out of the 372,950 hectares of Torbat Heydariyeh county, 339,150 hectares, equivalent to 91% of the total area of the region, are in the unsuitable habitat class, and 3,575 hectares, equivalent to 0.9% of the region, are suitable for the growth of Euphorbia. Based on results of Jacknife EC, PH, precipitation of wettest quarter and precipitation of direst month were the most important variable in the occurrence of Echinophora platyloba and Precipitation of direst quarter, EC, PH, precipitation of wettest quarter was determined as the most important environmental factors affecting the yield of essential oil of this plant. The optimal range of soil conditions for plant dispersal is electrical conductivity of 0.4-0.2 deciSiemens/meter and soil acidity of 7.95-7.93, and the probability of the species' presence increases when the total rainfall of the wettest consecutive quarter is between 125-130 mm. The evaluation accuracy of the model with AUC=0.96 for the suitability of the habitat and AUC= 0.945 for the location of habitats with suitable essential oils shows that the model has identified Maximum Entropy with very high accuracy of the desired habitats with optimal essential oils (10-11 percent).
Conclusion: Conclusion: Identifying habitats that have suitable essential oil yields will allow exploitation in these areas to be carried out with reduced destruction of natural resources. Identifying the country's native medicinal plants and determining the optimal conditions for growth and production and greater efficiency of their essential oil are among the first steps that can be taken for sustainable and economically viable exploitation of these plants. It is recommended that in rangeland management programs, if the goal is to plant plants for rangeland restoration, a habitat suitability map be used, but if the goal is to use the essential oil of this plant, a map predicting locations with suitable essential oil yields should be used. It is recommended that a map of areas with essential oil yields be prepared based on the important medicinal plants of each region and made available to the operator so that he can achieve an appropriate amount of essential oil with the least amount of plant harvesting in nature.