Unit Nine: FOREST BIOMES

• Forests cover more than 30% of Earth’s surface.

• Forests contain more than 75% of the Earth’s biomass.

• They are more diverse than any other terrestrial ecosystem.

• The rainforest covers 6-7% of Earth’s surface, but contains 50% of lands biomass and 70% of Earth’s terrestrial species.

Forests

• The forest biomes are crucial to humans.

• They contain wood, the most common building material on earth.

• However, they are an ecosystem that is in danger of destruction due to over harvesting of resources.

Forests

1. Describe the characteristics of the coniferous forest.

2. Explain adaptations that enable organisms to survive in coniferous forests.

I Can…

The coniferous forest biome is primarily located in the subarctic regions of North America, Europe, and Asia.

The summers are warm, and last from 2-4 months, while winters are long, cold and dry.

There is little sunlight.

Precipitation falls as rain during the summer and snow during the winter.

Coniferous Forests

The total precipitation that falls on the coniferous forest is between 40 to 200 cm a year.

In the Southern Hemisphere, coniferous forests are found high in mountains.

Coniferous Forests

Coniferous means cone-bearing.

Conifers are trees that produce seed cones.

Conifers have leaves called needles, which are long, thin, and covered in a waxy substance.

Needles help the trees conserve water.

Needles are lost and replaced throughout the year, not all at once.

Coniferous Forests

Examples:

pine, hemlock, fir, spruce, and cedar

In coniferous forests, you can often also find a few deciduous trees, such as, aspen and birch.

Coniferous forests do not tend to be diverse. There are usually only a few different species of trees.

Coniferous Forests

During the winter, soil moisture is frozen, so trees must be able to survive harsh conditions.

Soils tend to be acidic due to the needles of conifers being acidic and decomposing slowly.

The limiting factors in the coniferous forest are the harsh winters and the nutrient-poor soils.

Coniferous Forests

Ferns, lichens, and sphagnum moss are plants that can grow on the forest floor where there is little light.

The heavy snows that fall in the winter are important to the forests.

The snow acts like a blanket insulating the roots of the forest trees and preventing permafrost from forming.

Coniferous Forests

The insulating snow also allows some animals survive that would otherwise freeze to death. Mice for example.

Many other animals are also adapted to the cold winters.

Seed eaters, such as squirrels, jays, and other rodents and birds.

Insects are common in the summer months when the weather is warmer.

Coniferous Forests

Large herbivores like moose, elk, beaver, and snowshoe hares feed on plants and bark.

These herbivores are food for bears, wolves, and lynxes.

The adaptations these animals have, such as migrating, hibernating, or living under the snow, allow them to survive the harsh winters.

All of them have thick coats to protect them from the cold

Coniferous Forests

Large areas of coniferous forests can be found in the northern parts of Asia and North America.

The climate in these areas is harsh, and because of this they have not been logged off as much as other types.

The coniferous forests have been becoming more popular for logging, but it is yet to determined how much destruction they can sustain.

Coniferous Forests

Identify the characteristics of the deciduous forest.

Describe the organisms that inhabit deciduous forests.

I can…

In lower latitudes than coniferous forests, there exists the temperate zone.

The temperate zone has 4 distinct seasons.

The forests are largely deciduous trees, or a tree that sheds its leaves during a particular season of the year.

Deciduous Forests

Temperatures vary quite a bit in deciduous forests.

Temps in the summer can be as high as 30 degrees Celsius (86 F) to -30 (-22 F) in the winter.

Precipitation falls as both rain or snow, depending on the temperature.

Deciduous forests receive between 50-300 cm of precip/year

Deciduous Forests

Deciduous trees adapt to the variable climate.

The growing season lasts 6 months, and during this time the tree grows, produces food, and stores it for colder seasons.

In fall, cooling temps and shortening daylight trigger the trees to begin changing.

The trees shed their leaves and become dormant.

Deciduous Forests

The adaptation of losing leaves allows the tree to conserve water in the cold months.

Photosynthesis stops, and the tree survives by consuming food stored in its trunk, branches and roots.

The tree grows new leaves in spring, and photosynthesis begins again to prepare for the next winter.

Deciduous Forests

Examples of deciduous trees include:

maple, ash, beech, oak, hickory and birch

The number of inhabitants in deciduous trees is greater than in coniferous trees.

The deciduous forest has three distinct layers, and each layer has its own characteristics.

Deciduous Forests

The highest section of the deciduous forest is called the canopy.

The canopy includes the upper branches and leaves of tall trees.

The canopy captures most of the sunlight.

Deciduous Forests

Below the canopy is the understory.

The understory is made up of trees that are younger and shorter than those that make up the canopy.

There is also a layer of shrubs that grows in the understory.

Deciduous Forests

At the bottom of the deciduous forest is the forest floor.

The forest floor includes mosses, ferns, and other plants that grow on the ground.

The leaves that fall help enrich the forest soil.

The leaves decay quickly in the summer and produce humus.

Deciduous Forests

The deciduous forests produce large amounts of food and support a diverse community of organisms.

Fungi and other decomposers, invertebrates and insects are common and preyed upon by birds, rodents and small mammals.

Deer are common, but reptiles and amphibians are only present in warmer forests.

Predators include: wolves, cougar, foxes and birds of prey

Deciduous Forests

The deciduous forests have been changed by human activity.

The deciduous forest used to stretch across Europe, Asia, and the eastern United States.

Only small sections of the original forest remains, due to farming, orchards, and urban development.

Deciduous Forests

2 factors have affected the decline in the deciduous forests

1. rich soil – the humus in deciduous forests makes for fertile soil and great farmland.

2. hard wood – the wood is great for building uses, and fuels.

Deciduous Forests

Some of the deciduous forests have been replanted, but a forest ecosystem is more than just trees and cannot simply be replanted.

The forest ecosystem takes a very long time to regenerate.

The species that make up much of the ecosystem have disappeared and must come back, or other species must fill in the available niches.

Deciduous Forests

When forests are replanted, they are usually only one species of tree and thus are not diverse.

They tend to be very productive, but have a low biodiversity and are susceptible to disease, parasites, and pollution damage.

Deciduous Forests

Describe the characteristics of the tropical zone and of the rain forest.

Illustrate the complexity and diversity of the rainforest ecosystem.

I can…

The tropical zone is located near the equator.

It receives direct rays from the sun most of the year and temperatures reach close to 77 degrees year around.

The growing season can last 12 mos., and precipitation can be anywhere from 200-450 cm a year.

With an unchanging climate, water and temperature are not limiting factors. Soil richness, may be, though.

Tropical Zone

The ever present warmth and moisture have created the rain forest, the most diverse land biome on Earth.

Rain Forest – a dense canopy of evergreen, leafy trees, supported by at least 200 cm of rain a year.

Over 70% of land species on Earth live in the rain forest

Although the rainforest is only 6% of Earth’s surface, it holds 50% of the biomass.

Amazing species and biodiversity exist in the rainforest

Rain Forest Structure

There are thousands of species of trees in the rainforest.

Examples: cypress, balsa, teak, mahogany, etc.

Trees can reach heights of 50 to 60 meters!

Just like the deciduous forest, the rainforest has different, distinct layers.

Rain Forest Structure

The first layer is the canopy, just like the deciduous forest.

The canopy captures almost all of the sunlight that falls on the vegetation.

The vegetation on the forest floor is supported by the 1% that does filter through the canopy.

However, the forest floor is sparse due to little sunlight.

Rain Forest Structure

There is not much organic matter to enrich the soil in the rainforest.

The organic matter that does get to the soil is broken down quickly in days by decomposers and taken back up by the trees.

There are a lot of nutrients in the rainforest biome, but most of the nutrients are part of living things and are not contained within abiotic parts of the biome.

Rain Forest Structure

The topsoil in the rainforest is poor.

The richest soil is the top 5 cm, so trees tend to widen at the base with ridges of wood called buttress.

Tree roots are shallow to take advantage of the nutrients at the top of the soil.

Rain Forest Structure

Woody vines called lianas grow up the trunks of the trees to get to the sunlight at the top of the canopy.

Other plants such as orchids and bromeliads live on the trunks and limbs of the trees and absorb nutrients and moisture from the air.

Rain Forest Structure

Most activity occurs in the treetops in the rainforest.

Many of the organisms are arboreal, that is they live in the trees their whole lives.

Rain Forest Structure

There are 2 reasons the rainforest is so diverse.

1. diversity in the plants

2. variety of habitats

There is such a large diversity in the plant life in the rainforest that there is an unbelievable number of niches.

The conditions in each of the layers of the forest is so different, that different communities inhabit each area.

Rainforest diversity

Habitats in the rainforest differ between layers of the forest and types of trees.

There are many connections between food webs, and many have specialized species with complex relationships.

Millions of different species inhabit the rainforest.

Rain Forest diversity

Scientists are not sure how many different species live in the rainforest.

Biologist A.O. Wilson found 43 species of ant living on one tree, and Terry Irwin estimates 50 million species of insects on Earth, most of which live in the rain forest.

More species are found in the rainforest, making scientists believe that there are others that we do not yet know about.

Rain Forest diversity

In 1950, 10% of Earth’s surface was rainforest.

Rainforests now only cover 6% of the Earth.

Humans are using the resources and the land for more space and to further human pursuits.

Deforestation of the rainforest

Many rainforests are in developing countries where there is a large rate of population growth.

There is a need for land to be used for grazing, farming, mining and living space.

The soil is poor, so after a few growth seasons there is a need to clear more land to grow crops.

Deforestation of the rainforest

The rainforest is a vertical ecosystem, that is the habitats are all destroyed when trees are cut down.

Scientists are very concerned about the extinction of animals in the rainforest because of the deforestation.

If an area of the rainforest is burned, scientists think that it can be regenerated over 100’s of years if there is rainforest around it.

However, the diversity will be low and take many generations to get back to levels equal that of the forest around it.

Deforestation of the rainforest

If the rainforest is bulldozed or destroyed in large quantities, scientists think it will be unable to regenerate and will be lost permanently.

This has become a world-wide problem due to the large amounts of carbon that the rainforests remove from the atmosphere.

Scientists think that rainforest destruction may account for 25% of the rise in carbon dioxide each year.

Deforestation of the rainforest