1. Communities and Biomes
Chapter 3
Communities and Biomes

2. 3.1: Communities
Limiting factors- any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution, of organisms
Examples?

3. Sunlight
Climate
Atmospheric gases
Temperature
Water
Nutrients or food
Fire
Soil chemistry
Space
Competition, predation, parasitism

4. Tolerance
Ability of an organism to survive changes in biotic and abiotic factors

5. Section 3.1 Summary – pages 65-69
Ranges of tolerance
Limits of Tolerance
Organisms absent
Organisms absent
Organisms infrequent
Organisms infrequent
Greatest number of organisms
Zone of Physiological stress
Zone of Physiological stress
Population
Zone of intolerance
Zone of intolerance
Optimum range
Range of tolerance
Lower limit
Upper limit
Section 3.1 Summary – pages 65-69

6. Biological Succession
Succession- the process of change as it occurs to communities in an ecosystem
Species that can be found in a particular ecosystem change over time

7. Primary Succession Colonization of barren land by organisms
Pioneer species-first species to inhabit an area
Lichens, algae, bacteria, protists colonize bare rock, lava flows

10. Climax community
A stable community that remains relatively unchanged for a period of time
Represents by a variety of ecosystems- mature forest, grassland, coral reef, tundra, etc.

11. Secondary Succession
A sequence of changes that takes place after an existing community is disrupted
Disruption could be natural (fire, hurricane, flood) or human-influenced (farming, controlled burn, construction)

13. 3.2: Aquatic & Terrestrial Biomes
Regional climate influences the distribution of biological communities
Latitude and ocean currents influence the climate on different parts of the Earth

14. Section 3.2 Summary – pages 70-83
Latitude describes your position in degrees north and south of the equator.
North pole
Sun’s rays
66.5o
23.5o o
Sun’s rays O
Equator
23.5o
Sun’s rays
66.5o
South pole
Section 3.2 Summary – pages 70-83

15. Saltwater Ecosystems
Estuary- area where different types of water merge (temperatures, pH, salt/fresh)
Intertidal zone- area where
salt water and land meet,
alternately submerged and
exposed

16. Oceanic Zones
The oceans can be separated into a variety of zones based on depth and proximity to the shoreline

17. Oceanic Zones

18. Intertidal zone- alternately submerged and exposed
Continental shelf- submerged edges of continents, relatively shallow water, high diversity
Pelagic zone- open water, motile populations
Benthic zone- sea floor of both continental shelf and pelagic zone

19. Light Availability
Photic zone- portion of the water column which can be penetrated by light, from the surface to a couple of meters down
Aphotic zone- portion of the water column beneath the photic zone where light cannot penetrate
Phytoplankton- plant-like plankton, base of aquatic food chains, perform photosynthesis
Zooplankton- animal-like plankton

20. Oceanic Zones

21. Section 3.2 Summary – pages 70-83
Freshwater biomes
Greatest
Greatest species diversity
Warmer layer
Oxygen and
light penetration
Colder layer
Least
Section 3.2 Summary – pages 70-83

22. Terrestrial Biomes
Biome- major type of terrestrial ecosystem characterized by similar climate and resulting types of organisms

23. Tropical Forests Clustered near the equator
Can be tropical rain forests or tropical dry forests
Relatively poor soil due to rapid decomposition and recycling of materials

25. Savannas & grasslands
Biome dominated by grasses and small scattered trees
Lack of water limits the size and number of trees

27. Deserts Desert biomes are defined by lack of water, not by temperature
Deserts can be both hot and cold
Rain shadow- dry area on sides of mountains opposite prevailing winds

29. Desertification- conversion of other biomes into desert
Results from growing human populations, overgrazing, changing climate

30. Temperate Forests
Dominated by hardwood trees which require sufficient moisture
Deciduous trees- lose their leaves

32. Coniferous Forests Principal trees are coniferous
Needle-like leaves can remain all winter
Many adaptations to periodic fire
Taiga- northern boreal forest- fewer trees and harsher winters than coniferous forests, located just south of tundra

34. Tundra Arctic areas and tops of mountains
Permafrost- soil that is permanently frozen year round
Plant life is very low-lying, no trees