(^82) an environmenTal hisTory of Wildlife in england
hares-foot clover (Trifolium arvense), wall-pepper (Sedum acre), and ivy-
leaved toadflax (Cymbalaria muralis): in early blast furnaces limestone was
added to the flux and this, combined with impurities in the iron, produced a
lime-rich habitat in an otherwise base-poor area.
Dumped waste, in old quarries or in other contexts, often produced
unusual plant communities. Research in the 1970s into the distribution of
marsh orchids (Dactyllorhiza spp) in south-west Lancashire, Merseyside
and Greater Manchester revealed that 25 out of the 35 sites where the plants
occurred were ‘entirely man-made or grossly modified by man’, many in
fact being places where highly alkaline waste had been dumped.^40 All are
relatively recent sites, of later nineteenth or twentieth-century date, but
the patterns of colonization they display will again have been paralleled at
earlier periods in areas where lime waste, blast furnace slag with boiler ash,
and colliery washery waste and slurry were dumped. Colonization by the
orchids, which otherwise occur in the area only on coastal sites, appears to
have been rapid – within 15 years in some cases. A number of other rare
plants characteristic of coastal locations also occur in these places, such as
Pyrola rotundifolia subs Maritima.
A particularly important form of post-industrial habitat are the so-called
calaminarian grasslands which, as already noted, are associated with the
extraction of lead, silver, zinc, barium, chromium, copper and fluorspar. The
community develops either on old spoil or (more rarely) in river gravels
downstream from areas of mineral workings, where heavy metals have
been re-deposited. Succession is slowed or even arrested altogether by the
high levels of toxicity, and the open-structured plant communities which
develop include a range of lichens and bryophytes, and such vascular plants
as spring sandwort (Minuartia verna), alpine pennycress (Thlaspi arvense),
and particular varieties of thrift (Armeria maritime) and bladder campion
(Silene maritime) which have adapted genetically to the hostile conditions.^41
In England, such communities are mainly found in the Pennines and western
Cumbria. They characteristically occur on networks of pits and spoil
heaps crossing the countryside in lines called ‘rakes’, following the mineral
veins. Some are of sixteenth- and seventeenth-century date but most were
created in the eighteenth and nineteenth centuries.^42 This is not an entirely
anthropogenic community, for where mineral veins lay close to the surface, it
would have occurred naturally. But in England at least most extant examples
are associated with spoil. Calaminarian grasslands are now subject to their
own Biodiversity Action Plan, such is their rarity and importance. Apart
from being threatened by ‘restoration’ to recreational use, the community is
inherently unstable because, while soil toxicity reduces the rate of succession,
it seldom halts it completely. Many of these plant communities are now
being engulfed in birch, gorse and other scrub.
Indeed, in most contexts the distinctive communities created by industrial
processes were short-lived. Areas of extraction or dumping did what any
abandoned area of land will do if left to its own devices – regenerate to
elle
(Elle)
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