Warm-Up 9/12/11

Factors influencing Populations

Objective- For students to understand that every action

has a consequence.

Essential QuestionHow does the increase in

population effect the overall impact on the Earth?

Human Population Growth recap

• Human population has increased at an almost exponential rate.

• With this growth comes an increase in demand for land, food, water, energy and other resources.

• As human numbers grow species and their habitat diminish.

Biodiversity • Biodiversity is the variety of all forms of life

throughout an ecosystem.• High rates of extinction are quickly reducing

biodiversity especially in areas of the world with high human population density and growth.

• The direct and indirect effects that humans have had on biodiversity is challenging as can be seen from the following flow chart.

Human PopulationSize Resources use

Human Enterprises Agriculture Industry Recreation International Commerce

Land TransformationLand Clearing

ForestryGrazing

Intensification

Biotic Additionsand Loss

InvasionHuntingFishing

GlobalBiogeochemistry

CarbonNitrogenWater

Climate Change

Enhanced Greenhouse

AerosolsLand cover

Loss of Biological Diversity

Extinction of speciesAnd populations

Loss of ecosystemsVitousek et. al (1997) Science, 277, p.494-499

What is a resource?

• a source of supply, support, or aid, especially one that can be readily drawn upon when needed.– Webster’s Dictionary

What does this mean to us?

Allegorical Apple Demo

• What conclusions can we draw about the relationship between a growing population and a shrinking amount of land capable of growing food for those people?

Humans Change of the EarthExpressed as % Change

0102030405060708090

100

% Change

Land Transformation

CO2 concentration

Water use

Nitrogen Fixation

Plant Invasion

Bird Extinction

Marine Fisheries

Vitousek et. al (1997) Science, 277, p.494-499

Biodiversity and People • Places on earth with some

of the greatest biodiversity such as: South America, Equatorial Africa, India, Indonesia and Coastal regions also show the greatest density and fastest rate of growth of people.

Biodiversity

World Population

Extinction

• Extinction is the natural order. In fact, of all the species which have ever existed, 99.9 % are now extinct!

• The current extinction rates, however, may be as much as 40 - 100 times the normal “background” or natural rate for extinction.

Extinction

• Paul Ralph Ehrlich at Stanford University predicts that soon, this rate may be as much as 400 times the "normal", average, rate of extinction!

• Much of this increase in extinction rate appears to be due to the impact of humans.– Habitat Depletion– Pollution– Introduction of disease – Introduction of invasive species – Over exploitation

Extinction

• 25% of the earth’s birds species have been driven to extinction by humans (especially on islands).

• Threatened with Extinction– 11% of birds– 18% of mammals– 5% of fish – 8% of plants

Great Auk

Loss of birds

http://www.audubon.org/campaign/population_habitat/

Extinction Rate

The Oceans and the Coast

• Globally, the number of people living within 100 km of the coast increased from roughly 2 billion in 1990 to 2.2 billion in 1995 (39 percent of the world's population).

Coastal Area Population Density

• 3.2 Billion (1/2 of the planet) live and work within 125 miles from a coastline.

• 4 Billion (2/3) live within 250 miles from the coast.

Coastline, Estuaries and Reefs

• While 75% of the earth is covered by oceans, the greatest levels of marine biodiversity are found near the coast.

• This Neritic zone of the ocean has depth of less than 250 meters and so the abundant photosynthetic organisms create a habitat for great biodiversity.

Kelp Forest Near Monterey California

Approximately 50% of mangrove ecosystems globally have been transformed or destroyed by human activity

Great Barrier Reef, Australia

Human causes of Coral Reefs Depletions

• Pollution runoff: nitrates from fertilizers, point-source pollution, oil spills.

• Exploitation: Over 90% of saltwater aquarium fish are taken directly from reefs.

• Increased water temperatures: global warming, increased El Nino.

• Direct Destruction: Boats, fishing nets, removal of coral for sale.

Over fishing

Culture

0

Global Fish Supply

Year

19

80

19

50

19

60

19

70

19

90

20

00

20

25

Million

Metr

ic T

on

s

20

40

60

80

100

120

140

160

Capture

(Grainger 1998)

1) Aquaculture is a vital aspect of the food-production industry

2) Global human population is expected to rise to over 9 billion by 2050

3) Placing tremendous pressure on food-production systems

Tropical Rainforests Facts• Contains more than half

of the 5 to 80 million species of plants and animals worldwide.

• Approximately 1/3 of the world’s bird species are found in South American Rainforests.

Tropical Rainforests Facts

• Each year approximately 78 million acres of rainforest are destroyed.

• As many as 137 species are going extinct each day.

• The substrate (soil) is poor with most of the nutrients existing in the trees and plants.

Tropical Rainforest Facts

• Poor soil leads to burning the land to increase top-soil nutrients.

• Burning trees releases carbon into the atmosphere which exacerbates the greenhouse effect and increases temperature.

Tropical Rainforest and Population Growth

• Today, more than 3 billion people live in the tropics alone; more than lived in the entire world in 1950.

• Millions of people are destroying the rainforest simply to survive.

• These people, usually small farmers, have nowhere to grow crops to feed their families, so they wander into the rainforest.

Rainforest and Primates• Out of some 240 known primate species, 19 are

critically endangered, up from 13 in 1996. • Their remaining numbers range from less than a

few hundred to, at most, a few thousand individuals.

• Includes 8 monkeys from Brazil's Atlantic rainforest, where 97 percent of the forest has been lost, 2 apes and a monkey from Indonesia, 3 monkeys from Viet Nam, 1 each from Kenya and Peru, and 3 lemur species from Madagascar.

http://www.audubon.org/campaign/population_habitat/

Human activity = Impacts

• Human activity is a major cause of environmental change

• Environment degradation has an impact not only on human beings but on all species and most natural systems

Human dependence on the natural Environment

• a resource for food supply

• a major source of medicines

• an energy source • a source for

recreation • natural resources

for industrial products

N

E

E

D

S

W

A

N

T

S

W

A

N

T

S

Environment

Human wants are never ending

Conclusion

• Humans require a great deal of resources and space and have not had a record of sharing.

• The earth is losing biodiversity at a rate not seen since the mass extinction that killed the dinosaurs 65 million years ago.

• Our increasing numbers will certainly increase the rate at which animals and plants are lost.

Conclusion

• "For if one link in nature's chain might be lost, another might be lost, until the whole of things will vanish by piecemeal."- Thomas Jefferson

Exit Ticket

• Describe three things in your life that are NEEDS.

• Describe three things in your life that are WANTS