Global Mangrove Watch: Updated 2010 Mangrove Forest Extent (v2.5)

Abstract

This study presents an updated global mangrove forest baseline for 2010: Global Mangrove Watch (GMW) v2.5. The previous GMW maps (v2.0) of the mangrove extent are currently considered the most comprehensive available global products, however areas were identified as missing or poorly mapped. Therefore, this study has updated the 2010 baseline map to increase the mapping quality and completeness of the mangrove extent. This revision resulted in an additional 2660 km2 of mangroves being mapped yielding a revised global mangrove extent for 2010 of some 140,260 km2. The overall map accuracy was estimated to be 95.1% with a 95th confidence interval of 93.8–96.5%, as assessed using 50,750 reference points located across 60 globally distributed sites. Of these 60 validation sites, 26 were located in areas that were remapped to produce the v2.5 map and the overall accuracy for these was found to have increased from 82.6% (95th confidence interval: 80.1–84.9) for the v2.0 map to 95.0% (95th confidence interval: 93.7–96.4) for the v2.5 map. Overall, the improved GMW v2.5 map provides a more robust product to support the conservation and sustainable use of mangroves globally.

Global Mangrove Deforestation and Its Interacting Social-Ecological Drivers: A Systematic Review and Synthesis

“…The studied mangrove forests by our consolidated literature exhibited an overall decline (net loss) of more than 5% in global coverage between 1990 and 2020 [11,39,49,60] (Table 2). Globally, the mangrove cover declined by 8600 km 2 between 1990 and 2020 (Table 2) at a rate of 287 km 2 per year [61,62]. Sixty percent of the literature that reported changes in the mangrove forests distribution studied countries in the South and Southeast Asian region, which experienced the highest mangrove loss (3870 km 2 and more than 6% decline in the global coverage) between 1990 and 2020 [11,[62][63][64].…”

“…Globally, the mangrove cover declined by 8600 km 2 between 1990 and 2020 (Table 2) at a rate of 287 km 2 per year [61,62]. Sixty percent of the literature that reported changes in the mangrove forests distribution studied countries in the South and Southeast Asian region, which experienced the highest mangrove loss (3870 km 2 and more than 6% decline in the global coverage) between 1990 and 2020 [11,[62][63][64]. The mangrove habitat loss in South and Southeast Asia was recorded at an average rate of 0.34% and 0.33% per year between 2000 and 2010 and between 2010 and 2020, respectively, which is also the highest among the mangrove regions globally [12,31,38].…”

Global Mangrove Extent Change 1996–2020: Global Mangrove Watch Version 3.0

“…The most recent effort at mapping mangroves globally has been the Global Mangrove Watch project (GMW; [25,27,28]), where we used radar data from Japan's Advanced Land Observing Satellite (ALOS) Phased-Array L-band Synthetic Aperture Radar (PALSAR) and optical data from the Landsat Thematic Mapper (TM) to generate a baseline map for 2010. This baseline was subsequently refined using Sentinel-2 imagery, backdated to 2010, to increase the overall accuracy to 95.1% [29], thus creating a reliable and consistent baseline from which change can be detected. Hamilton and Casey [22] 2000-2012 1646 137 NA NA Goldberg et al [12] 2000-2016 3363 210 NA NA Bunting et al [25] (GMW v2.0)…”

“…Building on the GMW v2.5 baseline mapping of Bunting et al [29], the aim of this study was to establish the magnitude of change in mangrove extent at the global scale to inform overall trends from the mid-1990s to the present. This study provides the longest time period over which change in mangrove extent has been assessed on a global scale.…”

Multiscale Diagnosis of Mangrove Status in Data-Poor Context Using Very High Spatial Resolution Satellite Images: A Case Study in Pichavaram Mangrove Forest, Tamil Nadu, India

“…Each mangrove region has its own history, which reflects how species diversity and structural patterns adapt to local and evolving geomorphic and climatic settings [1,2]. The status of mangroves, however, remains insufficiently documented in many places of the world despite a consensus on their rates of global decline over decadal timescales [3][4][5][6][7][8][9]. Even if annual rates of mangrove loss tended to decrease between 2000 and 2012 (0.16-0.39%) compared to the 1980-2000 period (0.99%) [10][11][12][13][14], the present situation in South Asia and Southeast Asia remains illustrative of the major drivers of global mangrove loss, which include land-use conversion to aquaculture, timber harvesting, pollution, freshwater deficits, low silt deposition, shoreline erosion, and other environmental events, such as dieback, floods, and tropical storm landfalls [8,12,13].…”