|
Cliff-top grassland - loss to agriculture
In many areas more intensive farming methods have replaced pastoral use of
the land, with a reduction in grazing
pressure. At the same time the rich vegetation associated with cliff
tops has been lost directly through ploughing
and planting of arable crops, or reseeding of pastures. This has also destroyed
some of the best examples of maritime heath in areas such as on Orkney, in Scotland.
At other sites semi-natural calcareous cliff-top grassland has been similarly
effected, such as on the cliff tops at Beachy
Head. Additional problems occur associated with the use of the land
for arable crops, including localised eutrophication caused by fertiliser run-off
which encourages coarse, vigorous 'weed' species at the expense of the maritime
species. Agricultural land drains discharging on the cliff face may also cause
local acceleration of erosion.
Quantification of these changes are very difficult because of the absence of
good base line surveys. However, comparison of the 1st Edition of the Ordnance
Survey 6" (1:10,560) County Series maps of 1889 with the more recent 1:10,000
of 1963 have been used to provide some insight into the change in use of the
coastal cliff-tops of North Cornwall from Lands End to the Devon border (Bennett
1984). The two series of maps show that there has been an overall reduction
of 21% in the area of 'rough pasture' or 'scrub' as defined on the 1st edition
map. A similar pattern of loss appears to have occurred on the South Gower coast
in Wales.
Comment: Areas such as Beachy
Head where some vegetation still remains at the edge of the cliff,
losses are exacerbated as the chalk cliffs recede. It seems that in time the
combined effects of the two processes could result in the near total destruction
of important cliff-top grassland in parts of south east England. This makes
restoration from arable land
of this habitat particularly important.
References
Bennett, T.
1984.
Coastal/Marine Habitat Change Survey of North Cornwall.
Nature Conservancy Council, Peterborough.
|
