1. Ch.26 Ecosystems
Ecology

2. Section 1: How Ecosystems Change
Learning Objectives
Explain how ecosystems change over time.
Describe how new communities begin in areas without life.
Compare pioneer species and climax communities

3. Section 1: How Ecosystems Change
A. Ecological succession – normal, gradual changes that occur in the types of species that live in an area

4. 1. Primary succession begins in a place without soil.
a. Starts with pioneer species such as lichens, that can grow on rock.

5. b. New soil forms as weather and erosion break down rock.
c. Decaying plants add organic material to new soil

6. 2. Secondary succession begins in a place that has soil and once had living organisms
a. Example: after a fire or removal of buildings
b. Occurs faster and has different pioneer species than primary succession

8. B. Climax community – stable stage of ecological diversity and balance

9. Discussion Question
Why does primary succession take longer than secondary succession?

10. Discussion Question
Why does primary succession take longer than secondary succession?
 New soil has to form from rock and organic material

11. Section 2: Biomes Learning Objectives
Explain how climate influences land environments.
Identify seven biomes of Earth
Describe the adaptations of organisms found in each biome.

12. Section 2: Biomes A. Factors that affect biomes climate 1. Temperature
2. Precipitation

13. B. Major biomes – large areas with similar climates and ecosystems

14. Tundra

15. 1. Tundra – cold, dry, treeless region
a. Permanently frozen soil called permafrost
b. Average winter temperature: -12 °C (10 °F)
c. Average precipitation is less than 25 cm/year
d. Plants: mosses, grasses, small shrubs, lichens
e. Animals: insects, ducks, geese, other birds, mice, arctic hares, reindeer

16. Taiga

17. 2. Taiga – cold forest of mostly evergreen trees
a. Soil thaws in the short summer
b. Precipitation: mostly snow, 35 – 100 cm/year

18. Temperate Deciduous Forest

19. 3. Temperate deciduous forests – region with four seasons, mostly trees that lose their leaves in autumn
a. Temperatures range from below freezing in winter to 30 °C (86 °F) or more in summer.
b. Precipitation: throughout the year, 75 – 150 cm/year
Temperate = temperature that is mild or in the medium; not too warm or too cold; not too wet or too dry.

20. Temperate Rain Forest

21. 4. Temperate rain forest – tall trees with needlelike leaves
a. Average temperature: ~10 °C (~50 °F)
b. Precipitation: 200 – 400 cm/year

22. Tropical Rain Forest

23. 5. Tropical rain forest – the most biologically diverse of all biomes
a. Average temperature: 25 °C (77 °F)
b. Precipitation: 200 – 600 cm/ year
c. Four zones: forest floor, understory, canopy, emergents
d. Human impact: Habitats being destroyed by farmers and loggers

25. Desert

26. 6. Desert – driest biome, supports little plant life
a. Temperatures: vary from hot to cold
b. Precipitation: less than 25 cm/year
c. Soil: thin, sandy, or gravelly
d. Plant: cactus
e. Animals: Kangaroo rat, scorpions

27. Grasslands

28. 7. Grasslands – prairies or plains, dominated by grasses
a. Temperatures: temperate or tropical
b. Precipitation: 25 – 75 cm/year; dry season
c. Animals: kangaroos, wildebeests; cattle

29. Section 3: Aquatic Ecosystems
Learning Objectives
Compare flowing freshwater and standing freshwater ecosystems
Identify and describe important saltwater ecosystems
Identify problems that affect aquatic ecosystems.

30. Section 3: Energy Flow
A. Freshwater ecosystems – include flowing and standing water, low or no salt

31. 1. Rivers and streams – flowing water
a. Most nutrients washed into water from land
b. The faster the flow, the greater the oxygen content.

32. 2. Lakes and ponds – very little flow
a. Sunlight warms and lights pond bottom, supporting plant and animal life.
b. Deeper lakes support life along shallow shoreline or surface.

33. 3. Water pollution – a problem caused by fertilizer-filled runoff and sewage

34. 4. Wetlands – regions wet all or most of the year
a. Lie between solid land and water
b. Very fertile ecosystems

36. B. Salt water ecosystems – 95% of Earth’s water contains high concentration of salt, or high salinity.
 Amount of salt = salinity

37. 1. Open oceans – divided into lighted and dark life zones
a. lighted zone – upper 200 m and home of plankton
b. dark zone – below 200 m where animals feed on material that floats down or prey on each other
 Lighted zone
 Dark zone

38. 2. Coral reefs – diverse and fragile ecosystems formed form coral shells of calcium carbonate

39. 3. Seashores – along coastlines
a. Intertidal zone – covered with water at high tide and exposed to air at low tide
b. Drastic changes in temperature, moisture, salinity, and wave action

41. 4. Estuaries – where a river meets an ocean;
also called: bays, lagoons, harbors, inlets, sounds
a. Rich in nutrients
b. Changing mixture of salt water and freshwater

42. Discussion Question
What is the general relationship between sunlight and aquatic life?

43. Discussion Question
What is the general relationship between sunlight and aquatic life?
 The more sunlight, the more abundant the plant life