populations and ecocapital unit 2 population growth • how do populations grow? • exponential growth • bigger populations grow faster • begins slow, then ramps up • even if rate of increase stays the same • limits on population growth • biotic and abiotic factors • carrying capacity biotic factors • efficiency of energy flow • biomass pyramid • higher levels support lower biomass • dietary choices? • food prices? primary consumers tertiary consumers secondary consumers producers 10 kcal 100 kcal 1000 kcal 10,000 kcal 1,000,000 kcal sunlight Abiotic Factors • Limiting Factors • Many limiting factors define the viability of life. • temperature, light, oxygen, carbon dioxide, and precipitation • Optimum / ideal range for factors • Zones of stress -- above or below the ideal • Range of tolerance – includes optimum plus zones of stress • Limits of tolerance – upper and lower limit beyond which organism cannot survive
Transcript
populations and ecocapital
unit 2
population growth• how do populations grow?• exponential growth
• bigger populations grow faster• begins slow, then ramps up
• even if rate of increase stays the same• limits on population growth
• biotic and abiotic factors• carrying capacity
biotic factors• efficiency of energy flow
• biomass pyramid• higher levels support lower biomass
• dietary choices?• food prices?
primary consumers
tertiary consumers
secondary consumers
producers
10 kcal
100 kcal
1000 kcal
10,000 kcal
1,000,000 kcalsunlight
Abiotic Factors• Limiting Factors
• Many limiting factors define the viability of life.• temperature, light, oxygen, carbon dioxide, and precipitation
• Optimum / ideal range for factors• Zones of stress -- above or below the ideal• Range of tolerance – includes optimum plus zones of stress• Limits of tolerance – upper and lower limit beyond which
organism cannot survive
time
popu
lati
on s
ize
(N)
population growth• exponential growth model
• growth occurs exponentially if no limiting factors• G=rN
The Human Factor• 2. The Industrial Revolution - 200 years ago
• Created the modern world• Reliant on fossil fuels – coal, oil and gas• Pollution and exploitation of natural resources increased• Uninterrupted population growth and economic expansion
The Human Factor• 3. The Environmental Revolution –21st Century
• Building a sustainable society• Commitment to the ethic of stewardship• Caring for the environment• Reduce waste products and pollutants• Conservation
Ecosystem Capital• Ecosystems -> functional units of sustainable life on earth
• provide the good and services – ecosystem capital - that humans depend upon
• humans in ecosystems• We are part of the food web – using organic matter provided by
producers and other consumers• We influence the way food webs function – both positively and
negatively• We must learn to manage ecosystems in order to keep them
healthy and productive
footprint• ecological footprint
• to accommodate the expected population by 2025, food production must double
ecological footprint• what is your ecological footprint?
• IMPACT= POPULATION x AFFLUENCE x TECHNOLOGY• I = P x A x T• for less-developed countries population has greatest effect• for more developed countries consumption has greatest
effect
discussion questions• How are humans altering biotic and abiotic factors in our
ecosystems? • are we at or near carrying capacity?• What is the role of science in conserving our ecosystems?• should everyone have the right to have as many children as
