Three Decades of Remote Sensing Reveal Contrasting Trends of Biomass and Tree Regeneration in Argentine Dry Forests

Abstract

Dry forests are increasingly threatened by degradation, which determines their structural integrity, functional capacity, and the ability to provide essential ecosystem services. Degradation is the consequence of processes that reduce the different attributes of forests. This study aimed to (i) identify remote sensing proxies for above-ground biomass (AGB) and tree regeneration in three ecoregions of dry forest localized in west Argentina; (ii) analyze the temporal dynamics between 1993 and 2023; (iii) assess the role of precipitation in their temporal variability, and (iv) map their spatial distribution. The median Tasseled Cap Transformation Wetness (TCTW) was the best-performing spectral proxy for AGB, while median Enhanced Vegetation Index (EVI) best captured tree regeneration. In the time series of TCTW, no significant breakpoint was detected; however, a pronounced decline in the median EVI occurred in 1998 in the Monte of Plains and Plateaus and Monte of Hills and Basins ecoregions, particularly near watercourses. In the Dry Chaco, tree regeneration recovered after 2013; however, a decline after a breakpoint coincided with decreased precipitation. Overall, AGB and tree regeneration exhibited contrasting temporal and spatial patterns, underscoring the heterogeneity of dry forests. A weakening relationship between precipitation, a key driver of forests, and forest attributes suggests the influence of other factors, including topography and land use change.