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Invasive Species - YKL
Distribution Models and Preliminary Products
Matt Carlson, Jamie Trammell, and Megumi Aisu
http://plants.alaska.gov/images/dalton-gravelpit-infestation-ATV.jpg
• Invasive Species are treated as a
Change Agent in all REAs
• Current levels of infestation in
YKL are low
• Problems with invasive species
are increasing in the state
– Management decisions today will
impact future composition of
systems
Non-Native Plants Documented &
Established in Native Habitats
Approach to Invasives
Approach to Invasives
• Summary of Scope of
Invasive Species
Management Questions
1.
What is the current distribution and
abundance of non-native species in
the REA?
2.
Which areas are most susceptible
to invasive species currently?
3.
Which areas are most susceptible
to invasive species in the future?
4.
What are the likely vectors for nonnative species introductions?
What are the likely vectors for non-native
species introductions?
1. Approach:
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Literature review
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30 peer-reviewed, 5 reports
(few region-specific)
Review of spatial patterns
and species in AKEPIC
2. Products:
•
Written summary
Approach to Invasives
• Invasive Species Vectors
Preliminary Summary
A.
Ecological and economic damage from
invasive species requires:
1.
2.
3.
B.
Pathways of transportation are predictable
1.
2.
C.
Movements of people and goods
Habitat corridors (roads)
Vast majority of introductions are intentional
1.
D.
E.
Transportation of propagules
Establishment
Expansion to high biomass
Contaminants are an issue for plants in Alaska
(straw, agricultural seed, container pots,
imported fill)
Regional hubs are the most likely entry points
Weeds will establish in communities prior to
natural expansion
Approach to Invasives
• Current patterns of plant
invasion in YKL match
expectations
1.
2.
3.
Greater diversity and number of
infestations at hubs
Subset of less invasive, more disturbance
specialists in smaller communities
Very few infestations outside of
communities
Current Distribution of Invasives?
1. Infestation data from
AKNHP’s statewide nonnative plant database
(AKEPIC)
2. Products:
•
•
Develop GIS product
Tabular and written
descriptions
3. Preliminary outputs:
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41 plant species
273 acres infested
Non-native plant
occurrences (red circles) are
primarily associated with
developed areas (white
boxes)
Identification of areas susceptible to invasion
1. Relationship of non-native plant occurrences with
environmental and human variables
• Non-native plant and environmental/human variables summarized by
4th Level HUC for all Alaska
• CART & Random Forest models developed
• Important variables and thresholds identified
• Predicted “Infestation values” mapped back onto YKL
Predicted
Species
Richnes
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Non-Native Plant Species Richness by HUC8
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Quantifying plant infestations by HUC
1. Non-Native Plant Species Richness
2. Number
Highly Invasive
Infestations
What
is our of
measure
of non-native
species infestation?
Infestation Index
(not
infested vs. infested)
1.3. Non-Native
Species
Richness
Number of Highly Invasive Infestations per HUC
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2.
Number of Highly Invasive Infestations
•
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3.
Ranges from 0-136
Greater richness increases the probability of presence of a species that interferes with
management decisions (regardless of perceived “invasiveness”)
Somewhat less biased than infested area, number of records etc., by sampling
intensity
Correlated with other infestation metrics
Ranges from 0-3400
This represents conditions least favorable for land managers
Numbers of such infestations are likely partially biased by sampling intensity
Infestation Index
•
•
Review of data indicate two primary classifications: HUCs with only minor levels of
infestations of weakly invasive species and HUCs with numerous infestations including
species considered highly invasive
HUCs with ≥ 20 species almost always have highly invasive populations & splits the
data into similar sized pieces
Non-Native Plant Species Richness per HUC
Which variables are used to explain infestation levels?
1.
Human Variables (ISER)
•
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2.
Population size
Per capita income
Age of the oldest community in each HUC
Area of timber land
Area of agricultural land
Length of roads
Length of hiking trails
Length of permanent trails
Length of winter trails
Length of unclassified trails
Environmental Variables (SNAP 2010-2019)
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Mean annual temperature
Mean January temperature
Mean July temperature
Mean annual precipitation
Mean January precipitation
Mean July precipitation
Mean growing season length
Mean freeze date
Mean thaw date
Permafrost area
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Non-native species richness
1.
Explained mostly by:
•
•
•
2.
Population size (one major threshold)
Per capita income (one major threshold)
Length of roads (two thresholds)
Environmental Variables
•
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Explain far less of the variation
Variables associate with longer growing season tend to be
most important
Non-Native Plant Species Richness
Unconstrained Regression Tree
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Non-native species richness
Population
Income
Road Density
Ann. Temp.
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Non-native species richness
1.
Pruned regression tree
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Number of Highly Invasive Populations
1.
Explained mostly by:
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Population size (two thresholds)
Date of freeze (one threshold)
Annual precipitation
Length of roads
Date of
Freeze
Population
Road
Density
Ann. Precip.
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Number of Highly Invasive
Populations
1.
Pruned regression tree
•
Basically HUCs without many highly
invasive populations are those that
have some freezing in winter +
human populations of < 25,400 and
with per capita incomes < $25,000
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Infestation Index
1.
Explained mostly by:
•
•
•
•
Length of roads
Population size
Income
Precipitation
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Preliminary Results
Infestation Index
1.
Pruned regression
tree
• HUCs associated with
more roads, or HUCs
that do not freeze, or
those with high per
capita income tend to
have some nasty areas
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Current non-native plant
richness by HUC from survey
data
Which areas are most susceptible to non-native plant
invasion currently?
Preliminary CART Model Predictions
1. Most of YKL = Low Non-Native Species
Richness
(transparent = less than 10 spp.)
2. McGrath associated HUCs = Moderate
Species Richness
(red = > 10 spp.)
Which areas are most susceptible to non-native plant
invasion in the future?
Model Predictions
“Highly Infested” when
1. > 127 km roads &
2. > 522 mm annual
precipitation
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Which areas are most susceptible to non-native plant
invasion currently and in the future?
Area susceptible to
becoming highly infested
is expected to increase
in the future
Summary
1.
2.
3.
Infestations are primarily a function
of anthropogenic factors
•
Climate secondarily important
Current model outputs are coarse
Some utility in identifying thresholds
and areas of future susceptibility
Questions or Comments?
Matt Carlson
786-6390
[email protected]
or Jamie Trammell
786-4865
[email protected]
Canada thistle – UAF Cooperative Extention