Transcript World Biomes - Tartu Veeriku Kool

World Biomes
Tropical Rain forest
Distribution of biome
• The tropical rainforest is found between 10 ° N
and 10 ° S latitude at elevations below 1,000
m. There are three major, disjunct formations:
• Neotropical (Amazonia into Central America)
• African (Zaire Basin with an outlier in West
Africa; also eastern Madagascar)
• Indo- Malaysian (west coast of India, Assam,
southeast Asia, New Guinea and Queensland,
Australia.
Distribution
Climate
• The tropical rainforest is a forest of tall trees in
a region of year-round warmth. An average of
1250 to 6600 mm of rain falls yearly.
• The temperature in a rainforest rarely gets
higher than 34 °C or drops below 20 °C;
average humidity is between 77 and 88%.
There is usually a brief season of less rain. In
monsoonal areas, there is a real dry season.
Almost all rainforests lie near the equator.
Soil
• The soil is infertile, deeply
weathered and severely
leached. Rapid bacterial
decay prevents the
accumulation of humus.
The concentration of iron
and aluminium oxides gives
the soil a bright red colour
and sometimes produces
minable deposits (e.g.,
bauxite). On younger
substrates, especially of
volcanic origin, tropical soils
may be quite fertile.
Plants I
• A tropical rainforest
has more kinds of
trees than any other
area in the world.
Scientists have
counted about 100 to
300 species in one
1-hectare area in
South America.
Seventy percent of
the plants in the
rainforest are trees.
Plants II
• All tropical rainforests resemble one another
in some ways. Many of the trees have straight
trunks that don't branch out for 100 feet or
more. There is no sense in growing branches
below the canopy where there is little light.
The majority of the trees have smooth, thin
bark because there is no need to protect them
from water loss and freezing temperatures. It
also makes it difficult for epiphytes and plant
parasites to get a hold on the trunks. The bark
of different species is so similar that it is
difficult to identify a tree by its bark. Many
trees can only be identified by their flowers.
Kapok tree
Brazil nut
Rubber tree
Ruffled Fan palm
Orchids
Bromeliad
Fern tree
Carnivorous plants
Venus Fly Trap
Pitcher plant or Monkey Cup
Plants III (growth forms)
• Epiphytes: the socalled air plants
grow on branches
high in the trees,
using the limbs
merely for support
and extracting
moisture from the
air and trapping the
constant leaf-fall
and wind-blown
dust.
Plants IV (growth forms)
• Lianas: woody
vines grow rapidly
up the tree trunks
when there is a
temporary gap in
the canopy and
flower and fruit in
the tree tops.
Plants V (growth forms)
• Climbers: greenstemmed plants that
remain in the
understory. Many
climbers, including
the ancestors of the
domesticated yams
(Africa) and sweet
potatoes (South
America), store
nutrients in roots
and tubers.
Plants VI (growth forms)
• Stranglers: these
plants begin life as
epiphytes in the
canopy and send
their roots
downward to the
forest floor.
Fungi
• Fungi can live on the forest floor because they
do not need sunlight for growth.
Plants VIII
• Rainforests now cover less than 6% of Earth's
land surface. Scientists estimate that more
than half of all the world's plant and animal
species live in tropical rainforests. Tropical
rainforests produce 40% of Earth's oxygen.
• About 1/4 of all the medicines we use come
from rainforest plants. More than 1,400
varieties of tropical plants are thought to be
potential cures for cancer.
Animals
• Animal life is highly diverse. Common
characteristics found among mammals and
birds (and reptiles and amphibians, too)
include adaptations to an arboreal life (for
example, the long tails of New World
monkeys), bright colours and sharp patterns,
loud vocalizations, and diets heavy on fruits.
Insects
Amphibians and reptiles
Constrictor Python
Tree frogs
Chameleon
Birds
Harpy Eagle
Macaw
Paradise bird
Mammals
Sloth
Tapir
Howler Monkey
People I
People II
• Farming: huge tracts of rainforest are cleared
for large-scale commercial plantations or
livestock ranching. Ironically, rainforest soil is
useless to humans. Rainforest soils are
notoriously poor and cannot support human
agriculture for more than a few years. Crops
may grow well at first, mostly subsisting on the
minerals released when the forest is burnt. But
these minerals wash away quickly without the
protection of the thick forest canopy and the
soil soon becomes useless.
• Humans destroy by collecting and killing
wild animals and plants.
People III
• Rainforest is also cleared to make way for
homes for people, and infrastructure like
dams, roads, electrical and communications
installations.
• Rainforests are dug up as we mine for oil,
gold and other minerals. Small scale gold
prospectors use mercury which is toxic to
extract gold.
People IV
• Logging of trees for building materials,
firewood, paper products. Rainforests contain
50% of global standing timber. Unlike the
faster-growing temperate timber trees,
rainforest trees take decades to reach
economic size so it is not easy to harvest them
in a sustainable manner. Logging roads
usually allow other commercial exploitation to
follow.
People V
• Humans kill by breaking up a rainforest
into smaller clumps. It destabilises the forest
interior: temperature and humidity are no
longer constant. Such fluctuations kill plants
and animals adapted only for stable
conditions. If the fragment is too small, it can't
withstand natural seasonal changes. It also
prevents natural movement of plants and
animals from one part of the forest to another.