1. Carbon and Nitrogen Cycles Why they are important in an ecosystem

2. The Carbon Cycle and Food Chains  The carbon cycle is one of the most important cycles in an ecosystem because it the basis of all life.  To understand this we must look at what a food chain looks like and what a food chain is composed of.  All living things need food to grow.  Plants use carbon through photosynthesis to produce food for themselves.  Insects/herbivores eat plants.  Smaller animals eat the insects and some of the smaller herbivores.  The more dominant carnivores eat the smaller animals.  Finally the most dominant carnivore sits atop the food chain.

3. Carbon Cycle Continued  As mentioned in the previous slide carbon is crucial to the life cycle because it is the first building block in a food chain.  Plants absorb carbon from the atmosphere through the process of photosynthesis and this allows the plants to grow.  Plants are at the bottom of the food chain so an ecosystem with plentiful plants will flourish therefore allowing all consumers and predators above it to flourish.

4. How is it a Cycle?  Human activities such as driving cars and heating homes release carbon dioxide into the atmosphere.  Plants absorb the carbon dioxide from the atmosphere for food.  Insects/Animals eat the plants. They release carbon dioxide back into the atmosphere through respiration (breathing) to be reabsorbed by plants.  As insects and animals die, their bodies decompose and carbon compounds are released by the breakdown of bacteria and fungi.  Decomposing bodies turn into organic compounds which then after many, many years (millions) turn into fossil fuels which then can be used for human activities such as driving and heating your home.

5. The Carbon Cycle

6. Nitrogen Cycle – Why is it Important?  Plants use nitrogen and nitrates to build up proteins.  Herbivores that eat these plants are able to use these proteins to build their animal proteins to increase their ability to grow.  Predators and carnivores then in turn use the protein gained from the herbivores to build up protein and grow.

7. Nitrogen Cycle – How it Works  Our atmosphere is 78% nitrogen but plants do not absorb it the same way as carbon dioxide.  Nitrogen reaches the earth through rain fall and is absorbed by the plants through the soil. Bacteria also breaks down ammonia (used as fertilizer) to form nitrates.  As mentioned, the plants use the nitrogen to build proteins, herbivores eat the plants to build proteins of their own and finally the carnivores and top predators eat the herbivores to produce their proteins.  When animals defecate or die, nitrogen is released back into the soil in the form of ammonia.  Denitrifying bacteria breaks down the nitrates in the soil and releases is back into the atmosphere and the cycle starts over again.

8. Nitrogen Cycle