非表示:
キーワード:
wetlands; South America; extent; classification; biodiversity; management; threats; climate change
要旨:
The exact size of the wetland area of South
America is not known but may comprise as much as 20% of
the sub-continent, with river floodplains and intermittent
interfluvial wetlands as the most prominent types. A few
wetland areas have been well studied, whereas little is
known about others, including some that are very large.
Despite the fact that most South American countries have
signed the Ramsar convention, efforts to elaborate basic
data have been insufficient, thereby hindering the formulation
of a wetland-friendly policy allowing the sustainable
management of these areas. Until now, the low population
density in many wetland areas has provided a high level of
protection; however, the pressure on wetland integrity is
increasing, mainly as a result of land reclamation for agriculture
and animal ranching, infrastructure building,
pollution, mining activities, and the construction of hydroelectric
power plants. The Intergovernmental Panel on
Climate Change has predicted increasing temperatures,
accelerated melting of the glaciers in Patagonia and the
Andes, a rise in sea level of 20–60 cm, and an increase in
extreme multiannual and short-term climate events (El Nin˜o
and La Nin˜a, heavy rains and droughts, heat waves). Precipitation
may decrease slightly near the Caribbean coast as
well as over large parts of Brazil, Chile, and Patagonia, but
increase in Colombia, Ecuador, and Peru, around the
equator, and in southeastern South America. Of even
greater impact may be a change in rainfall distribution, with
precipitation increasing during the rainy season and
decreasing during the dry season. There is no doubt that the
predicted changes in global climate will strongly affect
South American wetlands, mainly those with a low hydrologic
buffer capacity. However, for the coming decades,
wetland destruction by wetland-unfriendly development
planning will by far outweigh the negative impacts of global
climate change. South American governments must bear in
mind that there are many benefits that wetlands bring about
for the landscape and biodiversity as well as for humans.
While water availability will be the key problem for the
continent’s cities and agroindustries, intact wetlands can
play a major role in storing water, buffering river and
stream discharges, and recharging subterranean aquifers.
