Download Range Expansions, Recognition of, and When are Range Expansions Invasive

Range expansions of non-native species:
recognizing problem plants in Alaska
Matthew L. Carlson, Lindsey Flagstad, Helen Cortés-Burns
Alaska Natural Heritage Program & Biological Sciences Department, UAA
[email protected]
Outline
1. Retrospective:
Distinguishing non-native
species movements
• Background
• Guidelines
• Remaining problem taxa
2. Prospective:
Evaluating potential for
future problem
movements
• Background
• Recommendations
Natural and Human-caused species movement
Plant species’ distributions change naturally
over time
–
Species originate in one place, their range expands,
then contracts
Suitable Habitat
Range of Species
Natural and Human-caused species movement
– Movement and establishment is a function of
1. Availability and degree of suitable habitat
2. Dispersal potential
3. Number of propagules
(Hultén’s “centrants” and “radiants”)
Natural and Human-caused species movement
Natural movements of species are insignificant
relative to current movements facilitated by people
–
–
–
–
Current movements of species is 100 to 1000 X times
the background rate (Gaston et al. 2003)
400,000 species moved by humans, most in last 200
years (Pimentel 2001)
Native species & ecosystem services are at risk
Globalization of floras as well as economies
Natural and Human-caused species movement
Distinguishing natural from anthropogenicassisted dispersal is usually easy
–
Examples of Vicia cracca, Crepis tectorum,
Polygonum cuspidatum…
Sometimes it isn’t so easy
–
Example of Rorippa curvisiliqua
Rorippa
curvisiliqua
distribution
(GBIF)
Natural and Human-caused species movement
Distinguishing natural vs. anthropogenic-assisted
migration
(See Bennett 2006. SIBERIAN WILD RYE (ELYMUS
SIBIRICUS L., POACEAE) IN WESTERN NORTH
AMERICA: NATIVE OR INTRODUCED? BOTANICAL
ELECTRONIC NEWS 366.)
1.
2.
3.
4.
What does the literature
suggest?
Are the earliest collections at
locations of high-use or
agricultural stations?
Are the collections in disturbed
habitats?
Does genetic data indicate AK
populations are a subset of total
variation?
Expectation for recent
dispersal
Are some populations of
big leaf lupine native to
Alaska? – M. Duffy
Natural and Human-caused species movement
Distinguishing natural vs.
anthropogenic-assisted migration
Questionable taxa
•
Artemisia dracunculus
•
Lupinus polyphyllus
•
Phalaris arundinacea – some
genotypes may be native (genetic work
underway)
•
Erysimum cheiranthoides
(“apparently indigenous in some areas” –
Rollins; one subspecies native to Alaska –
Hulten; introduced – Al-Shehbaz)
•
Potentilla norvegica (“probably native
and introduced” - Hulten)
•
Others…
Natural and human-caused
Distinguishing natural vs.
anthropogenic-assisted migration
•
What do we do with
anthropogenic-assisted
migrations within Alaska?
e.g., Raspberries in Glacier Bay
Lepidium densiflorum along
right-of-ways across Alaska?
Sitka spruce in the Aleutians
from 1800s and WWII plantings?
Pinus contorta var. latifolia on
the Kenai?
Alden & Bruce 1989
Part II: Future movements - Distinguishing
Problem Species
Premise 1:
Ecological and economic damage is not the
same for all non-native species
Vs.
Part II: Future movements - Distinguishing
Problem Species
Vs.
At any one time, impact to an area for a
species is a function of:
1. Pound for pound ecological impact
2. Pounds
(Invasiveness rankings attempt to distinguish potential levels of
ecological damage - http://akweeds.uaa.alaska.edu/akweeds_ranking_page.htm)
Pound for
pound variation
in impact Hypothetical
example of two
species
Total Ecological Impact
Distinguishing Problem Species
Ecological and economic damage is not the
same for all non-native species
v
Total Amount (biomass/area)
Distinguishing Problem Species
Ecological and economic damage is not the
same for all non-native species
Assuming all species have same impact/mass…
Ecological Impact
•
Expansion rate (Δabundance/year)
Distinguishing Problem Species
Premise 2:
Assuming two species have the same per unit
mass ecological impact, we should control:
1. The species with the lowest current amount,
2. The greatest potential amount, and
3. Greatest expansion rate of expansion
Distinguishing Problem Species
1. Identifying new arrivals
Management is most effective for new arrivals
Theoretically easy to do
• Simply survey the whole state every year
• (Confirm the species’ introduction to the
state is most likely due to people)
• Share data – make the results available
AKEPIC
CNIPM
DNR, Division of Agriculture
Distinguishing Problem Species
Recommendations for determining lowest current
amount?
(survey data, e.g., AKEPIC & EDDMapS)
Hieracium aurantiacum - AKEPIC
•
•
Hieracium pilosella - AKEPIC
How do we determine potential area occupied?
How do we determine rate of expansion?
Distinguishing Problem Species
2. Recommendation for determine potential area
occupied?
1. Habitat niche modeling (e.g., Bella et al. in prep.)
2. In general, species with known wide ecological
tolerances and similar habitats/climates to Alaska
Cirsium arvense – MaxEnt output
Distinguishing Problem Species
3. How do we determine how quickly they can
expand across potentially suitable habitat?
Distinguishing Problem Species
Expansion Rates of Invasive Species
Expansion
speed
Dispersal
Area occupied
Seed Density
1. Availability and degree of suitable habitat
2. Dispersal potential
Distance
3. Demography: (# of propagules/time)
“Once intermediate to high densities are reached the rate of
spread is accelerated” (Humston et al. 2005)
Population Size or Area Occupied
Is there a way to identify plants that can expand
more rapidly?
Only a fraction of introduced species establish and cause
significant problems
Saturation
(“Naturalization”)
Colonization
Establishment
Time
Distinguishing Problem Species
Three example expansions:
1.
Examples of what doesn’t
appear to be spreading
quickly here: Raphanus
sativus
Raphanus sativus
Raphanus sativus
1941-1968
2001-2009
Distinguishing Problem Species
Three example expansions:
Examples of Crepis tectorum – quick off the
starting blocks
Crepis tectorum
1941-1968
Crepis tectorum
2001-2009
Distinguishing Problem Species
Three example expansions:
Example of Prunus:
Still geographically restricted, but
expanding into many different
habitat types (black spruce to
krummholtz)
(Caragana in Fairbanks)
Birch-spruce forests
Subalpine
2009
floodplains
Distinguishing Problem Species
Recommendation of An Epidemiological
Approach:
1. Number of records increases rapidly (relative
to total weed records collected at that time)
2. Records appear in distant areas
3. Records in new habitat types
Distinguishing Problem Species
3. Those likely to expand?
Can we use information on its past or current
behavior to anticipate the future?
•
Observed lack of expansion does not mean it
will not occur
•
•
e.g., Starlings (unsuccessful in 1870s), reed canarygrass
in Alaska
However, current
aggressive behavior does
suggest future problems
Distinguishing Problem Species
3. Those likely to expand?
•
Those species that have expanded rapidly
elsewhere in similar ecosystems
•
•
For example, Japanese knotweeds (Polygonum
cuspidatum, P. × bohemicum, P. sacchilense) have
spread throughout Scandinavia
Or that have wide native distributions in similar
habitats (e.g., Leucanthemum vulgare)
Distinguishing Problem Species
3. Those likely to expand?
How much habitat is available and how continuous
the is the habitat?
Are there major gaps in habitat?
Distinguishing Problem Species
3. Those likely to expand?
What is the reproductive capacity?
Does the species have the capacity
for long-distance dispersal?
Recap and Recommendations
Native-introduced status is well accepted for
most plants in Alaska
– Some research is warranted for a handful of
species
Predicting rapidly expanding plants should
involve multiple approaches
1. Change in number and locations of records
2. We should be cautious in assuming plants that
aren’t rapidly expanding cannot
3. Examine dispersal capacity and seed production
Recap and Recommendations
Statewide management will greatly benefit if all
parties agree with control priorities
We should develop an acceptable statewide
prioritization system
•
•
Invasive Plants of Alaska Prioritization Tool
A system that incorporates invasiveness ranks and
distributional data and species with a higher
probability of establishing quickly