24 Wetland Futures Report 2013: The Value of Healthy Wetlands
The field trip – Askham bog
Background and management
Askham Bog is the remnant of valley mire that formed
between 7,000 and 10,000 years ago between two ridges
of glacial moraine just south west of the city of York.
Base rich ground water draining from the moraines has
led to the development of a rich fen community, which
demonstrates all the stages in the succession to fen
woodland. Other areas show characteristics of degraded
raised bog through to acidic woodland.
Askham Bog is a unique meeting place for the wetland
plants and animals from the south and east on the one
hand, and the north and west on the other. Great fen
sedge, characteristic of the East Anglian fens grows
mingled with bog myrtle, a plant of the mires of the
Atlantic coastline. Other specialities include royal ferns,
water violet and an array of rare sedges such as the
gingerbread sedge.
The quality of insect life outshines even that of its plants.
Some of the beetles and flies are found in very few
other places. The nationally rare marsh carpet and the
dentated pug moths feed on meadow rue and yellow
loosestrife respectively. And red data book diving beetle
Agabus undulatus
thrives here. It is designated a Site
of Special Scientific Interest (SSSI) for its botanical and
invertebrate importance.
Management of the reserve focuses on maintenance
of the open fen areas through continued work to
control scrub regeneration and encourage diversity
through grazing and mowing. The second main strand
of management focuses on open water. Many of the
invertebrate and botanical species important at Askham
Bog rely on the wetland habitat. A programme of ditch
works ensures there are a variety of stages of open water
habitats. As well as maintenance of the two ponds and
scrapes created in Middle and Near Wood. Patches of
woodland remain in Near and Middle Wood and these
and the expanse of woodland in Far Wood are managed
as a non-intervention area.
Management Issues
and ecosystem services
Water quantity/flood storage
Askham Bog has historically been managed with its
nature conservation interest in mind, in accordance with
the SSSI citation. Over the last 15 years around one third
of the wooded area of the reserve has been felled to
increase the extent of the nationally important fen area.
Does this management conflict with ecosystem services
the bog could provide? Would a more wooded landscape
help slow water movement through the Bog? Askham Bog
sits in the bottom of its catchment area and spends much
of a normal winter under several inches of water, providing
an important flood storage role. Water flowing from the
Bog eventually drains into the Ouse - well known for its
flooding issues in central York.
Water quality
Holgate beck, which flows along the northern boundary
of the reserve, has received effluent from local sewage
treatment works in the past. Through the Asset
Management Plan processes this has been reduced so
that output from the sewage works only occurs at times
of peak storm flow. However, influence is still seen on the
reserve boundaries close to the beck, where nettles reflect
the nitrification here. These water quality issues have
caused Yorkshire Wildlife Trust to install bunds to prevent
this water from entering the central dykes of the reserve.
Are there other ways we could help reduce the nutrient
load of this water? Constructed wetlands? Reedbeds
filtration?
Recreation and spiritual value
Access around the central part of the reserve is very good
with a boardwalk accessible to all. However, this is only
a small part of the reserve and there is much more to
explore. Are we providing enough opportunity for visitors
to get recreational and spiritual benefits from visiting the
reserve? What could we do to improve access without
compromising the sensitive habitats and wildlife there?
Group 1
Conference delegates enjoying the field trip to Askham Bog
photo: Hannah Freeman
