494
included a generous endowment of shallow water
and waterlogged lands. The original inhabitants
of the New World had possibly utilised the animals living amongst these wet places for food
and clothing, but they had, it appears, permitted
the land to essentially remain ‘unchanged’.
Concomitant to above, as cities, towns, villages, farms, etc., began to expand on a regional
scale, ‘wetlands’ were increasingly viewed as
‘wastelands’. There had been a growing tendency of draining these wetlands for reasons as
varied as disease control to agricultural expansion. Thus, there followed an unfortunate yet
understandable period in the country’s growth,
when wetland drainage and destruction became
an ‘accepted norm’. The Swamp Land Acts of
1849, 1850 and 1860 had set the tone for that
period by encouraging developmental activities
in 15 of the interior and west coast states.
Consequently, the coastal wetlands in the populated NE were drained and dissected to accommodate urban development. Many old-growth
forested bottomlands and swamps in the SE were
lumbered for their valuable products, refl ecting
little concern for their regeneration for the enjoyment and use by future generations. The USA
and large parts of Canada went through a period,
from the middle of the nineteenth century to the
middle of the twentieth century, in which wetland removal was not questioned. Nevertheless,
a rich wealth and a bewildering diversity of wetland types still exist in North America despite
the losses and derelictions they had suffered due
to various reasons.
23.1.1 The Status of North American
Wetlands
There are diverse types of wetlands in North
America. As such, it often becomes diffi cult to
inventorise the wetland resources mainly
because of their regional diversity and lack of
unanimity about the defi nition of a wetland.
Nevertheless, attempts are being made to ascertain how many wetlands there are in the USA
and Canada and to determine the rate at which
they are changing.
23.1.1.1 Presettlement Wetland
estimates
Roe and Ayres ( 1954 ) included drained wet soils
along with swamps and marshes to estimate
about 87 million ha of wetlands in presettlement
times, which are perhaps today called the lower
48 states. This estimate is often being compared
with existing wetland acreage to determine the
losses. It is important to note here that the US
Congress Offi ce of Technology Assessment had
suggested a range of 60–75 million ha of wetlands on the basis of interpretation of the prior
wetland and soil data. Some authors (Mitsch and
Gosselink 2000 ) admitted that the estimates ‘are,
to some extent, limited by the lack of good data
on the amount of land which had been drained or
otherwise reclaimed, and the relationship
between wetlands and wet soils’.
23.1.1.2 Present-Day Wetland
Estimates (In the USA)
In 1954, one of the fi rst wetland surveys was
carried out in the USA. It was based on wetland
habitat values rather than on values for agriculture. It was published by the US Fish and Wildlife
Service around 1956 as Circular 39 (Shaw and
Fredine 1956 ). This survey had relied on a classifi cation scheme of 20 wetland types. The survey had estimated that the nation had 30.1 million
ha of wetlands which were important to waterfowls. Out of this area, 25.7 million ha was identifi ed as inland freshwater wetlands, 0.6 million
ha as inland saline wetlands, 2.1 million ha as
coastal saline wetlands and 1.6 million ha as
coastal FW wetlands. However, the Circular 39
survey had considered only those wetlands which
were important for waterfowls in the USA. This
was said to be one of the shortcomings of Circular
No. 39.
Concomitant to above, a later assessment of
wetland abundance in the USA was conducted by
the US Fish and Wildlife Service. It was called
the National Wetlands Trends Study (NWTS)
(Frayer et al. 1983 ). This study had used the statistical analysis of wetland data derived from
detailed mapping for preparation of the National
Wetlands Inventory. This could estimate the total
coverage of the wetlands in the lower 48 states.
23 Wetlands of America
included a generous endowment of shallow water
and waterlogged lands. The original inhabitants
of the New World had possibly utilised the animals living amongst these wet places for food
and clothing, but they had, it appears, permitted
the land to essentially remain ‘unchanged’.
Concomitant to above, as cities, towns, villages, farms, etc., began to expand on a regional
scale, ‘wetlands’ were increasingly viewed as
‘wastelands’. There had been a growing tendency of draining these wetlands for reasons as
varied as disease control to agricultural expansion. Thus, there followed an unfortunate yet
understandable period in the country’s growth,
when wetland drainage and destruction became
an ‘accepted norm’. The Swamp Land Acts of
1849, 1850 and 1860 had set the tone for that
period by encouraging developmental activities
in 15 of the interior and west coast states.
Consequently, the coastal wetlands in the populated NE were drained and dissected to accommodate urban development. Many old-growth
forested bottomlands and swamps in the SE were
lumbered for their valuable products, refl ecting
little concern for their regeneration for the enjoyment and use by future generations. The USA
and large parts of Canada went through a period,
from the middle of the nineteenth century to the
middle of the twentieth century, in which wetland removal was not questioned. Nevertheless,
a rich wealth and a bewildering diversity of wetland types still exist in North America despite
the losses and derelictions they had suffered due
to various reasons.
23.1.1 The Status of North American
Wetlands
There are diverse types of wetlands in North
America. As such, it often becomes diffi cult to
inventorise the wetland resources mainly
because of their regional diversity and lack of
unanimity about the defi nition of a wetland.
Nevertheless, attempts are being made to ascertain how many wetlands there are in the USA
and Canada and to determine the rate at which
they are changing.
23.1.1.1 Presettlement Wetland
estimates
Roe and Ayres ( 1954 ) included drained wet soils
along with swamps and marshes to estimate
about 87 million ha of wetlands in presettlement
times, which are perhaps today called the lower
48 states. This estimate is often being compared
with existing wetland acreage to determine the
losses. It is important to note here that the US
Congress Offi ce of Technology Assessment had
suggested a range of 60–75 million ha of wetlands on the basis of interpretation of the prior
wetland and soil data. Some authors (Mitsch and
Gosselink 2000 ) admitted that the estimates ‘are,
to some extent, limited by the lack of good data
on the amount of land which had been drained or
otherwise reclaimed, and the relationship
between wetlands and wet soils’.
23.1.1.2 Present-Day Wetland
Estimates (In the USA)
In 1954, one of the fi rst wetland surveys was
carried out in the USA. It was based on wetland
habitat values rather than on values for agriculture. It was published by the US Fish and Wildlife
Service around 1956 as Circular 39 (Shaw and
Fredine 1956 ). This survey had relied on a classifi cation scheme of 20 wetland types. The survey had estimated that the nation had 30.1 million
ha of wetlands which were important to waterfowls. Out of this area, 25.7 million ha was identifi ed as inland freshwater wetlands, 0.6 million
ha as inland saline wetlands, 2.1 million ha as
coastal saline wetlands and 1.6 million ha as
coastal FW wetlands. However, the Circular 39
survey had considered only those wetlands which
were important for waterfowls in the USA. This
was said to be one of the shortcomings of Circular
No. 39.
Concomitant to above, a later assessment of
wetland abundance in the USA was conducted by
the US Fish and Wildlife Service. It was called
the National Wetlands Trends Study (NWTS)
(Frayer et al. 1983 ). This study had used the statistical analysis of wetland data derived from
detailed mapping for preparation of the National
Wetlands Inventory. This could estimate the total
coverage of the wetlands in the lower 48 states.
23 Wetlands of America