Mount St. Helens

1. Mount St. Helens • Erupted in 1980 • All life destroyed • What happens after that?

2. Ecological Succession • A series of predictable changes that occur in a community over time Slow changes occur after a sudden natural disaster. For example, fires or volcanoes. Can occur after human activity, like the clearing of a forest.

3. Primary Succession • Occurs on surfaces where no soil exists (after a volcanic eruption or after a glacier retreats) • The first species to populate the area is the pioneer species. Lichens are usually pioneer species. Why?

4. Secondary Succession • Occurs after a disturbance that destroys a community without destroying the soil (fire, disease, clearing of a forest)

5. Succession in a Marine Ecosystem – “Whale Fall” • Occurs in 3 stages

6. Marine Succession – Stage 1 • Begins when a whale dies and sinks to the ocean floor • Attracts scavengers & decomposers, which eat the soft tissue of the whale

7. Marine Succession – Stage 2 • After 1 year, most of the soft tissue has been eaten • Decomposition of the body enriches the sediment with nutrients, which attracts more marine life

8. Marine Succession – Stage 3 • Begins when only the skeleton remains • Bacteria decompose the oils inside the bones • The bacteria can support a community of marine life

9. Did you know? • The water we have on Earth today is the same water that was on Earth 4.5 billion years ago! Why?

10. Biogeochemical Cycles • Energy is transferred in one direction. • Matter is cycled through the ecosystem in the biogeochemical cycles!

11. The Water Cycle • How water moves through the air, land, and organisms • Evaporation: water  vapor from surface of bodies of water • Transpiration: water  vapor from plants • Condensation: vapor  water in clouds

13. The Carbon Cycle • Carbon Dioxide (CO2) cycles through the ecosystem through air, water, land, and organisms.

14. Carbon enters the atmosphere through fossil fuel emissions & animal respiration. Photosynthesis takes up CO2 from the atmosphere.

15. The Nitrogen Cycle Nitrogen (N) cycles through the atmosphere, organisms, and soil.

16. Nitrogen Fixation • Nitrogen Fixation- bacteria take nitrogen (N2) from the atmosphere and change it into a form that plants can take up from the soil called ammonium (NH4). • Nitrification- ammonium not taken up by plants are converted to nitrates and nitrites by bacteria which other plants can take up. • Denitrification- bacteria can turn the ammonium back to atmospheric nitrogen

17. The Nitrogen Cycle • Consumers eat and take in N in order to make proteins. • Dead organisms can return N to the soil or to the atmosphere with the help of bacteria

18. The Phosphorous Cycle It does not enter the atmosphere, but rather is cycled through the soil, oceans, and organisms through consumption and decomposition

19. Nutrient Limitations • An ecosystem needs a particular amount of each nutrient to thrive. A single nutrient can limit its success. An excess of a particular nutrient can cause over production of algae and plant growth. (Red Tide!)

20. Human Effects on Biogeochemical Cycles • Carbon- burning fossil fuels releases previously isolated carbon back to the atmosphere • Nitrogen and Phosphorus- we add fertilizers to assist crop growth and much of it gets washed away into rivers, lakes and oceans