BIOL 2060 Lecture 21: 21 Succession
3 May 2018
School
Department
Course
Professor
Succession
March 4, 2014
• How do communities and ecosystems change over time
• How do they recover after a disturbance?
• Is it random or are there mechanisms that govern these processes?
Succession: gradual change in plant and animal communities following a disturbance
• Pioneer species – first to colonize
• Primary succession – on newly exposed geological substrates
• Secondary succession – following disturbance that doesn’t destroy soil (forest fire, land
abandonment)
• Climax community – later successional community
Ex. Primary Succession on Surtsey, Iceland
• New plant species even after 35 years
Glacier Bay, Alaska
• Has been retreating, allowing more area for colonization
• Increasing diversity
• Changing species composition
• Pioneer Dryas Alder Spruce
• Over 2000 years
• Trees, tall shrubs and mosses, liverworts and lichens attained max diversity in 1 century
• Low shrub and herb diversity continued to increase through 1,500 years of succession
Secondary Succession: Forest Fire in Boreal Forest
• After 2 years, wild flowers start colonizing
• Similar community in 180 years
• Trees become more dense
• Changes in species:
o Paper birch and aspen decline over time (fast growing; not competitive)
Rocky Intertidal:
• Succession in intertidal boulder field
• New colonization after disturbance
• Must fast leveling than in forests
Rapid Succession in Sycamore Creek after Flash Flood
• Flood mobilizes sand and stones causing scouring and sedimentation
• Can eliminate >98% of algae of invertebrates
• Rapid recolonization (1 month)
Slow Succession in Shallow Lakes
• Sedimentation drives changes
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