عنوان مقاله [English]
In recent years, climate change has affected the ecosystem and its inhabitants. Climate change affects various biological aspects of species, so it has become a major concern for the management and protection of biodiversity. One of the important effects of climate change is changes in the range of distribution and distribution of living organisms. Therefore, the study of climate change on the distribution of plant and animal species is necessary. Climate change causes the geographical range of plants to shift. Forecasting the effect of climate change on the distribution of valuable plant species is considered essential in order to protect and evaluate the level of threats and management. he prediction of the geographical distribution of the species in the future requires the collection of information related to the presence of the species at present, environmental variables and the combination of this information with new environmental conditions. Modeling the distribution of species is currently the only tool that can be used to evaluate the amount of changes in the distribution of several species in response to climate change. For this purpose, many methods and models have been developed, predictive modeling of the distribution of plant species, as a prediction of the potential distribution of a plant species. Throughout the landscape, it is defined based on the relationship between the occurrence points of the plant species and the effective environmental variables, and it is based on the hypothesis that environmental factors control the distribution of the plant species. The habitat prediction models determine the suitability of the habitat for the establishment of plant and animal species and help the managers of natural resources to identify the factors that threaten the populations, determine the important factors in conservation planning, and examine the climate change scenarios with less time and cost. Geographical distribution of species, favorable habitats of plant and animal species, etc In this research, the current and future distribution of Bromus tomentellus Boiss species in Chaharmahal and Bakhtiari province under two scenarios RCP4.5 and RCP8.5 for the next three decades was investigated.
First, by using 10 synoptic stations in and adjacent areas of Chaharmahal and Bakhtiari province, the database including precipitation variables, minimum temperature, maximum temperature and average temperature of formation and 19 bio-climates were calculated (Table 1). Also, three physiographic variables, including slope, direction and height, were prepared using a digital elevation model (DEM) with an accuracy of 30 meters. Then, using maps of plant types of Chaharmahal and Bakhtiari province and field visits to the current habitat of the species under investigation, the presence and absence points of the species were determined. Using logistic regression (relationships 1 and 2), the growth behavior of this species at the level of the province was determined and the map was modeled and the relevant equations were calculated in the current conditions. A climate for 2050 was extracted from the worldclime site and by putting the extracted data into the equations of the current conditions, the future distribution map of the species Bromus tomentellus for the next three decades by the general circulation model MRI-ESM2-0 under two scenarios RCP4.5 and RCP8.5 was prepared in ArcGIS 10.5 software. The resulting map of the model contains the values of the probability of the presence of the species between zero and one for the desired habitat, which was evaluated using the kappa coefficient for the accuracy of the output map.
Species distribution prediction models can predict potentially favorable habitats for species distribution, therefore they play an important role in determining areas prone to pasture restoration (Pajehan, 2019). It is expected that the forecasting model in the present study will be effective for future protective strategies. In this research, the current range and potential future range of Bromus tomentellus species and for the next three decades (year 2050), under two climate warning models, a milder scenario and a more severe scenario (Rcp4.5 and Rcp8.5) using the model Logistic regression was predicted within the boundaries of Chaharmahal and Bakhtiari provinces located in central Zagros. The results showed that the spatial position of the target species in 2050 with the Rcp4.5 (balanced) scenario is almost the same as the current one. In the Rcp8.5 (pessimistic) scenario, the optimal habitat size of the selected plant will be reduced by 75-100%. Instead, in In some high areas, we will witness the appearance of habitats prone to the occurrence of species, and these areas will be suitable in terms of climatic conditions. So that this species can be seen in areas with an altitude of 2000 to 3200 meters, but in balanced conditions under the Rcp4.5 scenario, it changes its location to an altitude of 3350-2180 meters and in pessimistic conditions under the Rcp8.5 scenario to an altitude of 2400-3600 meters. Therefore, in the balanced and pessimistic scenario, 180 and 400 meters respectively, the habitat of this species will be moved to a higher altitude. In general, climate change and the consequent increase in temperature indices have caused the vertical expansion of Bromus tomentellus and its movement to higher latitudes along the altitude gradient. The results of Sanghoni (2016) also show that by 2080, more than 50% of the habitat area of Bromus tomentellus species will be reduced and it will migrate to higher altitudes. The results of the research on the mountain celery species in the Faridun Shahr area in the west of Isfahan province show that this species migrates to higher areas due to climate change and the habitat of this species will decrease by 80% in 2080. (Abolmaali et al. 2018) Also, the results of the habitat prediction map showed that as the temperature indices increase, the suitability of the habitat for the presence of the species will decrease in the future. Thuiller (2007) stated that on average, every 1ºc increase in temperature causes species of the northern hemisphere to move 160 kilometers towards The pole or 160 meters will be towards the heights. Of course, he said that the changes in different ecosystems are not the same and each ecosystem should be investigated with appropriate methods. As species move towards the poles or higher altitudes, they may disappear or become confined to a refuge away from others, while other species may expand their range.
In general, plant vegetation range models are useful and cost-effective tools for the use of natural resource managers and increase their awareness of the effects of climate change on species. The maps obtained from the models show the areas sensitive to climate change and the possible shelters of the selected species in the future for use in the protection and grazing plans of these areas. Progress in understanding species distribution models against climate change and modification of the spatial database can lead to the development of conservation strategies. which is useful for the ecosystem and the species. The maps obtained from the present research can be used in vegetation protection and revitalization programs. Since globally, they want to preserve biodiversity in the central Zagros and it is very important from an ecological point of view and biodiversity Therefore, the predicted potential distribution for the studied species in the central Zagros area provides valuable information for identifying suitable cultivation sites and also for managing the species in the future.