Transcript Warm-Up 10/2 - Adam Hardtke.com

Succession
How do ecosystems recover from
disturbances?
Succession
 Succession is the process of life taking
over disrupted ecosystems
 Primary succession occurs in barren
areas with no soil (eruptions, glaciers)
 Secondary succession occurs where soil
is still intact (grazing, logging, etc.)
Primary Succession
 With no soil, bare ecosystems are very hostile to life
 Pioneer species are first to colonize
 Pioneer species need little water, shade
 Typically small weeds, lichens
 R-selected and/or type III species
Who lives and who dies?
 Competition for resources determines who takes over
the new land
 Species that reproduce fast and don’t need many
resources survive best, become pioneer species
 Over time, less weedy species arrive and outcompete
the first colonizers
Later Succession
 As soil appears, larger grasses, shrubs, and shade-
intolerant trees appear
 The species that appear depend on the climate
Results of Succession
 Primary and secondary succession result in a climax
community
 Maintain species for a long period of time
 Sustainable (in energy balance)
 More organism symbioses than a changing community
May 18, 1980
Spirit Lake, before eruption
Spirit Lake, after and now
Windy Ridge Old
Growth Forest,
above Spirit
Lake
(before eruption)
Windy Ridge Old
Growth Forest,
after eruption
and now