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Chapter 10
Ecological Restoration
The Balance of Nature
– An environmental myth that states that the
natural environment, when not influenced by
human activity, will reach a constant status,
unchanging over time.
– Environmentalists in early 20th cent.
Formalized the idea
• Succession proceeds to a fixed, “classic” condition
called Climax Condition (steady state stage that can
persist indefinitely, max. organic matter, max.
storage of chemicals, max. biodiversity.
Restore to what !!
• Restore to original natural, permanent
condition.
• But…. What is this? This idea assumes that
nature is constant.
• Nature is NOT constant; it undergoes
change
• Some species require change to persist
What is Restoration
• Restoring an
ecosystem to its
historical range of
variation and to an
ability to sustain itself
and its crucial
functions, including
chemical cycling
• Upper Newport Bay
What needs to be restored?
•
1. Wetlands, Rivers and Streams
(Ex: Kissimmee River)
Channelization of the river,
2. Prairie Restoration
(Ex: Allwine Prairie)
Agricultural conversion
Kissimmee River Project
•
The Process of Ecological
Succession
Ecological Succession:
The process of the development of an ecological
community or ecosystem.
Two Types:
1. Primary Succession: The initial establishment
and development of an ecosystem
(following volcanic activity or edges of glaciers)
2. Secondary Succession: The reestablishment of
an ecosystem where there are remnants of a
previous biological community
(following a natural disaster: hurricane, flooding, fire)
Primary succession
•
• New growth on a cooled lava flow
Secondary Succession
• Following a forest fire
Patterns in Succession
1.
2.
3.
4.
An initial kind of vegetation specially adapted to the
unstable conditions (Pioneer Species)
Small plants and other early-successional species grow and
seeds spread rapidly.
Larger plants and other late successional species enter and
begin to dominate the site.
A mature forest develops.
(Succession is usually characterized as early (steps
1&2), middle and late.)
Examples of Succession:
Dune Succession, Bog Succession, Old-Field Succession
• Early successional species are fast growing,
small, adapted for harsher conditions. They
do not live long. Seeds widely disperse.
• Late successional species are slow growing
and longer living. Can live in shade. Seeds
not widely dispersed.
Succession and Chemical Cycling
• Biomass, production, diversity and
chemical cycling change during succession
• Biomass and diversity peak in midsuccession, increasing at first to a
maximum, then declining and varying over
time.
Species Change in Succession
Earlier and later species in succession may
interact in three ways:
1. Facilitation
2. Interference
3. Life history differences
If they do not interact, the result is termed
chronic patchiness
Facilitation
• During succession, one species prepares the
way for the next (and may even be
necessary for the occurrence of the next)
– Dune and bog succession
Interference
• During succession, one species prevents the
entrance of a later species into an
ecosystem.
• Ex) Some grasses produce dense and thick
mats so the seeds of trees cannot reach the
soil to germinate
Life History Difference
• The difference in the life histories of the
species allow some to arrive first and grow
quickly, while others arrive late and grow
more slowly
• Ex) seed disbursal
Primary Succesion
Primary Succession
Succession
Forest Fire
Forest succession