populations and ecocapital

Transcription

1 populations and ecocapital unit 2 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 biotic and abiotic factors carrying capacity biotic factors efficiency of energy flow biomass pyramid higher levels support lower biomass dietary choices? food prices? 10 kcal 100 kcal 1000 kcal tertiary secondary primary 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 10,000 kcal producers sunlight 1,000,000 kcal

2 exponential growth model growth occurs exponentially if no limiting factors G=rN logistic growth model growth with limiting factors carrying capacity (K) G=rN asymptotic(k-n) TFR - total fertility K rate life expectancy infant mortality time density-dependent factors intraspecific competition density-independent factors seasonal factors disturbance apr may jun jul aug sep oct nov dec month time human population boom / bust cycles predator / prey population cycles classic example snowshoe hare / lynx continues birth rate and death rate age structure? china s one child policy infant mortality rate? male female age declining expanding snowshoe hare lynx stable

3 life expectancy living longer? human population human carrying capacity? fertilizer Haber process other technology - farming in new places health care Three major revolutions for humanity 1. Neolithic revolution 12,000 years ago conversion from a hunter-gatherer to an agricultural society long term settlements Better care and protection reduced mortality rate reliable food production Population growth supported 2. The Industrial Revolution years ago Created the modern world Reliant on fossil fuels coal, oil and gas Pollution and exploitation of natural resources increased Uninterrupted and economic expansion

4 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 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?

5 IPAT model factors affecting environmental impact 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 they want? what is your ecological footprint? calculators/