Geography Reference
In-Depth Information
land's infertility, so the landscape remains mainly covered in forest in these sparsely
populated regions.
The southern tip of the Florida peninsula (0.3% of the US territory) differs from
neighboring regions with its subtropical climate. Winters are practically non-
existent, and frost exceptional. The climate is hot and humid during most of the
year, and allows for the development of a hardwood forest composed of evergreen
and semi-deciduous species. Wetlands prevail, whether in fresh water (as in the
Everglades) or brackish water, enabling the US to have mangroves. The flooded
cypress forest (Cypress Swamps) forms a landscape that is typical along the shores
of the Gulf of Mexico and in the state of Florida. Extending beyond the winterless
region of south Florida, this forest is found along the swampy coasts, including the
Mississippi delta. It is a fragile ecosystem. The development of plantation crops and
urbanization has substantially reduced the expansion of subtropical forests, wetlands
and the Cypress Swamps of the southeastern United States. These unique
environments, along with their unique wildlife (such as alligators), are therefore
seriously threatened. Since 1947, the pumping of groundwater to supply cities, as
well as irrigation and drainage for intensive agriculture around Lake Okeechobee
have severely disrupted the natural movement of groundwater which feeds the
freshwater marshes of the Everglades. The natural reserves of the Everglades and of
Big Cypress National Preserve are now in danger of drying up. Apart from these two
natural reserves, southern Florida no longer has any forest.
West of the Mississippi, north of the 38th parallel, or further south and above the
normal 1,000-mm isohyets, the forest gives way to the grassy vegetation of the
Great Plains. This vast region spans 2.2 million km², or 28% of the territory of the
conterminous United States, from the Mexican border in Texas all the way to the
Canadian border. This ecosystem extends into the Canadian Prairies of western
Canada. Consisting of vast plains naturally covered with grassland, its climates vary
from dry continental in the Northeast to semi-arid subtropical in the Southwest.
Prior to the period of westward expansion, the prairie was characterized by a dense
population of bison. There were a great number of Native American communities,
such as the Cheyenne, and the wars with these communities in the Great Plains were
far more unpardonable and drawn-out than anywhere else in the United States.
Westward expansion was followed by widespread land clearing and the slaughter of
the bison herds. The agriculture of the Great Plains relies heavily on climate. The
rich lands east of the prairie (Midwest), in the most humid region, continue to lend
themselves to intensive agriculture, while the more marginal lands of the West and
Southwest require the use of dry farming agricultural practices, as a result of the
devastation caused by wind erosion in the 1920s, and the area is often referred to as
the Dust Bowl. Starting in the 1950s, however, the pumping of groundwater from
