http://plants.alaska.gov/images/dalton-gravel-pit-infestation-ATV.jpg

Invasive Species - YKLDistribution Models and Preliminary ProductsMatt Carlson, Jamie Trammell, and Megumi Aisu

Approach to Invasives• 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

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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 non-native species introductions?

What are the likely vectors for non-native species introductions?

1. Approach:• Literature review

• 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 VectorsPreliminary Summary

A. Ecological and economic damage from invasive species requires:

1. Transportation of propagules2. Establishment3. Expansion to high biomass

B. Pathways of transportation are predictable1. Movements of people and goods2. Habitat corridors (roads)

C. Vast majority of introductions are intentional1. Contaminants are an issue for plants in Alaska (straw,

agricultural seed, container pots, imported fill)

D. Regional hubs are the most likely entry pointsE. Weeds will establish in communities prior to natural

expansion

Approach to Invasives• Current patterns of plant

invasion in YKL match expectations

1. Greater diversity and number of infestations at hubs

2. Subset of less invasive, more disturbance specialists in smaller communities

3. Very few infestations outside of communities

Current Distribution of Invasives?1. Infestation data from

AKNHP’s statewide non-native plant database (AKEPIC)

2. Products:• Develop GIS product• Tabular and written

descriptions 3. Preliminary outputs:

• 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

What is our measure of non-native species infestation?1. Non-Native Species Richness

• 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

2. Number of Highly Invasive Infestations• Ranges from 0-3400• This represents conditions least favorable for land managers• Numbers of such infestations are likely partially biased by sampling intensity

3. 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

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1. Non-Native Plant Species Richness2. Number of Highly Invasive Infestations3. Infestation Index (not infested vs. infested)

Which variables are used to explain infestation levels?

1. Human Variables (ISER)• 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

2. Environmental Variables (SNAP 2010-2019)• 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 ResultsNon-native species richness1. Explained mostly by:

• Population size (one major threshold)• Per capita income (one major threshold)• Length of roads (two thresholds)

2. Environmental Variables • 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 ResultsNon-native species richness

Population Road Density

Income Ann. Temp.

Which areas are most susceptible to non-native plant invasion currently and in the future?

Preliminary ResultsNon-native species richness1. Pruned regression tree

Which areas are most susceptible to non-native plant invasion currently and in the future?

Preliminary ResultsNumber of Highly Invasive Populations1. Explained mostly by:

• Population size (two thresholds)• Date of freeze (one threshold)• Annual precipitation• Length of roads

Population

Date of Freeze

Ann. Precip.

Road Density

Which areas are most susceptible to non-native plant invasion currently and in the future?

Preliminary ResultsNumber of Highly Invasive Populations1. 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 ResultsInfestation Index1. 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 ResultsInfestation Index1. 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 Predictions1. 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” when1. > 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

Summary1. Infestations are primarily a function

of anthropogenic factors• Climate secondarily important

2. Current model outputs are coarse3. Some utility in identifying thresholds

and areas of future susceptibility

Questions or Comments?Matt Carlson

786-6390mlcarlson@uaa.alaska.edu

or Jamie Trammell786-4865ejtrammell@uaa.alaska.edu

Canada thistle – UAF Cooperative Extention