1. 5.3 Population
TODAY:
In your blog: how do living organism affect the abiotic environment during succession?
Feedback distributer: Maria L.
ANNOUCEMENT:
1. Test – October 11

2. G2.8 Interactions with organism and the environment
Soils become deeper as a result of decay of plants
Allows well-draining soil
Organic matter (humus) in soil increases as a result of decay of plants
Organic matter quickly absorbs and releases water so is a good medium for plant growth
Mineral recycling increases
bacteria and fungi become more active in soils that have high organic matter
Soil erosion reduces
plant roots that stabilize the sand
Minerals added
Alder plants fix atmospheric nitrogen which leads to increase of nitrogen in the soil
Organic matter

3. 7 billion people and growing
National geographic celebrates 7 billionth person on October 31, 2011
Need 1.5 Earths to support current growing population
19th century: agricultural revolution increase food production, industrial revolution improved method of transporting food
20th century: advance in medicine, sanitation and nutrition

4. Logistic growth Q 6, 7, 8 Population growth
Add this question at the end:
List three abiotic or biotic factors which set limits to population increase

5. 5.3.4 What sets a limit to population increase?
density-dependent, biotic factors
mortality due to disease
mortality due to predation
intraspecific competition
density-independent, abiotic  factors
mortality due to weather
mortality due to natural disasters: fire, hurricane, floods, earthquakes

6. 5.3.2 – 5.3.3 Logistic growth curve
Exponential growth phase
Species doubles per unit time
No limiting factors: nutrients, oxygen, space in ample supply
Transitional phase
Population growth continues but at a slower rate
Limiting factors slow growth rate: nutrients, oxygen, space in short supply
Plateau phase
Population growth slows to zero
Limiting factors inhibit population growth: nutrients, oxygen, space in short supply
Carrying capacity (K) = maximum number of individuals in a species that can sustainably be supported in an environment

7. 5.3.1 Factors affecting population size
Natality: birth rate
Immigration: rate at which individuals move into a population
Mortality: death rate
Emigration: rate at which individuals move out of the population
P = (N + I) – (M + E)

9. Logistic growth curve Exponential growth phase Transitional phase
N + I > M + E
Transitional phase
Plateau phase
N + I = M + E

10. 7 billion people and growing
National geographic celebrates 7 billionth person on October 31, 2011
Need 1.5 Earths to support current growing population
19th century: agricultural revolution increase food production, industrial revolution improved method of transporting food
20th century: advance in medicine, sanitation and nutrition