Flashcards on Key Concepts in Population Ecology
Key Concepts in Population Ecology: A Student's Guide
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Ecological Succession
11 cards
Card 1
Question: What is a pioneer species in primary succession and give an example from rock surfaces?
Answer: A pioneer species is the first organism to establish after a disturbance; on rock surfaces lichens are pioneers.
Card 2
Question: Why can lichens colonize bare rock during primary succession?
Answer: They do not need soil to survive and can break down rock through physical weathering and biological activity.
Card 3
Question: How does soil begin to form during primary succession with lichens present?
Answer: Lichens and physical weathering break rocks into smaller pieces; when lichens die they decompose, adding organic matter to form soil.
Card 4
Question: Which pioneer species appear in secondary succession immediately after a disturbance?
Answer: Annuals (herbs and weeds) are the first species to appear in secondary succession.
Card 5
Question: What typically follows annuals in secondary succession after about a year?
Answer: Grasses and perennials appear about a year later; in forest gaps or wetter sites climbers may develop.
Card 6
Question: What ecological changes occur during the intermediate stage of succession?
Answer: Soil holds more water and becomes more fertile, temperatures are less extreme due to increased shade, allowing greater variety and number of organisms
Card 7
Question: How do plant communities change as soil builds up during the intermediate stage?
Answer: Non-woody herbaceous species give way to small hardy woody plants, then larger woody shrubs and small trees; grasses remain present.
Card 8
Question: What animal groups typically join a community during the intermediate stage?
Answer: Larger herbivores (hares, small antelope), small carnivores (caracal, wild cats), snakes and raptors join the community.
Card 9
Question: What is a climax community?
Answer: The climax community is the last semi-stable stage or endpoint of succession.
Card 10
Question: Give examples of different types of climax communities mentioned.
Answer: Climax communities can be large trees in forests, grasses and Acacia in savannah, or dwarf succulent shrubs in the Succulent Karoo biome.