CLM20-2 full issue-1 - Flipbook - Page 32
VIEWPOINT
Dams without beavers: could
beaver dam analogues yield
benefits in the UK?
Richard Fleming
T
his article proposes that the UK’s approach
to river restoration and flood management,
particularly in upland watersheds, has
been hampered by a very slow realisation of the
importance of beavers in shaping our landscapes
since the early postglacial period. As such, we
have come to rely on techniques, such as riparian
tree planting and the construction of leaky dams,
which, arguably, are poor replicas of features that
would have been created in abundance at times
when beavers were common. The reintroduction
of beavers to Britain is now making positive
progress, but while we wait for the animals to
become widespread throughout the countryside
I argue that we should seek to
replicate some of their beneficial
effects through the use of beaver
dam analogues (BDAs).
the wildlife in these habitats, and also provided
water and forage for cattle when European
colonists arrived. In streams fed by snowmelt,
water held back by beaver dams would inundate
valley floodplains in spring and recharge aquifers,
which helped to sustain vegetation when creek
flows were lower in summer.
The arrival of trappers, ranchers and miners
had a devastating impact on these watercourses.
Beavers were mostly eradicated by fur trappers,
and the subsequent loss of dams and wetlands
led to an increased flow of meltwater through
the valleys, causing erosion of the streambed
and the development of deeply incised channels.
Beavers in the USA’s
rivers
Beavers never went extinct
in the USA, although their
numbers were drastically
reduced from an estimated 400
million before the arrival of
European settlers to 100,000
by 1900, primarily due to
trapping for fur (see more
below), before recovering in
recent years to perhaps a tenth
of their original level (Worrall
2018). At peak abundance they
created complex valley-bottom
wetlands, which were crucial to
The BDA movement began in Bridge Creek, Oregon, and following
its success BDAs have become one of the most widely used
techniques in river restoration in the USA. Ben Goldfarb
30 Conservation Land Management Summer 2022 | Vol. 20 No. 2