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Over the past decade, climate change has already had a noticeable
impact on our flora, most experts now agree. But the situation
is complex, and the future difficult to predict. Over the long
term, many of our northern or wetland species may find it impossible
to cope with novel weather patterns, including summer droughts
and sudden storms (see Box). But at the same time, the very mild
wet winters in the south of England are introducing a more “Mediterranean”
aspect to our climate, which evidently suits a variety of southern
species.
Perhaps the most phenomenal example so far has been the reappearance
of sea knotgrass Polygonum maritimum, almost extinct for
many years except in a few spots on the south coast of Cornwall.
It reappeared at Hengistbury near Christchurch in Hampshire. First
found here by W. Bomer in 1836 “on the sandy shore towards
Mudeford”, it was not seen here again until 1990 when one
strong plant appeared. Two years later, there were 49 plants,
and in 1993 more than 140 individuals, stretching over some 200
metres of the south end of the Mudeford Spit.
In 1995 Paul Bowman also found 15 plants at the eastern end of
the Hampshire coast at Sandy Point, Hayling Island. Five years
later this population numbered more than 200 plants. In 1992,
it also appeared at Brighton Marina in Sussex, although this colony
was subsequently destroyed by a storm in 1996. Over the past six
or seven years it has appeared in quantity at West Wittering in
Sussex and at Norton Spit in the Isle of Wight, and has increased
in south Cornwall.
These records of a truly “Mediterranean” species give
hope that another southern plant, the sea cotton-weed Otanthus
maritimus, may reappear on south Britain’s coastline,
where it was recorded in the 17th and 18th centuries. It is still
in south-east Ireland and is abundant on the sandy coast east
of Cherbourg in Normandy only about 40 miles south of our south
coast. Surely it is only a question of time before it re-colonises
the south English coast.
The behaviour of some of our southern orchid species has also
been remarkable in recent years. Until the 1980s many botanists
believed that such species as the two spider-orchids - Ophrys
sphegodes the early spider-orchid, and O. fuciflora
the late spider-orchid - were on the way out in Britain. The Kent
botanist Eric Philp said to me in about 1985 that he doubted if
the latter species would survive into the 21st century. Since
then, the early spider orchid has not only increased in many of
its known sites, but appeared in completely new ones as at Dungeness
Beach and Sandwich Bay dunes. It is now more plentiful in Kent
and East Sussex and south-east Dorset, than I have ever seen it
in 60 years field work.
In this case, the creation of the artificial undercliff, Samphire
Hoe, west of Dover, as a means of disposing of the spoil
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MONARCH ventures into “climate
space”
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How will climate change affect Britain’s
species and habitats? A new report investigating this
hot topic is entitled Modelling Natural Resource Responses
to Climate Change, MONARCH for short. For a range of species,
it uses predictions from climate change models to compare
current and predicted future “climate space”-
that is, the geographical area where a given species could
potentially live if climate were the only factor influencing
distribution.
Climate change will present threats for some species and
opportunities for others. By and large, northerly species
will lose suitable climate space, while southerners could
potentially expand northwards. According to MONARCH, species
most at risk are those currently limited to northern Britain
including twinflower Linnaea borealis and globeflower
Trollius europaeus. Baltic bog moss Sphagnum
balticum is another potential casualty among the Back
from the Brink species, since it is more at home in the
colder regions of Scandinavia and the Baltic than in Britain.
Worse, there is no guarantee that a species will actually
be able to move to new areas, however hospitable their
climates may become. Difficulties in dispersal and colonisation
could further limit the availability of suitable habitat,
with serious implications for our more northern plants.
For more information on the latest research
see the website www.ukcip.org.uk
Dr Jenny Duckworth is Plantlife’s Biodiversity
Research Manager. |
from the excavation of the channel tunnel has created a wonderful
new site of chalk mixed with clay. The warm, sheltered, almost
frost-free habitat so formed has been colonised by many plants
from the cliff above in the past ten years. Ophrys sphegodes
now has a population here of more than 1000 plants (2001) on is
a site that was under the sea until recent years. Many of the
plants are not only very tall and vigorous, but are setting abundant
seed.
The late spider orchid has also shown a remarkable expansion in
numbers. The White Cliffs Project at Folkestone, funded by the
tunnel works, has restored much of the former late spider orchid
habitats about Folkestone, by clearing scrub from deteriorating
downlands, and provided fencing enabling grazing to take place
again after some 40 years in several places. This orchid is now
more plentiful than at any other time in the last 60 years, with
at least five populations on Folkestone Downs and at least four
populations on the Wye Downs NNR. Undoubtedly the “White
Cliffs” management work has helped greatly, but I doubt if
this would have occurred without the change to mild wet winters
of recent years.
All the same, it is quite clear that as time goes by, our more
exacting species will only survive in the limited areas of properly
managed nature reserves. The future existence of our most interesting
plants may well depend on such places, which is why Plantlife's
growing network of reserves is so important..
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