215
most of the studies in this regard are carried out in single sites, which might significantly impose errors in global estimates.
On the contrary, soil CO 2 fluxes are studied in many mangrove forests and at
various inter-tidal sites to examine the variability of fluxes. On the whole it can be
inferred that the magnitude of fluxes reported from the forest floor was much less
than the canopy uptake, implementing the net sink character of the mangroves to be
intact. Soil temperature, soil moisture, organic carbon content, and presence of soil
nutrients were the main regulating factors of soil CO 2 effluxes. However, much
more emphasis needs to be given to the processes undergoing in the soil surface
during inundated conditions, i.e. the pore water dynamics and the mineralization of
CO 2 to DIC should be properly characterized or else the soil CO 2 efflux could significantly underestimated throughout the world.
The studies conducted in Sundarban though covered all the regulating factors
like soil temperature, moisture, organic carbon content, soil texture and so forth.
However, compared to the stretch of Sundarbans the sampling sites were limited.
Thus Sundarban despite being the largest mangrove forest of the world cannot serve
as a suitable proxy to upscale the fluxes to global level.
Air-water CO 2 fluxes, though measured in many mangrove sites, most of them
are carried out in short term scales. It was evident from the present analysis that tidal
dynamics, spatial variation in salinity and organic carbon, along with the effect of
seasonality can substantially alter the air-water CO 2 fluxes. These aspects are still to
a large extent neglected in most of the studies. Mangroves being such an ecosystem
which constantly experiences a change in soil exposed area and adjacent water surface area, due to the dynamic encroachment and receding of tidally influenced water
regime, more effort needs to be taken to quantify properly the area of soil and water
surface.
The studies conducted in Sundarban further highlighted that based on the type of
estuary, i.e. enclosed or perennially open and depending upon the position of the
chosen sampling stations throughout the extent of the water ways the fluxes might
vary to a great extent. This aspect should be dealt with more importance in the
future studies to be carried out in different other mangroves of the world so as to
reduce the uncertainties in air-water CO 2 fluxes from the mangrove adjacent water
bodies. Keeping in mind all these factors and lessons learnt from the previous studies, a more holistic approach should be taken to quantify these fluxes taking place in
the mangrove ecosystems of the world.
A global model to up-scale the annual budget of these fluxes and a model applicable to all the mangroves of world can only be prepared if all the constraints and
regulating factors can be taken into account altogether vis-à-vis the changing
regional sea level rise and anthropogenic rate of destruction of mangroves. As a
concluding remark it can be stated further, that mangroves still prove to be an excellent option to combat the ongoing anthropogenic CO 2 emission. Hence, widespread
awareness and endeavors to restore, prevention of destruction, afforestation and
reforestation of degraded mangroves should be taken up globally to safeguard this
unique ecosystem and the services they provide to the mankind and the
environment.
7 CO 2 Fluxes in Mangrove Ecosystems
most of the studies in this regard are carried out in single sites, which might significantly impose errors in global estimates.
On the contrary, soil CO 2 fluxes are studied in many mangrove forests and at
various inter-tidal sites to examine the variability of fluxes. On the whole it can be
inferred that the magnitude of fluxes reported from the forest floor was much less
than the canopy uptake, implementing the net sink character of the mangroves to be
intact. Soil temperature, soil moisture, organic carbon content, and presence of soil
nutrients were the main regulating factors of soil CO 2 effluxes. However, much
more emphasis needs to be given to the processes undergoing in the soil surface
during inundated conditions, i.e. the pore water dynamics and the mineralization of
CO 2 to DIC should be properly characterized or else the soil CO 2 efflux could significantly underestimated throughout the world.
The studies conducted in Sundarban though covered all the regulating factors
like soil temperature, moisture, organic carbon content, soil texture and so forth.
However, compared to the stretch of Sundarbans the sampling sites were limited.
Thus Sundarban despite being the largest mangrove forest of the world cannot serve
as a suitable proxy to upscale the fluxes to global level.
Air-water CO 2 fluxes, though measured in many mangrove sites, most of them
are carried out in short term scales. It was evident from the present analysis that tidal
dynamics, spatial variation in salinity and organic carbon, along with the effect of
seasonality can substantially alter the air-water CO 2 fluxes. These aspects are still to
a large extent neglected in most of the studies. Mangroves being such an ecosystem
which constantly experiences a change in soil exposed area and adjacent water surface area, due to the dynamic encroachment and receding of tidally influenced water
regime, more effort needs to be taken to quantify properly the area of soil and water
surface.
The studies conducted in Sundarban further highlighted that based on the type of
estuary, i.e. enclosed or perennially open and depending upon the position of the
chosen sampling stations throughout the extent of the water ways the fluxes might
vary to a great extent. This aspect should be dealt with more importance in the
future studies to be carried out in different other mangroves of the world so as to
reduce the uncertainties in air-water CO 2 fluxes from the mangrove adjacent water
bodies. Keeping in mind all these factors and lessons learnt from the previous studies, a more holistic approach should be taken to quantify these fluxes taking place in
the mangrove ecosystems of the world.
A global model to up-scale the annual budget of these fluxes and a model applicable to all the mangroves of world can only be prepared if all the constraints and
regulating factors can be taken into account altogether vis-à-vis the changing
regional sea level rise and anthropogenic rate of destruction of mangroves. As a
concluding remark it can be stated further, that mangroves still prove to be an excellent option to combat the ongoing anthropogenic CO 2 emission. Hence, widespread
awareness and endeavors to restore, prevention of destruction, afforestation and
reforestation of degraded mangroves should be taken up globally to safeguard this
unique ecosystem and the services they provide to the mankind and the
environment.
7 CO 2 Fluxes in Mangrove Ecosystems