493
D. Kar, Wetlands and Lakes of the World,
DOI 10.1007/978-81-322-1023-8_23, © Springer India 2013
23.1 Wetlands of North America
Some authors classify wetlands into seven major
types, namely, (a) tidal salt marshes, (b) tidal
freshwater marshes, (c) mangrove wetlands, (d)
freshwater marshes, (e) peatlands, (f) freshwater
swamps and (g) riparian wetlands. There are
numerous and diverse types of wetlands in North
America. But drastic changes had occurred since
the presettlement times. Approximately 53 % of
the original wetlands in the coterminous USA
has been lost mainly because of drainage and
other human activities. However, the greatest
area of wetland losses, on a regional basis, had
occurred in the lower Mississippi alluvial plain
and the Prairie Pothole Region of the North
Central States. But the estimates of the original
wetlands in the lower 48 states vary around 89
million ha. Nevertheless, the present wetland
area has been quite accurately estimated as 42
million ha. Out of this, c 80 % are inland wetlands and 20 % are coastal. Current measures of
the wetland area in Alaska are about 71 million
ha. On the other hand, Canada has an estimated
127 million ha of wetlands which is more than
the total wetland area in the USA (including
Alaska). Canada had not suffered the same rate of
wetland loss as has the lower 48 states of the
USA. However, high wetland loss rates of
70–90 % are said to be common in the most populated southern Ontario. On overall basis, with
2.4 million km
2 , North America has about 30 %
of the world’s wetlands.
There had always been an abundance and
diversity of wetlands in North America. However,
the wetlands, which exist now, may represent
only a fraction of those seen by the early settlers
as they had advanced across the continent about
200 years ago. The salt marshes and the mangroves, perhaps, acted as unsurmountable barriers to many of the explorers and settlers as they
had arrived in the New World. Soggy marshes
and the wet meadows, probably, had evoked both
trepidation and awe amongst the fi rst settlers as
they had passed through the hills and mountains
of the east and had entered the level prairie of the
midwest. Peatlands and prairie potholes possibly
had to be the common sights to those who had
settled in the northern plains in what is now
Michigan, Wisconsin, Minnesota, the Dakotas
and the central Canadian provinces. Further, the
early explorers and settlers on the lower
Mississippi River or the rivers in the SE coastal
plain must have been marvelled at the mammoth
structures of many of the old-growth cypress
swamps and bottomland hardwood forests which
had lined those rivers. All these wetlands,
undoubtedly, had played a signifi cant role in the
development of North America. It is important to
note here that wetlands had been accepted as part
of the landscape in the early period of settlement
and there was, perhaps, little or no desire or capability to change their hydrologic conditions to
any degree. It had been reported that ‘the great
natural wealth’ which had originally made the
growth and development of the USA possible
23
Wetlands of America
D. Kar, Wetlands and Lakes of the World,
DOI 10.1007/978-81-322-1023-8_23, © Springer India 2013
23.1 Wetlands of North America
Some authors classify wetlands into seven major
types, namely, (a) tidal salt marshes, (b) tidal
freshwater marshes, (c) mangrove wetlands, (d)
freshwater marshes, (e) peatlands, (f) freshwater
swamps and (g) riparian wetlands. There are
numerous and diverse types of wetlands in North
America. But drastic changes had occurred since
the presettlement times. Approximately 53 % of
the original wetlands in the coterminous USA
has been lost mainly because of drainage and
other human activities. However, the greatest
area of wetland losses, on a regional basis, had
occurred in the lower Mississippi alluvial plain
and the Prairie Pothole Region of the North
Central States. But the estimates of the original
wetlands in the lower 48 states vary around 89
million ha. Nevertheless, the present wetland
area has been quite accurately estimated as 42
million ha. Out of this, c 80 % are inland wetlands and 20 % are coastal. Current measures of
the wetland area in Alaska are about 71 million
ha. On the other hand, Canada has an estimated
127 million ha of wetlands which is more than
the total wetland area in the USA (including
Alaska). Canada had not suffered the same rate of
wetland loss as has the lower 48 states of the
USA. However, high wetland loss rates of
70–90 % are said to be common in the most populated southern Ontario. On overall basis, with
2.4 million km
2 , North America has about 30 %
of the world’s wetlands.
There had always been an abundance and
diversity of wetlands in North America. However,
the wetlands, which exist now, may represent
only a fraction of those seen by the early settlers
as they had advanced across the continent about
200 years ago. The salt marshes and the mangroves, perhaps, acted as unsurmountable barriers to many of the explorers and settlers as they
had arrived in the New World. Soggy marshes
and the wet meadows, probably, had evoked both
trepidation and awe amongst the fi rst settlers as
they had passed through the hills and mountains
of the east and had entered the level prairie of the
midwest. Peatlands and prairie potholes possibly
had to be the common sights to those who had
settled in the northern plains in what is now
Michigan, Wisconsin, Minnesota, the Dakotas
and the central Canadian provinces. Further, the
early explorers and settlers on the lower
Mississippi River or the rivers in the SE coastal
plain must have been marvelled at the mammoth
structures of many of the old-growth cypress
swamps and bottomland hardwood forests which
had lined those rivers. All these wetlands,
undoubtedly, had played a signifi cant role in the
development of North America. It is important to
note here that wetlands had been accepted as part
of the landscape in the early period of settlement
and there was, perhaps, little or no desire or capability to change their hydrologic conditions to
any degree. It had been reported that ‘the great
natural wealth’ which had originally made the
growth and development of the USA possible
23
Wetlands of America