SPATIOTEMPORAL DYNAMIC OF OAK FOREST GREENNESS IN RESPONSE TO CLIMATE CHANGE DERIVED DROUGHT

Abstract

BACKGROUND: Climate change, which has mainly manifested in Iran in the form of intensifying periods of drought, can have profound effects on the valuable forest ecosystems of Zagros in the west of Iran. In this study, the drought trend in the period from 2000 to 2020 was investigated on the spatiotemporal dynamics of greenness of Zagros oak forests in Kohgiluyeh and Boyer Ahmad province in the west of Iran. SPI, PDSI, NDVI and EVI with modeling their relationship based on GWR was used. Also, based on two climate change scenarios RCP2.6 and RCP8.5, the simulation of drought conditions and changes in forest greenness until 2050 were studied.

RESULTS: The results showed that the peak greenness of the oak forests has a significant sensitivity to changes in rainfall and drought at the end of the cold period of the year and in the spring season. The negative phases of the drought have been completely consistent with the periods of greenness loss. Also, both the greenness and the area of the oak forests have decreased. The EVI index showed
the highest sensitivity to the PDSI, and the developed model based on these two indices had a spatial explanation coefficient between 40 and 70%.

CONCLUSION: The implementation of the developed model under two scenarios showed that the forest greenness will face a decrease of about 25% in the RCP8.5 scenario and about 15% in the RCP2.6 scenario until 2050. The relationship between drought and forest decline was proven in this study.