195
mangroves would be no less than any typical tropical and/or temperate (exclusively
terrestrial forest) provided the solar radiation remains optimum.
Monji et al. (1997) repeated another short term work in the same Phangnga
National Park Mangroves of Thailand during a dry season. The relationship obtained
between the solar radiation and the day time downward fluxes were the same, however, significant changes were observed in the magnitude of fluxes. In the dry season, the mean day time fluxes were almost similar to the mean night time fluxes,
hence making the forest neither act as sink nor source of CO 2 .Thus it was established for the first time that mangroves exhibit significant seasonality in terms of
atmosphere-biosphere fluxes. In order to verify the observations from the two short
term works, 2 years later Monji et al. (2002) carried out a comparatively long term
work in the dry and wet seasons in the Phangnga National Park Mangroves. Even in
this study, the previous observations of seasonal differences in CO 2 fluxes held true;
i.e. wet season exhibited larger –NEE than dry season. In addition to these findings
they also found that a substantial quantity of CO 2 was getting stored inside the
canopy during the night time (with larger amount of storage during low wind condition and vice-versa), however, the stored CO 2 was getting utilized in the first hours
of morning with the initiation of photosynthetic activities.
7.2.3 NEE and Water Logging in Mangroves
Kang et al. (2008) recoded similar magnitudes of CO 2 fluxes in the Guangzhou
Mangroves of China. They also made a crucial observation that under water logged
conditions, the CO 2 sink strength of the mangroves was substantially high, whereas,
higher emissions were observed when the forest floor was not all logged with water.
This observation was later explained by Barr et al. (2010) (during their prolonged
study in the Everglades National Park Mangroves of USA) as under waterlogged
conditions most of the soil and pneumatophore respired CO 2 came into direct contact with the water column and it was eventually tidally exported to the adjacent
water bodies as dissolved inorganic carbon (DIC) instead of being emitted straight
away as CO 2 .
7.2.4 Observations from Everglades National Park – Longest
Continuous Flux Monitoring in Mangrove
The results published in Barr et al. (2010) and Barr et al. (2012) are perhaps the
longest continuous micrometeorological measurements carried out over a mangrove
forest by means of eddy covariance technique. Barr et al. (2010) found a strong correlation between NEE and the ambient temperature both in diurnal as well as seasonal scale. Higher inward fluxes always coexisted with high ambient temperature
7 CO 2 Fluxes in Mangrove Ecosystems
mangroves would be no less than any typical tropical and/or temperate (exclusively
terrestrial forest) provided the solar radiation remains optimum.
Monji et al. (1997) repeated another short term work in the same Phangnga
National Park Mangroves of Thailand during a dry season. The relationship obtained
between the solar radiation and the day time downward fluxes were the same, however, significant changes were observed in the magnitude of fluxes. In the dry season, the mean day time fluxes were almost similar to the mean night time fluxes,
hence making the forest neither act as sink nor source of CO 2 .Thus it was established for the first time that mangroves exhibit significant seasonality in terms of
atmosphere-biosphere fluxes. In order to verify the observations from the two short
term works, 2 years later Monji et al. (2002) carried out a comparatively long term
work in the dry and wet seasons in the Phangnga National Park Mangroves. Even in
this study, the previous observations of seasonal differences in CO 2 fluxes held true;
i.e. wet season exhibited larger –NEE than dry season. In addition to these findings
they also found that a substantial quantity of CO 2 was getting stored inside the
canopy during the night time (with larger amount of storage during low wind condition and vice-versa), however, the stored CO 2 was getting utilized in the first hours
of morning with the initiation of photosynthetic activities.
7.2.3 NEE and Water Logging in Mangroves
Kang et al. (2008) recoded similar magnitudes of CO 2 fluxes in the Guangzhou
Mangroves of China. They also made a crucial observation that under water logged
conditions, the CO 2 sink strength of the mangroves was substantially high, whereas,
higher emissions were observed when the forest floor was not all logged with water.
This observation was later explained by Barr et al. (2010) (during their prolonged
study in the Everglades National Park Mangroves of USA) as under waterlogged
conditions most of the soil and pneumatophore respired CO 2 came into direct contact with the water column and it was eventually tidally exported to the adjacent
water bodies as dissolved inorganic carbon (DIC) instead of being emitted straight
away as CO 2 .
7.2.4 Observations from Everglades National Park – Longest
Continuous Flux Monitoring in Mangrove
The results published in Barr et al. (2010) and Barr et al. (2012) are perhaps the
longest continuous micrometeorological measurements carried out over a mangrove
forest by means of eddy covariance technique. Barr et al. (2010) found a strong correlation between NEE and the ambient temperature both in diurnal as well as seasonal scale. Higher inward fluxes always coexisted with high ambient temperature
7 CO 2 Fluxes in Mangrove Ecosystems