Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Melaleuca quinquenervia; paper bark tree

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

n

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

y

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

y

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

y

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

n

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

3

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

7.05

Propagules water dispersed

y=1, n=-1

y

7.06

Propagules bird dispersed

y=1, n=-1

n

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

n

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

n

8.03

Well controlled by herbicides

y=-1, n=1

y

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

n

Total score:

15

Source

Notes

1.01

no evidence

1.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"This species seeds profusely and can become a weed, especially where periodic fires provide a suitable seedbed, such as in southern Florida. M. quinquenervia was first introduced to Florida as an ornamental tree, yet is now regarded as a serious weed. "

1.03

no evidence

2.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

M. quinquenervia is a native of the coastal region in eastern Australia, from near Sydney (New South Wales) to Cape York (northern Queensland). It occurs mainly in a belt within 40 km of the sea. This species extends into southern Papua New Guinea and Irian Jaya, Indonesia, and has an extensive distribution in New Caledonia, especially on the north-west of the island (Blake, 1968; Holloway, 1979; Cherrier, 1981). In Australia and Papua New Guinea M. quinquenervia is generally confined to the lowlands (below 100 m), but in New Caledonia it forms extensive stands in uplands to an altitude of 900-1000 m. 

2.02

2.03

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.cp.nsw.gov.au/research/species.htm (3)http://www.floridaplants.com/Eflora/melaleuca_quinquenervia.htm (4)http://www.nps.gov/plants/alien/fact/mequ1.htm (5)http://weedbiocontrol.org/report/ecology/index.html

Natural latitude range
Approximate limits north to south: 8S to 34S
Climate
In southern regions of it's distribution, M. quinquenervia occurs in warm sub-humid and humid climates. In the northern regions it is found in the hot humid zone. The following data pertain to the species' natural range in Australia, while Booth and Jovanovic (1988), Marcar et al. (1995) and Geary (1988) provide climatic profiles for M. quinquenervia (see climate data table) combining information from both natural and planted occurrences.
The mean maximum temperature of the hottest month ranges from 26C in the south, to about 34C in the north. The corresponding minimum temperatures of the coolest month are 4C and 20C. There are few days over 38C in coastal areas, temperatures over 32C varies from about 20 days in the south, to 100 days or more in the north. Heavy frosts are absent in northern coastal areas, but a few kilometres inland, in southern Australia, frosts occur 1-5 times a year.
The 50 percentile rainfall is 900-1250 mm,

2.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

M. quinquenervia is a native of the coastal region in eastern Australia, from near Sydney (New South Wales) to Cape York (northern Queensland). It occurs mainly in a belt within 40 km of the sea. This species extends into southern Papua New Guinea and Irian Jaya, Indonesia, and has an extensive distribution in New Caledonia, especially on the north-west of the island (Blake, 1968; Holloway, 1979; Cherrier, 1981). In Australia and Papua New Guinea M. quinquenervia is generally confined to the lowlands (below 100 m), but in New Caledonia it forms extensive stands in uplands to an altitude of 900-1000 m. 

2.05

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

The species has been planted in the tropical lowlands of India, Mexico, northern Nigeria, Philippines, Puerto Rico, southern Africa, West Indies, and in southern California, Florida, Hawaii and in the extreme south of Texas, USA (Streets, 1962; Ruskins, 1983; Turnbull, 1986; von Carlowitz, 1991; Geary, 1988). It is recorded that two million trees have been planted on State Forest Reserve alone in Hawaii. M. quinquenervia was first introduced into southern Florida in the early 1900s, where it escaped cultivation on seasonally wet sites and has assumed weed status (Ruskins, 1983). It occurs now on some 186,000 ha or about 6% of the land in southern Florida (Cost and Craver, 1981).

3.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"This species seeds profusely and can become a weed, especially where periodic fires provide a suitable seedbed, such as in southern Florida. M. quinquenervia was first introduced to Florida as an ornamental tree, yet is now regarded as a serious weed. "

3.02

Loope, L.; Duever, M.; Herndon, A.; Snyder, J.; Jansen, D. (1994) Hurricane impact on uplands and freshwater swamp forest. BioScience, 1994, Vol.44, No.4, pp.238-246, 28 ref.

AB: "The post-hurricane spread of invasive exotic plant species (especially Melaleuca quinquenervia , Schinus terebinthifolius and Casuarina spp.) "; "This species seeds profusely and can become a weed, especially where periodic fires provide a suitable seedbed, such as in southern Florida." [disturbance promote invasion, not answered because of positive answer to 3.04, no evidence of garden or amenity weed]

3.03

no evidence

3.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"Unmanaged stands may have stockings of 7000-20,000 stems/ha thus crowding out native vegetation and wildlife habitats"

3.05

http://farrer.riv.csu.edu.au/ASGAP/weeds1.html

Melaleuca armillaris and M.hypericifolia, ranging in height from 0.3m to 3m and quite impenetrable

4.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

no description of these traits

4.02

Duryea, M. L., R. J. English, et al. (1999). "A comparison of landscape mulches: chemical, allelopathic, and decomposition properties." Journal of Arboriculture 25(2): 88-97.

AB: "In a standard test of allelopathy, all fresh mulches inhibited germination of lettuce seed, and although variable in concentration, all mulches contained hydroxylated aromatic compounds that could have caused these allelopathic effects. After 9 months and 1 year, pine straw and GRU still exhibited allelopathic effects on germination. Cypress, melaleuca, and pine bark retained their colour after 1 year, while the other 3 mulches changed to a pinkish gray."

4.03

no evidence

4.04

http://www.agroforestry.net/pubs/NTFP.pdf

[Not a fodder plant]

4.05

www.anu.edu/BoZo/BillsLab/PDF%20files/kbrev.pdf

eaten by koalas [no evidence of poisoning in other animals]

4.06

Host range of Puccinia psidii , a potential biological control agent of Melaleuca quinquenervia in Florida.
AU: Rayachhetry, M. B.; Van, T. K.; Center, T. D.; Elliott, M. L.
AA: Fort Lauderdale Research and Education Center, University of Florida, 3205 College Avenue, Fort Lauderdale, FL 33314, USA.
SO: Biological Control, 2001, Vol.22, No.1, pp.38-45, 27 ref.

AB: " In host range tests, 18 myrtaceous species were inoculated with uredospores of either of the 2 Puccinia psidii isolates, MISOL (obtained from Melaleuca quinquenervia ) and PISOL (obtained from Pimenta dioica ), at a concentration of 3.7 x 105 and 5.0 x 105 uredospores/ml, respectively. Both isolates infected Callistemon viminalis, Eugenia reinwardtiana, Melaleuca decora, Melaleuca quinquenervia, Myrcianthes fragrans, Myrciaria cauliflora, Pimenta dioica and Psidium guajava . Eucalyptus grandis, Eugenia paniculatum [E. paniculata ] and Syzygium cumini were considered resistant, but still exhibited chlorotic halos and brown leaf spots but no sporulation, while Calyptranthes pallens, Eugenia confusa, Eugenia foetida, Eugenia uniflora, Feijoa sellowiana [Acca sellowiana ], Psidium cattleianum and S. gambos were completely resistant to both isolates. "
[Puccinia psidii infect many fruit crops and forestry species in Myrtaceae but many important Guava and Eucalypts are resistant]]

4.07

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://aquat1.ifas.ufl.edu/mcplnt2a.html

(1)" In southern Florida, the pollen is suspected to cause serious allergic reactions and acute respiratory problems (Geary, 1988)." [suspected?] (2)expenditures for allergy treatment by $0.5- 2.0 million per year [Florida]

4.08

http://www.bangor.ac.uk/~afs101/iwpt/web-sp9.htm

The thick spongy bark of the trunk is fire proof but the outer layer highly flammable.

4.09

Dehgan, B. (1998) Landscape Plants for Subtropical Climates. University Press of Florida., Gainesville, FL. 638pp.

p.189 "full sun to partial shade."

4.1

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

Soil and physiography
"In Australia, M. quinquenervia normally grows on level or gently undulating coastal lowlands. The soils are often peaty humic gleys, sandy at the surface but silty or clayey below, and with a high organic matter content."; " M. quinquenervia in New Caledonia occurs extensively on well-drained slopes and ridges in the uplands, as well as on marshy plains (Gillison, 1983). Here it is found on all soil types but mainly on sedimentary or metamorphic soils, and rarely on soils derived from ultrabasic rocks (Cherrier, 1981; Valet et al., 1998)."
Descriptors
- Soil texture: light; medium; heavy
- Soil drainage: impeded; seasonally waterlogged
- Soil reaction: very acid; acid; neutral
- Special soil tolerances: saline; infertile
- Soil types: acid soils; alluvial soils; calcareous soils; clay soils; fluvisols; gleysols; peat soils; podzols; swamp soils; ultisols; saline soils; ferralsols

4.11

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"A small to medium-sized tree, commonly 8-12 m tall, but ranging 4-25 m depending on local growing conditions."

4.12

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"The best-developed stands of M. quinquenervia occur as open-forest or woodland on favourable sites, but elsewhere are reduced to low woodland or tall shrubland. It is usually the dominant species, and frequently occurs in more or less pure stands. "; "Seeds also disperse and establish readily in wetlands. Unmanaged stands may have stockings of 7000-20,000 stems/ha thus crowding out native vegetation and wildlife habitats"

5.01

Lockhart, C. S. (1996) Aquatic heterophylly as a survival strategy in Melaleuca quinquenervia (Myrtaceae). Canadian Journal of Botany, 1996, Vol.74, No.2, pp.243-246, 15 ref.

AB: The broad-leaf paper bark or melaleuca tree (Melaleuca quinquenervia ) is an emergent, semiaquatic tree whose morphological plasticity allows it to invade wetland and terrestrial habitats. While studying the effect of hydroperiod on melaleuca seedlings, two types of aquatic leaf forms were observed under submersed conditions. Linear leaves developed at least 9.5 cm below the water surface and were associated with short internodes. Short, broad, incurved transitional leaves formed as the seedlings approached the water surface. Aerial leaves were flat and spatulate to oblanceolate. Leaf length to width ratios, stomatal density, and shoot internode lengths were significantly different between the three leaf forms. Characteristics of submersed melaleuca seedlings are similar to those of other aquatic heterophyllic plants that grow in areas where water levels fluctuate. An increased understanding of morphological variations of this invasive tree may lead to additional control methods and mechanisms. [not nor

5.02

tree; Myrtaceae

5.03

no evidence

5.04

tree

6.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"M. quinquenervia remains fairly common throughout its natural range and currently there are no general conservation concerns."

6.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"Propagation is usually by seed, which germinate readily under favourable conditions, and do not require pre-germination treatment."

6.03

no evidence

6.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.05

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"Melaleucas have hermaphrodite, protandrous flowers and are pollinated mainly by insects, but also by birds and small mammals. "

6.06

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"The species has the ability to coppice readily, but root suckers are not commonly produced."

6.07

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"Flowering in young trees commences as early as 3 years"

7.01

Nonindigenous Aquatic and Semi-Aquatic Plants in Freshwater Systems
Nonindigenous Semi-Aquatic Plants. Melaleuca, Cajeput Tree (Melaleuca quinquenervia)(Cau.) S.T. Blake. Available at: <http://aquat1.ifas.ufl.edu/mcplnt2a.html>

" This exotic tree grows along roadsides"

7.02

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

The species has been planted in the tropical lowlands of India, Mexico, northern Nigeria, Philippines, Puerto Rico, southern Africa, West Indies, and in southern California, Florida, Hawaii and in the extreme south of Texas, USA.

7.03

no evidence

7.04

Browder, J. A.; Schroeder, P. B. (1981) Melaleuca seed dispersal and perspectives on control. Proceedings of Melaleuca Symposium, Sept. 23-24, 1980., 1981, pp.17-21, 11 ref.

AB: "The model predicted that: out of one million seeds released by one tree during an ordinary year, no seeds would be expected to travel further than one km; only 1% of seeds released would travel beyond 170 m, and of these, only 5% would be viable. The max. 'most probable distance' that seed would be carried by hurricane-force (100-knot) winds is 7.1 km"

7.05

Author: Meagan Cooke (Last Edited: October 29, 2001) Introduced Species Summary Project, Australian Paperbark (Melaleuca quinquenervia). A webpage available at:
<http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Melaleuca_quinquenervia.html>

"The small, lightweight seeds are carried by water and wind."

7.06

fruit a woody capsule

7.07

no evidence

7.08

no evidence of ingestion

8.01

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"There is an average of 2,660,000 viable seeds/kg" [very small seeds]

8.02

Regeneration potential of the canopy-held seeds of Melaleuca quinquenervia in south Florida.
AU: Rayachhetry, M. B.; Van, T. K.; Center, T. D.
AA: Fort Lauderdale Research and Education Center, University of Florida, 3205 College Avenue, Fort Lauderdale, Florida 33314, USA.
SO: International Journal of Plant Sciences, 1998, Vol.159, No.4, pp.648-654, 31 ref.

AB: "Melaleuca quinquenervia produces and maintains extensive seed reservoirs in the forest canopy. Extracted seeds were soaked for 10 days in sterile deionized water and/or 2,3,5,-triphenol tetrazolium chloride (TTC) stain to assess viability. Microscopic inspections revealed that only 15% of the seeds were embryonic (filled), 50% of embryonic seeds were viable (stained red with TTC), and 73% of viable seeds were germinable after 10 days. The remaining 27% of viable seeds may have been dormant or, possibly, required special conditions for germination"
[seed bank on canopy but is easily removed by cutting trees, so does not meet the risk factor of a soil propagule bank]

8.03

(1)Criteria Used for the Selection of Herbicides on Melaleuca quinquenervia (Melaleuca). <http://www.wes.army.mil/el/aqua/apis/herbicides/html/criter15.html >
(2) Plant Conservation Alliance, Alien Plant Working Group (August 1997). <http://www.nps.gov/plants/alien/fact/mequ1.htm>

(1) It contains detail informations about how to select herbicides to control Melaleuca quinquenervia.
(2) Herbicides are usually needed for extensive infestations and mature paperbark trees and may be applied to freshly cut stumps or to girdled trunks. However, as noted previously, herbicide use will cause paperbark tree to release large caches of stored seeds.

8.04

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

"M. quinquenervia is highly fire-tolerant, except during the early seedling stages."; "The species has the ability to coppice readily, but root suckers are not commonly produced." 

8.05

no evidence