A forest is an area with a high density of trees.
• rainforests are characterized by high rainfall, and by
definition have a normal annual rainfall between 68 inches
to 78 inches, or more.(1750 mm and 2000 mm)
Rainforests are home to twothirds of all the living flora
and fauna species on the
planet.
It has been estimated that
many hundreds of millions of
new species of plants,
insects and microorganisms
are still undiscovered.
Typical Tropical Rainforest Climograph
• temperature
• precipitation
Can you tell
which
hemisphere this
rainforest is
within?
Southern Hemisphere
Tropical Rainforests are forests that form near the
equatorial regions on the Earth…and fit the
general rainy nature of the definition.
Average Temperature:
22° C (72° F)
Annual precipitation:
50-260 in.
As you can see
from the bar graph,
rainforests are the
wettest biomes on
Earth.
Mt. Waialeale
is thought to
be the
wettest spot
on earth,
receiving well
over 400
inches of rain
a year!
Temperate Rainforests can be found in North
America including the northwestern coast of the
United States and the Pacific coast of Canada.
The temperate rain forest has seasonal variation, with
summer temperatures rising to about 80°F and winter
temperatures dropping to near freezing.
In the northernmost regions, winter may be cold enough for
some ice and snow.
• The tropical rainforest is a region of year-round
warmth.
• Almost all rainforests lie near the equator.
• Rainforests are now one of the most endangered
biomes, and cover less than 6% of Earth's land
surface. But they are home to over 50% of all
known species of living organisms.
• Tropical rainforests produce much of the oxygen
for Earth’s atmosphere.
• Tropical Rainforests have very nutrient-poor soil,
and are second only to deserts for this.
• Curare, from a tropical vine, is
used as an anesthetic, and to
relax muscles during surgery.
• Quinine, from the cinchona
tree, is used to treat malaria.
• A person with lymphocytic
leukemia has a 99% chance
that the disease will go into
remission because of the rosy
periwinkle.
• More than 1,400 varieties of
tropical plants are thought to be
potential cures for cancer.
Emergent trees:
are widely spaced, and 100 to 120
feet tall with umbrella-shaped
canopies that grow above the
forest. Because emergents are
exposed to drying winds, they tend
to have very small leaves.
This is an adaptation similar to
what you would find in the desert,
and it is helpful in conserving water
for the plant.
of 80-foot trees allows light
The upper canopy to be easily available at the
top of this layer, but
greatly reduced below it.
The upper canopy is home to many arboreal animals
In the lower canopy:
At the 60-foot level, there is
little air movement. As a
result the humidity is
constantly high in this area.
As you move down through the canopy, life becomes even
more abundant
Besides these three canopy
layers, a shrub/sapling layer
receives about 3 percent of
the light that filters in
through the canopies.
These stunted trees are
capable of a sudden growth
surge when a gap in the
canopy opens above them.
• The ground layer: Sparse plant
growth.
Less than one percent of the light that
strikes the top of the forest penetrates
to the forest floor. Most areas of the
forest floor receive so little light that
few bushes or herbs can grow there. As a
result, a person can easily walk through
most parts of a tropical rain forest.
If the leaf canopy is
destroyed or thinned
for any reason, the
ground beneath is
soon colonized by a
dense tangled growth
of vines, shrubs and
small trees called
jungle.
The air beneath the lower canopy is always
humid. The trees themselves give off water
through the stomata of their leaves. This
process, called transpiration, can account
for as much as half of the rain in the
Amazon rain forest!
El
Yunque
in
Puerto
Rico
Emergent Trees: tiny leaves
that allow them to combat
the drying effects of the
sun and wind they are
exposed to.
With between 100-200
inches of rain per year,
some plants have
adaptations that help them
shed water off their leaves.
Many plants have drip tips
and grooved leaves for this
purpose.
Trees from the lower canopy,
and rainforest floor have
enormous leaves.
Some plants grow in the
upper canopy on larger
trees to get sunlight.
These are the epiphytes
such as orchids and
bromeliads.
Many trees have buttress
and stilt roots for extra
support in the shallow, wet
soil of the rainforests.
The adaptation of prehensile tails
(tails that can grip an object, and as
such be used as an appendage) is only
seen in New World monkeys. Monkeys
from the Old World do not have this
adaptation.
Old World: Africa
and Asia
New World: South
America
Other characteristics
are bright colors and
sharp patterns, loud
vocalizations, and
diets heavy in fruits.
Insects make up the largest
single group of animals that
live in tropical forests.
They include brightly
colored butterflies,
mosquitoes, frogs
camouflaged stick insects,
and huge colonies of ants.
As said earlier, scientists
estimate that more than
half of the entire world's
plant and animal species
may live in tropical rain
forests!
How do you
know?
Tropical Rainforests
Temperate Rainforests