Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 20
Biogeosciences, 12, 6169–6180, 2015
https://doi.org/10.5194/bg-12-6169-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 6169–6180, 2015
https://doi.org/10.5194/bg-12-6169-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 28 Oct 2015

Research article | 28 Oct 2015

Sediment properties and CO2 efflux from intact and cleared temperate mangrove forests

R. H. Bulmer1, C. J. Lundquist1,2, and L. Schwendenmann3 R. H. Bulmer et al.
  • 1Institute of Marine Science, University of Auckland, Auckland, New Zealand
  • 2National Institute of Water and Atmospheric Research Ltd (NIWA), Hamilton, New Zealand
  • 3School of Environment, University of Auckland, Auckland, New Zealand

Abstract. Temperate mangrove forests in New Zealand have increased in area over recent decades. Expansion of temperate mangroves in New Zealand is associated with perceived loss of other estuarine habitats, and decreased recreational and amenity values, resulting in clearing of mangrove forests. In the tropics, changes in sediment characteristics and carbon efflux have been reported following mangrove clearance. This is the first study in temperate mangrove (Avicennia marina) forests investigating the impact of clearing on sediment CO2 efflux and associated biotic and abiotic factors.

Sediment CO2 efflux rates from intact (168.5 ± 45.8 mmol m−2 d−1) and cleared (133.9 ± 37.2 mmol m−2 d−1) mangrove forests in New Zealand are comparable to rates measured in tropical mangrove forests. We did not find a significant difference in sediment CO2 efflux rates between intact and cleared temperate mangrove forests. Pre-shading the sediment for more than 30 min prior to dark chamber measurements was found to have no significant effect on sediment CO2 efflux. This suggests that the continuation of photosynthetic CO2 uptake by biofilm communities was not occurring after placement of dark chambers. Rather, above-ground mangrove biomass, sediment temperature and chlorophyll a concentration were the main factors explaining the variability in sediment CO2 efflux in intact mangrove forests. The main factors influencing sediment CO2 efflux in cleared mangrove forest sites were sediment organic carbon concentration, nitrogen concentration and sediment grain size. Our results show that greater consideration should be given regarding the rate of carbon released from mangrove forest following clearance and the relative contribution to global carbon emissions.

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This is the first study investigating the effect of clearing on sediment CO2 efflux in temperate Avicennia marina forests. We found that rates of sediment CO2 efflux from cleared and intact temperate Avicennia marina forests are comparable to rates observed in other temperate and tropical forests. Our results show that greater consideration should be made regarding the rate of carbon released from mangrove forest following clearance and the relative contribution to global carbon emissions.
This is the first study investigating the effect of clearing on sediment CO2 efflux in temperate...
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