210
7.5.2 CO 2 Flux Scenario
7.5.2.1 Research Gap in Bangladesh Counterpart of Sundarban
Being the world’s largest mangrove forest, Sundarbans undoubtedly demands a special attention and several works have been done regarding characterization of the
atmosphere-biosphere, soil derived and air-water CO 2 fluxes (Tables 7.1, 7.2 and
7.3). However, all of these works were carried out in the Indian part of Sundarbans.
Though several works based on the assessment of carbon stock and delineating
mangrove cover with respect to climate change and sea level rise have been undertaken in the Bangladesh part of Sundarbans (Rahman et al. 2011; Rahman et al.
2015; Chanda et al. 2016), none of them directly measured CO 2 fluxes.
7.5.2.2 Atmosphere-Biosphere CO 2 Flux – Initial Short Term Studies
Endeavors attempting to quantify the atmosphere-biosphere CO 2 flux in Sundarbans
began since the year 1999. Mukhophadhya et al. (2001) in their short term study
found the marine compartments of the mangrove canopy to be a mild source of
CO 2 . However, surprisingly in the following study by Mukhopadhyay et al. (2002)
which was conducted every month and completed an annual cycle throughout the
years 1998–2000 also found the terrestrial compartments of Sundarbans to be a net
source for CO 2 . None of the other studies in other mangroves of the world recorded
this kind of atmosphere-biosphere CO 2 fluxes. They concluded that net source character exhibited by the mangroves could be due to the regional micrometeorological
conditions and slow turnover of biomass accumulation in the young stands as well
as the CO 2 flux character of the Sundarban mangroves is transient in nature.
Almost all the studies carried out in the Sundarban during this phase and more
studies that followed were based on discrete data sets acquired in hourly intervals
throughout one particular day of each month. Moreover, the fluxes were computed
by means of flux gradient method which is known to have a limitation of depicting
the CO 2 exchange of a low footprint, whereas, eddy covariance technique usually
acquires data continuously and depending upon the height of the flux towers it can
give a broad picture of the gaseous exchange. Thus uncertainties in up-scaling the
fluxes for the entire Sundarban was much high in these studies.
7.5.2.3 Atmosphere-Biosphere CO 2 Flux – Spatial and Temporal
Variability
Ganguly et al. (2008) and Ray et al. (2011) carried out comprehensive works and
found the Sundarban to be net sink for CO 2 having flux magnitudes (negative NEE)
very much comparable or sometimes much higher than that observed in the other
studies around the world.
A. Akhand et al.
7.5.2 CO 2 Flux Scenario
7.5.2.1 Research Gap in Bangladesh Counterpart of Sundarban
Being the world’s largest mangrove forest, Sundarbans undoubtedly demands a special attention and several works have been done regarding characterization of the
atmosphere-biosphere, soil derived and air-water CO 2 fluxes (Tables 7.1, 7.2 and
7.3). However, all of these works were carried out in the Indian part of Sundarbans.
Though several works based on the assessment of carbon stock and delineating
mangrove cover with respect to climate change and sea level rise have been undertaken in the Bangladesh part of Sundarbans (Rahman et al. 2011; Rahman et al.
2015; Chanda et al. 2016), none of them directly measured CO 2 fluxes.
7.5.2.2 Atmosphere-Biosphere CO 2 Flux – Initial Short Term Studies
Endeavors attempting to quantify the atmosphere-biosphere CO 2 flux in Sundarbans
began since the year 1999. Mukhophadhya et al. (2001) in their short term study
found the marine compartments of the mangrove canopy to be a mild source of
CO 2 . However, surprisingly in the following study by Mukhopadhyay et al. (2002)
which was conducted every month and completed an annual cycle throughout the
years 1998–2000 also found the terrestrial compartments of Sundarbans to be a net
source for CO 2 . None of the other studies in other mangroves of the world recorded
this kind of atmosphere-biosphere CO 2 fluxes. They concluded that net source character exhibited by the mangroves could be due to the regional micrometeorological
conditions and slow turnover of biomass accumulation in the young stands as well
as the CO 2 flux character of the Sundarban mangroves is transient in nature.
Almost all the studies carried out in the Sundarban during this phase and more
studies that followed were based on discrete data sets acquired in hourly intervals
throughout one particular day of each month. Moreover, the fluxes were computed
by means of flux gradient method which is known to have a limitation of depicting
the CO 2 exchange of a low footprint, whereas, eddy covariance technique usually
acquires data continuously and depending upon the height of the flux towers it can
give a broad picture of the gaseous exchange. Thus uncertainties in up-scaling the
fluxes for the entire Sundarban was much high in these studies.
7.5.2.3 Atmosphere-Biosphere CO 2 Flux – Spatial and Temporal
Variability
Ganguly et al. (2008) and Ray et al. (2011) carried out comprehensive works and
found the Sundarban to be net sink for CO 2 having flux magnitudes (negative NEE)
very much comparable or sometimes much higher than that observed in the other
studies around the world.
A. Akhand et al.