Assessing mangrove cover change in Madagascar (1972–2019): Widespread mangrove deforestation is slowing down

Abstract

Between the 1970s and early 2000s, Madagascar witnessed significant mangrove extent and condition declines due to deforestation and degradation. Data on mangrove extent prior to the early 1990s is scarce, contributing to uncertainties in long-term trend analyses. Recent estimates (since 2010) have reported widely varying mangrove extents from 2000 km² to 3400 km², indicating large uncertainties in current trends. Leveraging five decades of Landsat satellite data, this study offers a methodologically consistent approach to classify Madagascar's mangrove extent, providing a comprehensive dataset from 1972, 1989, 1999, 2009, to 2019. Our findings reveal an overall decrease of 8 % from 2935 km² in 1972–2699 km² in 2019, with loss rates decelerating from 0.4 % per year in the initial period to 0.2 % per year post-1999. This decline primarily reflects anthropogenic pressures, notably in the northern regions. Conversely, the last decade has witnessed a 5 % increase in mangrove coverage, primarily in the central and southern regions, thanks to concerted conservation and reforestation efforts, highlighting a positive shift in mangrove management and protection strategies. This study's long-term perspective is crucial for understanding the dynamics of mangrove coverage and guiding effective intervention strategies in Madagascar.