Transcript Restoration Ecology and the Conservation of

Restoration Ecology and the
Conservation of Biodiversity
Basic principles of ecology
have practical use for solutions
to human problems
NRES 420 Restoration Ecology
Objectives
• Human transformation of landscape
created need
• Illinois – a state in great need
• Restoration ecology & conservation
biology
• Blending science into practice
• Important ecological principles for
restoration
• Practice of restoration
Landscape Transformation
1870’s
Advent of clay drainage tile systems
Decreased rail transportation costs
Legislation to create drainage districts
1800
1840
1920
1880
1836
Steel plow invented
1869 Transcontinental
railroad
1850
Swamp & Overflowed Lands Act
1862
Homestead Act
1956
Interstate Highway
System
1903
First flight
1923
First commercial hybrid
maize
1893
First gasoline automobile
1960
2000
1970s
Environmental protection legislation
1999
Executive Order 13112
(invasive species)
Early
Settlement
1800
1820
Start of
Agriculture
1840
1860
Prairie
Drainage
1880
1900
Diversified
Farming
1920
1940
Monoculture
1960
1980
Elk
Bison
Black Bear
Mountain Lion
Gray Wolf
CHANGES IN
MAJOR
LANDSCAPE
ELEMENTS IN
ILLINOIS SINCE
1800 AND
IMPACTS ON
SELECTED
MAMMALS
Fisher
Deer
Beaver
Bobcat
Otter
Coyote
Hectares (millions) in Illinois
8.0
Dry Prairie
Wet Prairie / Marsh
6.4
Forests
Pasture
4.8
3.2
1.6
0
1800
1820
1840
1860
1880
Year
1900
1920
1940
1960
1980
Habitat Lss
Fragmentation
FOREST PARCELS BY AREA CATEGORY
NUMBER OF HIGH QUALITY PRAIRIES REMAINING IN
ILLINOIS CLASSIFIED BY SIZE CATEGORY
>240
Area Category (ha)
Number of Sites
120
80
40
40-240
20-40
4-20
0.4-4
<0.4
0
100
0-0.5
0.5-2
2-4
4-8
Prairie Size (ha)
8-20
20-40
1,000
10,000
>40
Number of Parcels
100,000
1,000,000
Invasive Species
% of Illinois Flora
Non-Natives in the Illinois Flora*
30
20
10
0
1846
1950
1986
2004
*2004: 961 non-native of 3,074 taxa
97 of 173 families (56%) lack nonnative taxa
Spread of Alliaria petiolata
Illinois in Need
• Clearly a need –
– Remaining habitat:
• 0.01% prairie
• 9.9% wetland
• 31.4% forest
– U.S. Rank:
• Indiana 48
• Illinois 49
• Iowa 50
Restoration Ecology
Using research to better
understand ecological processes
within highly disturbed
ecosystems in order to enhance
their complexity and long-term
persistence
POPULATION
ECOLOGY
COMMUNITY
ECOLOGY
RESTORATION ECOLOGY
ECOSYSTEM
ECOLOGY
LANDSCAPE
ECOLOGY
Improving the Ecology of a Disturbed
Area by:
– increase diversity in highly disturbed system
– reintroduce ecosystem function
– reestablish characteristic species and
community structure/function
– may have to start restoration from scratch
van Diggelen, Grootjans & Harris (2001)
Ecosystem
function
What are the goals of
restoration?
Ecosystem
structure
A. D. Bradshaw, “Reclamation of Land and Ecology of Ecosystems”
Restoration Ecology
Applying ecological principles within a
social context to revitalize habitats and
conserve species
POLICY
POPULATION
ECOLOGY
SOCIETY
COMMUNITY
ECOLOGY
ECOLOGICAL RESTORATION
ECOSYSTEM
ECOLOGY
LANDSCAPE
ECOLOGY
POLITICS
ECONOMICS
Ecology Theory Relevant to Restoration
• Population Ecology
– Vulnerability of small populations
• Genetic depression, swamping
• Metapopulation theory + MVP size
• Community Ecology
•
Species-area relationships
–
Island biogeography theory
–
Problems with fragmented habitats
•
Intermediate disturbance hypothesis
•
Succession & community assembly
•
Diversity-stability theory; community structure
• Landscape Ecology
• Ecosystem Ecology
What aspects of Population Ecology
are relevant to Restoration Ecology?
• Species survival depends on
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maintaining minimum viable population levels
(>500).
maintaining genetic diversity.
using locally adapted genotypes.
having a metapopulation structure with strong
source subpopulations to rescue sink ones.
COMMUNITY ECOLOGY:
How is the Species-Area curve relevant?
S = c + z log A
S = c Az
log S = log c + z log A
Figure 1
How is Island Biogeography Theory
relevant?
Immigration
Extinction
Small
Large
Near
Number of Species
Far
Figure 2
Patch relationships:
What is take-home message?
Figure 3
(From Forman, 1995)
Ecological Disturbance: What are its
dimensions? How relate to restoration?
1
2
3
Figure 4
(D.T. Krohne, ‘General Ecology’)
Intermediate Disturbance Hypothesis:
at which level does disturbance aid
restoration?
Competitive
exclusion
Disturbance Rate
Small
species
pool
Figure 5
Selected Natural & Anthropogenic
Disturbances: reversible vs. permanent
change?
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Natural Events**
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Fire
Disease epidemic
Flood
Herbivory
Drought
Hurricane, tornado, windstorm
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–
Avalanche, landslide
Volcanic eruption
Ice storm
** Entries
Anthropogenic Events**
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–
–
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Residential development
Road, trail, railroad line
Telephone line, electrical
power line
Dam, water diversion, canal
Commercial development
Modern agriculture
Mining
Logging
Grazing
in italics connote reversible disturbances; others
represent long-term or permanent conversion of habitat.
Succession
• an orderly change in relative abundances of
dominant species in a community following a
disturbance until a stable community (‘climax’like predisturbance) results
 1° succession begins
on mineral soils
 2° succession begins
on soils with seeds
Succession: Species-Species Interactions
How do these interactions influence community
development?
– Facilitation – early species make environment less
suitable for themselves, but more suitable
for later species -- nurse crops
- Tolerance - early species make environment less suitable
for recruitment of similar early species, but they neither help
nor hinder later species
- Inhibition - early species make environment inhospitable
to later-arriving species
Early prairie reconstructions overly dominated by warm
season grasses
Community Assembly
• development of the ecological community
• is determined by random variation in
species' colonization of a disturbed area &
subsequent species interactions
Which orientation to follow?
Succession vs. Community Assembly
• Succession
– Deterministic
– Internal interactions & environment determine
outcome
• Assembly
– Stochastic
– Supply of propagules determines outcome
– Multiple stable assemblies
How can succession be managed
to aid restoration?
General causes
Contributing processes
Modifying factors
Site availability
Disturbance
Size, severity, time, dispersion
Species availability
Dispersal
Landscape configuration, dispersal agents
Propagules
Land use, time since last disturbance
Resources
Soil, topography, site history
Ecophysiology
Germination requirements, assimilation rates,
growth rates, genetic differentiation
Life history
Allocation, reproductive timing & mode
Stress
Climate, site history, prior occupants
Competition
Competition, herbivory, resource availability
Allelopathy
Soil chemistry, microbes, neighboring species
Herbivory
Climate, predators, plant defenses & vigor,
community patchiness
Species performance
Restoration: Managing Succession
Designed Disturbance
Managing
Succession
Controlled
Colonization
Controlled Species
Performance
Managing Succession: in Practice
Designed Disturbance
Controlled Colonization
Controlled Species Performance
Burning
Burning
Burning
Bulldozing, Scraping, Topsoil Mixing
Broadcast seeding, Drill seeding,
Direct planting
Cabling
Cabling
Cutting
Grazing, Excluding grazers
Chopping, Clipping
Grazing
Fertilization, Reducing soil fertility
Flooding & draining
Fertilization, Herbicide spraying
Herbicide application
Herbicide application
Irrigation, Water level change
Mowing, Selective cutting
Plowing
Topsoiling & live soiling
Irrigation, Water level change
Solarization (thermal shock)
Rotovating
Soil compaction
Scraping
Soil fabrics
How can community structure influence
stability of restored community?
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Top-down control of trophic abundances
Cascade effects: indirect effects extended
through multiple levels
Can have chain of extinctions if highly
dependent
Keystone organisms must be preserved
Non-redundant species, key species
that maintain stability/diversity
How can Diversity Complexity Stability
be enhanced?
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An increase in the structural diversity of
vegetation increases species diversity.
Full restoration of native plant communities
sustains diverse wildlife populations.
A high diversity of plant species assures a
year-round food supply for the greatest
diversity of wildlife
Landscape Ecology
• How does the landscape context of the restoration
influence everything discussed earlier?
Spatial Principles
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Large areas sustain more species than small areas.
Many small patches in an area will help sustain regional
diversity.
Patch shape is as important as size.
Fragmentation of habitats, communities, and ecosystems
reduces diversity.
Isolated patches sustain fewer species than closely
associated patches.
Species diversity in patches connected by corridors >
than for disconnected patches.
A heterogeneous mosaic of community types sustains
more species & is more likely to support rare species
than a single homogeneous community.
Ecotones between natural communities support a variety
of species from both communities & species specific to
the ecotone.
Minimum Dynamic Area in Restoration
Design
 Largest patch
size
 Patch
longevity
 Disturbance
frequency
 Habitat
requirements
Ecosystem Ecology: how is it
relevant?
Interactions
between the biotic
& abiotic
components of the
ecosystem