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State 4 - disturbed shingle surface
Definition: A state where the depth of the disturbance/excavation is
at or above the water table
Human
action can seriously damage or disrupt this surface vegetation. Typically
large expanses of shingle provide a ready source of accessible gravel for a
variety of building purposes. Excavation
of the shingle destroys the surface vegetation and any associated interests.
The extent and nature of any restoration depends on whether the excavation is
above or below the water table. Disruption of the shingle surface can damage
or destroy the vegetation. In this state, as the surface is excavated the void
does not fill with water and remains either dry or damp depending on the depth
of disturbance or excavation. The structure of the shingle (ridges and lows),
vegetation and associated animals is almost always lost. However although the
original surface is lost, shingle remains the dominant
substrate.
NB. A distinction can be made here between disturbed shingle surfaces which
remains dry and those where the surface is close to the water table. The opportunities
for good plant establishment and growth affect the State
4 values. In the former situation colonisation of the 'dry' shingle
may be slow. For the latter, species-rich secondary communities can develop
such as those at Kingston (Spey Bay Shingle,
Annex 08) and at Dungeness
(Annex
05) . This can occur both within the body of the shingle structure
as well as at the edges of sites and may increase the overall biodiversity (see
Chapter 9.4.1 Doody 2001).
 .
Caption:
Disturbed (excavated shingle) at Spey
Bay. The excavations took place in the
1940s, note the 'tank traps'. The vegetation has since recovered and includes
communities with black bog-rush Schoenus nigricans (in the foreground)
a plant of damp places.
| General guidance: Where disturbance or excavation remains above
the water table for most of the time then vegetation can, potentially at
least, be restored on the shingle surface, taking the shingle from State
4 to State 3. 'Dry' shingle stable communities are likely to
take a considerable time to revert to their natural state. From this state
it is also possible to re-create shingle habitat, unlike State
5 where excavation takes place to below the water table leaving
the void filled with water. |
References
Doody, J.P.
2001.
Coastal Conservation and Management: an Ecological Perspective. Kluwer, Academic Publishers, Boston, USA, 306 pp.
Conservation Biology Series, 13
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