Fen Management Handbook - Scottish Natural Heritage

establish. The use of nurse crops is fraught with problems as plants suited to initial
establishment tend to persist as strong components of the vegetation. Examples
are reed canary grass and reedmace which will colonise silty nutritious substrates,
but continue to dominate for many years if nutrients are available. An alternative is
to use non-wetland plants, but this requires ability to control water levels precisely,
gradually flooding the area once stabilised.
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On cut-over fen peatlands in Minnesota it was found that a cover crop
made up of a mixture of oat (40%), winter wheat (40%) and annual
ryegrass (20%) increased the rate of establishment of fen plants
significantly on bare peat (Johnson & Valppu 2003).
9.10.5 Weed competition
Where previous land use was agricultural, short-term colonisation by weedy
species may have to be accepted as a phase which the fen will go through. Given
time, the excess nutrients will usually be mopped up by the vegetation and soil, and
a more stable fen community will develop. On newly created fen sites where arable
weeds threaten to outcompete desirable fen species, herbicide such as glyphosate
may be required. Approval is needed prior to herbicide use in or near water.
Disturbing the soil surface before seeding can stimulate the germination of arable
weeds. This can significantly reduce the growth of competing species but there is
no guarantee that the same species will not subsequently germinate later if the soil
is disturbed.
9.11 Post establishment management
Management is not usually required in the first year after establishment, but
thereafter most vegetation will require some management to avoid accumulation
of dead leaf litter which will reduce opportunities for colonisation by smaller fen
species. Plans should be put in place before the fen is created for the introduction
of appropriate grazing and cutting regimes, for scrub control (see Section 6: Fen
Vegetation Management) and for control of water levels (see Section 7: Fen Water
Management). Replacement of sown or planted target species may be necessary
where there has been excessive loss due to intensive grazing by livestock, birds or
other wild animals.
9.12 References
Amon, J.P., Jacobson, C.S. & Shelley, M.L. 2005. Construction of fens with and
without hydric soils. Ecological Engineering 24, 341-357.
Galatowitsch, S., Budelsky, R.& Yetka, L. 1999. Revegetation strategies for
northern temperate glacial marshes and meadows. In: W. Streever (ed.) An
International Perspective on Wetland Rehabilitation, pp. 225-241. Kluwer
Academic Publishers.
Garbisch, E.W. 2005. Hableton Island restoration: Environmental Concern’s first
wetland creation project. Ecological Engineering 24, 289-307.
Johnson, K.W. & Valppu, S.H. 2003. Fen restoration final project report. Natural
Resources Research Institute, University of Minnesota, Duluth.