realignment, The Wash, UK. International Journal of Applied
Earth Observation and Geoinformation, 18, 57–68.
Garbutt, R. A., Reading, C. J., Wolters, M., Gray, A. J., and Rothery,
P., 2006. Monitoring the development of intertidal habitats on
former agricultural land after the managed realignment of coastal
defences at Tollesbury, Essex, UK. Marine Pollution Bulletin,
53(1–4), 155–164.
IPCC, 2007. Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change.
Cambridge University Press, Cambridge, UK
Luisetti, T., Turner, R. K., Bateman, I. J., Morse-Jones, S., Adams,
C., and Fonseca, L., 2011. Coastal and marine ecosystem services valuation for policy and management: managed realignment case studies in England. Ocean and Coastal
Management, 54(3), 212–224.
Mazik, K., Musk, W., Dawes, O., Solyanko, K., Brown, S., Mander,
L., and Elliott, M., 2010. Managed realignment as compensation
for the loss of intertidal mudflat: a short term solution to a long
term problem? Estuarine, Coastal and Shelf Science, 90(1),
11–20.
Möller, I., Spencer, T., French, J. R., Leggett, D. J., and Dixon, M.,
2007. The sea-defence value of salt marshes: field evidence from
North Norfolk. Journal of the Chartered Institution of Water and
Environmental Management, 15, 109–116.
Mossman, H. L., Davy, A. J., and Grant, A., 2012. Does managed
coastal realignment create saltmarshes with ‘equivalent biological characteristics’ to natural reference sites? Journal of Applied
Ecology, doi:10.1111/j.1365-2664.2012.02198.x.
Roca, E., and Villares, M., 2012. Public perceptions of managed
realignment strategies: the case study of the Ebro Delta in the
Mediterranean basin. Ocean and Coastal Management, 60,
38–47.
Rotman, R., Naylor, L., McDonnell, R., and MacNiocaill, C., 2008.
Sediment transport on the Freiston Shore managed realignment
site: an investigation using environmental magnetism. Geomorphology, 100(3–4), 241–255.
Rupp-Armstrong, S., and Nicholls, R. J., 2007. Coastal and estuarine retreat: a comparison of the application of managed realignment in England and Germany. Journal of Coastal Research,
23(6), 1418–1430.
Spencer, K. L., and Harvey, G. L., 2012. Understanding system disturbance and ecosystem services in restored saltmarshes: integrating physical and biogeochemical processes. Estuarine,
Coastal and Shelf Science, 106, 23–32.
Spencer, K. L., Cundy, A. B., Davies-Hearn, S., Hughes, R., Turner,
S., and MacLeod, C. L., 2008. Physicochemical changes in
sediments at Orplands Farm, Essex, UK following 8 years of
managed realignment. Estuarine, Coastal and Shelf Science,
76(3), 608–619.
Teuchies, J., Beauchard, O., Jacobs, S., and Meire, P., 2012. Evolution of sediment metal concentrations in a tidal marsh restoration
project. Science of the Total Environment, 419(1), 187–195.
Wolters, M., Garbutt, A., and Bakker, J. P., 2005. Salt-marsh restoration: evaluating the success of de-embankments in north-west
Europe. Biological Conservation, 123(2), 249–268.
Cross-references
Climate Change
Coastal Risks: Floods
Coastal Squeeze
Coastal Wetlands
Habitat Loss
Saltmarshes
MANGROVES
Daniel M. Alongi
Australian Institute of Marine Science, Townsville MC,
QLD, Australia
Synonyms
Mangal
Definition
Mangroves are dicotyledonous woody trees and scrubs
that grow above mean sea level to form intertidal forests
along subtropical and tropical coasts.
Introduction
Mangroves are forested wetlands living along coasts
within low latitudes. These tidal trees and scrubs occur
on rocky and sandy shores, but they attain peak size and
luxuriance in sheltered muddy areas where quiescent conditions foster establishment and growth of propagules
(Lugo and Snedaker, 1974; Chapman, 1976). Forest establishment involves positive feedback in that the saplings
and trees trap silt and clay particles brought in by tides
and rivers, helping to consolidate the deposits on which
they grow. This feedback process continues for the life
of the forest until, eventually, the forest floor lies above
the reach of tides. Over years and decades, terrestrial
plants eventually outcompete and replace the mangroves
assuming that geological and ecological processes are in
equilibrium. The intertidal zone and its biota are highly
dynamic and ever changing, disturbed often enough by
weather events, such as storms and cyclones, disease,
pests, and anthropogenic intrusions that the progression
to terrestrial forest occurs infrequently along most coastlines. Mangroves occupy a harsh environment, subjected
daily to tidal and seasonal variations in temperature, salinity, and anoxic soils, and are fairly robust and highly
adaptable or tolerant to such changes.
Mangroves occur in a variety of coastal settings dominated by rivers (and the lack thereof), tides, and waves
and develop and persist over timescales in which morphological evolution of coastlines occurs; they are pioneers
colonizing newly formed mudflats, but they can also shift
their intertidal position in the face of environmental
change. In relation to changes in sea level, mangrove
development can follow one of six patterns: (1) the mangrove surface accretes asymptotically until sediment accumulation raises the forest floor above tidal range – this
pattern occurs when sea level is in equilibrium; (2) accretion of sediment keeps pace with a constant rise in sea
level; (3) the forest floor accretes at times above tidal
range when sea-level rise is irregular; (4) with episodic
subsidence but with a stable sea level, the forest floor
accretes back to the tidal range; (5) mangrove accretion
continues at an irregular pace under conditions of episodic
MANGROVES
393
Earth Observation and Geoinformation, 18, 57–68.
Garbutt, R. A., Reading, C. J., Wolters, M., Gray, A. J., and Rothery,
P., 2006. Monitoring the development of intertidal habitats on
former agricultural land after the managed realignment of coastal
defences at Tollesbury, Essex, UK. Marine Pollution Bulletin,
53(1–4), 155–164.
IPCC, 2007. Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change.
Cambridge University Press, Cambridge, UK
Luisetti, T., Turner, R. K., Bateman, I. J., Morse-Jones, S., Adams,
C., and Fonseca, L., 2011. Coastal and marine ecosystem services valuation for policy and management: managed realignment case studies in England. Ocean and Coastal
Management, 54(3), 212–224.
Mazik, K., Musk, W., Dawes, O., Solyanko, K., Brown, S., Mander,
L., and Elliott, M., 2010. Managed realignment as compensation
for the loss of intertidal mudflat: a short term solution to a long
term problem? Estuarine, Coastal and Shelf Science, 90(1),
11–20.
Möller, I., Spencer, T., French, J. R., Leggett, D. J., and Dixon, M.,
2007. The sea-defence value of salt marshes: field evidence from
North Norfolk. Journal of the Chartered Institution of Water and
Environmental Management, 15, 109–116.
Mossman, H. L., Davy, A. J., and Grant, A., 2012. Does managed
coastal realignment create saltmarshes with ‘equivalent biological characteristics’ to natural reference sites? Journal of Applied
Ecology, doi:10.1111/j.1365-2664.2012.02198.x.
Roca, E., and Villares, M., 2012. Public perceptions of managed
realignment strategies: the case study of the Ebro Delta in the
Mediterranean basin. Ocean and Coastal Management, 60,
38–47.
Rotman, R., Naylor, L., McDonnell, R., and MacNiocaill, C., 2008.
Sediment transport on the Freiston Shore managed realignment
site: an investigation using environmental magnetism. Geomorphology, 100(3–4), 241–255.
Rupp-Armstrong, S., and Nicholls, R. J., 2007. Coastal and estuarine retreat: a comparison of the application of managed realignment in England and Germany. Journal of Coastal Research,
23(6), 1418–1430.
Spencer, K. L., and Harvey, G. L., 2012. Understanding system disturbance and ecosystem services in restored saltmarshes: integrating physical and biogeochemical processes. Estuarine,
Coastal and Shelf Science, 106, 23–32.
Spencer, K. L., Cundy, A. B., Davies-Hearn, S., Hughes, R., Turner,
S., and MacLeod, C. L., 2008. Physicochemical changes in
sediments at Orplands Farm, Essex, UK following 8 years of
managed realignment. Estuarine, Coastal and Shelf Science,
76(3), 608–619.
Teuchies, J., Beauchard, O., Jacobs, S., and Meire, P., 2012. Evolution of sediment metal concentrations in a tidal marsh restoration
project. Science of the Total Environment, 419(1), 187–195.
Wolters, M., Garbutt, A., and Bakker, J. P., 2005. Salt-marsh restoration: evaluating the success of de-embankments in north-west
Europe. Biological Conservation, 123(2), 249–268.
Cross-references
Climate Change
Coastal Risks: Floods
Coastal Squeeze
Coastal Wetlands
Habitat Loss
Saltmarshes
MANGROVES
Daniel M. Alongi
Australian Institute of Marine Science, Townsville MC,
QLD, Australia
Synonyms
Mangal
Definition
Mangroves are dicotyledonous woody trees and scrubs
that grow above mean sea level to form intertidal forests
along subtropical and tropical coasts.
Introduction
Mangroves are forested wetlands living along coasts
within low latitudes. These tidal trees and scrubs occur
on rocky and sandy shores, but they attain peak size and
luxuriance in sheltered muddy areas where quiescent conditions foster establishment and growth of propagules
(Lugo and Snedaker, 1974; Chapman, 1976). Forest establishment involves positive feedback in that the saplings
and trees trap silt and clay particles brought in by tides
and rivers, helping to consolidate the deposits on which
they grow. This feedback process continues for the life
of the forest until, eventually, the forest floor lies above
the reach of tides. Over years and decades, terrestrial
plants eventually outcompete and replace the mangroves
assuming that geological and ecological processes are in
equilibrium. The intertidal zone and its biota are highly
dynamic and ever changing, disturbed often enough by
weather events, such as storms and cyclones, disease,
pests, and anthropogenic intrusions that the progression
to terrestrial forest occurs infrequently along most coastlines. Mangroves occupy a harsh environment, subjected
daily to tidal and seasonal variations in temperature, salinity, and anoxic soils, and are fairly robust and highly
adaptable or tolerant to such changes.
Mangroves occur in a variety of coastal settings dominated by rivers (and the lack thereof), tides, and waves
and develop and persist over timescales in which morphological evolution of coastlines occurs; they are pioneers
colonizing newly formed mudflats, but they can also shift
their intertidal position in the face of environmental
change. In relation to changes in sea level, mangrove
development can follow one of six patterns: (1) the mangrove surface accretes asymptotically until sediment accumulation raises the forest floor above tidal range – this
pattern occurs when sea level is in equilibrium; (2) accretion of sediment keeps pace with a constant rise in sea
level; (3) the forest floor accretes at times above tidal
range when sea-level rise is irregular; (4) with episodic
subsidence but with a stable sea level, the forest floor
accretes back to the tidal range; (5) mangrove accretion
continues at an irregular pace under conditions of episodic
MANGROVES
393