Ch.4. Unit 2 – Life on Earth (Ecology) Part 1. Human Population & the Environment. Why has human population grown so rapidly in the last 100 years? expansion of agriculture and industrial production and lower death rates from improvements in hygiene and medicine. - PowerPoint PPT Presentation
t 2 – Life on Earth (Ecology) Part 1 HUMAN POPULATION & THE ENVIRONMENT Ch.4 Why has human population grown so rapidly in the last 100 years? – expansion of agriculture and – industrial production and – lower death rates from improvements in hygiene and medicine. o In 2006, the population of developed countries grew exponentially at 0.1% per year. o Developing countries grew 15 times faster at 1.5% per year. Why do the populations in developed countries grow more slowly than in developing countries? – more educational opportunities for women leads to more women in the workforce and a delay in 1 st childbearing
Transcript
Unit 2 – Life on Earth (Ecology) Part 1
HUMAN POPULATION & THE ENVIRONMENT
Ch.4
Why has human population grown so rapidly in the last 100 years?
– expansion of agriculture and – industrial production and
– lower death rates from improvements in hygiene and medicine.
o In 2006, the population of
developed countries grew exponentially at 0.1% per year. oDeveloping
countries grew 15 times faster at 1.5%
per year.
Why do the populations in developed countries grow more
slowly than in developing countries?
– more educational opportunities for women leads to more women in the
workforce and a delay in 1st childbearing
– Increased awareness of birth control
Unit 2 – Life on Earth (Ecology) Part 1 Ch.4
Unit 2 – Life on Earth (Ecology) Part 1
POPULATION AGE STRUCTURE Ch.4
oUsed to make population & economic projections
What do each of these structures
indicate?
Populations with a large proportion of its people in the preproductive ages (1-14) have a
large potential for rapid population growth.
Unit 2 – Life on Earth (Ecology) Part 1
EXPONENTIAL VS. LOGISTIC GROWTH Ch.4
No population can grow exponentially indefinitely.
Logistic Growth Curveo “S” shaped
oPop. Growth slows as it reaches carrying capacity
Logistic Carrying Capacity
oBirth rates = Death ratesoNo net change in
population
Unit 2 – Life on Earth (Ecology) Part 1
EXPONENTIAL VS. LOGISTIC GROWTH Ch.4
If a country has a CBR of 21 per 1000 and a CDR of 7 per 1000, the natural annual percent increase of its
population isa) .3%b) 1.4%c) 3%
d) 14%e) 28%
21/1000 – 7/1000 = 14/1000 = 1.4/100 = 1.4%
Unit 2 – Life on Earth (Ecology) Part 1
A DECLINING POPULATION CAN CAUSE PROBLEMS AS WELL:
Ch.4
Which of these problems do you believe are the
most important?
Unit 2 – Life on Earth (Ecology) Part 1
REPRODUCTIVE STRATEGIES
Ch.4
r-strategists (opportunists) Large number of smaller offspring with little parental care (populate quickly but little ability to compete at K).
K-strategists (competitors) Fewer, larger offspring with higher invested parental care (populate slowly but able to compete at K).
r (population growth). K (carrying capacity)
Unit 2 – Life on Earth (Ecology) Part 1
DEMOGRAPHIC TRANSITIONCh.4
As countries become economically developed, their birth and death rates tend to decline.
Population Momentumwhen total fertility
declines, there is a lag period before the rate of
natural increase declines. This is due to all the people already at
reproductive age
Unit 2 – Life on Earth (Ecology) Part 1
Biogeochemical CyclesCh.5
The complete path a chemical takes through the four major components – or reservoirs – of Earth’s systems
– or sinks –
Unit 2 – Life on Earth (Ecology) Part 1
Biogeochemical CyclesCh.5
Limiting Factors
Macronutrients
Micronutrients
S P O N C HRequired by all life
Required in small amounts by all life or in moderate amounts by some living things.
Na K CaWhen elements are not available at the right times, in the right amounts and in the right concentrations relative to each other
