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==Vegetation== ==Vegetation==
] ]
Sand dunes which already exist on the upper beach but ] can be stabilized by ] plants onto the dune. What type of plants are used is generally dictated by where on the dune the plants are going to be placed. A coastal dune is composed of the foredune, which is the angled side of the linear dune which faces the ocean, the broad sand plain which may or may not be present on some coastal dunes, but is the flat expanse on the top of the dune, and the backdune which is the other angled side of the dune which faces away from the ocean. The location on the dune limits the types of plant that can thrive there. Beach dunes consist of the ''foredune'', the angled side which faces the ocean, the ''sand plain'' at the top of the dune, which may or may not be present, and the ''backdune'', the angled side that faces away from the ocean.

===Foredune flora=== ===Foredune flora===
Plants that thrive on the foredune must be tolerant to ], strong winds, and sand burial. Vegetation typically found on the foredune are ], ], ], and ]. Plants that thrive on the foredune must be tolerant to ], strong winds, and burial by blowing/accumulating sand. Typical vegetation includes ], ], ], and ] coarctata.<ref name=martinez/>

===Backdune flora=== ===Backdune flora===
Plants which thrive on the broad dune plain and backdune have characteristics which cause the grasses to grow together into dense vegetation termed a "Dune Mat" that firmly holds the sand dune together. Vegetation typical of the broad sand plain and backdune are ], ], ], and ]. Sometimes these species can be invasive to native plant and animal life, however in dunes where no habitat currently exists, they pose no great threat. Plants which thrive on the broad dune plain and backdune grow together into dense patches termed ''dune mat''s that hold the dune together. Vegetation typical of the plain and backdune include ] tomentosa, ], ] imbricata, and Eregeron glaucus. Introduced ] can outcompete native plants and disrupt animal life, making them formally "invasive species".<ref name=martinez/>


===Shrub stage===
After the ] species mentioned above have taken root and developed fully on the dune, the next stage of stabilization, or "shrub stage" can begin. During this phase, larger shrubs with deeper extending root systems are introduced to the habitat. Some examples are ], ], and ]. The shrub stage is usually the final phase of stabilization and may last for short or long periods of time depending on microclimatic conditions such as distance from the ], availability of ], or salt spray effects<ref>{{cite book|last=Martinez|first=M. L. |coauthors=Psuty, N. P. |year=2004 |title=Coastal Dunes: Ecology and Conservation |publisher=Springer-Verlag Berlin Heidelberg |isbn=3-540-40829-0}}</ref>. The above are ]s. After they have rooted and developed fully, a second stage, the "] stage", can begin. During this phase, larger plants with deeper root systems can be planted. Examples are ], ], and ]. The shrub stage is usually the final phase and may last for short or long periods of time depending on microclimatic conditions such as distance from the ], availability of ], or salt spray effects.<!--why would it not continue?--><ref>{{
cite book|last=Martinez|first=M. L. |coauthors=Psuty, N. P. |year=2004 |title=Coastal Dunes: Ecology and Conservation |publisher=Springer-Verlag Berlin Heidelberg |isbn=3-540-40829-0}}</ref>.


==Public and private coastal management== ==Public and private coastal management==

Revision as of 04:50, 23 September 2010

Sand dunes are common features of shoreline and desert environments. Dunes provide habitat for highly specialized plants and animals, including rare and endangered species. They can protect beaches from erosion and recruit sand to eroded beaches. Dunes are threatened by human activity, both intentional and unintentional. Countries such as the United States, Australia, Canada, New Zealand, the United Kingdom, and Netherlands, operate significant dune protection programs.

Stabilizing dunes involves multiple actions. Planting vegetation reduces the impact of wind and water. Fences catch sand and other material. Footpaths protect dunes from damage from foot traffic.

Vegetation

Ammophila or "Beachgrass"

The location on the dune limits the types of plant that can thrive there. Beach dunes consist of the foredune, the angled side which faces the ocean, the sand plain at the top of the dune, which may or may not be present, and the backdune, the angled side that faces away from the ocean.

Foredune flora

Plants that thrive on the foredune must be tolerant to salt spray, strong winds, and burial by blowing/accumulating sand. Typical vegetation includes Ammophila arenaria, Honckenya peploides, Cakile maritima, and Spartina coarctata.

Backdune flora

Plants which thrive on the broad dune plain and backdune grow together into dense patches termed dune mats that hold the dune together. Vegetation typical of the plain and backdune include Hudsonia tomentosa, Spartina patens, Iva imbricata, and Eregeron glaucus. Introduced species can outcompete native plants and disrupt animal life, making them formally "invasive species".

Shrub stage

The above are herbaceous plants. After they have rooted and developed fully, a second stage, the "shrub stage", can begin. During this phase, larger plants with deeper root systems can be planted. Examples are Empetrum nigrum, Ilex vomitoria, and Vaccinium ovatum. The shrub stage is usually the final phase and may last for short or long periods of time depending on microclimatic conditions such as distance from the shoreline, availability of groundwater, or salt spray effects..

Public and private coastal management

Often, long stretches of shoreline are not owned by a single owner, but are instead divided into segments usually owned by many separate owners. Because of this, it is sometimes difficult to stabilize an entire linear dune which may run the length of the beach due to private unwillingness to cooperate or from extended deliberation when deciding if and how to best stabilize the dune. Vegetation on private lots is chosen at the discretion of the lot owner and thus can be decided based on aesthetic appearance and personal taste rather than on traits that would best characterize the plant for that position. Because of this, dune integrity can be segmented, known as a fragmented or decoupled gradient which creates weak points in the dune that are ineffective against mitigating floods. Fragmented dune gradients are in an environmentally degraded state, however they can provide unique opportunities for nature to grow where it otherwise may not have.

References

  1. "A guide to managing coastal erosion in beach/dune systems". Scottish Natural Heritage. Retrieved December 12 2009. {{cite web}}: Check date values in: |accessdate= (help)
  2. ^ Cite error: The named reference martinez was invoked but never defined (see the help page).
  3. Martinez, M. L. (2004). Coastal Dunes: Ecology and Conservation. Springer-Verlag Berlin Heidelberg. ISBN 3-540-40829-0. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. Nordstrom, Karl F. (2008). Beach and Dune Restoration. Cambridge University Press. ISBN 978-0-521-85346-0.

See also

External links


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