Humans in the Biosphere

Chapter 6

Dr. Donna HowellBiology IBlacksburg High School

Our Ecosystem• Human activities

that affect the biosphere are:– Hunting and

gathering– Agriculture– Industry– Urban

development

Hunting and Gathering• The hunger-gatherer

way of life makes relatively few demands on the environment.

• However, the use of technology does: guns, automobiles, tools, etc.

Agriculture• The Green

Revolution is an effort to create sustainable agriculture

• Purpose was to increase the world’s food supply

Agriculture• Ecological

challenges:– Pest control– Finding irrigation

water

Industrial Growth• Growth of

industry has led to problems:– Pollution of

air, water, and soil

– Need for energy

Urban Development• Problems associated

with:– Waste disposal– Consumes farmland

and natural habitats– Stress on animal

populations

Resources• Environmental goods

and services may be classified as– Renewable– Nonrenewable

Renewable Resources• Renewable resources

are those that can be regenerated or replenished in a reasonable amount of time.– Ex: land, forests,

fisheries, air, water

Nonrenewable Resources• Nonrenewable

resources are those that cannot be regenerated or replenished in a reasonable amount of time.– Ex: fossil fuels

Sustainable Development• A way of using

natural resources without depleting them, and of providing for human needs without causing long-term damage to the environment.

Land Resources• Plowing the

land removes roots that hold soil in place, causing erosion.

• Contour plowing reduces erosion.

Forest Resources• Deforestation is the

loss of forests by human activities.

• Leads to severe erosion.

• Replace trees, produce faster growing trees via breeding.

Fishery Resources• Overfishing is

harvesting fish faster than they can reproduce.

• Affects other species in lakes, streams, oceans also.

• Aquaculture, limits on catch

Air Resources• Condition of air

affects organism’s health.

• Smog, pollution and acid rain are problems

• New technology to control emissions

Freshwater Resources• Pollution of water

can affect our health• Includes waste such

as chemicals, sewage, fertilizers, etc.

• Conservation, protection via filtering

Biodiversity• Biodiversity is

the sum total of all organisms in the biosphere.

• One of Earth’s greatest natural resources– Provide drugs,

food, etc.

Biodiversity• Human activity

can reduce biodiversity by altering habitats, over hunting, adding waste, and introducing foreign species.

Biodiversity• Pollution greatly

reduces biodiversity.• DDT was a problem.• Rachel Carson wrote

about in “Silent Spring”

• Discussed biomagnification.

Biological Magnification• Biological

magnification is when concentrations of harmful substances increase in organisms in the higher trophic levels in a food chain.

Introduced Species• Invasive species

are those that are introduced into new habitats, and they reproduce quickly.

• Harm existing species, and alter niches.

Introduced Species• Zebra mussels

came over in 1980’s from Europe.

• Spread through Great Lakes and rivers.

• Driving other native species to extinction.

Data Gathering• Researchers

collect data on systems to help monitor effects of humans on environment.

• Two are ozone layer and global climate system.

Ozone Depletion• 20-50 km above Earth, O3 is found.• Protects us from harmful UV rays.• Scientists are finding a hole in ozone caused

by CFC’s.

Global Climate Change• Scientists are

concerned with global warming.

• Partially due to burning of fossil fuels.

• Ice caps melting, sea levels rising, could cause extinctions.

The End