1. Material Cycling in Ecosystems
1.7

2. What role do decomposers play in an ecosystem?
What nutrients are important to ecosystems?
Materials in an ecosystem are used over and over again-4 Cycles- Carbon, Nitrogen, Minerals and Water

3. Carbon Cycle Why is carbon important to ecosystems?
All living things are composed mainly of carbon
Cycle: Producers take in CO2 during photosynthesis, consumers eat producers. When consumers break down their food using cellular respiration Carbon is released back into the atmosphere

5. Human Effects on C-Cycle
What are fossil fuels?
Coal, oil, natural gas- comes from dead organisms from millions of years ago
Burning fossil fuels- add carbon dioxide to the atmosphere- contributing to global warming

6. Nitrogen Cycle All organisms need nitrogen to build proteins
Nitrogen (N) makes up 78% of the atmosphere
The only organisms that can use nitrogen directly are nitrogen fixing bacteria
they take N from the atmosphere and transform, or ‘fix’ it into a form that plants can use
These bacteria live in the roots of some plants- use sugars from the plant for energy and produce N in the form of ammonia that the plant can use
Other plants get N from the soil
How do consumers get nitrogen?

7. Nitrogen fixing bacteria have a mutualistic relationship with plants.
The bacteria live w/in the nodules on the roots of some plants-they use sugar from the plant for energy and in return produce a form a nitrogen the plants can use to survive

9. Human Impact on Nitrogen cycle
Farming has a large impact on the Nitrogen cycle
Farmers add Nitrogen rich fertilizers to crops to help them grow, this puts more nitrogen into the ecosystem
Burning fossil fuels also contribute to more Nitrogen in the atmosphere and can lead to acid rain

10. Hydrologic (water) Cycle
The hydrologic cycle describes the movement and storage of water on Earth
Process that moves water from one place to another between the atmosphere and Earth
Sun’s heat evaporates water from the Earth’s surface, as water vapor cools and condenses, it forms droplets in the clouds. When clouds meet cold air, water returns to the Earth as precipitation-rain, sleet, snow
Where does the precipitation go?

11. Water Cycle cont’d
Precipitation falls into oceans, lakes, rivers; some is absorbed by plants and soil
Some gets trapped as groundwater-underground water that may rise to the surface again or be pumped up (wells)
Water is also used by plants, taken up through their roots
Water the plants don’t use is released back into the atmosphere as water vapor- this process is called transpiration

13. Human Impact on Water Cycle
Discuss with group:
What are some human actions that affect the water cycle?