B
leak, frequently shrouded in
low cloud and with rain never
far away, blanket bogs initially
appear to be desolate and
forsaken places. Yet these vast,
treeless landscapes are at last becoming
more widely appreciated. The UK holds
around 13 per cent of the world’s surviving
blanket bog, which – you might be surprised
to learn – covers just under a tenth of our
total landmass. These peaty wildernesses are
also crucial for both conserving a range of
declining species and helping to slow down
the juggernaut of climate change.
Blanket bogs began to form here about
7,000 years ago, when Britain’s climate
became wetter and warmer. The crucial
factor in bog formation is for rainfall to
be higher than the loss of water throughevaporation and via transpiration from
plants. These perennially moist conditions
favour the growth of bog mosses, such as
sphagnum, which turn into peat when
they die back.
Over time, accumulated layers of peat
gradually create a barrier between the bog
vegetation and both groundwater and the
underlying bedrock. Since the only source
of water is rainfall, the bog becomes
progressively more acidic and even
lower in nutrients.Blanket cover
Blanket bogs extend from
Devon in the south to Shetland
in the north, but are at
their most extensive and
widespread in the west andnorth. Sometimes, despite being considered
an upland habitat, they even occur down to
sea level where drainage is poor. Many
blanket bogs are considered semi-natural,
as ultimately they formed due to the forest-
felling actions of our ancestors. Tree
removal causes waterlogging, so
favours bog formation.
But certainly in Scotland’s Flow
Country, which covers swathes
of Caithness and Sutherland,
the cool, wet climate is
thought to have driven the
natural development of the
region’s immense blanket
bogs. Distinctive peaty pools,
separated by drier hummocks and
verdant sphagnum ‘lawns’, create a
complex mosaic that, from the air,18 BBC Wildlife July 2020WILDLIFE WATCHING
In his series of great places to watch wildlife in the UK, the star of BBC
One’s The One Show this month turns our attention to the bene ts of
blanket bogs for nature and the environment.MIKE DILGER’S
BLANKET BOGS
IN JULY