Revealing the change of the frost indices as a consequence of climate change, a case study of Northern Zagros forests (Azerbaijan)

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Background and objectives: The forest ecosystem of Zagros has been attacked by pests and diseases in the last two decades. One of the most significant effects of climate change has been the reduction of frost days, especially in forest ecosystems. Reducing the frequency, intensity, and duration of the frost phenomenon facilitates the wintering of pests and reduces losses and deaths, intensifying their outbreaks. Northern Zagros forests (case study of Azerbaijan). Knowledge of the amount of changes in frost days leads managers and planners of the forest ecosystem toward better solutions to adapt to climate change.
Methodology: In this research, the ClimPACT software package was used in the R environment to investigate the changes in glacier indices. The indicators used in this research have been prepared by the World Meteorological Organization (WMO), the Climatology Commission (CCL), and the expert team on climate risk and specific climate indicators (ETCRSCI) to monitor, evaluate, and detect climate change in a place or region. The daily data of minimum temperature, maximum temperature, and precipitation for the statistical period of 1986 to 2019 at Piranshahr station and the statistical period of 1988 to 2019 at Sardasht station were obtained from the National Meteorological Organization. The data was prepared in the required format for entry into the ClimPACT model. The ClimPACT software package was implemented in the R environment, and the climate change-revealing indicators were screened as the output of the model. The cold indicators revealing the occurrence of climate change were separated in the limits of the Piranshahr and Sardasht deterioration monitoring sites in West Azerbaijan province in North Zagros: four cold temperature indicators were selected from among them. For the index of days with frost, severe frost, very severe frost, and icy days, changes in trend line, trend slope error, and significance in the statistical range of p-value = 0.05 were calculated, and changes for all indicators in the R software environment, drawing, and case analysis were conducted.
Results: Examining the linear trend slope, slope, and the significance of changes (p-value) in the index of days with frost in oak decay monitoring sites in Piranshahr and Sardasht showed that this index had a significant decreasing trend. This index showed a decrease of 48 days in Piranshahr and 63 days in Sardasht during the studied statistical period. Changes in the trend and significance of the extreme frost days index within the monitoring sites in Piranshahr and Sardasht showed that this index had a significant decreasing trend. This index decreased by 38 days in Piranshahr and 56 days in Sardasht during the studied statistical period. Examining the slope of the trend line, the error of the trend slope, and the significance of the changes in the index of extreme frost days in the range of monitoring sites in Piranshahr showed a significant decreasing trend, while in Sardasht, a significant increasing trend was observed. Changes in the trend and significance of the ice days index in the range of monitoring sites in Piranshahr showed a decreasing and non-significant trend, while in the range of monitoring sites in Sardasht, it showed a decreasing and significant trend.
Conclusion: One of the most critical challenges facing Iran’s natural environment today is the decline of Zagros oak forests. Various factors have contributed to the deterioration of these ecosystems, but climatic conditions stand out as the most significant. Cold climate indicators in the Piranshahr and Sardasht forests have shown a notable decreasing trend. This decline indicates that the wintering range for many pests and diseases has shrunk, creating favorable conditions for their growth. Considering other factors, this trend is likely to continue due to increasing temperatures in the coming years. Consequently, there will be increased stress related to temperature and humidity, leading to more outbreaks of pests and diseases. Zagros forests, particularly oak trees, play a vital role in maintaining natural resources, storing underground water, and mitigating the effects of climate change. Therefore, it is essential to preserve these valuable resources by leveraging scientific, technical, managerial, and executive approaches.