1. Life and Death, Nutrient Cycles, Sustainable Development
Cycles of Life
Life and Death, Nutrient Cycles, Sustainable Development

2. Nutrient Cycles Why do the nutrients on the Earth need to be cycled?
The Earth is considered a closed system.
This means that there is little or no input of new materials from outside the system.
Organics = H and C, often O and N (proteins, fats, sugars)
Inorganics – not containing C and H
Nutrients can be in the biotic environment or abiotic environment.

3. The Carbon Cycle
Plants make carbohydrates through a process known as photosynthesis.
6CO H2O + E  C6H12O O2
Capture of carbon from atmosphere
Carbon is returned to the atmosphere via cellular respiration.
C6H12O O2  6CO2 + 6H2O + E

4. The Nitrogen Cycle
Nitrogen is also very important and it will also circulate between the biotic and abiotic parts of the environment.
Proteins and DNA
Fertilizers contain N, P and K to facilitate growth
If there is no fertilizer then how does the plant acquire N?

5. Phosphorus Cycle Long and Short Cycles Long Rocks of the earth’s crust
Phosphate ions (PO43-) dissolve out of rocks (due to solubility) and are absorbed by photosynthetic organisms
Short
Living organism’s waste is cycled.

6. Agriculture and Nutrient Cycles
Phosphate Accumulation
Algae growth = algal bloom
Bacteria break down algae and use oxygen to do so
Fish and animals die
Problems become worse

7. Changes in Populations
Changes to populations
Growth = natality (birth rate); immigration
Decline = mortality (death rate); emigration

8. Limits on Populations Biotic Potential
Maximum number of offspring that a species could produce if resources were unlimited.
Carrying Capacity
Maximum number of individuals of a species supported indefinitely by an ecosystem. Affected by 4 factors:

9. Carrying Capacity Factors
Materials and E  amount of usable E from sun, as well as water, carbon and other essential nutrients
Food Chains  populations are affected by populations below (food source) and above (food source for others)

10. Carrying Capacity Factors
Competition  all individuals in a population are vying for the same resources
Intraspecific Competition – same species
Interspecific Competition – different species
Density  only so many organisms can live in an area at one time
Density dependent factors – aggression, neglect of offspring will decrease birth rate and increase death rate.
Density independent factors – fire, flood, extreme weather

11. Closing the Loop Sustainable Development
Ecosystems are sustainable in that they perpetuate themselves indefinitely and require little or no additional materials each year.
Sustainable development is taking this idea and applying it to humans
Development that meets the needs of the present without compromising the ability of future generations to meet their own needs