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CHAPTER 9.3 Rain Forests
Rain Forests
CHAPTER 9.3 Rain Forests
Rain Forests
Objectives Describe the characteristics of the tropical
zone and of the rain forest. Illustrate the complexity and diversity of
the rainforest ecosystem.
Rain Forests
Rain Forests The tropical zone is located at latitudes
near the equator. It receives direct rays from the sun during
most of the year. Temperatures in thetropical zone average about 25oC all yearlong.
The growing season can last 12 months.
Rain Forests
Rain Forests Precipitation falls as rain except on the tops
of high mountains. The amount of precipitation varies from
200 to 450 cm a year. Soil nutrients is the limiting factor.
Rain Forests
Rain Forest Structure Constant warmth and abundant rain have
given rise to the rain forest. It is the most diverse terrestrial biome on
Earth. A rain forest is a biome with a dense
canopy of evergreen, broadleaf treessupported by at least 200 cm of rain eachyear.
Rain Forests
Rain Forest Structure Rain forest may contain as much as 70% of
all the terrestrial species on the Earth. Rain forest cover only 6% of Earth’s land
surface. Rain forest hold 50% of Earth’s land
biomass. Rain forest have great biodiversity.
CHAPTER 9.3 Rain Forests
Rain Forests
Rain Forest Structure Trees are the basis of the rain forest. Thousands of species of cypress, balsa,
teak, mahogany, and other trees grow inthis biome.
Many trees reach 50 or 60 m in height. Their leafy tops form a dense canopy. The canopy captures almost 99% of the
light falling on the forest.
Rain Forests
Rain Forest Structure The 1% that filters through supports the
lower levels of vegetation. Vegetation on the forest floor is sparse
because there is not enough sunlight ornutrients to support many plants.
Rain Forests
Levels of RainforestEMERGENT LAYER
The tallest trees are theemergents, towering as muchas 200 feet above the forest
floor with trunks that measureup to 16 feet around. Most ofthese trees are broad-leaved,
hardwood evergreens.Sunlight is plentiful up here.Animals found are eagles,
monkeys, bats and butterflies.
Rain Forests
Levels of RainforestCANOPY LAYER
This is the primary layer of theforest and forms a roof overthe two remaining layers.Most canopy trees have
smooth, oval leaves that cometo a point. It's a maze of
leaves and branches. Manyanimals live in this area since
food is abundant. Thoseanimals include: snakes,toucans and tree frogs.
Rain Forests
Levels of RainforestUNDERSTORY LAYER
Little sunshine reaches thisarea so the plants have togrow larger leaves to reachthe sunlight. The plants inthis area seldom grow to 12feet. Many animals live hereincluding jaguars, red-eyed
tree frogs and leopards.There is a large concentration
of insects here.
Rain Forests
Levels of RainforestFOREST FLOOR
It's very dark down here.Almost no plants grow in this
area, as a result. Since hardlyany sun reaches the forestfloor things begin to decay
quickly. A leaf that might takeone year to decompose in aregular climate will disappearin 6 weeks. Giant anteaters
live in this layer.
CHAPTER 9.3 Rain Forests
Rain Forests
Rain Forest Structure Dead organic matter that enriches the soil
in other biomes does not last that long inthe rain forest; only a couple of days orweeks.
Warm temperatures and moisture of rainforest are ideal for decomposers likeinsects, fungi, and bacteria.
Rain Forests
Rain Forest Structure Nutrients that fall to the forest floor are
quickly recycled and lifted back up into thetrees.
Because most of the matter in the forest isin the organisms the topsoil is thin andpoor.
Almost all of these nutrients are in the top5 cm of soil.
Rain Forests
Rain Forest Structure This results in the trees forming buttresses
to support the trees. This is because of the shallow topsoil. Woody vines called lianas grow up the
sides of tree trunks to reach the sun light. Other plants called epiphites live entirely
on the trunks or limbs of trees, absorbingairborne nutrients and moisture.
Rain Forests
Rain Forest Structure
Rain Forests
Rain Forest Structure
Rain Forests
Rain Forest Structure
CHAPTER 9.3 Rain Forests
Rain Forests
Rain Forest Structure
Rain Forests
Rain Forest Structure Most activity occurs in the canopy of the
forest. Many of the species are arboreal or tree-
dwelling. These organisms may never touch the
ground.
Rain Forests
Organisms and Diversity The animal diversity in a rain forest is
caused by two factors. Diversity of plants Variety of habitats at different forest levels
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
CHAPTER 9.3 Rain Forests
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
CHAPTER 9.3 Rain Forests
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
CHAPTER 9.3 Rain Forests
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity
Rain Forests
Organisms and Diversity Scientist are not sure how many species
may live in the rain forest. American biologist E. O. Wilson found 43
species of ants on a single tree. British ecologist Terry Erwin estimates
there may be over 50 million species ofinsects on Earth.
Rain Forests
Deforestation Difficult conditions kept most nonnative
peoples out of the rain forest. In 1950, over 10% of Earth’s land surface
was covered by rain forests. Rain Forest now only cover 6%, and this is
decreasing. The destruction of forest as a result of
human activity is called deforestation.
Rain Forests
Deforestation The force behind the destruction of the rain
0forests is the human population’s need forspace and wood.
Rainforest trees are logged for export andburned to clear land for farming, grazing,mining, and living space for people.
Because the soil has poor fertility, newland must be cleared every few years.
Rain Forests
Deforestation When the habitats in the canopy are destroyed the
animals that evolved to live in them becomeextinct.
It takes several hundred years for a rainforest toregenerate if there is rainforest around the clearedarea.
If the the forest is destroyed in large tracts or ifthe fragile soil is bulldozed, the rain forest willnever come back.
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