Download 6.3 Ecological Succession

6.3 Ecological Succession
Two types of Succession
Primary Succession
▫ Occurs only where an ecosystem has
never existed.
 (Ex. 1963 Volcanic Island of Surtsey, new
molten rock formed land off the coast of
Iceland) seeds washed ashore and primary
succession begins.
Steps of Primary Succession
 Step 1- Pioneer species (mosses &
lichens) beginning stage of succession.
They will break down and form soil.
 Step 2/3/4- Then new larger species
can grow (Larger shrubs, small trees)
 Step 5- The process continues until the
ecosystem reaches a CLIMAX
COMMUNITY- last stage of succession
(mature trees)
Secondary Succession
• Process that begins when something has
disturbed or destroyed a natural
community or ecosystem. (natural
disaster or human activities)
Stages
 Step 1- annual weeds (quick
growing)
 Step 2- perennial weeds/grasses
(push out smaller vegetation)
 Step 3- Shrubs will dominate
 Step 4- small forests, spreads seeds
more effectively, shades out shrubs
 Step 5- Last stage, mature trees
(climax community)
What causes ecological succession?
• Natural disasters can often interrupt cycles such
as succession
▫ Volcanic eruptions, tornados, hurricanes, floods…
▫ What else?