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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specialized for agriculture▪ Native animals have been replaced by herds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.