Regional NDVI reconstruction over the last 600 years in Northwestern Patagonia reveals a rapid decline

Abstract

Understanding the long-term variability of forest productivity is crucial in the context of climate change. While remote sensing data provide valuable information on vegetation dynamics, their temporal coverage is often limited. Tree-ring width, however, serves as a reliable proxy for reconstructing past forest productivity and extending NDVI records. In this study, we reconstructed the Normalized Difference Vegetation Index (NDVI) for Austrocedrus chilensis forests in northwestern Argentine Patagonia using multi-centennial tree-ring chronologies. A total of 162 wood samples from living trees and 65 from dead trees were used to develop the regional chronology, which exhibited a significant and positive correlation with NDVI from January to March over the period 1981–2019. Based on this relationship, a linear regression model was applied to reconstruct NDVI for these months extending back to 1405. The reconstruction explained 44 % of the total NDVI variance and showed significant positive associations with the Standardized Precipitation Evaporation Index (SPEI), the Palmer Drought Severity Index (PDSI), and the Southern Annular Mode (SAM). Long-term cycles in vegetation productivity were detected, potentially linked to solar activity and other low-frequency climate forcings. The results indicate secular changes in forest productivity dynamics, reflecting the influence of ongoing climate change. By providing a multi-century perspective on NDVI variability, this reconstruction offers critical insights into past forest dynamics and establishes a robust baseline for understanding contemporary ecosystem functioning. Moreover, these findings provide a valuable framework for predictive modeling of future productivity responses under changing climatic conditions.