Biosphere
Biosphere
Ecosystems
4.3 ECOLOGICAL
SUCCESSION
Communities
Populations
Organisms
What is succession?
TIME
Is Disturbance a Good Thing?
• Life is always changing
and then responding to that change.
• Plant (& therefore animal) species are
constantly being replaced with more complex
species
• This is called ecological succession
Arrange the pics in the correct
order…
Ecological Succession
• Primary OR Secondary Succession?
• Depends on starting conditions:
– Is there any soil present?
– Does not matter if life had been there
previously or not
PRIMARY SUCCESSION
– Lifeless beginnings
– Starts WITHOUT SOIL.
• Examples:
– Bare rock exposed by glaciers or severe erosion
– Newly cooled lava
– Abandoned highway or parking lot
– Newly created shallow reservoir
PRIMARY
• Life begins with
PIONEER SPECIES
• Hardy, small
• Population grows quickly
• Grow close to the ground
• Ex: bacteria, moss, lichens
SUCCESSION
SECONDARY SUCCESSION
• Starts WITH SOIL.
• start from roots or seeds remaining or seeds carried in
by wind or animals
• Examples:
– Abandoned farms
– Heavily polluted streams
– Ponds from dams or flooding
Climax Community
• Succession is unpredictable
• While it generally proceeds from small to tall,
each disturbance is unique and each pioneer is
unique…leading to unique community
developments
• The most mature community is called the
climax community