Tree-Ring Reconstruction of Changes in Surface Vegetation Cover in west Asia since AD 1943

Vegetation is sensitive to climate change, and the Normalized Difference Vegetation Index (NDVI) is an important indicator in studies of changes in surface vegetation coverage. However, observed NDVI data only became available in the 1980s, and thus reconstructing long-term changes in NDVI on the Earth's surface has become an important topic in paleoclimate reconstruction. In this study we established a tree-ring width index chronology for Juniperus excelsa in the western Elburz Mountains in west Asia; we then analyzed the correlation between the tree-ring width index and NDVI, and reconstructed the vegetation dynamics in response to climate change in this region since 1943. Our findings show that the tree-ring width index effectively represented the changes in NDVI from April to August. The NDVI changes reconstructed from the tree-ring width index show that fluctuations in the vegetation cover since the 1990s were more pronounced compared to the 1940s–1980s. Notably, periods of low vegetation cover occurred in the early 21st century, while high vegetation cover occurred in the early 2020s. Overall, our study integrates dendrochronology and remote sensing techniques to develop a methodology for the long-term reconstruction of the vegetation dynamics in the study region, and the results contribute to an improved understanding of the vegetation dynamics in west Asia and their response to climate change.