"Nature Guide Journal"
24 January 2002
From our back yards to the front page of our newspapers,
wetlands have been especially visible lately.
Fed by rain, river, or sea, "wetlands" are places
where the water table is at or near the surface of the land. A wetland is
saturated with water or covered by shallow water for prolonged or regularly
occurring periods. Though many people confuse the terms, a "swamp"
is a wetland with trees or shrubs.
The heavy soaking limits the plant life to species specially
adapted to constant or periodic drowning. The extensive water causes the
development of characteristic soils.
Improved science has brought us a long way from thinking of
wetlands as useless because they're "too thick to drink and too thin to
plow." Long thought to be "wastelands," we now know wetlands
perform many functions vital to people.
Throughout the watershed, wetland soils and plants catch and
hold floodwaters, then slowly disperses them. It is estimated that an acre of
wetland can store as much as 6,000 cubic meters (about 7,800 cubic yards) of
floodwater. Gradually released from the wetland, the water steadily
replenishes the stream or river system or recharges the underground aquifer.
The water slows as it enters the wetland, causing water-borne
materials to settle out onto the wetland soils. Too much sediment in open
water can obscure light and smother animals; too much nitrogen and phosphorous
in open water ecosystems can over-fertilize the plants and throw the system's
balance out of whack. However, certain levels of organic nutrients that are
troublesome in open water can be enriching in the wetland soil environment:
wetland plants take up the "overabundant" nutrients, drawing them
into the food web.
Wetland plants can remove germs, some heavy metals, and even
some other toxic materials from the water. This cleaning ability has led
particular human communities, from Arcata, California to Calcutta, India, to
develop natural-system wetlands as part of their sewage treatment systems.
Wetlands produce and recycle huge numbers of plants and
animals and vast amounts of organic material—some of which is passed on to
adjacent land and water habitats. In wetlands that are seasonally or
periodically flooded, the organic material is regularly carried downstream to
other parts of the watershed, perhaps traveling great distances.
Further, wetland ecosystems are critical permanent or nursery
habitat for myriad species of plants and animals. Two-thirds of marine fish
species eaten by people—including salmon, clams, oysters, and crab—depend
on coastal wetlands at some stage of their lives. The diet staple for over 3
billion people, rice, is a wetland plant. Taking a larger view: all freshwater
ecosystems combined cover only about 1% of the earth's surface, but hold more
than 40% of the planet's plant and animal species.
Wetlands along the edges of open waters buffer the shoreline
from erosion.
World-wide, wetlands mitigate the effects of climate change.
Wetlands even play a big part in recreation for fishers, birdwatchers,
boaters, and more.
Wind rippling verdant grasslands; raucous calls of migrating
waterfowl; meandering sloughs teeming with life: wetlands serve our spiritual
needs as well as our physical ones.
To commemorate the inestimable value of wetlands, next
Saturday, 2 February 2002, has been designated "World Wetland Day"
by the Ramsar Convention on Wetlands. The Ramsar Convention is an
intergovernmental treaty that provides a framework for world-wide cooperation
for the conservation and wise use of wetlands. (Many of the details in this
article were obtained from the Ramsar
Convention's informative website.)
In the Coos County area, World Wetland Day will be observed
Monday through Friday of next week at South Slough National Estuarine Reserve,
near Charleston.
