8 Elements of the Conservation Garden

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8 Elements of the Conservation Garden
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The Conservation GardenInvasive Alien Plants
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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
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...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
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THE HOMOGOCENES BIODIVERSITY EQUATION When does
11 not equal 2? Native Spp Alien
Spp Total Comment/example 1 1 2 Complementa
rity Daylilies? 1 1 1 Competition
Japanese honeysuckle? 1 1 lt1 Changed
process Melaleuca in Florida Myrica
in Hawaii
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Podophyllum
Jeffersonia
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E Asian-E North American Disjunction Genera
Representative woody plants Buckleya
Hamamelis Panax Calycanthus Hydrangea Parthen
ocissus Carya Itea Pieris Catalpa Liriodendro
n Pyrularia Cladrasits Magnolia
Sassafras Epigaea Menispermum
Stewartia Gleditsia Mitchella
Wisteria Gymnocladus Nyssa Halesia Pachysandra
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East Asian-Eastern North America
Disjunction Subgeneric Relationships in
Widespread Genera Acer Hydrangea Adiantum Alnu
s Juglans Clintonia Aesculus Malus Convallar
ia Betula Quercus Maianthemum Carpinus Rhododen
dron Pyrola Cornus Ribes Tiarella Fagus Tilia
Trientalis Fraxinus Ulmus Vaccinium
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Close taxonomic relationship has its own
problems Specialized pests diseases Chestnut
blight, Dogwood anthracnose, Balsam Hemlock
woolly adelgids MANY OTHERS!
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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
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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)
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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

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1a. Innate Biology Weediness
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REICHARDS SCREENING CRITERIA FOR RISK
ASSESSMENT Quick vegetative spread/vegetative
reproduction Juvenile period lt 5 years
(trees) lt 3 years (shrubs, vines) Rapid growth
in first 2 years No pretreatment for
germination History of invasion Related to
Known Invaders
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THE ASYMMETRY OF ERRORS IN RISK
ASSESSMENT The consequences of error are not
equal Weeds Non-Weeds Accept More
important error Good! Reject Good! Less
important error Evaluate --------------------Mini
mize----------------------
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REICHARDS OUTCOMES 204 Invaders Correct Inco
rrect Unknown Accept ----- 2 Reject 85 ----
- Evaluate/Monitor 13 98 of invaders
rejected or held for monitoring 87
Non-invaders Correct Incorrect Unknown Accept 4
6 ----- Reject ----- 18 Evaluate/Monitor
36 82 of non-invaders accepted or held for
monitoring
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REICHARDS OUTCOMES 204 Invaders Correct Inco
rrect Unknown Accept ----- 2 Reject 85 ----
- Evaluate/Monitor 13 98 of invaders
rejected or held for monitoring 87
Non-invaders Correct Incorrect Unknown Accept 4
6 ----- Reject ----- 18 Evaluate/Monitor
36 82 of non-invaders accepted or held for
monitoring
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POSSIBLE PROBLEMS WITH REICHARDS SCREENING
CRITERIA Criterion Genetic var. Problem,
comment History of invasion Spatial
availability, time of observation Quick
vegetative spread Probably ok Juvenile period
Y Vary with environment, lt 5 years
(trees) soil, year to year climate, lt 3
years (shrubs, vines) climate change,
biotic environment Rapid growth first
2 yr Y No pretreatment Y Temperate,
boreal species need pretreatment
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TRAITS OF SUCCESSFUL INVADERS Trait Hortic
ultural selection? Environmentally
fit Yes! Rapid growth 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) Success
ful 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!
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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!

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Australian Weed Risk Assessment System --from
Pheloung 1995 First Tier Prohibited/Allowed
Species Lists Second Tier Reject/Evaluate/Accep
t New Introductions Third Tier Temporary
Clearance, Post Entry Evaluation
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Second Tier Reject/Evaluate/Accept New
Introductions --from Pheloung 1995 49
Questions 1 Weedy Trait 0 Dont
Know -1 Non-Weedy Trait Scoring lt0 Accept 1-6 Ev
aluate gt7 Reject
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Second Tier Categories for the 49 Questions
--from Pheloung 1995 Category Notes Domestic
ation/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 Correlat
es with rate of spread Dispersal
Mechanisms Correlates with rate of
spread Persistence Attributes Correlates with
survival once established
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Test Reject/Evaluate/Accept New Introductions
--from Pheloung 1995 Weeds Non-Weeds Minor
Weeds Reject 84 7 45 Evaluate 16 34 3
7 Accept 0 59 18
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AQIS System Points Free floating
aquatic 20 History of invasiveness 20 Relative
of an invasive species 10 Spiny,
burrs 10 Harmful to humans or
animals 8 Vegetative reproduction 8 Stolonifero
us 5 Wind dispersed 8 Animal/Machine
dispersed 8 Water dispersed 5 Bird
dispersed 5 Scoring Reject
gt20 Evaluate 12-19 Accept lt12
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1b. Innate Biology Competitiveness

• Diversity in native range vs. introduced range
  coevolved competitiveness hypothesis
• As diversity in native range
• competitiveness

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1c. Innate Biology Tolerance

• Native geographic range hypothesis
• As native range
• Invasiveness

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1d. Innate Biology Preadaptation
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2. Enemy release hypothesis (ERH)Biotic
resistance hypothesis (BRH)
Mitchell Power 2003
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Kilronomos 2002
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Kilronomos 2002
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Classical Biocontrol Cactoblastis on Opuntia
Female Cactoblastis ovipositingon Opuntia,
linear egg mass attached to a cactus spine
Damage to Opuntia by Cactoblastis larvae,pad
destroyed, plant open to infection
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3. Community Invasibility Hypotheses

• 3a. Diversity (competitive release)
• 3b. Productivity (birth, growth rates higher)
• 3c. Disturbance (mortality, turnover rates higher)

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Rebecca Brown 2002
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Rebecca Brown 2002
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DISTURBANCES AND INVASIONS Hobbs Huenneke
1992 Fire Grazing Soil disturbance Nutrient
inputs Trampling Fragmentation Disturbance
interactions
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4. Availability Hypothesis
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TRAITS OF SUCCESSFUL INVADERS Trait Hortic
ultural selection? Environmentally
fit Yes! Rapid growth 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) Success
ful 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!
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Initial Release StrategyFLOSS Tradeoff
Given a finite release stock
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Experimental ReleasesGrevstad 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

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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

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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)

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__________________________________________________
________ 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 Gardens highest quality natural
areas by eradicating invasive exotic
species __________________________________________
________________
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The Chapel Hill Thesis (1999)
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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 non-invasiveness 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
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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)
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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
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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
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Linking Ecology and Horticulture To Prevent
Plant Invasions II October 2002 Chicago,
Illinois
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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.
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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.

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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

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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 goals 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.
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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
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Elements of the Codes

• Prevention, risk assessment on a regional basis
• Distribution
• Removal
• Public awareness, demand
• Alternatives
• Training
• Databases communication
• Important export rules

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_______________________________________ 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 _____________________
_______________________________
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