ECan 30 species report FY21R2.pdf (958.52 kB)

Weed Risk in Canterbury – an assessment of 30 species

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  1. This report presents weed risk rankings for 30 plant species identified by Environment Canterbury as potential weed threats to the Canterbury region using four different models, each based on the species’ weed status elsewhere in the world.
  2. The models varied in complexity. The simplest model, Model 1, is the global weed risk score from the ‘Global Compendium of Weeds, Third Edition’ (Randall, 2017). Model 2 adds a climate preference adjustment to Model 1. Model 3 is a modification of Model 2 with the Global Compendium of Weeds risk score replaced by the number of published scientific papers about the species as a weed and the number of invaded-range occurrences along with the climate preference adjustment. Model 4, the most comprehensive model, combines Models 2 and 3.
  3. According to Model 4, the top 8 species, in weed risk rank order are: rum cherry (Prunus serotina); Himalayan balsam (Impatiens glandulifera); tree of heaven (Ailanthus altissima); Bermuda buttercup (Oxalis pes-caprae); African love grass (Eragrostis curvula); nutgrass (Cyperus rotundus); noogoora bur (Xanthium strumarium); Bathurst bur (Xanthium spinosum).
  4. To prioritise these ‘risky’ species (or a subset of them) for regional-scale weed management in Canterbury, a comprehensive ‘risk analysis’ and ‘cost-benefit analysis’ is recommended underpinned by the development and analysis of a climate niche model for each species.


Rights statement

This report has been prepared for Environment Canterbury. You may reproduce, store and use the content of this report for personal, informational and non-commercial purposes only. Otherwise, no portion of the content may be copied or used without the written permission of Environment Canterbury.

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  • PRJ0110123


  • English

Does this contain Māori information or data?

  • No


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