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Ecological Succession
Ch 19 Section 2
Succession
• The gradual development of a community
over time.
Primary Succession
• A small community begins to grow where
none had lived before
• No soil, it is created from rocks and decaying
organic matter.
• Lichen are usually the first living things here.
They are the pioneer species.
Secondary Succession
• Regrowth of a community after a disaster like
a fire or a flood.
• Soil is already there.
• Humans can cause this also by logging or
clearing land for farming.
Biodiversity
• The variety of species that are present in an
area.
• As succession continues, more species
become established
• The early, species are fast growing and spread
seeds quickly
• The later species are slower growing and
better adapted.
• Biodiversity is important because it protects
the community in case of some problem- like
the invasion of insects. Insects usually infest
only one species of tree and wouldn’t wipe
out the whole forest.
Climax Community
• The climax community has many that are well
adapted and that have lived together for a
long time.
Keystone Species
• A keystone species is a species that plays a
critical role in maintaining the structure of an
ecological community
The jaguar acts as a keystone predator by its
widely varied diet, helping to balance the
mammalian jungle ecosystem with its
consumption of 87 different species of prey
• Some sea stars prey on sea urchins, mussels,
and other shellfish that have no other natural
predators. If the sea star is removed from the
ecosystem, the mussel population explodes
uncontrollably, driving out most other species,
while the urchin population destroys coral
reefs.
• In the African savanna, the larger herbivores,
especially the elephants, shape their
environment. The elephants destroy trees,
making room for the grass species. Without
these animals, much of the savanna would
turn into woodland.