1. Limits to Population Growth

2. No population can grow forever Limit 1 – the 10% rule: Amount of energy at each trophic level is 10% of the level below

4. Just like energy, biomass (the amount of matter—or “stuff”) forms a pyramid also.

5. Number of organisms follows the same pyramid pattern.

6. Limit 2: Carrying capacity of ecosystem Carrying capacity = how many organisms of a given species the ecosystem can support Limited by Available resources: food, water, shelter, soil, sunlight, etc. Other factors: disease, parasites, weather, natural disasters, man-made disasters

7. Population grows exponentially until it reaches its limit.

8. If it overshoots, some factor like starvation, predation, or disease reduces the number and keeps the population in check.

9. What about humans? Disease—modern medicine has drastically reduced it even in poorest countries

10. Space – Now we build upwards

11. Food supply – Better technology and genetic engineering of crops and animals has increased food supply

12. But … There is only so much land All land cannot be farmed due to terrain, temperature or soil type Cutting down forests for farming causes problems of erosion (loss of soil), habitat destruction, loss of other resources like wood or medicine