274
than peat soils. These are overlain with autochthonous inputs of organic matter from the productivity of the vegetations. The chemistry of
inland marshes could be discussed in contrast to
that of ‘ombrotrophic’ bogs at one end and the
eutrophic tidal wetlands at the other. Distinctions
are related to the magnitude of nutrient and other
chemical inputs and to the relative importance of
groundwater and surface water infl ow. Inland
marshes are generally minerotrophic in contrast
to bogs.
18.6.10 Ecosystem Structure
The vegetation of FW inland marshes is generally composed of the following plants: Phragmites
australis (reed grass) , Typha spp. (cattail),
Zizania aquatica (wild rice), Scirpus validus
(bulrush), Eleocharis spp. (spike-rush), Sagittaria
spp. (arrowhead), Polygonum spp. (smartweed),
etc. It may be noted here that Cyperus papyrus
fl ourishes in marshes and on fl oating mats in
southern and eastern Africa. However, the composition of vegetation differs in the FW inland
marshes in Asia.
Invasive species are non-native plant species
which are often part of the vegetation of FW
marshes. These generally unsolicited vegetation
are popularly called ‘weeds’. Aquatic macrophytes
(AM), such as Eichhornia crassipes (water hyacinth), Pistia spp., Lemna minor (duckweed),
Salvinia molesta, S. cucullata (salvinia),
Alternanthera philoxeroides, A. sessilis (alligator
weed), Enhydra fl uctuans , Eleocharis acutangula, Echinochloa stagnina, Scirpus eriophorum,
Vallisneria spiralis, Polygonum spp., Euryale
ferox and Ipomoea spp., have been invading
mainly the tropical and subtropical regions of the
world. E. crassipes is considered as a nuisance
weed almost throughout the world mainly because
of its prolifi c growth rate (Penfound and Earle
1948 ; Dey and Kar 1989 ; Kar 2007 ). Conversely,
the plant has been praised for its ability to sequester nutrients and other chemicals from the water
and has often been proposed as part of natural
wetlands to purify wastewater (Ma and Yan 1989 ).
There could be various theories about alien AM.
However, there is some validity to the concept
that disturbed ecosystems are most susceptible to
biological invasions (Mitchell and Gopal 1991 ).
Inland marshes are generally detrital ecosystems. It is probable that small decomposers, such
as nematodes and enchytraeids, are relatively
more important than larger decomposers in
marshes compared to terrestrial woodlands.
Further, invertebrates are said to be the main
links between the plants and their detritus on the
one hand and animals, such as fi sh, ducks and
other birds and even several mammals, on the
other (Weller 1994 ). Birds, particularly the waterfowls, are abundant in FW marshes, mainly
because of abundant food and proper resting,
nesting and breeding grounds. Certain mammals,
notably the muskrat ( Ondatra zibethicus), inhabit
the FW marshes. However, the abundance and
diversity of fi sh in FW marshes is dependent on
the depth of the marsh and openness of the system to large rivers or lakes (Derksen 1990;
Stephenson 1990 ; Kar 2007 ). Concomitantly, the
amphibians are an important group of organisms
in FW marshes, often serving as the link between
insect populations and wading birds, mink, raccoons and some fi sh in complex food webs.
18.6.11 Ecosystem Function
and Models
The primary productivity of inland marshes has
been reported in a number of studies. Estimates
are generally quite high. Some of the best
estimates come from fi sh ponds in former
Czechoslovakia. They generally take into account
underground as well as above-ground production.
Consumers play a signifi cant role in detrital cycle.
Various models have investigated the dynamics of FW marshes whether for predicting wildlife use or nutrient dynamics. Metzker and Mitsch
( 1997 ) tested the concept of self-design in a
18 Classifi cation of Wetlands
than peat soils. These are overlain with autochthonous inputs of organic matter from the productivity of the vegetations. The chemistry of
inland marshes could be discussed in contrast to
that of ‘ombrotrophic’ bogs at one end and the
eutrophic tidal wetlands at the other. Distinctions
are related to the magnitude of nutrient and other
chemical inputs and to the relative importance of
groundwater and surface water infl ow. Inland
marshes are generally minerotrophic in contrast
to bogs.
18.6.10 Ecosystem Structure
The vegetation of FW inland marshes is generally composed of the following plants: Phragmites
australis (reed grass) , Typha spp. (cattail),
Zizania aquatica (wild rice), Scirpus validus
(bulrush), Eleocharis spp. (spike-rush), Sagittaria
spp. (arrowhead), Polygonum spp. (smartweed),
etc. It may be noted here that Cyperus papyrus
fl ourishes in marshes and on fl oating mats in
southern and eastern Africa. However, the composition of vegetation differs in the FW inland
marshes in Asia.
Invasive species are non-native plant species
which are often part of the vegetation of FW
marshes. These generally unsolicited vegetation
are popularly called ‘weeds’. Aquatic macrophytes
(AM), such as Eichhornia crassipes (water hyacinth), Pistia spp., Lemna minor (duckweed),
Salvinia molesta, S. cucullata (salvinia),
Alternanthera philoxeroides, A. sessilis (alligator
weed), Enhydra fl uctuans , Eleocharis acutangula, Echinochloa stagnina, Scirpus eriophorum,
Vallisneria spiralis, Polygonum spp., Euryale
ferox and Ipomoea spp., have been invading
mainly the tropical and subtropical regions of the
world. E. crassipes is considered as a nuisance
weed almost throughout the world mainly because
of its prolifi c growth rate (Penfound and Earle
1948 ; Dey and Kar 1989 ; Kar 2007 ). Conversely,
the plant has been praised for its ability to sequester nutrients and other chemicals from the water
and has often been proposed as part of natural
wetlands to purify wastewater (Ma and Yan 1989 ).
There could be various theories about alien AM.
However, there is some validity to the concept
that disturbed ecosystems are most susceptible to
biological invasions (Mitchell and Gopal 1991 ).
Inland marshes are generally detrital ecosystems. It is probable that small decomposers, such
as nematodes and enchytraeids, are relatively
more important than larger decomposers in
marshes compared to terrestrial woodlands.
Further, invertebrates are said to be the main
links between the plants and their detritus on the
one hand and animals, such as fi sh, ducks and
other birds and even several mammals, on the
other (Weller 1994 ). Birds, particularly the waterfowls, are abundant in FW marshes, mainly
because of abundant food and proper resting,
nesting and breeding grounds. Certain mammals,
notably the muskrat ( Ondatra zibethicus), inhabit
the FW marshes. However, the abundance and
diversity of fi sh in FW marshes is dependent on
the depth of the marsh and openness of the system to large rivers or lakes (Derksen 1990;
Stephenson 1990 ; Kar 2007 ). Concomitantly, the
amphibians are an important group of organisms
in FW marshes, often serving as the link between
insect populations and wading birds, mink, raccoons and some fi sh in complex food webs.
18.6.11 Ecosystem Function
and Models
The primary productivity of inland marshes has
been reported in a number of studies. Estimates
are generally quite high. Some of the best
estimates come from fi sh ponds in former
Czechoslovakia. They generally take into account
underground as well as above-ground production.
Consumers play a signifi cant role in detrital cycle.
Various models have investigated the dynamics of FW marshes whether for predicting wildlife use or nutrient dynamics. Metzker and Mitsch
( 1997 ) tested the concept of self-design in a
18 Classifi cation of Wetlands