Transcript Ecological Succession - Neshaminy School District / Overview

Warm-up: Succession
• Read the Case Study,
“Communities Maintained by Fire”
on pages 130 – 131.
• Write two things you have learned and
• answer questions #1 & 2.
Warm-up Answers
• 1. New things you have learned…
•
The purple plant Fireweed covers the burned
forest areas of the Rocky Mountains.
•
Ecological Communities (Biomes) that are
maintained by fire are:
Chaparral of California, Temperate Grasslands of the
Midwest, many Southern and Western Coniferous
forests.
• Seeds of some species will not germinate until
exposed to temperatures of several hundred degrees.
Changes in Ecosystems:
Ecological Succession
What is Ecological Succession?
• Natural, gradual changes in the
types of species that live in an
area
• Can be primary or secondary
• The gradual replacement of one
plant community by another
through natural processes over
time
Primary Succession
• Primary succession occurs where there
was no previous community, such as on
bare rock or sand.
• Begins in a place without any soil:
»Sides of volcanoes
»Landslides
»Flooding
»Glacial retreat
• Primary succession begins with
PIONEER SPECIES.
Pioneer organisms can tolerate extreme
conditions: hot and cold; dry and wet.
Moss, dune grass, and lichens are pioneer
organisms.
• First, lichens that do not need soil to
survive grow on rocks
• Next, mosses grow to hold newly made
soil
Pioneer Species
Lichens break down rock to
form soil.
Low, growing moss
plants trap moisture
and prevent soil
erosion
Lichens
Lichens are algae and fungus growing
together in a mutualistic relationship.
• Algae make the food
• Fungus anchor and capture water.
Primary Succession
• Soil starts to form as lichens and
the forces of weather and erosion
help break down rocks into smaller
pieces
• When lichens die, they decompose,
adding small amounts of organic
matter to the rock to make soil
Primary Succession with lichens and mosses.
Primary Succession
• Simple plants like mosses and ferns
can grow in the new soil
Primary Succession
• The simple plants die, adding more organic
material (nutrients to the soil)
• The soil layer thickens, and grasses,
wildflowers, and other plants begin to take
over
Primary Succession
• These plants die, and they add more
nutrients to the soil.
• Shrubs and trees can survive now.
Primary Succession
• Insects, small birds, and mammals have
begun to move into the area.
• What was once bare rock, now supports a
variety of life.
Secondary Succession
• Begins in a place that already has
soil and was once the home of
living organisms
• Occurs faster and has different
pioneer species than primary
succession
Secondary Succession
• Newer communities make it harder
for the older communities to survive.
– Example: Younger birch trees will
have a harder time competing with
taller, older birch trees for sun,
but a shade loving tree may replace
the smaller birch trees.
When does secondary
succession occur?
• After forest fires
• After cultivated land is abandoned
• Temporary flooding from storms, etc.
Climax Community
• A relatively stable group of plants
and animals that is the end result of
the succession process
– However, stability never happens for long in
ecology! The only constant is CHANGE!
• Does not always mean big trees
– Grasses in prairies
– Cacti in deserts
• The following slide is an example of
the Secondary Succession of a deep
freshwater pond.
https://www.youtube.com/watch?v=k03vxRYsJ4Y