Nitrogen sequestration capacity of two salt marshes from the Tagus estuary |
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Authors: | Isabel Caçador A L Costa C Vale |
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Institution: | (1) Institute of Oceanography, Faculty of Sciences, University of Lisbon, Campo Grande, Lisbon, 1749-016, Portugal;(2) IPIMAR - National Institute for Agronomy and Fisheries Research, Av. Brasília, Lisbon, 1449-006, Portugal |
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Abstract: | The role of salt marshes as nitrogen sink is examined taking into consideration the seasonal variation of above and belowground
biomass of Spartina martima and Halimione portulacoides in two marshes from Tagus estuary, Pancas and Corroios, and the degradation rates of belowground litter. Total nitrogen was
determined in plant components, decomposing litter and sediment. Biomass was higher in Corroios, the saltier marsh, with 7190
g m−2 y−1 dw of S. maritima and 6593 g m−2 y−1 dw of H. portulacoides and the belowground component contributed to 96% and 90% of total biomass, respectively. In the other marsh, Pancas, belowground
biomass contributed to 56% and 76% of total biomass for S. maritima and H. portulacoides, respectively. Litterbag experiment showed that between 25% and 50% of nitrogen is lost within the first month and remained
relatively constant in the next four months. Slower decomposition is observed in sediments with higher nitrogen concentration
(max. 0.7% N in the saltier marsh). Higher concentrations of N were found in the sediment upper layers. Considering the sediment-root
system, most of the nitrogen is stored in the sediment compartment and only about 1–4% of the total N was found in the roots.
Considering these results, Tagus salt marshes act as a sink for nitrogen. |
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Keywords: | Nitrogen Salt marsh Spartina maritima Halimione portulacoides Tagus estuary |
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