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Species Abstracts of Highly Disruptive Exotic Plants

Exotic Species Ranking System


I. SIGNIFICANCE OF IMPACT

  1. Current Level of Impact

    1. Distribution relative to disturbance regime

      1. found only within sites disturbed within the last three years or sites regularly disturbed = -10
      2. found in sites disturbed within the last 10 years = 1
      3. found in mid-successional sites disturbed 11 to 50 years BP = 2
      4. found in late-successional sites disturbed 51 to 100 years BP = 5
      5. found in high quality natural areas with no known major disturbance for 100 years = 10

    2. Abundance

      1. number of populations (stands)
        1. few, scattered (<5) = 1
        2. intermediate number; patchy (6-10) = 3
        3. several; widespread and dense (>10) = 5
      2. areal extent of populations
        1. <5 ha = 1
        2. 5-10 ha = 2
        3. 11-50 ha = 3
        4. >50 ha = 5

    3. Effect on natural processes and character

      1. plant species having little or no effect = 0
      2. delays establishment of native species in disturbed sites up to 10 years = 3
      3. long-term (more than 10 years) modification or retardation of succession = 7
      4. invades and modifies existing native communities = 10
      5. invades and replaces native communities = 15

    4. Significance of threat to park resources

      1. threat to secondary resources negligible = 0
      2. threat to areas' secondary (successional) resources = 2
      3. endangerment to areas' secondary (successional) resources = 4
      4. threat to areas' primary resources = 8
      5. endangerment to areas' primary resources = 10

    5. Level of visual impact to an ecologist

      1. little or no visual impact on landscape = 0
      2. minor visual impact on natural landscape = 2
      3. significant visual impact on natural landscape = 4
      4. major visual impact on natural landscape = 5

      TOTAL POSSIBLE = 50

  2. Innate Ability of Species to Become a Pest

    1. Ability to complete reproductive cycle in area of concern

      1. not observed to complete reproductive cycle = 0
      2. observed to complete reproductive cycle = 5

    2. Mode of reproduction

      1. reproduces almost entirely by vegetative means = 1
      2. reproduces only by seeds = 3
      3. reproduces vegetatively and by seed = 5

    3. Vegetative reproduction

      1. no vegetative reproduction = 0
      2. vegetative reproduction rate maintains population = 1
      3. vegetative reproduction rate results in moderate increase in population size = 3
      4. vegetative reproduction rate results in rapid increase in population size = 5

    4. Frequency of sexual reproduction for mature plant

      1. almost never reproduces sexually in area = 0
      2. once every five or more years = 1
      3. every other year = 3
      4. one or more times a year = 5

    5. Number of seeds per plant

      1. few (0-10) = 1
      2. moderate (11-1000) = 3
      3. many-seeded (>1000) = 5

    6. Dispersal ability

      1. little potential for long distance dispersal = 0
      2. great potential for long distance dispersal = 5

    7. Germination requirements

      1. requires open soil and disturbance to germinate = 0
      2. can germinate in vegetated areas but in a narrow range or in special conditions = 3
      3. can germinate in existing vegetation in a wide range of conditions = 5

    8. Competitive ability

      1. poor competitor for limiting factors = 0
      2. moderately competitive for limiting factors = 3
      3. highly competitive for limiting factors = 5

    9. Known level of impact in natural areas

      1. not known to cause impacts in any other natural area = 0
      2. known to cause impacts in natural areas, but in other habitats and different climate zones = 1
      3. known to cause low impact in natural areas in similar habitats and climate zones = 3
      4. known to cause moderate impact in natural areas in similar habitats and climate zones = 5
      5. known to cause high impact in natural areas in similar habitats and climate zones = 10

TOTAL POSSIBLE = 50

II. FEASIBILITY OF CONTROL

  1. Abundance Within Park

    1. Number of populations (stands)

      1. several; widespread and dense = 1
      2. intermediate number; patchy = 3
      3. few, scattered = 5

    2. Areal extent of populations

      1. >50 ha = 1
      2. 11-50 ha = 2
      3. 5-10 ha = 3
      4. <5 ha = 5

  2. Ease of Control

    1. Seed banks

      1. seeds remain viable in the soil for at least three years = 0
      2. seeds remain viable in the soil for two to three years = 5
      3. seeds viable in the soil for one year or less = 15

    2. Vegetative regeneration

      1. any plant part is a viable propagule = 0
      2. sprouts from roots or stumps = 5
      3. no re-sprouting following removal of above-ground growth = 10

    3. Level of effort required

      1. repeated chemical or mechanical control measures required = 1
      2. one or two chemical or mechanical treatments required = 5
      3. can be controlled with one chemical treatment = 10
      4. effective control can be achieved with mechanical treatment = 15

    4. Abundance and proximity of propagules near park

      1. many sources of propagules near park = 0
      2. few sources of propagules near park, but these are readily dispersed = 5
      3. few sources of propagules near park, but these are not readily dispersed = 10
      4. no sources of propagules are in close proximity = 15

  3. Side Effects of Chemical/Mechanical Control Measures

    1. control measures will cause major impacts to community = 0
    2. control measures will cause moderate impacts to community = 5
    3. control measures will have little or no impact on community = 15

  4. Effectiveness of Community Management

    1. the following options are not effective = 0
    2. cultural techniques (burning, flooding) can be used to control target species = 5
    3. routine management of community and/or restoration or preservation practices (e.g., prescribed burning, flooding, controlled disturbance) effectively controls target species = 10

  5. Biological Control

    1. biological control not feasible (not practical, possible, or probable) = 0
    2. potential may exist for biological control = 5
    3. biological control feasible = 10
      TOTAL POSSIBLE = 100

URGENCY

  1. Delay in action will result in large increase in effort required for successful control = High
  2. Delay in action will result in moderate increase in effort required for successful control = Medium
  3. Delay in action will result in little increase in effort required for successful control = Low

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