200
7.3.4 Leaf Area Index, Litter Fall and Benthic Microbial
Community
Lovelock (2008) carried out an exhaustive work covering 11 mangrove sites in
Caribbean, Australia and New Zealand spread over a latitudinal range of 27°N to
37°S. One of the most crucial observations made in this study was that the magnitude of soil CO 2 effluxes was similar to that observed in terrestrial forest soils which
are mostly due to enhanced microbial activities in the mangrove soils. Lovelock
(2008) examined that soil CO 2 flux significantly correlated (positive correlation)
with leaf area index (LAI), litter fall rate as well as magnitude and above ground
primary productivity (especially in case of dwarf mangrove patches).
7.3.5 Biogenic Structures
Kristensen et al. (2008) observed that sediments with biogenic structures like pneumatophores and crab burrows showed significantly higher effluxes (especially during the dark hours) compared to those mangrove sediments which are devoid of
those structures. They also observed that the CO 2 efflux from pneumatophores varied significantly from species to species and has a strong relation with the shape and
size of the pneumatophores. On the contrary, the authors argued that CO 2 flux estimation in a crab burrow might slightly overestimate the soil CO 2 fluxes as most of
the crab burrows are inhabited by crabs (Skov et al. 2002) and depending upon their
size they may respire CO 2 substantially which is erroneously considered as soil
respired CO 2 .
Troxler et al. (2015) observed that soil CO 2 flux from soils rich in pneumatophores emitted CO 2 substantially higher than soils without any pneumatophores as
emphasized by earlier studies of Kristensen et al. (2008). All these observations
made the authors to conclude that site specific measurement of soil CO 2 fluxes only
in places without any biogenic structures might underestimate the global soil respiration to a large extent.
7.3.6 Soil Temperature and Moisture
Soil temperature and moisture were found to be the main covariates responsible for
regulating the seasonal fluxes (Fig. 7.3b). A similar dependency of soil temperature
on the soil CO 2 fluxes was observed by Poungparn et al. (2009) while working in the
Trat River Mangroves of Eastern Thailand. Most of the studies observed an exponential relationship between the magnitude of soil CO 2 efflux and soil temperature.
Lovelock (2008) observed an increase in soil respiration with increasing soil temperature, however, in most cases the soil respiration rate was found to decline at
A. Akhand et al.
7.3.4 Leaf Area Index, Litter Fall and Benthic Microbial
Community
Lovelock (2008) carried out an exhaustive work covering 11 mangrove sites in
Caribbean, Australia and New Zealand spread over a latitudinal range of 27°N to
37°S. One of the most crucial observations made in this study was that the magnitude of soil CO 2 effluxes was similar to that observed in terrestrial forest soils which
are mostly due to enhanced microbial activities in the mangrove soils. Lovelock
(2008) examined that soil CO 2 flux significantly correlated (positive correlation)
with leaf area index (LAI), litter fall rate as well as magnitude and above ground
primary productivity (especially in case of dwarf mangrove patches).
7.3.5 Biogenic Structures
Kristensen et al. (2008) observed that sediments with biogenic structures like pneumatophores and crab burrows showed significantly higher effluxes (especially during the dark hours) compared to those mangrove sediments which are devoid of
those structures. They also observed that the CO 2 efflux from pneumatophores varied significantly from species to species and has a strong relation with the shape and
size of the pneumatophores. On the contrary, the authors argued that CO 2 flux estimation in a crab burrow might slightly overestimate the soil CO 2 fluxes as most of
the crab burrows are inhabited by crabs (Skov et al. 2002) and depending upon their
size they may respire CO 2 substantially which is erroneously considered as soil
respired CO 2 .
Troxler et al. (2015) observed that soil CO 2 flux from soils rich in pneumatophores emitted CO 2 substantially higher than soils without any pneumatophores as
emphasized by earlier studies of Kristensen et al. (2008). All these observations
made the authors to conclude that site specific measurement of soil CO 2 fluxes only
in places without any biogenic structures might underestimate the global soil respiration to a large extent.
7.3.6 Soil Temperature and Moisture
Soil temperature and moisture were found to be the main covariates responsible for
regulating the seasonal fluxes (Fig. 7.3b). A similar dependency of soil temperature
on the soil CO 2 fluxes was observed by Poungparn et al. (2009) while working in the
Trat River Mangroves of Eastern Thailand. Most of the studies observed an exponential relationship between the magnitude of soil CO 2 efflux and soil temperature.
Lovelock (2008) observed an increase in soil respiration with increasing soil temperature, however, in most cases the soil respiration rate was found to decline at
A. Akhand et al.