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Lecture Slides on Succession and Stability - Ecology | BIOL 250, Study notes of Ecology and Environment

Material Type: Notes; Professor: Blair; Class: Ecology; Subject: Biology; University: Xavier University; Term: Unknown 1989;

Typology: Study notes

Pre 2010

Uploaded on 08/19/2009

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Today’s Outline
Ecology (BIOL 250)
Lecture 19: Succession and Stability
Announcements
Introduction
Primary Succession
Secondary Succession
Disturbance
Ecosystem Recovery
Mechanisms of Succession
Community and Ecosystem Stability
!Succession: Gradual change in plant and
animal communities in an area following
disturbance.
"Primary succession on newly exposed geological
substrates.
"Secondary succession following disturbance that
does not destroy soil.
!Climax Community: Late successional
community that remains stable until disrupted
by disturbance.
Introduction
!Reiners et.al. studied changes
in plant diversity during
succession.
"Total number of plant species
increased with plot age.
"Species richness increased
rapidly in early years of
succession and more slowly
during later stages.
!Not all groups increased in density
throughout succession.
Primary Succession
at Glacier Bay
Primary Succession
at Glacier Bay
Primary Succession
at Glacier Bay
!Chapin documented substantial changes in
ecosystem structure during succession at
Glacier Bay.
"Total soil depth and depth of all major soil horizons
show significant increase from pioneer community.
!In addition, organic content, moisture, and N
concentrations all increased.
Physical and biological systems are inseparable.
!Oosting found number of woody plant species
increased during secondary succession at
Piedmont Plateau.
"A separate study found increase in bird diversity
across successional sequence closely paralleled
increase in woody plant diversity observed by
Oosting.
Secondary Succession
in Temperate Forests
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Today’s Outline

Ecology (BIOL 250)

Lecture 19 : Succession and Stability

Introduction^ Announcements Primary Succession Secondary Succession Disturbance Ecosystem Recovery Mechanisms of Succession Community and Ecosystem Stability !Succession: Gradual change in plant and animal communities in an area following disturbance.

"Primary succession on newly exposed geological

substrates.

"Secondary succession following disturbance that

does not destroy soil.

!Climax Community: Late successional community that remains stable until disrupted by disturbance. Introduction ! Reiners et.al. studied changes in plant diversity during succession.

"Total number of plant species

increased with plot age.

"Species richness increased

rapidly in early years of

succession and more slowly

during later stages.

!Not all groups increased in density throughout succession. Primary Succession

at Glacier Bay

Primary Succession

at Glacier Bay

Primary Succession

at Glacier Bay

! Chapin documented substantial changes in ecosystem structure during succession at Glacier Bay.

"Total soil depth and depth of all major soil horizons

show significant increase from pioneer community.

!In addition, organic content, moisture, and N concentrations all increased.

  • Physical and biological systems are inseparable. ! Oosting found number of woody plant species increased during secondary succession at Piedmont Plateau.

"A separate study found increase in bird diversity

across successional sequence closely paralleled

increase in woody plant diversity observed by

Oosting.

Secondary Succession

in Temperate Forests

Secondary Succession

in Temperate Forests

More commonly observed pattern.. .Why? Secondary Succession

in Temperate Forests

Impact of disturbance on diversity ! Bormann and Likens found felling trees in Hubbard Brook substantially increased nutrient losses.

"Herbicide used to suppress

regrowth.

!When application stopped, succession proceeded, nutrient losses decreased,and primary production increased.

"Vegetation can’t account for all

nutrient loss.

!Reduced nutrient amounts in ecosystem.

Recovery of Nutrient Retention

Following Disturbance

!Biomass Accumulation Model !Reorganization ( 10 - 20 yrs)

  • Forest loses biomass and nutrients. !Aggradation ( 100 + yrs)
  • Ecosystem reaches peak biomass. !Transition
  • Biomass declines from peak. !Steady-State
  • Biomass fluctuates around mean. Model of Ecosystem Recovery !Proposes many species may attempt to colonize newly available space.

"Only certain species will establish.

!Colonizers “Pioneer Species” modify environment so it becomes less suitable for themselves and more suitable for species of later successional stages. Model of Ecosystem Recovery

Facilitation

!Initial stages of colonization are not limited to pioneer species.

"Early successional species do not facilitate later

successional species.

Model of Ecosystem Recovery

Tolerance