Forests in a semi-arid climate die with a memory: satellite signals predict forest mortality years after drought

Abstract

Widespread tree mortality is increasingly associated with extreme drought, yet its mechanisms remain poorly understood. To address this, we investigated which indicators most accurately delineate the relationship between climatic stressors and satellite-derived metrics related to tree crown/forest canopy conditions and forest decline for conifers and evergreen broadleaves. The study was performed between 1990 and 2020 in woodlands of Cyprus dominated by Juniperus phoenicea, Pinus brutia, and Quercus alnifolia (endemic to Cyprus). Landsat 5, 7, 8 and 9 images were used to assess the condition of tree crowns via 8 remote sensing (RS) indicators (NDMI, EVI, GPP, LAI, NBR, NDVI, NDWI, SAVI) correlated, thereafter, with the SPI, SPEI and PDSI drought indicators. Our findings clearly outline that very severe drought conditions