Linking Restoration and Ecological Succession (Springer ... - Inecol

Chapter 5 Succession and Restoration of Drained Fens 91
Table 5.1 Species composition of fen plant communities in northwestern Europe.
Plant community Common plant species
Alnion glutinosae (wet alder carrs) Alnus glutinosa, Carex elongata, Carex elata, Thelypteris
palustris
Alnion glutinosae (dry alder carrs) Alnus glutinosa, Urtica dioica, Galium aparine, Poa trivialis
Caricion elatae (tall sedge reeds) Carex acutiformis, Carex acuta, Rumex hydrolapathum, Cicuta
virosa
Scheuchzerio-Caricetea (small sedge reeds) Carex rostrata, Carex nigra, Viola palustris, Menyanthes
trifoliata
Molinietalia (wet meadows) Caltha palustris, Silene flos-cuculi, Lotus uliginosus, Myosotis
scorpioides
Lolio-Potentillion (wet pastures) Agrostis stolonifera, Glyceria fluitans, Alopecurus geniculatus,
Ranunculus repens, Juncus articulatus, Lolium perenne
Arrhenatheretalia (mesic grasslands) Festuca pratensis, Rumex acetosa, Poa pratensis, Taraxacum
officinale
(Pfadenhauer and Grootjans 1999; see Chapter 6). Widespread fen degradation
has led to the loss of many ecological services resulting in high carbon losses
to the atmosphere and nutrient additions to ground and surface waters. Furthermore,
intensive land uses have caused a decrease in the number of characteristic
and rare fen species.
Several studies have shown that because of increasing lack of interest to
use fens for agricultural purposes farmers began to abandon them in the 1970s
and more fens continue to be abandoned to this day. Abandonment involves
cessation of management inputs and active land use. A major conservation issue
in northwestern Europe arises from the abandonment of seminatural fen
ecosystems and the loss of species found in Scheuchzerio-Caricetea (small
sedge reeds) and Molinietalia (wet meadows) plant communities (Table 5.1).
The natural habitats of these species are border areas of bogs, riparian
zones of oligotrophic and mesotrophic lakes, oligotrophic discharge fens, and
undisturbed riverbanks, and these habitats are almost extinct in northwestern
Europe.
Recently, action plans for mire conservation and restoration based on the
“Guidelines for Global Action on Peatlands” (Ramsar Convention 2002) have
been developed worldwide (Bragg and Lindsay 2003, GEC 2003, Wetlands
International Russia 2003). Due to the range of sociocultural conditions and
fen characteristics in the different countries involved, strategies for these action
plans differ. In countries such as Russia with a high proportion of undisturbed
fens and bogs, protection of these areas has a high priority. By way of contrast,
in other countries such as Germany with a high proportion of degenerated mires,
the focus is on restoration activities.
In Germany and elsewhere in northwestern Europe, management is aimed at
restoring degenerated fens and can be divided into two types. The first approach
pursues the maintenance and development of species-rich, weakly degraded
fens by mowing or grazing without fertilization in combination with moderate
rewetting. The second aims to reestablish high water tables with periodic
flooding to induce a succession that restores the nutrient retention capacity of
the original fen.
Here we outline key ecosystem features (functional variables of the water, nitrogen
and carbon budget, species density and composition, and seed longevity)
operating in intact and degraded fens. The variables have been selected on the