Ecological Variability and Carbon Stock Estimates of Mangrove Ecosystems in Northwestern Madagascar

Abstract

Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Despite their value, world-wide, mangroves are being rapidly degraded and deforested. Madagascar contains approximately 2% of the world's mangroves, >20% of which has been deforested since 1990 from increased extraction for charcoal and timber and conversion to small to large-scale agriculture and aquaculture. Loss is particularly prominent in the northwestern Ambaro and Ambanja bays. Here, we focus on Ambaro and Ambanja bays, presenting dynamics calculated using United States Geological Survey (USGS) national-level mangrove maps and the first localized satellite imagery derived map of dominant land-cover types. The analysis of USGS data indicated a loss of 7659 ha (23.7%) and a gain of 995 ha (3.1%) from 1990-2010. Contemporary mapping results were 93.4% accurate overall (Kappa 0.9), with producer's and user's accuracies ≥85%. Classification results allowed partitioning mangroves in to ecologically meaningful, spectrally distinct strata, wherein field measurements facilitated estimating the first total carbon stocks for mangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroves have average total vegetation carbon values of 146.8 Mg/ha (±10.2) and soil organic OPEN ACCESSForests 2014, 5 178 carbon of 446.2 (±36.9), supporting a growing body of studies that mangroves are amongst the most carbon-dense tropical forests.

Madagascar’s Mangroves: Quantifying Nation-Wide and Ecosystem Specific Dynamics, and Detailed Contemporary Mapping of Distinct Ecosystems

“…Regardless of management rights, comprehensive and effective management, which impedes mangrove degradation and loss, is lacking for almost all mangrove ecosystems in Madagascar. Due to the lack of governance, an increasing demand in fuel-wood and timber, as well as the expansion of agricultural land, the pressure on mangrove ecosystems from anthropogenic activities continues to rise [25]. If degradation and conversion continue unimpeded, biodiversity will be imperiled, greenhouse gas emissions will increase, and many important services provided to coastal communities will be seriously compromised [86].…”

Spatiotemporal Variation in Mangrove Chlorophyll Concentration Using Landsat 8

“…Estimates suggest that mangrove C storage ranges between ~160 Mg·ha −1 and ~1000 Mg·ha −1 depending on location, species composition, height, and canopy closure [6,7]. Data on C stocks have been published for numerous mangrove systems across the globe including Australia [6], China [8], Indo-Pacific [7,9], Western-Pacific [10], Caribbean [11], and Mexico [12]. In addition, C removal from the atmosphere has been estimated at around 1,170 ± 127 g·C·m −2 ·year −1 [13].…”

Dynamique de croissance et taux de mortalité de <i>Rhizophora spp</i>. dans les mangroves de l'estuaire du Rio del Rey: Site de Bamusso (Sud-Ouest Cameroun)

“…Écotone entre milieu terrestre et marin, l'écosystème de mangrove constitue une zone d'une grande originalité structurale et fonctionnelle (Betoulle, 1998), jouant un rôle dans les chaînes trophiques côtières (Dittmar et al, 2001;Laedgaard & Johnson, 2001 ) et constituant un important puits de carbone (Twilley et al, 1992 ;Gattuso et al, 1998). Les travaux les plus récentes sur les mangroves prouvent la capacité de cet écosystème à juguler le phénomène de changement climatique par la séquestration du carbone de ces différents composantes (Trevor et al, 2014;Adame et al, 2013;Donato et al, 2012;Lovelock et al, 2011). En outre, les mangroves jouent un rôle de barrière contre les catastrophes naturelles.…”