Restoration of mires and wet grasslands - Restoration Ecology - page 120

Diggelen 1998). Soil degradation consists of irrevers-
ible changes in the structure of organic matter, which
in extreme cases can become water repellent in dry
periods and after rewetting does not have the ability
to retain water as much as less-decomposed peat
types. The reduced capillary rise from the groundwater
can cause severe drought in the topsoil even when the
groundwater tables are relatively high (Schmidt 1995,
Schrautzer et al. 1996, Succow & Joosten 2001).

area from canals and agricultural drainage ditches. A
proper way to deal with the complex relationships in
the water systems and human exploitation (drinking
water, navigation and tourism) is to practise integral
water management. This includes management of a
chain of problems in a specified watershed, such as
pollution of underwater sediments, local and regional
input of pollutants, shoreline management, manage-
ment of water levels in the whole catchment, abstrac-
tion of drinking water as well as industrial use of
groundwater.
Not all terrestrialization mires need management. In
oligotrophic lakes terrestrialization soon leads to the
development of bog or fen vegetation. In eutrophic
lakes, however, terrestrialization can lead to mono-
cultures of reed ( Phragmites australis ), especially
when flooding with eutrophic surface water occurs. In
such cases, reed cutting, either in summer or during
the winter, can be a practical measure to increase bio-
diversity in such mires.
Beltman et al. (1995) reported on attempts to
regenerate rich fen vegetation by sod cutting to
remove the existing vegetation or digging of shallow
ditches to remove the acid-precipitation surplus. They
showed that rich fen vegetation survived after 2 years
only in the areas where both measures had been
applied and even then this was only successful in areas
with upward groundwater movement (Beltman et al.
2001).
Excavating new turf ponds is an expensive way of
starting terrestrialization anew, and should only be
practised when the new turf ponds can be supplied
with very clean water, preferably groundwater (Beltman
et al. 1996). However, not all plant species can reach
such restoration areas, since they are usually isolated
from the surrounding watercourses. Connecting peat-
cut areas with larger surface-water systems may be
positive for dispersal of propagules, but is often not
an option when the surface-water system is influ-
enced by intensive agricultural production areas.

Transplantation

Transplantation of threatened (meadow) vegetation to
botanical gardens already has a long tradition in Ger-
many. A well-documented example of fen meadow
transplantation in Switzerland was given by Klötzli
(1987), who monitored vegetation changes in trans-
planted turfs at the Zürich national airport, where
nutrient-poor fen meadow vegetation had to make
way for a new runway. The turfs were transplanted
to a newly prepared site next to the runway. Lessons
to be learned from this project were that in wetlands
it can take several decades before the species com-
position of a transplanted vegetation changes, but that
eventually such an ecosystem has to change, because
the hydrological conditions of the newly constructed
site are always different from the original site.
Hutchings and Stewart (2002) also question the suc-
cess of transplantations of vegetation turfs in dry
calcareous grasslands. Transplantation of individual
species to restoration sites has been applied in
restoration projects on a large scale (Perrow & Davy
2002b) and is generally accepted as a tool to speed
up the restoration process or to test whether or not
the ecological conditions of a restoration site meet the
requirements of the target species (van Duren et al.
1998; see also Chapter 7).

9.5.3 Restoration of terrestrialization
mires

9.5.4 Restoration of spring mires Restoring terrestrialization mires often starts with

improving the water quality of the lakes. Technical
solutions, such as sewage-treatment plants, can
restore the oxygen balance in surface water and can
decrease the nutrient concentrations. In most cases
this is not enough, since a large amount of nutrients
originates from diffuse sources that can enter a nature

Most spring-mire systems in Europe cannot be restored
anymore since the original peats and sediments have
often disappeared and the water discharge sites have
shifted to lower sections of the spring system and
cannot be directed upwards. The replacement commun-