1. Communities, Biomes, and Ecosystems
Chapter 3
Communities, Biomes, and Ecosystems

2. Section 3.1: Community Ecology
All living organisms are limited by factors in the environment
Communities
A group of interacting populations that occupy the same area at the same time
Includes biotic factors: plants, other animals, bacteria, fungi, etc. and the abiotic factors: rocks, water, soil, air, pH, temperature, etc.

3. Communities Not every community includes the same variety of organisms
Urban vs. rural
Desert vs. arctic

4. Communities
Organisms adapt to the conditions in which they live

5. Communities
Limiting factors – any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms
Abiotic limiting factors: sunlight, climate, temperature, water, nutrients, fire, soil, space
Biotic limiting factors: living things such as other plant and animal species

6. Communities Range of tolerance
Upper limit and lower limit for any environmental factor that defines the conditions in which an organism can survive
Tolerance: the ability of any organism to survive when subjected to abiotic or biotic factors
Figure 3.2 example Steelhead trout page 61

7. Ecological Succession
Ecosystems are constantly changing
The change in an ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors is ecological succession
two types –
Primary succession
Secondary succession

8. Primary Succession
The establishment of a community in an area of exposed rock that does not have topsoil
Usually occurs slowly at first
Usually consists of bacteria and perhaps fungi, small plants, lichens, grasses, and perennial herbs

9. Primary Succession Most plants require soil for growth
Pioneer species help create soil by secreting acids that help break down rocks
As pioneer organisms die, their decaying organic matter, along with bits of sediment from the rocks, make up the first stage of soil development

10. Primary Succession
Once soil is established, other organisms can grow in the newly formed soil
Eventually, enough soil is present to support shrubs and trees
A mature community can eventually develop from bare rock.
Stable mature community that has little change in the composition of species is called a climax community
A true climax community is unlikely to occur due to ongoing changes

11. Secondary Succession
Disturbances such as fire, flood, or a windstorm can disrupt a community
Creates new species
Over time, secondary succession: the orderly and predictable change that takes place after a community of organisms has been removed but the soil has remained intact - occurs

12. Secondary Succession
Pioneer species – mainly plants that begin to grow in the distributed area- are the first species to start secondary succession where the community changes over time

13. Succession’s End Point
Ecological succession is likely a very complex process that involves many factors
Cannot be predicted
Constant change at different rates
Very slow process
Human interaction a factor
Difficult to determine

14. Section 3.2: Terrestrial Biomes
Ecosystems on land are grouped into biomes primarily based on the plant communities within them
Effects of Latitude and Climate are a factor
Weather is a condition of atmosphere at a specific place and time

15. Effects of Latitude and Climate
Latitude – the distance of any point on the surface of Earth north or south from the equator
Ranges from 0 degrees at the equator to 90 degrees at the poles
Sun strikes Earth more directly at the equator
Earth’s surface is heated differently in different areas (polar, temperate, & tropical zones)

16. Climate
The average weather conditions in an area, including temperature and precipitation
Latitude has a large effect
Winds and ocean currents also play a role
Reminder: A biome is a large group of ecosystems that share the same climate and have similar types of communities

17. Climate
Global warming – result of the greenhouse effect

18. Major Land Biomes
Biomes are classified primarily according to the characteristics of their plants
Also characterized by
temperature
Precipitation
Animal species

19. Terrestrial Biomes Tundra Boreal forest (Taiga) Temperate forest
Temperate woodland and shrubland
Temperate grassland
Desert
Tropical savanna
Tropical seasonal forest
Tropical rain forest

20. Tundra
Below polar ice caps across northern North America, Europe, and Siberia in Asia
Treeless biome with a layer of permafrost
Figure 3.8 on page 68

21. Boreal Forest (Taiga) South of tundra Evergreen forest
Figure 3.9 on page 68

22. Temperate Forest
Southeastern Canada, eastern US, most of Europe, parts of Asia and Australia
Composed mostly of broad-leaved, deciduous trees
Figure 3.10 on page 69

23. Temperate Woodland and Shrubland
Areas surrounding the Mediterranean Sea, western coasts of North and South America, South Africa and Australia
Chaparral – dominated by shrubs
Figure 3.11 on page 69

24. Temperate Grassland Fertile soil
Called steppes, prairies, pampas, llanos, cerrados, savannas, rangelands or velds
Figure 3.12 on page 70

25. Desert
Exist on every continent except Europe
Figure 3.13 on page 70

26. Tropical Savanna Characterized by grasses and scattered trees
Occur in Africa, South America, and Australia
Figure 3.14 on page 71

27. Tropical Seasonal Forest
Tropical dry forests found in Africa, Asia, Australia, and South and Central America
Resemble temperate deciduous forest during dry season
Figure 3.15 on page 71

28. Tropical Rain Forest
Found in Central and South America, southern Asia, western Africa, and northeastern Australia
Figure 3.16 on page 72

29. Other Terrestrial Areas
Mountains
Polar regions

30. Biome Activity
On the index cards provided put one biome on each side of the index card
Be sure to include the information found in Figures for each biome
Use these cards as a study tool for your upcoming test

31. Section 3.3: Aquatic Ecosystems
Aquatic ecosystems are grouped based on abiotic factors such as water flow, depth, distance from shore, salinity, and latitude

32. The Water on Earth Largely covered by water
Includes freshwater, transitional, and marine aquatic ecosystems

33. Freshwater Ecosystems
Includes ponds, lakes, streams, rivers and wetlands
Plants and animals are adapted to the low salt content in freshwater and unable to survive in areas of high salt concentration
About 2.5% of water on Earth is freshwater

34. Freshwater Ecosystems
Of the 2.5% of freshwater
68.9% is in glaciers
30.8% in groundwater
0.3% in lakes, ponds, rivers, streams and wetlands
Almost all freshwater species live here

35. Rivers and Streams Water flows in one direction
Begins at source (headwater) and travels to the mouth
Empties into a larger body of water
May start from underground springs or snowmelts
Slope of landscape determines direction and speed of water flow

36. Rivers and Streams
When slope is steep, water flows quickly causing a lot of sediment to be picked up and carried by the water
As slope levels, speed of water flow decreases and sediment deposited in form of silt, mud and sand

37. Rivers and Streams Interactions between wind and water adds oxygen
Interactions between land and water results in erosion
Currents or turbulence prevents much accumulation of organic materials and sediment
More species found in slow-moving water

38. Lakes and Ponds Inland body of standing water Can be small or large
Seasonal temperature changes and wind mixes top and bottom layers -oxygenating it and bringing nutrients to top
Oligotrophic – nutrient-poor lake
Often found in mountains

39. Lakes and Ponds Eutrophic - nutrient-rich lake
Usually found at lower altitudes
More plant and animal species present

40. Lakes and Ponds
Divided into three zones based on amount of sunlight that penetrates the water
Littoral zone – area closest to shore
Limnetic zone – open water area that is well lit and dominated by plankton
Profundal zone – minimal light, deepest area of lake

41. Transitional Aquatic Ecosystems
Wetlands : areas of lands such as marshes, swamps, and bogs
Saturated with water and support aquatic plants
Estuaries: among most diverse ecosystems
Formed where freshwater from a river or stream merges with salt water from the ocean

42. Transitional Aquatic Ecosystems
Salt marshes are similar to estuaries
Support seagrasses, shrimp, shellfish

43. Marine Ecosystems
Intertidal zone: a narrow band where the ocean meets land
Further divided based on communities that exist in each zone
Spray zone
High-tide zone
Mid-tide zone
Low-tide zone
Page 79 Figure 3.26

44. Marine Ecosystems Open ocean ecosystems
Photic zone(pelagic zone, euphotic zone): shallow, sunlight penetrates
Aphotic zone: below photic zone, sunlight unable to penetrate, dark and generally cold
Benthic zone: along ocean floor
Abyssal zone: deepest region of ocean, very cold

45. Open Ocean Ecosystems

46. Coastal Ocean and Coral Reefs
Sensitive to changes in environment
Often studied
Southern tip of Florida among world’s most diverse