Environmental Engineering Reference
In-Depth Information
Ecosystem Function in Some Wetland Types a
TABLE 22.4
Methane
Production
production
(g C m 2
(mg C m 2
year 1 )
day 1 )
Type
Distribution
Nutrient retention
Freshwater marsh
Worldwide
1000-6000
45-285
Sometimes N and P sink
Tidal freshwater
Mid- to high latitude,
1000-3000
440
N and P sink
marsh
in regions with a
broad coastal plain
Riparian wetland
Worldwide
600-1300
?
Sometimes N and P sink
Northern wetland
Cold temperate climates
240-1500
0.1-90
Usually N and P sink,
of high humidity,
may be an N source
generally in Northern
Hemisphere
Deepwater swamp
Southeast United States
200-1700
1-15
a After Mitsch and Gosselink (1993). See Table 4.4 for description of wetland types.
pool is derived from trees in the wetland. The majority of the carbon fixed
by photosynthesis is released by respiration and burial, but the swamp
serves as a net source of organic carbon to the stream water.
Invertebrate communities in wetlands rely heavily on detritus from
emergent plants and algae, with macrophyte tissue being less important
(Batzer and Wissinger, 1996). In contrast to streams, shredders that are
specifically adapted to directly process plant litter are rare. Exclusion of in-
sect larvae does not decrease rates of leaf breakdown. Numerous inverte-
brates, particularly midge larvae, specialize on algal producers. Availabil-
ity of algae can limit production of these invertebrates (Batzer and
120
100
80
60
40
20
0
Boreal
Temperate
Subtropical
Wetland habitat
FIGURE 22.11
Sediment deposition rates for wetlands (data from Schlesinger, 1997).
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