Vegetation Index (NDVI) reconstruction from western Himalaya through dendrochronological analysis of Cedrus deodara

The high-resolution temporal records (1738-2018 CE) of the dendrochronological analysis on Cedrus deodara from Uttarakhand and Himachal Pradesh in the western Himalayan region were generated. An analysis of the association between the Normalized Difference Vegetation Index (NDVI) and tree-ring radial growth indicated a significant positive relationship from April to July. The association between tree rings and other hydroclimatic variables was used to further evaluate this relationship. Based on the observation, mean April-July NDVI variability since 1790 CE was reconstructed based on the regional tree-ring chronology. Comparisons of the reconstructed NDVI with gridded precipitation, drought records, and proxy-based hydroclimatic reconstructions revealed a consistent agreement over a large spatial domain extending beyond the study region. We observed a correlation between the region's NDVI browning (reduction) and past droughts and famines. Comparison has been made to the regional proxy-based hydroclimatic reconstruction and stable oxygen isotope datasets with the present NDVI reconstruction. This revealed the commonalities in the regional hydroclimatic scenario recorded in these data sets over the last few centuries. This first tree-ring-based NDVI reconstruction from the western Himalayas infers regional climate-vegetation dynamics during the past two centuries. This reconstruction provides valuable input for modeling vegetation dynamics for predicting vegetation changes due to climate variations in the western Himalaya.

Automated summary

This study generated high-resolution temporal records from dendrochronological analysis on Cedrus deodara in the western Himalayan region. It found a significant positive relationship between the Normalized Difference Vegetation Index (NDVI) and tree-ring radial growth from April to July. The reconstruction of mean April-July NDVI variability since 1790 CE revealed consistent agreement with precipitation, drought records, and hydroclimatic reconstructions. The study also observed a correlation between NDVI browning and past droughts and famines. Comparisons with other datasets showed similarities in regional hydroclimatic scenarios over the last few centuries.