Mount St. Helens

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

2. Remember! Community Ecology • We know how population sizes can fluctuate & we know how populations interact with each other. But what happens when entire communities are wiped out?

3. Ecological Succession

4. Ecological Succession • A series of predictable changes that occur in a community over time Slow changes occur after a sudden natural disaster (fires, volcanoes, etc.). Or, it could occur after human activity, like the clearing of a forest.

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

6. Lichens have the ability to grow on bare rock. The acids they secrete help to turn rocks into soil! When the soil is made, a variety of plants can begin growing in the area.

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

8. Which type of succession do you think takes longer? • Primary • Secondary • The same amount of time Primary Succession takes longer, because it takes many years for the soil to form! Here, you see a picture of the same glacier 29 years later. When glaciers retreat, they leave behind bare rock.

9. Rebuilding Communities in Marine Ecosystems • Succession in a marine ecosystem – “Whale Fall” • Occurs in 3 stages When a large marine creature dies, it supports a new burst of life!

10. 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

11. 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.

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

13. Succession can be good for a community! • Disturbances & disasters can sometimes be necessary for the development of a community. • Opens many niches to be filled • Rejuvenates the community – like starting fresh

14. Did you know? • The water we have on Earth today is the same water that was on Earth billions of years ago! Why?

15. Biogeochemical Cycles

16. Questions That Ecologists Ask • What limits the production in ecosystems? • How do nutrients move in the ecosystem? • How does energy move through the ecosystem?

17. Biogeochemical Cycles • We know that energy is transferred in just 1 direction… But MATTER is cycled through the ecosystem in the biogeochemical cycles!

18. Generalized Nutrient Cycling Decomposition connects all trophic levels!

19. 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 Transpiration Evaporation Condensation

20. The Water Cycle • How water moves through the air, land, and organisms • Precipitation: clouds become too full & rain, snow, etc. fall • Runoff: water collects into bodies of water • Infiltration/Seepage: water from the surface sinks into ground water storage

21. Water from the bodies of water evaporate & water from the surface of plants transpires into the atmosphere. They condense back into liquid around tiny particles in the air, which forms clouds. Once the clouds get too heavy, precipitation falls to Earth to be consumed/absorbed by organisms!

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

23. Photosynthesis takes up CO2 from the atmosphere. Carbon moves through all organisms by consumption. Carbon is released through respiration. Carbon from dead organisms is released into the soil & compacted into fossil fuels over millions of years.

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

25. 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).

26. 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.

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

28. 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 in bodies of water can cause an overgrowth of protists, which causes Red Tide!

29. How do humans play a role in the biogeochemical cycles?

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

31. Human Effects on Biogeochemical Cycles • Eutrophication: overgrowth of photosynthetic organisms in a body of water due to an excess of nitrates & phosphates from urban & agricultural runoff This can occur in oceans, lakes, & in estuaries. The excess growth can choke the waters of gas exchange.

32. Breaking the Water Cycle • Deforestation breaks the water cycle! • Ground water is not transpired to the atmosphere, so precipitation is not created! Forest  Desert Desertification