Environmental Engineering Reference
In-Depth Information
3.2. Secondary Alkali Marshes
Secondary stands of alkali marshes are generally formed by artificial modification of
water balance (river regulation works, establishment of drainage canals or irrigation), which
generates secondary salinisation processes in the soil. These secondary stands have generally
the same species pool as
Schoenoplectus
or
Bolboschoenus
marshes and alkali reeds, but the
ratio of salt-tolerant species is lower than in pristine stands. A special type of secondary alkali
marshes occurs in floodplains, which is generally a result of secondary salinisation process
due to river regulations. These secondary alkali marshes are often invaded by the shrub
Glycyrrhiza echinata.
These wetlands are situated on alluvial plains or on the banks of rivers
Tisza and Körös. They are generally inundated and have a slight alkali character. Typical
monocot species are
Glyceria maxima, Phalaroides arundinacea, Phragmites australis
and
Schoenoplectus lacustris.
These habitats harbour several generalist wetland species such as
Iris pseudacorus, Lycopus
spp.
, Lysimachia nummularia
and
Lythrum virgatum
. Floodplain
alkali marshes usually harbour several ruderal species, such as
Amorpha fruticosa, Cirsium
arvense, Elymus repens
and
Rubus caesius
.
4.
T
RADITIONAL
M
ANAGEMENT AND
T
HREATS
4.1. Traditional Management
Alkali marshes are characterised by astatic water regime and saline soils. When these
edaphic and hydrological conditions are provided, alkali marshes do not require special
management techniques for their maintenance. However, the use of traditional and alternative
management techniques can enhance habitat quality and assist in sustaining mosaic habitat
patterns.
Alkali marshes had an important role in traditional land use practices in the past.
Generally they were utilised as pastures for free ranging breeds
.
Alkali marshes were mostly
grazed by Hungarian grey cattle and water buffalo (Bartosiewicz 1997). Their grazing and
trampling formed diverse mosaic structures of grazed and non grazed patches and even
provided open muddy surfaces harbouring Nanocyperion species.
Bolboschoenus
stands were
utilised as pastures for traditional swine breeds such as mangalitsa swine. Mangalitsa swine
especially favours the roots of
Bolboschoenus
; they create a mosaic vegetation structure in
Bolboschoenus
stands and also provide open muddy surfaces by digging up roots. Besides
grazing, alkali marshes provided several additional ecosystem services in the past, including
fishing, hunting and providing edible and medical plants.
4.2. Threats
The main threat for alkali marshes is the alteration of their water balance. Due to large-
scale river regulation works of the 19
th
century and the local drainage activities of the 20
th
century the formerly regular floods disappeared and the water table decreased at the regional-
scale (Varga et al. 2013). This resulted in an irreversible loss of alkali marshes in several
