Amazon Basin shows reduced forest loss but increased forest spatial fragmentation in 1992–2020

Abstract

The Amazon Basin has the largest tropical rainforest in the world, but the rainforest ecosystem faces many threats due to severe deforestation, so understanding the dynamics of the Amazon forest is critical to the regional and global ecological balance. Previous studies usually focused on forest change after 2000, and it is necessary to explore long time series of forest loss and especially fragmentation across the entire basin and among different countries within it. In this study, we combined the hotspot analysis, landscape indices and fragmentation model to analyze the spatial and temporal patterns of forest loss and fragmentation in the Amazon Basin during 1992–2020. The results show that the annual mean forest loss area decreased from 16,664.23 km² during 1992–2003 to 4486.64 km² during 2003–2020. The main cause of forest area loss was the transition of forests to cropland and grasslands, which accounting for >85 % of forest loss, mainly in Brazil and Bolivia. However, there was a marked increase in small-size forest loss, especially in loss patches with area <50 ha. Furthermore, the hotspots of forest loss extended from the south-east to the north and west of the basin, with new hotspots of forest loss emerging in Peru, Ecuador and Colombia. Interior forests characterizing forest integrity considerably declined by 8.82 % during 1992–2020, especially the significant increase in perforated forests by 3.33 % between 2003 and 2020. Bolivia was the country with the most forest fragmented in the basin. This study indicates that the integrity of forest landscapes can be greatly affected by small-size encroachment on forests that may seem insignificant, and the induced perforation and fragmentation of forests deserve more attention. The findings point out where forest protection still needs attention and suggest potential risks and challenges for future forest management and protection in the Amazon Basin.