2.4 Succession and Zonation

Question 1

How an ecosystem changes along an environmental gradient

Determines the boundaries of where a species can live (niche)

Answer 1

Zonation

Question 2

Zonation is Impacted by:

Answer 2

• Temperature
• Elevation
• Precipitation
• Insolation
• Soil type
• Interactions between species
(competition)
• Human activities

Question 3

Succession

Answer 3

changes in a species composition in a species composition over time; make an ecosystem more stable/biodiverse

Gradual replacement of simple organisms with
more complex organisms over time

Question 4

Pioneer Species

Answer 4

first organisms to arrive in an area

Question 5

Climax community

Answer 5

the oldest stage of succession

Question 6

Primary Succession

Answer 6

• Begins in a place without soil; ROCK
• Events that trigger: Volcanic Eruptions (lava hardens into rock), Rock slide
• Pioneer Species – Lichen and moss (grow in extreme conditions; break down rock into soil)
• Can reach a climax community in 1,000 years
• Change in number of species is very slow at the beginning

Question 7

Secondary Succession

Answer 7

• Begins in an area that only has SOIL, but used to have organisms
• Events the trigger: Construction (bulldozing or clearing land), Natural disasters like floods or
hurricanes
• Pioneer Species – Grass (seeds are already in soil or brought in by wind/water/animals)
• Can reach a climax community in 100 years
• Change in number of species happens at a steady rate

Question 8

r-selected species

Answer 8

those that emphasize high growth rates, typically exploit less-crowded ecological niches, and produce many offspring, each of which has a relatively low probability of surviving to adulthood

Question 9

K-selection

Answer 9

those species that produce few “expensive” offspring and live in stable environments

Question 10

Mount St. Helens (1980 - Largest volcanic eruption in US history) is an example of

Answer 10

primary succession