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Invasiveness Criteria

Intensity Ratings
Lowest Threat (L)
Medium Low (ML)
Medium High (MH)
Highest Threat (H)
Germination /Propagule RequirementsRequires specific environmental factors that are not part of an annual cycle of the system to germinate (eg specific temperatures, floods, fire) OR human caused disturbance such as ploughing.Requires unseasonal or uncommon natural events for germination, eg (flooding, fire.) Requires natural seasonal disturbances such as seasonal rainfall, spring/summer temperatures for germination / striking/ set root.Opportunistic germinator, can germinate or strike/ set root at any time whenever water is available.
Seedling/ Propagule Establishment RequirementsRequires additional and very specific factors such as nutrient and water that are deliberately added or highly eutrophic conditions.Requires more specific requirements to establish eg open space or bare ground with access to light and direct rainfallCan establish under moderate canopy/litter coverCan establish without additional factors.
How much disturbance is required for seedling establishment to occur.Major disturbance required with little or no competition from other plant species.Establishes in highly disturbed natural ecosystems (roadsides, wildlife corridors- or areas which have a greater impact by humans - such as tourist areas or campsites) or in overgrazed pastures/poorly growing or patchy crops. Establishes in relatively intact or only minor disturbed natural ecosystems (wetlands, riparian, riverine, grasslands, and open woodlands); in vigorously growing crops OR in well-established pastures.Establishes in healthy and undisturbed natural ecosystems .(eg mallee, alpine, heathlands)
Growth/ Competitive Ability
Life FormOthersGeophytes, Climber or creepersGrasses, Leguminous plantsAquatic (submerged, emergent, floating) and semi aquatic.
Allelopathic propertiesNoneMinor propertiesAllelopathic properties seriously affecting some plantsMajor allelopathic properties inhibiting all other plants.
Ability to tolerate herbivory pressure and produce propagules Preferred food of herbivores. Eliminated by moderate herbivory or reproduction entirely prevented.Consumed and recovers slowly. Reproduction strongly inhibited by herbivory but still capable of vegetative propagule production (rhizomes or tubers); weed may still persistConsumed but non-preferred or consumed but recovers quickly; Capable of flowering /seed production under moderate herbivory pressure. (Moderate = normal; not overstocking or heavy grazing)Favoured by heavy grazing pressure as not eaten by animals/ insects and not under a biocontrol program in Aust/NZ.
Normal growth rate Slow growth, will be exceeded by many other species.Maximum growth rate less than many species of same life-form.Moderately rapid growth that will equal competitive species of same life form.Rapid growth rate that will exceed most other species of same life form.
Stress Tolerance of established plants to frost, drought, water logging, salinity, fireMaybe tolerant of 1 stress, susceptible to at least 2Tolerant to at least 2 and susceptible to at least 2Highly tolerant of at least 2 of (Drought, Frost, Waterlogging, Fire and Salinity) and maybe tolerant of another. Susceptible to at least 1.Highly resistant to at least 2 of (Drought, Frost, Waterlogging, Fire and Salinity) not susceptible to more than 1 (cannot be Drought or Waterlogging).
Reproductive systemSexual but either cross OR self pollinationSexual (self and cross pollination)Vegetative reproductionBoth vegetative and sexual reproduction
Number of propagules produced per flowering eventLess than 5050-10001000-2000Above 2000
Propagule LongevitySeeds survive <5yrs, or lower viability but survive 5-10yrs OR vegetatively reproduces.> 25% of seeds survive 5-10 yrs in soil, or lower viability but survive 10-20 yrs>25% of seeds survive 10-20 yrs in soil, or lower viability but survive 20+ yrs>25% of seeds can survive >20yrs in the soil.
Reproductive periodMature plant produces viable propagules for only 1yr.Mature plant produces viable propagules for only 1 – 2 yrs.Mature plant produces viable propagules for 3 –10yrsMature plant produces viable propagules for 10yrs or more, or species forms self-sustaining dense monocultures.
Time to reach reproductive maturity.Greater than 5yrs to reach sexual maturity.2-5yrsProduces propagules between 1-2yrs after germination.Reaches maturity and produces viable propagules in under a year.
Number of dispersal mechanisms?Propagules mainly spread by gravityPropagules can also be spread by attaching to humans or animals Propagules spread by wind, water, animals (not birds) or light vehicular traffic.Very light, wind dispersed seeds, OR bird dispersed seeds OR has edible fruit that is readily eaten by highly mobile animals.
Probability (or chance) that propagules will disperse to a distance greater than 1 km.Very unlikely to disperse greater than 200m most will be less than 20mVery few to none will disperse to 1 km, most 20-200mFew propagules will disperse greater than 1 km but many will reach 200-1000mVery likely that some propagules will disperse greater > 1 km
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