Biomes and Humans

RAINFOREST

Forest exploitation

Forests have been destroyed for centuries Cleared for agriculture and farming. Building materials Fire wood Living space

Rain Forests

In 1950, over 10% of Earth’s land was covered by rain forests.

Currently only 6%, and decreasing.

Forest Exploitation

Sustained yield A balance between net growth and

harvest. Maximum sustained yield

The level of consumption at which the population declines if exceeded.

Recall Rainforest Ecosystem

Most plant and animal biodiversity on Earth.

As a result of deforestation, animals’

habitats are also destroyed.

Recall Ecological Succession

succession can take several hundred years to restore a climax community.

The required time for succession to reach climax community takes longer when biodiversity is greater.

Succession may not be possible if large stands are destroyed

Temperate Deciduous Forest

Temperate Deciduous Forests

Harvested for farms, orchards, and urban development.

Two factors driving exploitation of deciduous forests The rich soil is excellent for farmland. Hardwood trees are great material for

furniture, flooring, and fuel.

Urban Development

Habitat Fragmentation

Temperate Forests

Replanting efforts with Monocultures Low tree biodiversity = few animal

niches = low animal biodiversity Low biodiversity ▪ Ecosystem is more fragile.

Coniferous Forests

Coniferous Forests

Have not been logged as extensively as other forest types

But, the growing need for wood has led to increased harvesting

Countries in need of money are selling large stretches of forests to domestic and foreign companies.

Global Effects of Deforestation

Climate Change

Tundra

Recall: Little Biodiversity. Short growing season.

Tundra

Very fragile Low biodiversity = simple food webs Short growing season = slow succession

Tundra

Until recently, the tundra was relatively undisturbed by humans

Our growing need for oil increases human activity in tundra ecosystems

Tundra

Global climate change The largest warming trends are in the

tundra. Warming ▪ Thaws the permafrost.

Grasslands

Grasslands

Steppes and Prairies Human agriculture ▪ Native grasses are replaced with species

specialized for agriculture▪ Native animals have been replaced by herds

of grazing cattle and sheep. This greatly decreases biodiversity

Grasslands

Grasslands to Deserts

Humans and desertification Caused by ▪ Livestock overgrazing▪ Poor farming practices

Process ▪ Without plants, wind erodes topsoil. ▪ Recall: plant roots act as binding agent for

soil.

The Great Dust Bowl

Midwestern United States in 1930s

Biome Cultures

People from all over the world are dependent on plants & animals in their environments.

Humans as Apex Predators

We attempt to maintain these resources by balancing population recruitment and harvest. Recall: sustainable yield.

Overharvesting can threaten the existence of populations.

Potential consequences of overharvesting

Threatened: Threatened species are vulnerable to

endangerment in the near future. Endangered:

An endangered species is one which has been categorized as likely to become extinct.

Extinct: Species or populations which no longer

exists.