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.