Fen Management Handbook - Scottish Natural Heritage

The species listed in Appendix IV which characterise a wide range of types of
fen vegetation likely to establish in different conditions should be viewed as the
minimum species required. Phragmites australis – Urtica dioica fen has been
left out because of its low value and high cover of the invasive and undesirable
nettle. A number of montane/upland fen vegetation types have also been left out,
as the opportunities for creating these types of fen habitat will rarely occur. The
sub-communities and constancy tables detailed in Rodwell (1995) give further
information on characteristic species and requirements.
9.9.2 Options for establishing fen vegetation
Options for establishing plants on a bare substrate include introduction of seed,
plug plants and spreading hay as a seed source, but experience from a wide range
of different sites has demonstrated that use of pre-grown plugs or vegetative
cuttings, tussocks or rhizomes are the most reliable means of establishing many
species of fen plant (Amon et al. 2005, Galatowitsch et al. 1999). The rhizomatous
nature of many fen species helps achieve fairly rapid cover, which is desirable
where invasive species are a threat. A high intensity sowing or planting of the target
species will not necessarily prevent the establishment of weedy species, but may
suppress their growth.
Hydroseeding (i.e. spraying a specially mixed slurry comprising water, seed, mulch,
fertiliser and a binder in one operation) over large areas is likely to be prohibitively
expensive and have a low degree of success because of the poor germination rate
of many wetland species.
9.9.3 Site preparation and timing of vegetation establishment
If the site substrate contains a high proportion of peat or organic matter, especially
after peat extraction, the peat may be dry and oxidised. To aid plant establishment,
it may be necessary to raise the water level to the surface or above, which will
reduce the establishment of rank weedy species and favour more diminutive
wetland plants. Design of sluices, bunds and other water control structures should
take into account the need to maintain this elevated water level in perpetuity.
9.9.4 Seeds
Some seed merchants supply native wetland plant species of UK provenance, but
the range is limited and large quantities are costly. Consult Flora Locale (www.
floralocale.org) for further information and guidance. Establishing a few plug plants
in suitable areas and allowing these to spread can be more cost effective than
broadcasting seeds.
Seeds of some families of wetland plant germinate readily (e.g. Asteraceae
Caryophyllaceae Brassicaceae and Poaceae), whilst others may only germinate
after stratification, which involves subjecting the seeds to alternate periods of
freezing and warmer temperatures.
Propagating Carex from seed in a nursery is notoriously difficult. In one study
the highest rate of germination of bottle sedge seeds was around 20% for fresh
seeds whilst several other species required stratification (Budelsky & Galatowitsch
1999). Cold, moist storage of sedge seeds improves germination, but it is easier to
propagate sedges from rhizomes or tillers.
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