شهودی بر تغییر اقلیم در نواحی رویشی زاگرس (مطالعه‌ موردی: سایت‌های زوال درختان بلوط استان ایلام)

از آن‌جایی‌که تغییرات اقلیمی یکی از مهم‌ترین عوامل محدودکننده‌ رشد درختان و تخریب و زوال جنگل‌‌های زاگرس هستند، در این تحقیق براساس شاخص‌‌‌‌های استاندارد که توسط سازمان جهانی هواشناسی تعیین و به‌روز شده‌ است، اقدام به آشکارسازی وقوع رخداد تغییر اقلیم در شش سایت‌ پایش زوال درختان بلوط در استان ایلام شامل سرابله، مله‌سیاه و تنگه‌ دالاب از دو جهت شمالی و جنوبی صورت گرفت. به این منظور نزدیک‌ترین ایستگاه سینوپتیک به هر یک از سایت‌ها شناسایی و از داده‌های روزانه‌ پارامترهای دمای حداقل، دمای حداکثر و بارش در بازه‌ زمانی 1987 تا 2019 استفاده شد. شاخص‌های موثر بر تنش گرما (شاخص‌های دمایی گرم و دمایی سرد) و تنش رطوبتی، با استفاده از نرم‌افزار climpact در محیط برنامه‌ r محاسبه شدند. نتایج بررسی روند و معناداری شاخص‌های آشکارسازی تغییر اقلیم نشان داد از 16 شاخص گرمایی مورد بررسی به‌ترتیب در ایستگاه ایوان و ایلام، 11 شاخص (حدود70 درصد) و نُه شاخص (حدود 56 درصد) روند معناداری داشتند. مطالعه‌ موج‌های گرم نشان داد نواحی شمالی و شمال ‌غرب استان با دوره‌های متعدد موج گرم مواجهه شده است این مطلب تاییدی برگرم شدن نواحی مرتفع‌تر کوهستانی در نتیجه‌ پدیده‌ تغییر اقلیمی است. شاخص‌های دمایی مبتنی بر سرما از هشت شاخص مورد بررسی بهترتیب در ایستگاه ایوان و ایلام 11 شاخص (حدود 70 درصد) و نُه شاخص (حدود 56 درصد) روند معناداری داشتند. در ایستگاه ایوان‌غرب تعداد هفت شاخص حدود 87 درصد و ایستگاه ایلام سه شاخص حدود 38 درصد روند معنادار بوده است. نتایج بررسی روند و معناداری شاخص‌های ترکیبی آشکارسازی تغییر اقلیم در ایستگاه ایوان‌ غرب 100 درصد و در ایستگاه ایلام 50 درصد را نشان دادند. شاخص‌های مربوط به فراوانی و شدت بارش‌ه‌ای سنگین و طول دوره‌های خشک و مرطوب تغییرات معناداری نداشته است. در نهایت، می‌توان نتیجه گرفت منطقه‌ رویشی زاگرس در استان ایلام تغییرات شدید دمایی از نوع گرمایشی را طی سال‌های مورد مطالعه تجربه کرده و نمود تغییر اقلیم در شمال ناحیه‌ رویشی زاگرس از نوع افزایش دما بوده که گستره‌ آن از سال 2008 به بعد به نواحی شمال غرب این ناحیه نیز کشیده شده است.

intuition on climate change in zagros vegetative regions case study of oak tree decline sites in ilam province

introduction climate change is one of the greatest challenges of our time to achieve sustainable development. the dangers of global warming and climate change can be recognised and planned for, so efforts should be made to identify the consequences and methods of adaptation to reduce their impact, as trees and plants are sensitive to climate change, heat and moisture stress, and forest ecosystems are affected by these changes. climate change is one of the greatest challenges of our time to achieve sustainable development. the threats of global warming and climate change can be identified and planned for, so efforts should be made to identify the consequences and methods of adaptation and reduce their impacts because the sensitivity of trees and plants to climate change, heat and moisture stress, forest ecosystems are affected by these changes. forest degradation due to climate change is a global phenomenon affecting many tree species. one of the major challenges to iran’s natural resources is the degradation of oak forests. the increase in temperature in recent years has lengthened the growing season of iranian oak, and due to the lack of rainfall, the intensity of water stress on this forest species has increased. understanding the extent of climate change in the zagros ecosystem based on standard indicators that show climate change can help managers and planners take action to adapt to conservation and restoration conditions.materials and methods in this study, based on the standard indicators established and updated by the world meteorological organization, the occurrence of climate change in six sites monitoring the decline of oak trees in ilam province, including sarabeleh, mala siah and dalab strait, was detected in both north and south directions. the trend slope line, trend slope error and trend significance of the indices in the statistical range p value=0.05 were calculated using climpact software in r program environment. the characteristics of heat, cold, combined, and precipitation indices such as day, number of occurrences, and continuity of the index in the nearest synoptic station to each site were identified, and daily data of minimum temperature, maximum temperature, and precipitation parameters were used between 1987 and 2019. the variations of each index were plotted and analyzed as graphs in the r software environment. accordingly, the trend slope and significant indices affecting heat stress (hot temperature indices and cold-temperature indices) and water stress were calculated with the software climpact in the r programme environment.results and discussion the results of the trend and significance of thermal indicators for climate change detection showed that of the 16 heat indices studied, in ivan station, 11 indicators showed a significant trend of about 70% and in ilam 9 indicators showed a significant trend of about 56%.the heat-based temperature indices, especially those based on maximum temperatures, showed a significant change towards warming, while those based on minimum temperatures showed no significant trend. the study of heat waves showed that the northern and northwestern regions of the province were subjected to several periods of heat waves, which occurred with greater frequency and continuity in the northwestern part of the province (malah siah and dolab strait sites) than in the northern part (sarab sites) of the province, confirming the emergence of high mountain regions as a result of climate change. cold-based temperature indices of 8 studied indices in ivan-e-sorchrove station, 7 indices were above 87% and ilam 3 was about 38% the trend was significantthe cold-based temperature indices in ivan west station show a significant change in the direction of a decrease of frost and cold and their persistence and warming, and in ilam station the decrease of cold and warming of air after 2008 indicates a decrease of cold and warming. the results of the trend and significance of the combined indices for climate change detection in ivan west station were 100% and in ilam station 50% showed significant trend. the combined indices confirm climate change in terms of increase in air temperature due to increase in growing season and increase in trend of change in maximum temperature. the study of the trend and significance of ten precipitation indices related to the frequency and intensity of heavy rainfall and the length of dry and wet periods showed only one index in ivan-e-west station, which was about 10%. the station ilam did not show significant changes in the precipitation index.conclusion it can be concluded that zagros vegetative region in ilam province has experienced severe thermal changes during 1987-2019 and climate change in the north of zagros vegetative region is a type of temperature increase that has been extended to the northwestern regions of this region since 2008. the results show that in deterioration sites, in addition to increasing temperature, some precipitation has increased. therefore, it can be said that the occurrence of climate change phenomenon causes increasing temperature, occurrence of floods, emergence of droughts and creating dust phenomenon, especially from neighboring countries and intensifying it in the country, all of these factors are the starting factors of the decline of oak trees in ilam province. what seems to be important is to take necessary measures to prevent and mitigate the effects of climate change. these two measures can be effective and useful in reducing the effects of flood severity and risk. therefore, managers and planners of forest ecosystems should have adaptive strategies to climate change in order to maintain and revive their executive plans so that zagros can survive as a forest ecosystem. although the occurrence of climate change phenomenon is one of the most important factors of drought and deterioration of zagros forests, conservation and restoration of oak forest ecosystems can help reduce greenhouse gas emissions and climate change.