Fen Management Handbook - Scottish Natural Heritage

Old trees and
dead wood
Continuous and
near-continuous
scrub/woodland
with shaded wet
conditions
Fen-edge
transitions
Seasonally
exposed marginal
sediments
Temporary pools
and areas of
seasonal flooding
Seepages and
surface flow
Saproxylic beetles of a range of families;
also saproxylic flies, including hoverflies,
craneflies, Tipuloidea, and a range of other
groups; solitary bees and wasps nesting in
dead wood, especially old beetle holes; and
a good range of phytophagous species,
with the varied structure of older trees
providing a range of hibernation sites.
Diptera, especially craneflies, but also a
range of other families; species associated
with foliage and timber will be similar to
those of more scattered trees and shrubs;
they will be generally less diverse, but will
include specialist species not found in more
open conditions.
A wide scatter of species in varied groups,
with phytophagous beetles, bugs and
moths key amongst them. Fen-edge
grassland shares some species with
calcareous grassland; the marsh moth
(Athetis pallustris) and the marsh fritillary
(Eurodryas aurinia) are both found in
relatively dry grassland.
Surface-active beetles, especially ground
beetles and rove beetles; many flies with
larvae which develop in the sediments or
stranded snails.
There are temporary pool specialists in
a number of groups, especially including
a number of uncommon water beetles;
a wider range of species tolerant of
seasonality may benefit from the absence of
fish and the oxidation of organic sediments
in temporary waters.
Various groups of flies, especially soldierflies
at unshaded seepages and craneflies
at shaded seepages.
Standing living trees with dead wood provide
the best resource, but dead standing trees
and fallen wood may be valuable. Fallen wood
on shaded seepages has a particular fauna.
Permanently or near-permanently wet
conditions are critical for high interest,
because many larvae develop in the surface
layers. All conditions from sheltered but sunny
areas amongst scrub to densely shaded wet
leaf litter support interesting species.
Transitional habitats may be anything from
open grassland to woodland. Open grassland
and grass/scrub mosaics are generally the
richest in uncommon and characteristic
species.
Bare sediments in a mosaic with or wellstructured
transition to wetland vegetation are
usually richest.
The richest specialist faunas are in unshaded
pools, but those amongst taller vegetation
or beneath shade of woody vegetation have
uncommon species of their own.
Continuous seepages over a substantial
area are best; seepages are long-lasting but
often isolated and of limited area, so historical
continuity of conditions may be critical to their
interest.
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