پیش بینی اثر تغییر اقلیم بر پراکنش گونه سنبل الطیب (valeriana sisymbriifolia) با استفاده از مدل حداکثر آنتروپی در استان اصفهان

وضعیت پوشش گیاهی ایران، متاثر از وضعیت طبیعی آب و هوایی منطقه است. به‌طوری‌که از نظر کمی و کیفی باعث سرعت رشد و یا عدم رشد و مساعد شدن و نشدن محیط گیاهان می‌شود. هدف از این مطالعه بررسی اثر تغییر اقلیم بر پراکنش گونه سنبل‌الطیب (valeriana sisymbriifolia) با استفاده از مدل حداکثر آنتروپی در استان اصفهان است. لذا با استفاده از 50 نقطه از حضور گونه و متغیرهای اقلیمی ناشی از سناریوهای اقلیمی rcp4.5 و ssp2 و همچنین 3 متغیر فیزیوگرافی، پراکنش سنبل‌الطیب برای سال‌های 2020، 2050 و 2100 پیش‌بینی گردید. نتایج مطالعه نشان داد که پراکنش یا رویشگاه مطلوب گونه سنبل‌الطیب در استان اصفهان تحت سناریوی rcp4.5 از سال 2020 تا 2100 از 3/07 درصد به 0/047 درصد و تحت سناریوی ssp2 از 3/74 درصد به 1/554 درصد کاهش پیدا خواهد کرد. درواقع تحت هر دو سناریوی اقلیمی موردمطالعه، رویشگاه مطلوب گونه سنبل‌الطیب کاهش داشته و در برخی از مناطق به‌طور کامل از بین خواهد رفت. به‌علاوه با توجه به منحنی‌های عکس‌العمل گونه از نظر فیزیوگرافی هرچه شیب و ارتفاع در منطقه موردنظر افزایش یابد، مقدار پراکنش گونه سنبل‌الطیب نیز افزایش می‌یابد و با توجه به مشاهدات میدانی می‌توان گفت که گونه موردنظر در شیب و ارتفاعات بسیار بالا مشاهده می‌شود به‌طوری‌که در هنگام برداشت نمونه گونه موردنظر تا ارتفاع 3000 متری حضور داشت که این امر به دلیل داشتن ریشه‌های قوی گیاه است که توان زادآوری در شرایط سنگلاخی را ایجاد می‌کند و از طرف دیگر به دلیل اینکه گونه‌های دیگر تحمل شرایط مشابه را ندارند حضور آن‌ها کم می‌شود و رقابت برای گونه سنبل‌الطیب کاهش می‌یابد. منحنی‌های عکس‌العمل گونه نسبت به تغییرات بارندگی نیز نشان می‌دهد که هرچه بارش سالیانه از 250 میلی‌متر بیشتر گردد احتمال حضور  گونه افزایش می‌یابد. لذا تحت تاثیر تغییرات اقلیمی اعم از کاهش بارش و افزایش دما از رویشگاه مطلوب گونه موردمطالعه کاسته خواهد شد.

predicting the effect of climate change on distribution of valerian (valeriana sisymbriifolia) species using maxent model in isfahan province

extended abstractintroductionclimate change is one of the most important issues in the world, which has great effects on ecosystems and their diversity. one of the most important factors of climate change is the increase in temperature and change in the precipitation pattern, which affects the distribution of plant species. the use of species distribution models is one of the most reliable techniques for investigating the impact of climate change on the distribution of plant species. one of the methods of plant distribution modeling is using the maximum entropy model. this model uses environmental conditions such as temperature, precipitation, and geographic altitude as inputs, and based on that, plant distribution is predicted. this model predicts the probability of species distribution in the new environment based on the theory of maximum entropy and based on the available data. in this model, based on the information we have about species distribution in different environments, a probability distribution is obtained for species distribution, which has the highest entropy. however, for the best prediction of the distribution of the species, we need to have detailed information about the biophysical, ecological and environmental characteristics of the species in question. in this method, instead of trying to model all aspects of the species and the environment, only the available information about the distribution of the species is used. in this study, the effect of climate change on the distribution of valerian (valeriana sisymbriifolia) species is predicted using the maximum entropy model in isfahan province.materials and methodsin this study, the effect of climate change on the prediction of the distribution of valeriana sisymbriifolia species in isfahan province was investigated using maxent model. for this purpose, 50 points of presence of example in may 2022 in different regions were first registered by gps device by random sample method and after collecting environmental data including 10 climate changes and 3 physiographic changes, the effect of climate change on the distribution of the plant species valeriana sisymbriifolia in isfahan province was investigated using the entropy machine model and in the time periods of 2020, 2050 and 2100, under two scenarios: ssp2 and rcp4.5. to study the effect of climate change on the distribution of valeriana sisymbriifolia plant species in isfahan province, new climate scenarios including ssp (shared socioeconomic pathways) and rcp (representative concentration pathways) scenarios were used. the ssp scenarios in the gfdl-esm4 general circulation model correspond to a combination of paths in which the economy, population, and politics will change in the future. the rcp scenarios in hadgem2-cc general circulation models also correspond to different levels of future greenhouse emissions.results and discussionthe results showed that the distribution of valeriana sisymbriifolia species in isfahan province will decrease from 3.07% to 0.047% under rcp4.5 scenario in 2020 to 2100. also, the distribution of this species under the ssp2 scenario showed that from 2020 to 2100, the distribution of the species and its favorable habitat will decrease from 3.74% to 1.554%. in fact, under both studied climate scenarios, the ideal habitat of valerian has decreased and will be completely lost in some areas. the entropy machine model showed that there are several factors affecting the distribution of valerian including slope, rainfall in the coldest season of the year, annual rainfall and altitude. also, this model obtained auc=0.95 in the evaluation, which shows the excellent prediction of the entropy model in predicting species distribution.conclusionaccording to the output maps from the maxent model and also according to the influence of important variables in this process, it can be concluded that the distribution of the species in question is decreasing under the influence of climate change in successive years. in addition, according to the response curves of the species in terms of physiography, as the slope and height increase in the area in question, the amount of distribution of the hyacinth species also increases. also, according to the field observations, it can be said that the species in question is observed in the slope and at very high altitudes, such that during sample collection the species in question was present at an altitude of 3000 meters, and the reason for this can be attributed to the strong roots of the plant, which creates the ability to reproduce in rocky conditions. on the other hand, because other species do not tolerate the same conditions, their presence decreases and the competition it decreases for the hyacinth species. the response curves of the species to changes in rainfall also show that the more the annual rainfall and the rainfall in the cold months, the more likely the presence of the species will be, such that the more the annual rainfall exceeds 250 mm, the more likely it will occur.