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