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term ‘Mangroves’ came into existence from the Portuguese word ‘Mangue’ meaning ‘community’ and the English word ‘Grove’ meaning trees or bushes. Macnae
(1968) coined the term ‘Mangal’ to define these set of tidal halophytic species
which are found to thrive luxuriantly in saline habitats like estuaries, and coastal
regions like bays, lagoons etc. throughout the tropics and subtropics of the globe.
Later on, Lear and Turner (1977) expressed the word ‘mangrove’ while depicting
the entire ecosystem comprising the floral and faunal communities of these specialized coastal communities, and subsequently the works of Mepham and Mepham
(1984) and Tomlinson (1986) firmly established the definition of mangrove ecosystems. Usually mangroves are characterized by morphological adaptation/specialization such as aerial roots, viviparous germination etc. along with physiological
mechanisms like salt exclusion and/or salt excretion which enables them to inhabit
regions which are physiologically dry in nature or otherwise not suitable for sustaining any floral life (Parani et al. 1998; Lacerda et al. 2002). However, the aspect of
mangrove ecosystems that drew the attention of the environmental scientists and
climate change experts is their remarkable ability to sequester carbon. Mangrove
forests are one of the most highly productive and bio-diverse ecosystems known to
exist on earth having productivity rate almost 20 times higher than average oceanic
production (Gouda and Panigrahy 1996). In order to adapt with harsh conditions
like saline habitat, mangroves developed an advantageous physiological mechanism
of maximizing carbon gain and minimizing water loss with high water-use and
nutrient-use efficiencies and low transpiration rates (Alongi 2014). Despite thriving
in saline waterlogged soils, mangroves exhibit rapid CO 2 uptake and respiratory
release (Ball 1988) and owing to these unique ecological characteristics of mangroves they are capable of competently make use of limiting nutrients and store
substantial quantities of carbon (Alongi 2009; Feller et al. 2010). Contrary to other
terrestrial forests, mangroves have the option of exchanging inorganic and organic
materials, nutrients and solutes through tidal mixing with the adjacent coastal water
bodies and it usually lead to net sedimentation as well as carbon burial (Adame and
Lovelock 2011).
7.1.3.1 The Global Coverage of Mangroves and Carbon Storage
According to a recent high resolution estimate, mangroves occupy about 0.1% of
the total continental surface of the earth (Hamilton and Casey 2016) covering an
area of 137,760 km
2
(Giri et al. 2011) and yet they comprise one of the most carbon
rich sectors of the world (Bouillon et al. 2008; Donato et al. 2011) owing to a high
above-ground primary productivity (Alongi et al. 2004), rich below ground carbon
content compared to other tropical forests (Komiyama et al. 2008; Lovelock 2008)
and high litter degradation rate accompanied by efficient recycling of autochthonous and allochthonous nutrients (Bouillon et al. 2002). Globally, total aboveground carbon stock of mangroves have been estimated at present to be 2.83 Pg and
together with the belowground carbon and soil carbon stock it can reach up to
8.95 Pg (Inoue 2018). Other blue carbon ecosystems, like seagrass have an
7 CO 2 Fluxes in Mangrove Ecosystems
term ‘Mangroves’ came into existence from the Portuguese word ‘Mangue’ meaning ‘community’ and the English word ‘Grove’ meaning trees or bushes. Macnae
(1968) coined the term ‘Mangal’ to define these set of tidal halophytic species
which are found to thrive luxuriantly in saline habitats like estuaries, and coastal
regions like bays, lagoons etc. throughout the tropics and subtropics of the globe.
Later on, Lear and Turner (1977) expressed the word ‘mangrove’ while depicting
the entire ecosystem comprising the floral and faunal communities of these specialized coastal communities, and subsequently the works of Mepham and Mepham
(1984) and Tomlinson (1986) firmly established the definition of mangrove ecosystems. Usually mangroves are characterized by morphological adaptation/specialization such as aerial roots, viviparous germination etc. along with physiological
mechanisms like salt exclusion and/or salt excretion which enables them to inhabit
regions which are physiologically dry in nature or otherwise not suitable for sustaining any floral life (Parani et al. 1998; Lacerda et al. 2002). However, the aspect of
mangrove ecosystems that drew the attention of the environmental scientists and
climate change experts is their remarkable ability to sequester carbon. Mangrove
forests are one of the most highly productive and bio-diverse ecosystems known to
exist on earth having productivity rate almost 20 times higher than average oceanic
production (Gouda and Panigrahy 1996). In order to adapt with harsh conditions
like saline habitat, mangroves developed an advantageous physiological mechanism
of maximizing carbon gain and minimizing water loss with high water-use and
nutrient-use efficiencies and low transpiration rates (Alongi 2014). Despite thriving
in saline waterlogged soils, mangroves exhibit rapid CO 2 uptake and respiratory
release (Ball 1988) and owing to these unique ecological characteristics of mangroves they are capable of competently make use of limiting nutrients and store
substantial quantities of carbon (Alongi 2009; Feller et al. 2010). Contrary to other
terrestrial forests, mangroves have the option of exchanging inorganic and organic
materials, nutrients and solutes through tidal mixing with the adjacent coastal water
bodies and it usually lead to net sedimentation as well as carbon burial (Adame and
Lovelock 2011).
7.1.3.1 The Global Coverage of Mangroves and Carbon Storage
According to a recent high resolution estimate, mangroves occupy about 0.1% of
the total continental surface of the earth (Hamilton and Casey 2016) covering an
area of 137,760 km
2
(Giri et al. 2011) and yet they comprise one of the most carbon
rich sectors of the world (Bouillon et al. 2008; Donato et al. 2011) owing to a high
above-ground primary productivity (Alongi et al. 2004), rich below ground carbon
content compared to other tropical forests (Komiyama et al. 2008; Lovelock 2008)
and high litter degradation rate accompanied by efficient recycling of autochthonous and allochthonous nutrients (Bouillon et al. 2002). Globally, total aboveground carbon stock of mangroves have been estimated at present to be 2.83 Pg and
together with the belowground carbon and soil carbon stock it can reach up to
8.95 Pg (Inoue 2018). Other blue carbon ecosystems, like seagrass have an
7 CO 2 Fluxes in Mangrove Ecosystems