Transcript Ecosystem Resistance and Resilience

Lesson 4
Presentation 1
Ecosystem Resistance and
Resilience
Considerable amount of literature
supports idea that resilience is
important for ecosystem restoration
Rank the following species for
protection
Score 6 for 1st priority
 Score 1 for last priority

Giant Panda
Lemon shark
Jupiter
Charter tours
Massassauga
Rattlesnake
WWF
COSEWIC
Bebb’s
willow
Unive Manitoba
Gorilla
Nat. Geog.
Sea Otter
US Nat Parks
Outline
Definition of ecosystem resistance and
resilience
 Use of these terms to evaluate natural and
human events/activities
 Ecosystem management

Ecosystem Resistance
Ability to resist change due to external
event
 Rubber band analogy: How much force
needed to stretch the band

Ecosystem Resilience
Resistance to disturbance and speed of
return to equilibrium state
 I.e. ability to “bounce back”
 “Degree, manner, and speed of recovery of
structure, composition and function of the
original ecosystem after disturbance”
 Rubber band: How quickly band returns to
initial shape

How resilient?

Resilience dependent on:
 Type, intensity and frequency of event
 Site factors
 Adaptation of life forms
Important!
Name some natural events that
cause changes in ecosystems
Wind events
 Fire
 Rain/storms
 Floods/landslides
 Ice/snow
 Insects/Diseases
 Age
 Earthquakes/Volcanoes/Meteors

Terrestrial example
White pine forest
Tree species
 White pine, red pine, white spruce,
balsam fir, aspen, white birch
 Plants
 Hazel, raspberries, dogwood

Adaptations of pines to fire
crowns
high
above the
forest
floor
thick bark
seeds
do not
store
roots deep
in soil
High resistance
Moderate
resilience
Adaptations of white birch and
aspen
Low resistance but
high resilience
Trees killed
Resprout or sucker
High/frequent seed
production
Light seed
Adaptations of Balsam fir & W.
Spruce
Thin bark, crowns low
 Seed not stored
 Balsam: Low resistance
and resilience
 White spruce: Less
flammable bark

Results after fire
Large pine trees more likely to live
 Some trees die (name species)
 Some plants die
 Some duff burned: nutrient flush
 Require live trees to reproduce pine
 Seed dropped after fire likely to grow

Low resistance and resilience for
pine and spruce
Compare with historic logging



Large conifers (pine& spruce) targeted for
removal
Balsam fir & white birch left
Result:
 Less pine and spruce in new stands
 More low quality stems
 Less profit & jobs
 Increase in insect & disease damage
Insect and disease of white pine
white pine: less pest
damage in partial shade and
with structure of natural
forest
white pine blister rust
Native species
white pine weevil
Alien species
Current practices
•
•
•
•
•
retain large seed bearing trees
thin from below
retain veteran trees
control competition
retain down woody debris,
mast and cavity trees
• genetic diversity
How are current practices
implemented?
Crown Forest Sustainability Act and
Environmental Assessment Declaration
Order
 Guides that describe standards of practice
 Training and certification
 What else is required for you to know if this
system is working/being applied correctly?

Ecosystem management or
emulation forestry
The new practices are an example of stand
level ecosystem management or emulation
forestry
 Try to manage human activities to more
closely match those of nature
RATHER THAN
 Try to manage ecosystems

Note: Source of Problem

What is important for ecosystem restoration
is what we leave behind

What is important for economics is what we
remove
Questions