Human impact on the Biosphere

• Hunting and Gathering… Early history– All materials necessary for survival

is taken from the local ecosystem• Forces evolution or extinction of prey

species

– Still practiced in indigenous tribes

Agriculture• Practice began ~11,000 years ago

with wheat, rice and potatoes– Quickly expanded into raising animals:

goats, pigs, cows, and horses– Allowed for the formation of larger

communities… civilization– Practice expanded dramatically in the

1800s and 1900s with plows and specialized equipment for the processing of materials… commerce• Monoculture practice ensues… growing

a single type of crop on a field

Green Revolution• The green revolution… Despite the

practice of monoculture farming and the development of specialized equipment, there were obvious food shortages in the mid 20th century– Fertilizers were introduced that

increased crop yields dramatically– Burbank and such introduced hybrid

varieties that were heartier and produced larger individual fruits

Limitations & Challenges faced by the Green Revolution

• Ecological impact– Practice of monoculture has led to

the evolution and rapid growth of the insect population leading to increased insecticide use

– Increased fertilization leads to eutrophication of ponds and lakes• Both practices endanger the water

supply

– Irrigation of arid land leads to saltification of the soil as minerals dissolve

– Irrigation of fields leads to loss of ground water needed for our communities• Supplies expected to dry up in 15-

20yrs

Industrial Revolution• Movement created convenience and

dependence on fossil fuels– Grew faster than our understanding of

the environment• Early practices included simply dumping

waste into the environment• Created the need for a waste disposal

system– Concentrates waste into toxic proportions

– Although there have been many advances, many ecologists are concerned that continued urban sprawl reduces farmable land and increases water use and pollution concentration