1. Ecology
CYCLING IN NATURE

2. About Cycles
Ecosystem structure is influenced by the availability of nutrients and energy.
The five main elements plants use include:
carbon
oxygen
hydrogen
nitrogen
phosphorous.
Cycles, Alright!

3. About Cycles The elements essential for life tend to move in cycles.
Elements are transferred from the environment, to organisms, then back to the environment.
Organisms
Environment

4. Hydrologic Cycle
                                           
Cold and warm ocean currents, clouds, winds, and rainfall are all a part of the global hydrologic cycle. The hydrologic cycle is driven by solar energy.

5. Hydrologic Cycle

6. Hydrologic Cycle What are two ways water moves into the atmosphere?
Evaporation- water changes from liquid form to an atmospheric gas.
Transpiration: evaporation of water from leaves of plants.
It remains as water vapor, clouds, and
ice crystals until it falls back to
earth.

7. How does water fall back to Earth?
Hydrologic Cycle
How does water fall back to Earth?
Condensation- water cools and forms clouds.
Precipitation- water falls to earth and remains on land for about 10 to 120 days.
Then some of it evaporates or is carried by rivers and streams to the seas where, with evaporation, the cycle begins.

8. Hydrologic Cycle
Water is an important way in which nutrients move into and out of ecosystems. As the water goes through the hydrologic cycle, it carries the nutrients with it.
Raise your hand if you love the hydrologic cycle!!!

9. Carbon Cycle

10. The Carbon Cycle
Carbon moves in through the atmosphere and oceans, through organisms, and then back to the environment as dead organisms deteriorate.
Carbon enters the atmosphere through
respiration,
fossil fuel burning, and
volcanic eruptions, which release carbon from rocks deep in the earth’s crust.

11. The Carbon Cycle

12. The Carbon Cycle
Carbon exists as gas in the atmosphere- CO2 (carbon dioxide). About half of all the carbon entering the atmosphere each year will move into two large “holding stations” or sinks or reservoirs.
The two places where most of the CO2 is housed are:
1) oceans
2) plant biomass

13. The Carbon Cycle
Each year photosynthesizers capture airborne CO2 and turn it into organic compounds, like food.

14. The Carbon Cycle
In aquatic food webs, carbon is turned into the shells and other hard parts of marine organisms. When the shelled organisms die, they sink to they bottom where they can remain buried for millions of years.
This carbon may slowly be converted
into “fossil fuel”:
gas,
petroleum
coal

15. Nitrogen cycle

16. The Nitrogen Cycle

17. The Nitrogen Cycle
Of all of the nutrients influencing the growth of land plants, nitrogen is often in the shortest supply.
The atmosphere is the largest supply of nitrogen (sink or reservoir), but it is in a form that cannot be used by organisms.

18. The Nitrogen Cycle
Nitrogen Fixation: process of converting nitrogen gas (N2) into ammonia (NH3)
Bacteria that are found in the soil and on the roots of legumes undergo this process.

19. Atmospheric Nitrogen Fixation

20. The Nitrogen Cycle
Nitrogen fixing bacteria can convert N2 into forms that can be used in ecosystems. The N2 is turned into ammonia NH3 by the bacteria. The ammonia is then used in the production of proteins by plants.
 N2  NH3 (nitrogen fixation!)
Plants use the nitrogen in their tissues, the nitrogen is then transferred to animals when they consume the plant.
!!! The Nitrogen Cycle Yipee!!!

21. The Nitrogen Cycle
Nitrogen is returned to the environment when bacteria and fungi break down nitrogen-containing wastes and the remains of plants and animals.
Denitrification: conversion of nitrates into nitrogen gas (N2)