Humans in the Biosphere

Chapter 6Mrs. Yanac

Limited Resources• All organisms on Earth must share the planet’s

resources and they are LIMITED.• Humans are the main source of environmental

change:o Hunting & Gatheringo Agricultureo Industryo Urban development

Hunting and Gathering

• Prehistoric hunters and gathers changed the environment and even drove some species to extinction.

Agriculture• Farming increased the amount of food produced & allowed

cities to form• People in cities produced wastes• Advances in agriculture included use of pesticides &

monoculture (planting of same crop year after year) which led to green revolution & an increase in world food supply

• Problems Pollution from pesticides

Industry• (-) Used more resources & produced more

pollution than ever before• (+) Machines made life easier for humans

Urban Development• Changes the landscape, displaces animals,

destroys habitat, causes pollution, etc

Renewable Resources• Any resource that can be easily replaced or

replenished

Nonrenewable Resources

• Any resource that can NOT be easily replaced or replenished (takes millions of years to replace)

Human Activities• Threaten many resources & can affect the quality

& supply if renewable resources such as land, forests, fisheries, air & fresh watero Sustainable development is a way of using resources w/o depleting

them

• Soil erosion occurs when water or wind remove surface soil (removing nutrients & leaving land like a desert desertification)o Sustainable development would include alternating crop planting &

contour planting

Human Activities• Deforestation is the loss of forests which provide

oxygen, wood, & other resourceso Sustainable development would include

planting trees to replace those cut down

• Overfishing reduces fish populationso Sustainable development would include

aquaculture (raising aquatic animals for food)

Human Activities• Smog and acid rain are a result of air

pollution due to burning fossil fuelso Sustainable development would

include emission controls to reduce air pollution

• Sewage & discarded chemicals can pollute the water supplyo Sustainable development would include

protecting wetlands & maintaining regulations on wastewater treatment

Biodiversity• Biodiversity is the sum of all kinds of organisms in

the biosphere• ECOSYSTEM DIVERSITY – all habitats,

communities,& ecological processes in ecosystems

• SPECIES DIVERSITY – the # of different species in the biosphere

• GENETIC DIVERSITY – the genetic info carried in all living things on earth

Ecosystem Diversity

Species Diversity

Genetic Diversity

Threats to Biodiversity• Humans alter habitats, hunt species to extinction,

introduce pollution into food webs & introduce foreign species into new environments

• HABITAT FRAGMENTATION• EXTINCTION• BIOLOGICAL MAGNIFICATION• INVASIVE SPECIES

Habitat Fragmentation

Extinction• Several mass extinctions over geologic time (i.e.

Dinosaurs)• Humans have driven many species to extinction

On the verge of extinction

• Many are listed as o THREATENED – Population numbers are rather low

& they must be protected & monitored

o ENDANGERED – Population numbers are extremely low and they must be protected,

Conservation• Conservation is the wise

management of natural resources

• Protecting entire ecosystems as well as a single species

• Protecting the ecosystem ensures that the natural habitat is preserved & the interactions of many different species at the same time.

The Future• Effects on the Ozone Layer

o Ozone protects Earth from harmful radiationo CFC’s (found in aerosols) caused damage to the ozone o CFC’s have since been banned

• Global Warmingo Increased production of CO2 has thickened the “blanket” around the

earth resulting in the trapping of more heat, raising the average temperature of the planet

o Runaway greenhouse effect (Global Warming) could result in coastal flooding and drastic weather patterns