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Decomposition of mangrove roots: Effects of location, nutrients, species identity and mix in a Kenyan forest

Huxham, Mark; Langat, Joseph; Tamooh, Fredrick; Kennedy, Hilary; Mencuccini, Maurizio; Skov, Martin W.; Kairo, James


Joseph Langat

Fredrick Tamooh

Hilary Kennedy

Maurizio Mencuccini

Martin W. Skov

James Kairo


Mangrove trees may allocate >50% of their biomass to roots. Dead roots often form peat, which can make mangroves significant carbon sinks and allow them to raise the soil surface and thus survive rising sea levels. Understanding mangrove root production and decomposition is hence of theoretical and applied importance. The current work explored the effects of species, site, and root size and root nutrients on decomposition. Decomposition of fine (≤3 mm diameter) and coarse (>3 mm diameter, up to a maximum of ∼9 mm) roots from three mangrove species, Avicennia marina, Bruguiera gymnorrhiza and Ceriops tagal was measured over 12 months at 6 sites along a tidal gradient in Gazi Bay, Kenya. C:N and P:N ratios in fresh and decomposed roots were measured, and the effects on decomposition of root size and age, of mixing roots from A. marina and C. tagal, of enriching B. gymnorrhiza roots with N and P and of artefacts caused by bagging roots were recorded. There were significant differences between species, with 76, 47 and 44 % mean dry weight lost after one year for A. marina, B. gymnorrhiza and C. tagal respectively, and between sites, with generally slower decomposition at dryer, high tidal areas. N enriched B. gymnorrhiza roots decomposed significantly faster than un-enriched controls; there was no effect of P enrichment. Mixing A. marina and C. tagal roots caused significantly enhanced decomposition in C. tagal. These results suggest that N availability was an important determinant of decomposition, since differences between species reflected the initial C: N ratios. The relatively slow decomposition rates recorded concur with other studies, and may overestimate natural rates, since larger (10–20 mm diameter), more mature and un-bagged roots all showed significantly slower rates.


Huxham, M., Langat, J., Tamooh, F., Kennedy, H., Mencuccini, M., Skov, M. W., & Kairo, J. (2010). Decomposition of mangrove roots: Effects of location, nutrients, species identity and mix in a Kenyan forest. Estuarine, Coastal and Shelf Science, 88(1), 135-142. doi:10.1016/j.ecss.2010.03.021

Journal Article Type Article
Acceptance Date Mar 17, 2010
Online Publication Date Mar 27, 2010
Publication Date Jun 10, 2010
Deposit Date Nov 23, 2016
Journal Estuarine, Coastal and Shelf Science
Print ISSN 0272-7714
Electronic ISSN 1096-0015
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 88
Issue 1
Pages 135-142
Keywords Aquatic Science; Oceanography; Mangrove; Roots; Carbon; Decay; Nitrogen; Species-mixing
Public URL

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