Transcript No Slide Title

8 Elements of the
Conservation Garden…
The Conservation Garden
Invasive Alien Plants
Of 235 woody plants that invade
natural areas in the US
85% were imported for ornamental
and landscape purposes
14% were imported for agricultural
uses
--from Reichard & Campbell 1996
...in the very early times, say
100 million years ago in the
Cretaceous Period, the world's
fauna was much more truly
cosmopolitan, not so much
separated off by oceans,
deserts, and mountains. If there
had been a Cretaceous child
living at the time...he would
have read...'Very large
dinosaurs occur all over the
world except in New
Zealand'...There would have
been much less use for zoos.
C. S. Elton, The Ecology of
Invasions by Plants and Animals,
1958
THE HOMOGOCENE’S BIODIVERSITY EQUATION
When does 1+1 not equal 2?
Native Spp
1
Alien Spp
+
1
Total Comment/example
=
2
Complementarity
Daylilies?
1
+
1
=
1
Competition
Japanese
honeysuckle?
1
+
1
=
<1
Changed process
Melaleuca in Florida
Myrica in Hawaii
Podophyllum
Jeffersonia
E Asian-E North American Disjunction
Genera – Representative woody plants
Buckleya
Hamamelis
Panax
Calycanthus
Hydrangea
Parthenocissus
Carya
Itea
Pieris
Catalpa
Liriodendron
Pyrularia
Cladrasits
Magnolia
Sassafras
Epigaea
Menispermum
Stewartia
Gleditsia
Mitchella
Wisteria
Gymnocladus
Nyssa
Halesia
Pachysandra
East Asian-Eastern North America Disjunction
Subgeneric Relationships in Widespread Genera
Acer
Hydrangea
Adiantum
Alnus
Juglans
Clintonia
Aesculus
Malus
Convallaria
Betula
Quercus
Maianthemum
Carpinus
Rhododendron
Pyrola
Cornus
Ribes
Tiarella
Fagus
Tilia
Trientalis
Fraxinus
Ulmus
Vaccinium
Close taxonomic relationship has its own
problems
Specialized pests & diseases
Chestnut blight, Dogwood anthracnose,
Balsam & Hemlock woolly adelgids
MANY OTHERS!
Degree of exotic threat
Species that do not persist after cultivation; dependent on cultivation
Species that persist after cultivation but do not spread
Species that spread locally after cultivation by vegetative means, but not by
seed
Species that spread locally after cultivation by seed or seed and vegetative
means
Species that spread only in human-created habitats: roadsides, lawns, fields
Species that spread into native habitats, but do not reduce native species
Species that spread into native habitats, reduce or eliminate native
species
Species that spread into native habitats, change ecosystem function,
reducing whole suites of native species
INVASIVES ARE A SMALL PERCENT OF EXOTICS
INVASIVES ARE A SMALL PERCENT OF SALES
--Florida data from Lippincott & Hall 1996
Taxa
%
Exotics in cultivation
25,000
--
Naturalized
1,000
4
Weedy
750
3
Possible natural area impacts 125
0.5
Sold in the trade today
40
0.16
Economically important
13
0.05 (32.5% of 40)
4 invasion hypotheses
1a-d. Innate biology: Weediness,
competitiveness, tolerance,
preadaptation
2. Enemy release/Biotic resistance
3a-c. Community invasibility: diversity,
productivity, disturbance
4. Availability
1a. Innate Biology:
Weediness
REICHARD’S SCREENING CRITERIA
FOR RISK ASSESSMENT
Quick vegetative spread/vegetative
reproduction
Juvenile period
< 5 years (trees)
< 3 years (shrubs, vines)
Rapid growth in first 2 years
No pretreatment for germination
[History of invasion]
[Related to Known Invaders]
THE ASYMMETRY OF ERRORS
IN RISK ASSESSMENT
The consequences of error are not equal
Weeds
Accept
Reject
Evaluate
Non-Weeds
More important error
Good!
Good!
Less important error
--------------------Minimize----------------------
REICHARD’S OUTCOMES
204 Invaders
Correct
Accept
----Reject
85%
Evaluate/Monitor
Incorrect
2%
-----
Unknown
13%
98% of invaders rejected or held for monitoring
87 Non-invaders
Correct
Accept
46%
Reject
----Evaluate/Monitor
Incorrect
----18%
Unknown
36%
82% of non-invaders accepted or held for monitoring
REICHARD’S OUTCOMES
204 Invaders
Correct
Accept
----Reject
85%
Evaluate/Monitor
Incorrect
2%
-----
Unknown
13%
98% of invaders rejected or held for monitoring
87 Non-invaders
Correct
Accept
46%
Reject
----Evaluate/Monitor
Incorrect
----18%
Unknown
36%
82% of non-invaders accepted or held for monitoring
POSSIBLE PROBLEMS WITH REICHARD’S
SCREENING CRITERIA
Criterion
Genetic var.
Problem, comment
History of invasion
Spatial availability,
time of observation
Quick vegetative spread
Probably ok
Juvenile period
< 5 years (trees)
< 3 years (shrubs, vines)
Y
Rapid growth first 2 yr
Y
No pretreatment
Y
Vary with environment,
soil, year to year climate,
climate change, biotic
environment
Temperate, boreal species
need pretreatment
TRAITS OF SUCCESSFUL INVADERS
Trait
Environmentally fit
Rapid growth
Horticultural selection?
Yes!
Yes, both for client and for holding in
nursery
Early maturity (flowering) Yes, both for client and for display
Prolific seed production
Some species (seasonal color, wildlife
populations)
Successful dispersal
No, except perhaps species for wildlife
populations
Ease of germination
Yes, easier to propagate
Ease of establishment
Yes, easier to propagate and hold
Fast vegetative spread
Some species (erosion control, ground
covers)
No major pests
Yes!
Is time limiting?
The Problem
of the Tortoise and the Hare
Slow rate has its advantages for
control
BUT the race changes: Friends,
enemies, & the nature of the race
track
a suggestion of time lags!
Australian Weed Risk Assessment System
--from Pheloung 1995
First Tier:
Second Tier:
Third Tier:
Prohibited/Allowed Species Lists
Reject/Evaluate/Accept New Introductions
Temporary Clearance, Post Entry Evaluation
Second Tier:
Reject/Evaluate/Accept New Introductions
--from Pheloung 1995
49 Questions:
+1
Weedy Trait
0
Don’t Know
-1
Non-Weedy Trait
Scoring:
<0
Accept
1-6
Evaluate
>=7 Reject
Second Tier: Categories for the 49 Questions
--from Pheloung 1995
Category
Notes
Domestication/Cultivation Low risk of weediness if domesticated
species
Climate/Distribution
Environmental match, breadth of
tolerance
Undesirable Traits
Spiny, burrs, poisons, pollen
Plant Type
Free floating aquatics, Vines
Weedy Elsewhere
Highly predictive of pest species
Reproduction
Correlates with rate of spread
Dispersal Mechanisms
Correlates with rate of spread
Persistence Attributes
Correlates with survival once
established
Test:
Reject/Evaluate/Accept New Introductions
--from Pheloung 1995
Reject
Evaluate
Accept
Weeds
84%
16%
0%
Non-Weeds
7%
34%
59%
Minor Weeds
45%
37%
18%
AQIS System
Free floating aquatic
History of invasiveness
Relative of an invasive species
Spiny, burrs
Harmful to humans or animals
Vegetative reproduction
Stoloniferous
Wind dispersed
Animal/Machine dispersed
Water dispersed
Bird dispersed
Points
20
20
10
10
8
8
5
8
8
5
5
Scoring:
Reject
Evaluate
Accept
>=20
12-19
<12
1b. Innate Biology:
Competitiveness
Diversity in native range vs. introduced
range: coevolved competitiveness
hypothesis
As diversity in native range
competitiveness
1c. Innate Biology:
Tolerance
Native geographic range hypothesis
As native range
Invasiveness
1d. Innate Biology:
Preadaptation
2. Enemy release hypothesis (ERH)
Biotic resistance hypothesis (BRH)
Mitchell & Power 2003
Kilronomos 2002
Kilronomos 2002
Classical Biocontrol: Cactoblastis on Opuntia
Female Cactoblastis ovipositing
on Opuntia, linear egg mass
attached to a cactus spine
Damage to Opuntia by Cactoblastis larvae,
pad destroyed, plant open to infection
3. Community Invasibility
Hypotheses
3a. Diversity (competitive release)
3b. Productivity (birth, growth rates
higher)
3c. Disturbance (mortality, turnover
rates higher)
Rebecca
Brown
2002
Rebecca
Brown
2002
DISTURBANCES AND INVASIONS
Hobbs & Huenneke 1992
Fire
Grazing
Soil disturbance
Nutrient inputs
Trampling
Fragmentation
Disturbance interactions
4. Availability Hypothesis
TRAITS OF SUCCESSFUL INVADERS
Trait
Environmentally fit
Rapid growth
Horticultural selection?
Yes!
Yes, both for client and for holding in
nursery
Early maturity (flowering) Yes, both for client and for display
Prolific seed production
Some species (seasonal color, wildlife
populations)
Successful dispersal
No, except perhaps species for wildlife
populations
Ease of germination
Yes, easier to propagate
Ease of establishment
Yes, easier to propagate and hold
Fast vegetative spread
Some species (erosion control, ground
covers)
No major pests
Yes!
Initial Release Strategy:
FLOSS Tradeoff
Given a finite release stock
Few, Large
or
Several, Small
Experimental Releases
Grevstad 1999
Treatment and Indicator Variables
– 4 release sizes 20, 60, 180, 540 individuals
– 2 species G. calmariensis and G. pusilla
– 5 site characteristics
•
•
•
•
•
stand area
stand density
early plant height
terminal plant height
plant N
– 9 reps
Response - Larger populations are less
likely to go extinct and they have higher
mean growth rates
4 invasion hypotheses
1a-d. Innate biology: Weediness,
competitiveness, tolerance, preadaptation:
SOME SPP ARE INVASIVE, SCREEN
2. Enemy release/Biotic resistance: MOST
SPP ARE INVASIVE, ASSESS ROLE OF
ENEMIES
3a-c. Community invasibility: diversity,
productivity, disturbance: SOME
COMMUNITIES ARE INVASIBLE, SCREEN,
MANAGE AGAINST INVASION
4. Availability: MOST SPP ARE INVASIVE,
REDUCE AVAILABILITY
Encouragements that we can
lessen the problem!
• A small percent of horticultural plants
are invasive
• Risk assessment can work
• It can be done: How Illinois kicked the
exotic plant habit (Harty 1993)
__________________________________________________________
NCBG EXOTIC SPECIES POLICY
__________________________________________________________
To possess plant collections that do not harm natural areas and
the native plant diversity of North Carolina and the Southeast
To protect and restore the Garden’s highest quality natural areas
by eradicating invasive exotic species
__________________________________________________________
The Chapel Hill
Thesis (1999)
The Chapel Hill Thesis: A Challenge to Botanical
Gardens and Horticultural Institutions (1999)
1. Perform risk assessment for introductions; do not introduce likely
invasives
2. Remove invasives from plant collections
3. Control invasives in garden natural areas
4. Develop non-invasive and native plant alternatives and certify noninvasiveness for the trade
5. Do not distribute seeds/plants that will be invasive elsewhere
6. Educate the public
7. Become partners with conservation organizations
8. Obey import rules and enact strong procedures to minimize the risk of
introducing diseases and pest organisms
The Public Garden & AABGA
In search of the conservation garden (1993)
A bill falls due: botanical gardens &
the exotic species issue (1995)
Policy statement (1996)
Index seminum et sporarum (1998)
The Chapel Hill Thesis (1999)
Vancouver Annual Meeting
Conservation ethics in botanical gardens
Asheville Annual Meeting, WBG Congress
(2000)
Linking Ecology and Horticulture
To Prevent Plant Invasions
December 2001
St. Louis, Missouri
Organizers: Kennedy, Randall, Raven, Reichard, White
Bringing together:
Botanical Gardens
Nursery Industry
Landscape Architects
The Gardening Public
Government
Linking Ecology and Horticulture
To Prevent Plant Invasions
December 2001
St. Louis, Missouri
STATEMENT OF PURPOSE
To Agree on a Statement of the Problem
To Draft Voluntary Codes of Conduct for Each
Group
To Discuss Application of the Codes
To Discuss Next Steps
Linking Ecology and Horticulture
To Prevent Plant Invasions II
October 2002
Chicago, Illinois
FINDINGS
Findings 1-2:
The magnitude of human dispersal is unprecedented and
has allowed dispersal of species that manifest aggressive traits
in new areas.
Plant introduction and improvement are the foundation of
modern agriculture and horticulture, yielding diversity to our
supply of plants used for food, forestry, landscapes and gardens,
medicinal and other purposes.
Findings 3-4:
A small proportion of introduced plant species become
invasive and cause unwanted impacts to natural systems and
biological diversity as well as economies, recreation, and
health.
Plant species can be invasive in some regions, but not in
others. The impacts of invasive plant species can occur at
times and places far removed from the site of introduction.
Issues addressed
•
•
•
•
•
•
•
•
Existing displays & collections
New introductions
Plant distribution
Control in natural areas
Alternative non-invasive plants
Public awareness to lower demand
Professional training
Communication, databases
Principles (a.k.a. The St. Louis Six): 1-4
Plant introduction should be pursued in a manner that both
acknowledges and minimizes unintended harm.
Efforts to address invasive plant species prevention and
management should be implemented consistent with national goal
or standards, while considering regional differences to the fullest
extent possible.
Prevention and early detection are the most cost effective
techniques that can be used against invasive plants.
Research, public education and professional training are
essential to more fully understanding the invasive plant issue and
positively affecting consumer demand, proper plant use,
development of non-invasive alternatives, and other solutions.
Principles (a.k.a. The St. Louis Six): 5-6
Individuals from many fields must come together to undertake
a broad-based and collaborative effort to address the challenge,
including leaders in horticulture, retail and wholesale nurseries,
weed science, ecology, conservation groups, botanical gardens,
garden clubs, garden writers, educational institutions, landscape
architects, foundations and government.
A successful invasive plant species strategy will make use of
all available tools including voluntary codes of conduct, best
management practices, and appropriate regulation. Codes of
conduct for specific communities of interest are an essential first
step in that they encourage voluntary initiative, foster
information exchange, and minimize the expense of regulation
Elements of the Codes
• Prevention, risk assessment on a regional
basis
• Distribution
• Removal
• Public awareness, demand
• Alternatives
• Training
• Databases & communication
• Important & export rules
_______________________________________
REASONS FOR NATIVE PLANTS
_______________________________________
Uniqueness of place
Local products, local value
Working with nature in our backyards, the value of
nature everywhere
Support of coevolutionary relationships
____________________________________________________