How are anatomical and hydraulic features of the mangroves Avicennia marina and Rhizophora mucronata influenced by siltation?
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This article provides significant data in the debate on whether siltation might have a negative impact on the hydraulic functioning of two widespread mangrove tree species Avicennia marina and Rhizophora mucronata.
Elevated sediment addition, or siltation, within mangrove ecosystems is considered as being negative for trees and saplings, resulting in stress and higher mortality rates. However, little is known about how siltation influences the hydraulic functioning of mangrove trees. Comparing two mangrove tree species (Avicennia marina Vierh. Forsk. and Rhizophora mucronata Lam.) from low and high-siltation plots led to the detection of anatomical and morphological differences and tendencies. Adaptations to high siltation were found to be either mutual among both species, e.g., significant smaller single leaf area (p A.marina = 0.058, F1.38 = 3.8; p R.mucronata = 0.005, F1.38 = 8.7; n = 20 × 20) and a tendency towards smaller stomatal areas (p A.marina = 0.131, F1.8 = 2.8; p R.mucronata = 0.185, F1.8 = 2.1, n = 5 × 60), or species-specific trends for A. marina, such as higher phloem band/growth layer ratios (p = 0.101, F1.8 = 3.4, n = 5 × 3) and stomatal density (p = 0.052, F1.8 = 5.2, n = 5 × 4). All adaptations seemingly contributed to a comparable hydraulic conductivity independent of the degree of siltation. These findings indicate that silted trees level off fluctuations in their hydraulic performance as a survival mechanism to cope with this less favourable environment. Most of the trees’ structural adaptations to cope with siltation are similar to known drought stress-imposed adaptations.
KeywordsHydraulic conductivity Wood anatomy Stomata Leaf area Phloem band/growth layer ratio
The authors are very grateful for the attribution of George Onduso and Eric Okuku, without whom the measurement campaign never would have succeeded. For all the help during the measurement campaign and laboratory work, we would like to thank Samuel Njoroge, Naftali Mukua, Oduor Nancy Awuor, Jan Van Den Bulcke and Piet Dekeyser. Soil analysis was performed by Sturcky Okumu and Oliver Ochola. For statistical support, the authors are grateful towards Rosanna Overholser (FIRE—Fostering Innovative Research based on Evidence—statistical consulting). We also want to thank Veerle De Schepper and Elisabeth M.R. Robert for commenting the M.Sc. text. For logistic support we like to thank Jared Bosire (Kenya Marine and Fisheries Research Institute, KMFRI), Hans Beeckman (Laboratory of Wood Biology and Xylarium, Royal Museum for Central Africa) and Joris Van Acker (Laboratory of Wood Technology—Woodlab, UGent). Additionally, the authors gratefully thank the 3 anonymous reviewers for their constructive comments.
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Conflict of interest
The authors declare that they have no conflict of interest.
- APHA (1998) Standard method for the examination of water and waste-water. 20th edn. American Public Health Association, Washington, DCGoogle Scholar
- Brakel W (1982) Tidal patterns on the East African coast and their implications for the littoral biota. In: Proceedings of the symposium on the coastal and marine environment of the Red Sea, Gulf of Aden and tropical Western Indian Ocean, pp 403–418Google Scholar
- Brugnoli E, Lauteri M (1991) Effects of salinity on stomatal conductance, photosynthetic capacity, and carbon isotope discrimination of salt-tolerant (Gossypium hirsutum L.) and salt-sensitive (Phaseolus vulgaris L.) C3 non-halophytes. Plant Physiol 95:628–635. doi: 10.1104/pp.95.2.628 PubMedCentralCrossRefPubMedGoogle Scholar
- Gordon DM (1987) Disturbance to mangroves in tropical-arid Western Australia: hypersalinity and restricted tidal exchange as factors leading to mortality/David M. Gordon. Technical series (Western Australia. Environmental Protection Authority); no. 12. Environmental Protection Authority, Perth. Accessed from http://nla.gov.au/nla.cat-vn1827098
- Gu MM, Rom CR, Robbins JA, Oosterhuis DM (2007) Effect of water deficit on gas exchange, osmotic solutes, leaf abscission, and growth of four birch genotypes (Betula L.) under a controlled environment. HortScience 42:1383–1391Google Scholar
- Kathiresan K, Bingham BL (2001) Biology of mangroves and mangrove ecosystems. In: Southward AJ, Tyler PA, Young CM, Fuiman LA (eds) Advances in marine biology, vol 40. Advances in marine biology. pp 81–251. doi: 10.1016/s0065-2881(01)40003-4
- Lieth H, Berlekamp J, Fuest S, Riediger S (1999) Climate diagrams of the world. CD-series: climate and biosphere. Blackhuys Publishers, LeidenGoogle Scholar
- Lovelock CE, Ball MC, Choat B, Engelbrecht BMJ, Holbrook NM, Feller IC (2006) Linking physiological processes with mangrove forest structure: phosphorus deficiency limits canopy development, hydraulic conductivity and photosynthetic carbon gain in dwarf Rhizophora mangle. Plant, Cell Environ 29:793–802. doi: 10.1111/j.1365-3040.2005.01446.x CrossRefGoogle Scholar
- Lugo AE, Cintron G (1975) The mangrove forests of Puerto Rico and their management. In: Proceedings of the international symposium on biology and management of mangroves, Gainesville, University of FloridaGoogle Scholar
- Ounis A, Cerovic Z, Briantais J, Moya I (2005) Rasband WS, Image J. US National Institutes of Health, BethesdaGoogle Scholar
- Parson TR, Maita Y, Lalli CM (1984) A manual of chemical and biological methods for seawater analysis. Pergamon Press, OxfordGoogle Scholar
- Quisthoudt K, Adams J, Rajkaran A, Dahdouh-Guebas F, Koedam N, Randin CF (2013) Disentangling the effects of global climate and regional land-use change on the current and future distribution of mangroves in South Africa. Biodivers Conserv 22:1369–1390. doi: 10.1007/s10531-013-0478-4 CrossRefGoogle Scholar
- Tomlinson PB (1986) The botany of mangroves. University Press, CambridgeGoogle Scholar
- van Mensvoort T (1998) Mangrove research discussion list. CommunicationGoogle Scholar
- Zwieniecki MA, Hutyra L, Thompson MV, Holbrook NM (2000) Dynamic changes in petiole specific conductivity in red maple (Acer rubrum L.), tulip tree (Liriodendron tulipifera L.) and northern fox grape (Vitis labrusca L.). Plant, Cell Environ 23:407–414. doi: 10.1046/j.1365-3040.2000.00554.x CrossRefGoogle Scholar