Pacific Island Ecosystems at Risk (PIER)

Themeda quadrivalvis


Note:  Risk assessment prepared for Australia

Information on Risk Assessments

        Themeda quadrivalvis
A. Biogeography/     grader Grass
  historical     P&C
1 Domestication/ 1.01 Is the species highly domesticated? N
  cultivation 1.02 Has the species become naturalised where grown? Y
    1.03 Does the species have weedy races? N
2 Climate and 2.01 Species suited to Australian climates (0-low; 1-intermediate; 2-high) 2
  Distribution 2.02 Quality of climate match data (0-low; 1-intermediate; 2-high) 2
    2.03 Broad climate suitability (environmental versatility) N
    2.04 Native or naturalised in regions with extended dry periods N
    2.05 Does the species have a history of repeated introductions outside its natural range?  
3 Weed 3.01 Naturalised beyond native range Y
  Elsewhere 3.02 Garden/amenity/disturbance weed  
  (interacts with 2.01 3.03 Weed of agriculture  
  to give a weighted 3.04 Environmental weed  
  score) 3.05 Congeneric weed  
B. Biology/Ecology    
4 Undesirable 4.01 Produces spines, thorns or burrs N
  traits 4.02 Allelopathic N
    4.03 Parasitic N
    4.04 Unpalatable to grazing animals  
    4.05 Toxic to animals N
    4.06 Host for recognised pests and pathogens  
    4.07 Causes allergies or is otherwise toxic to humans  
    4.08 Creates a fire hazard in natural ecosystems  
    4.09 Is a shade tolerant plant at some stage of its life cycle N
    4.10 Grows on infertile soils Y
    4.11 Climbing or smothering growth habit  
    4.12 Forms dense thickets  
5 Plant 5.01 Aquatic N
  type 5.02 Grass  
    5.03 Nitrogen fixing woody plant  
    5.04 Geophyte  
6 Reproduction 6.01 Evidence of substantial reproductive failure in native habitat N
    6.02 Produces viable seed. Y
    6.03 Hybridises naturally  
    6.04 Self-compatible or apomictic  
    6.05 Requires specialist pollinators  
    6.06 Reproduction by vegetative fragmentation N
    6.07 Minimum generative time (years) 1
7 Dispersal mechanisms 7.01 Propagules likely to be dispersed unintentionally (plants growing in areas with much vehicle movement) Y
    7.02 Propagules dispersed intentionally by people  
    7.03 Propagules likely to disperse as a produce contaminant N
    7.04 Propagules adapted to wind dispersal N
    7.05 Propagules water dispersed N
    7.06 Propagules bird dispersed N
    7.07 Propagules dispersed by other animals (externally) Y
    7.08 Propagules survive passage through the gut  
8 Persistence 8.01 Prolific seed production (>2000/m2) N
  attributes 8.02 Evidence that a persistent propagule bank is formed (>1 yr) Y
    8.03 Well controlled by herbicides Y
    8.04 Tolerates, or benefits from, mutilation or cultivation Y
    8.05 Effective natural enemies present in Australia Y
      Outcome: Evaluate
      Score: 1
  Statistical summary   Biogeography 2
  of scoring   Score partition:                       Undesirable attributes 1
      Biology/ecology -2
      Biogeography 4
      Questions answered:                       Undesirable attributes 6
      Biology/ecology 16
      Total 26
      Agricultural 2
      Sector affected:                                   Environmental 2
      Nusiance 0
   A= agricultural, E = environmental, N = nuisance, C=combined  

Risk assessment prepared by Rod Randall

Need more info? Have questions? Comments? Information to contribute? Contact PIER!

[ Return to PIER homepage ]

This page new 15 June 2003.