Ecology Part 6 Carbon & Nitrogen Cycles R. Martinez, 2012

Biochemical Cycles 1. Materials (e.g. elements) cycle within an ecosystem. 2. They cycle among organisms the physical environment. 3. Types of Cycles: A. Carbon Cycle B. Nitrogen Cycle C. Water Cycle D. Phosphorous Cycle https://encrypted-tbn0.google.com/images?q=tbn:ANd9GcSYXekZym19hN8_Ssd2R4jgZusrsUk0pfPq-O4surN2C0lDXX9T http://www.astrobio.net/albums/climate/adp.jpg

What is Carbon? An element The basis of life on earth Found in all living organisms Also found in rocks, oceans, atmosphere Two main types: Carbon sources Carbon sinks

The Carbon Cycle A. Carbon sources: Release carbon into the atmosphere. i. Types include: Cellular Respiration: Burning of fossil fuels (combustion) Decomposers: Decomposers like bacteria and fungi, use the energy trapped in dead plants and animals and release CO2 Plants absorb CO2 (photosynthesis) and release CO2 (respiration). Plants use sugar to make their cell walls so they absorb far more carbon dioxide than they produce. Most animals cannot digest cellulose which is what plants cell walls are made of, so when plants are eaten or die, the carbon that was absorbed by the plant is trapped. This is where decomposers come in...

The Carbon Cycle Plants absorb CO2 (photosynthesis) and release CO2 (respiration). Plants use sugar to make their cell walls so they absorb far more carbon dioxide than they produce. Most animals cannot digest cellulose which is what plants cell walls are made of, so when plants are eaten or die, the carbon that was absorbed by the plant is trapped. This is where decomposers come in... B. Carbon sinks: Remove carbon from the atmosphere. i. Type includes: 1. Photosynthesis: a. Photosynthesis conducted by: i. Terrestrial – Plants/Trees ii. Aquatic - Phytoplankton

What is Nitrogen? 79% of the atmosphere is nitrogen gas Atmospheric N2 is in a form most living things cannot use. N2 free nitrogen

The Nitrogen Cycle Nitrogen Cycle: The nitrogen cycle is complex and has several stages: Organisms need nitrogen and phosphorus to build proteins and nucleic acids.

How do we get Nitrogen? A. Nitrogen is processed into a useable form by the following (known as nitrogen fixation): Nitrogen fixation is N2  NH3 (ammonia) Nitrogen-fixing bacteria convert nitrogen into ammonia/nitrates. Plants absorb nitrates. Animals eat plants. N2 in air nitrogen-fixing bacteria NITRATES

How do we get Nitrogen? normal conditions. 5. Nitrogen fixation can also be caused by lightning!

How does Nitrogen return to the atmosphere? B. Denitrifying bacteria convert the nitrates back into nitrogen.

The Role of the Decomposer When plants and animals die, the nitrogen contained in these organisms is digested by decomposers and released into the soil as ammonia. Without these decomposers, the nitrogen would remain trapped in the dead animals. These decomposers recycle the nitrogen and are a key component of the cycle.