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

5
Succession and Restoration of
Drained Fens: Perspectives from
Northwestern Europe
Joachim Schrautzer, Andreas Rinker, Kai Jensen, Felix Müller, Peter Schwartze,
and Klaus Dierßen
90
Key Points
1. Changes of ecosystem features are described for several stages of retrogressive
succession due to land-use intensification and secondary progressive
succession due to abandonment in European fens.
2. Agricultural intensification causes a loss of ecosystem features in fens, which
in turn reduces the capacity of fens to provide multiple ecosystem services.
3. Abandonment will not always lead to the development of the desired successional
stages, so technical manipulation such as rewetting, grazing, or
mowing may be needed.
5.1 Introduction
Fens are peat-forming wetlands that receive nutrients from upslope sources
through drainage from surrounding mineral soils and from groundwater movement
(EPA 2006). Fens are dominated by graminoids (grasses, sedges, and
reeds), which distinguishes them from bogs (the other major type of mire or
peat-forming ecosystem) that are dominated by mosses. Globally, fens are a
widespread type of wetland (Mitsch and Gosselink 2000, Fraser and Keddy
2005), covering large areas of the Holarctic boreal zone (North America, Scandinavia,
eastern Europe, and western Siberia). They are also regionally abundant
in tropical Southeast Asia, temperate South America, and New Zealand at high
elevations. Various kinds of fens receive different amounts of precipitation and
different proportions of surface water and drainage water from their catchment
areas. Water tables in pristine fens fluctuate near the peat surface. Due to these
abiotic conditions, fens supply several important ecological services, including
the ability to retain or convert nutrients. Moreover, they offer habitats for rare,
hygrophilous plants and animals.
In most countries of northwestern Europe (e.g., The Netherlands, the
United Kingdom, Denmark, Germany) more than 90% of fen ecosystems have
been transformed into meadows and pastures during the last several decades
(Rosenthal et al. 1998, Joosten and Couwenberg 2001). As a consequence, pristine
fens belong to one of the most threatened ecosystems of these countries