| The
Llanos |
|
| Venezuela / Colombia |
| |
| Earth's Natural Wonders
in South America |
| |
| Total area of
the Llanos: 173,314 square miles |
| Elevation
of the grassland: up to 260 feet |
| Rock type: Igneous
Precambrian |
| |
| |
Los
Llanos in Columbia[1] |
The Llanos is a seasonally
flooded grassland that covers nearly
one-third of Venezuela and on one-eighth
of Colombia. It is most flooded in
the central part which occurs on the
huge saucer shaped depression that
contains the floodplain of the mighty
Orinoco. Underlying Pre-cambrian rocks
follow the shallow basin's broad dips
and rises, while recent sediments
provide it with its character, created
a mosaic effect of different habitats,
both within the flooded area and in
drier extremities. [4]
Located on a large downward
flexure of the Earth’s crust,
the Llanos lies at the intersection
of the Andes ridge and the Caribbean
ridge in the northern part of South
America. The most flooded area is
the middle part, which drains into
the Río Orinoco and is transected
by its tributaries from west to east.
Situated over pre-Cambrian basement
rocks, the Llanos is composed primarily
of alluvial deposits from the Tertiary
and Quaternary periods.
A great diversity of
wildlife exists, many of the most
specialized occuring around rocky
outcrops. The Llanos is most famous
for its swamp-based wildlife of Orinoco
goose, scarlet ibis, and capybara,
as well as a host of migrant species.
Flooding is at a maximum between July
and October. In the dry season many
watercourses dry up, leaving the larger
rivers and clay-panned estuaries to
slake the thrist. The Llanos has over
3,400 recorded flowering plants, 40
of which are unique to this area.
Among the 475 bird species is the
Orinoco soft-tail, which included
among the 148 mammals is the Llanos
long-nosed armadillo. The area's reptiles
include the green anaconda, the world's
largest snake species, and the rare
Orinoco crocodile.
Los llanos (meaning
the flat plains) is a vast tropical
grassland plain situated at the east
of the Andes in northwestern South
America (Colombia and Venezuela).
Its main river is the Orinoco.The
climate change of the Llanos is extreme.
During the rainy season from June
to October, parts of the Llanos can
flood up to a meter. This makes the
area unfit for most agriculture before
the advent of modern, industrial technology;
therefore, during the colonial era,
the prime economic activity of the
area came from the herding of millions
of heads of cattle. The term llanero
("plainsman") became synonymous
with the cowhands that took care of
the herds, and had some cultural similarities
to the compare to the gauchos of the
Pampas or the vaqueros of Spanish
and Mexican Texas.The area slopes
gradually away from the highland areas
that surround it; elevation above
mean sea level in the llanos never
exceeds 200 meters.
Originally, llano is
the Spanish word for "plain".
It became the Spanish-American term
for prairie[3]
Location
and General Description
This moist forest ecoregion
encompasses the high altitude cloud
forests of the Andean Venezuelan Cordillera,
representing an ecological barrier
that separates the great basins of
Maracaibo Lake and the Llanos of Venezuela.
This ecoregion occupies montane forests
at middle elevations of the Venezuelan
Andes or Venezuelan Andean Cordillera,
a northeastern branch of the Andes.
They are separated form the eastern
Andes of Colombia by the Tachira depression
at the border between Colombia and
Venezuela. The end of the ecoregion
lies roughly at 450 meters (m) northeast
in the depression of Barquisimeto.
These mountains reach altitudes between
4,000 and 5,007 m, and separate the
Maracaibo lake basin from the plains
of the Llanos. The Venezuelan Andes
montane forest also includes those
forests located around Tamá
Massif , a relatively isolated montane
area located between the Eastern Andes
of Colombia and the Táchira
depression.
|
Politically,
the Venezuelan Andes montane
forests include almost all the
Mérida and Trujillo states,
a large part of the Táchira
state, and the adjacent highlands
of Lara and Barinas states.
Many of the rivers born in the
summits created great valleys
that separate the Cordillera
montane ranges. One of the most
important rivers, the Chama,
crosses the Cordillera at its
middle portion, along its northeast-
southwest axis. This breaks
the Cordillera in to two main
sections: the Cordillera de
Mérida in the south and
the Sierra de la Culata in the
north. Other important rivers
are the Santo Domingo, the Boconó
and Motatán. These rivers
also indicate physiographical
barriers along the Cordillera.
|
Los
Llanos in Venezuela[1] |
The Venezuelan Andes
were formed from surrounding areas
during the Paleocene, and they continued
developing until the end of the Pliocene,
at which time they attained their
greatest height. The geological constitution
consists mainly of quartzite schists,
gneisses, limestones, and isolated
granitic and diabasic intrusions.
Soils are predominantly inceptisols,
but entisols are also common in the
slopes and areas exposed to erosion.
The climate is strongly
influenced by the north eastern trade
winds, especially during the dry season,
from December to April. From April
to November, the inter-tropical convergence
zone brings the highest rainfall of
the year. In general, this ecoregion
has mesothermic conditions with average
annual temperatures of 24–12°C
between 800–2,500 meters (m)
altitude, and micrometric conditions
with average annual temperatures of
less than 12°C above 2,500 m.
Annual rainfall is about
2,000-3,000 millimeters (mm), but
can be strongly variable. On the slopes
that face the Llanos, high rainfall
averages begin at 2,400 m, changing
gradually with elevation, whereas
on the Maracaibo Lake facing slopes,
the high rainfall averages begin at
1,200 m. The internal slopes are driest,
with some very dry xeric areas common
in the Andean valleys.
Vegetation of this ecoregion
is characterized by evergreen transition
forests and evergreen montane cloud
forests. Located between 800–1,800/2,000
m altitude, evergreen transition forests
are dense middle-high forests structured
in two or three layers, in which Lauraceae,
Moraceae, Myrtaceae, Bignomiaceae,
Euphorbiaciae, and Araliaceae are
the most common families.
Very dense evergreen
montane cloud forests occur in higher
elevations between 2,000 and 3,000
meters. These are high forests with
two or three structural layers, and
a well-developed understory with abundant
epiphytes. The most common species
are Decussocarpus (Podocarpus) rospingliosii,
Prumnopytis (Podocarpus) montana,
Podocarpus oleifolius, Alnus jorullensis,
Oreopanax moritzii, Brunellia integrifolia,
Hedyosmum glabratum, Weinmannia jahnii,
W. microphylla, Tetrorchidium rubrivenium,
Beilschemieda sulcata, Ruagea glabra,
and R. pubescens.[2]
Venezuelan national
parks included in this ecoregion are:
the Sierra Nevada, Sierra de la Culata,
General Pablo Peñalosa (Batallón
and La Negra páramos), General
Cruz Carrillo (at Guaracamal), Dimira
(Sierra de Barbacoa), Yacambú,
El Tamá, and the Tamá
National Park in Colombia. Protected
areas constitute only 20.78% of the
total area of this ecoregion. Almost
all montane forests (which would include
both semi-evergreen and the evergreen
forests of low to mid altitudes) are
being invaded with varying intensity.
Most of the slopes are, or have been
worked by shifting cultivators. This
has given the slopes a mosaic appearance
and fragmented habitat.
