Criteria | Intensity Ratings | |||
Lowest Threat (L) | Medium Low (ML) | Medium High (MH) | Highest Threat (H) | |
Establishment | ||||
Germination /Propagule Requirements | Requires 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 Requirements | Requires 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 rainfall | Can establish under moderate canopy/litter cover | Can 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 Form | Others | Geophytes, Climber or creepers | Grasses, Leguminous plants | Aquatic (submerged, emergent, floating) and semi aquatic. |
Allelopathic properties | None | Minor properties | Allelopathic properties seriously affecting some plants | Major 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 persist | Consumed 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, fire | Maybe tolerant of 1 stress, susceptible to at least 2 | Tolerant to at least 2 and susceptible to at least 2 | Highly 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). |
Reproduction | ||||
Reproductive system | Sexual but either cross OR self pollination | Sexual (self and cross pollination) | Vegetative reproduction | Both vegetative and sexual reproduction |
Number of propagules produced per flowering event | Less than 50 | 50-1000 | 1000-2000 | Above 2000 |
Propagule Longevity | Seeds 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 period | Mature plant produces viable propagules for only 1yr. | Mature plant produces viable propagules for only 1 – 2 yrs. | Mature plant produces viable propagules for 3 –10yrs | Mature 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. | 2-5yrs | Produces propagules between 1-2yrs after germination. | Reaches maturity and produces viable propagules in under a year. |
Dispersal | ||||
Number of dispersal mechanisms? | Propagules mainly spread by gravity | Propagules 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 20m | Very few to none will disperse to 1 km, most 20-200m | Few propagules will disperse greater than 1 km but many will reach 200-1000m | Very likely that some propagules will disperse greater > 1 km |