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Emission of Methane and Nitrous Oxide by Australian Mangrove Ecosystems
Author(s) -
Kreuzwieser J.,
Buchholz J.,
Rennenberg H.
Publication year - 2003
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2003-42712
Subject(s) - avicennia marina , nitrous oxide , mangrove , aerial root , methane , sink (geography) , ecosystem , avicennia , environmental chemistry , substrate (aquarium) , biology , ecology , chemistry , cartography , geography
The fluxes of the greenhouse gases methane (CH 4 ) and nitrous oxide (N 2 O) were measured in mangrove wetlands in Queensland, Australia, using the closed chamber technique. Large differences in the fluxes of both gases from different study sites were observed, which presumably depended on differences in substrate availability. CH 4 emission rates were in the range of 20 to 350 μg m ‐2 h ‐1 , whereas N 2 O fluxes were lower, amounting to ‐ 2 to 14 μg m ‐2 h ‐1 . In general, the field sites with high substrate availability showed higher emissions than sites with poor nutrient supply. This assumption is supported by the observation of dramatically increased N 2 O emissions (150 ‐ 400 μg m ‐2 h ‐1 ) if study sites were artificially fertilised with additional N. As expected, N fertilisation did not alter CH 4 fluxes during the period of investigation. In the present study, it was confirmed that the mangrove vegetation may play a role as a transport path for CH 4 and N 2 O by facilitating diffusion out of the soil. Prop roots from Rhizophora stylosa emitted CH 4 and N 2 O at rates of 2.6 and 3.3 μg m ‐2 root surface h ‐1 , respectively, whereas the soil of this stand acted as a sink for CH 4 . As a consequence, the ecosystem as a whole could constitute a CH 4 source despite CH 4 uptake by the soil. In contrast to prop roots, the presence of pneumatophores in Avicennia marina led to a significant increase in CH 4 emissions from mangrove soils, but did not enhance N 2 O emissions. These findings indicate that mangrove ecosystems may be considered a significant source of N 2 O and that anthropogenic nutrient input into these ecosystems will lead to enhanced source strengths. For an up‐scaling of greenhouse gas emissions from mangrove forests to a global scale, more information is needed, particularly on the significance of vegetation.