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Relative importance of macrophyte leaves for nitrogen uptake from flood water in tidal salt marshes

Bouma, T.J. and Stapel, J. and Van der Heiden, J. and Koutstaal, B.P. and Van Soelen, J. and Van IJzerloo, L.P. (2002) Relative importance of macrophyte leaves for nitrogen uptake from flood water in tidal salt marshes. Marine Ecology Progress Series, 240, 93-104. ISSN 0171-8630.

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Official URL: http://dx.doi.org/10.3354/meps240093

Abstract

Nitrogen limits plant growth in most salt marshes. As foliar N-uptake makes a significant contribution to the overall N-requirements of submerged plant species such as (e.g.) seagrasses, we tested if foliar N-uptake was also significant in Spartina anglica Hubbard, a species that dominates the lowest, regularly flooded areas of salt marshes in the SW Netherlands. Foliar N-uptake was compared for plants from 2 estuaries with contrasting N-loads in their water column. N-uptake was quantified by (1) flooding detached leaves in test tubes, (2) spraying leaves still attached to the plants, and (3) flooding whole plants, with solutions containing either 15NO3- or 15NH4+. We found that detaching the leaves from the plant underestimated NH4+ uptake by between 30 and 50%. Higher salinity also reduced foliar N-uptake. Uptake rates were higher for NH4+ than for NO3-, as has been found for many submerged and terrestrial angiosperms and marine algae. Methodology also had a major effect on the uptake rate, with flooding of intact plants yielding higher uptake rates than spraying attached leaves. However, in general, foliar N-uptake rates were low at the NO3- and NH4+ concentrations that are actually present in the tidal waters during the growth season, and may at most contribute to around 10% of the growth requirement. This percentage is much less than for seagrasses, but in line with data for some terrestrial systems. We conclude that in contrast to seagrasses, foliar N-uptake does not form a significant contribution to the overall N-requirements of S. anglica. This low N-uptake capacity of the S. anglica leaves appears to be a consequence of adaptations to survive tidal flooding. [KEYWORDS: Foliar uptake · Nitrate · Ammonium · Tidal marsh · 15N labelling]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11121
Deposited On:24 Nov 2011 01:00
Last Modified:14 Oct 2013 11:28

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