Geoscience Reference
In-Depth Information
undertake intensive modii cations of water sup-
plies, which lead to degradation and loss of wet-
lands. The hydraulic approach has been dominant
around the world for the past i ve centuries; as a
consequence, the modern wetland total is no
more than half of pre-development coverage.
Wetland conservation began about a century
ago with initial emphasis on protecting habitats
for migrating waterbirds. The United States
undertook bilateral treaties with the United
Kingdom (Canada), Mexico and other countries.
Among the most successful early programs was
the U.S. Migratory Bird Hunting and Conserva-
tion Stamp, commonly known as “duck stamps,”
which still continues today. Many federal agen-
cies are involved in wetland research and man-
agement in the United States, and similar agencies
exist in many other countries. Likewise several
non-governmental wetland organizations are
active in North America and other parts of the
world. International efforts culminated with the
Ramsar Convention on Wetlands in 1971; to date,
the number of contracting parties has reached
160, and nearly 1900 sites covering more than
185 million hectares have been listed as wet-
lands of international importance.
Given the broad range of wetland functions,
their feedback relationships with other environ-
mental factors, and human impacts, it is not
surprising that scientii c investigations of wet-
lands have become important for many reasons.
So-called wetland science involves biological,
physical and cultural aspects of environments
and human impacts on wetlands. Several scien-
tii c societies and publications are devoted to
multidisciplinary wetland science and manage-
ment. In addition, ecotourism to wetlands has
emerged as a popular leisure activity, thereby
exposing many more people to the beauty and
values of wetlands.
