Developing an effective weed inventory method

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Developing an effective weed inventory
method Lisa Rew, Bruce Maxwell Richard
Aspinall
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Invasive Plant Species Purpose of an Inventory
Plants transported to new, often distant, ranges
where their descendants proliferate, spread and
persist.
Mack et al., 2000

• Seek destroy vs Inventory
• What species are present?
• What is their frequency in the environment?
• Is it correlated with environmental variables?

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Objectives

• Conduct a preliminary study to determine the most
  efficient means to inventory exotic plant species
  in the northern range of YNP
• Computer simulation to determine the most
  efficient sampling scheme for a range of assumed
  weed distributions and infestation sizes
• Conduct field sampling to verify likely weed
  distributions

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Random weed distribution(2000 points or 0.6)
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Sampling strategies
Random point (15 or 0.75)
Grid (23 or 1.2)
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Random walk (12 or 0.6)
Transects (19 or 0.95)
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Weightedweed distribution
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Random points (11 or 0.55)
Grid (16 or 0.8)
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Random walk (12 or 0.6)
Transects (34 or 1.7)
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Model Simulation Results

• For a range of weed distributions with
  consideration of sampling efficiency transects
  orientated perpendicular to roads trails were
  found to be the most effective methodology for
  creating an inventory of the exotic plant
  species.

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Study area
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Field Methods

• 2 person teams located the starting point of
  transect with a GPS
• Walked the continuous transect on a given azimuth
• Recording weed locations changes in vegetation
  habitat type

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Reduced exotic plant species list for preliminary
sample

• Selection of indicator species was based on
  ability to see the plants in the field, their
  growth habit, restricted habitats, etc.
• 9 species
• Dalmatian toadflax - Timothy
• Houndstongue - Smooth brome
• Spotted knapweed - Downy brome
• Canada thistle - Yellow sweetclover
• Ox-eye daisy

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YNP - Northern Range Exotic Plant Inventory
Spotted Knapweed (Centaurea maculosa)
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YNP - Northern Range Exotic Plant Inventory
Houndstongue (Cynoglosum officinale)
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YNP - Northern Range Exotic Plant Inventory
Dalmation Toadflax (Linaria dalmatica)
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YNP - Northern Range Exotic Plant Inventory
Timothy (Phleum pratense)
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Frequency ()
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Distance from roads/trails (m)(Weighted
frequency)
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Vegetation habitat occurrence(Weighted frequency)
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Summary

• Purpose of inventory
• Seek destroy vs unbiased sample
• Pilot study
• Stratification on known distribution influencing
  factors e.g. distance from roads/trails
• Inventory
• Proportional sampling
• Stratify on distance from roads/trails habitat
  type

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• Also involved
• Tad Weaver MSU, Frank Dougher MSU, Don Despain
  USGS, Lane Cameron, NPS.
• In the field
• Matt Hulbert, Jerad Corbin, Kit Sawyer,
• Judit Barosso, Jeremy Gay, Nicole Wagner.