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Species Abstracts of Highly Disruptive Exotic Plants

Exotic Species Ranking System

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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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