Eucalyptus cladocalyx Risk – California Invasive Plant Council

Created by: Elizabeth D. Brusati
Created on: Thursday, Apr 21st, 2016

Evaluation Summary

Summary:

General Evaluation Information

Date of Evaluation:

April 21, 2016

Evaluation Time (hrs):

2 Hours

Evaluation Status:

Completed

Plant Information

Plant:

Eucalyptus cladocalyx

Plant Material:

If the plant is a cultivar, and if the cultivar's behavior differs from its parent's (behavior), explain how:

Regional Information

Region Name:

California

Climate Matching Map

These maps were built using a toolkit created in collaboration between GreenInfo Network, PlantRight, Cal-IPC, and Agricultural Sustainability Institute at UC Davis.

Link to Climate Matching Map:

Climate Matching Maps PDF:

Invasive History and Climate Matching

1. Has the species (or cultivar or variety, if applicable; applies to subsequent "species" questions) become naturalized where it is not native?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

Naturalized in South Africa, California, Hawaii. (Native to South Australia)

Reference(s):

USDA, ARS (2016). Germplasm Resources Information Network (GRIN).

Jepson Flora Project (2014). Jepson eFlora.

Queensland Government (2011). Weeds of Australia Biosecurity Queensland Edition.

2. Is the species (or cultivar or variety) noted as being naturalized in the US or world in a similar climate?

Yes or No:

Yes

Points:

Confidence Level:

Answer / Justification:

In California, naturalized in disturbed coastal areas. Recorded in 5 counties in Calflora, including during a Bioblitz at Santa Monica Mountains National Recreation Area.

Reference(s):

Jepson Flora Project (2014). Jepson eFlora.

Calflora (2015). Calflora.

3. Is the species (or cultivar or variety) noted as being invasive in the U.S. or world?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

Invasive in South Africa, where it is a Category 2 listed invasive plant and invades fynbos (shrubland), forest gaps, plantations, watercourses and roadsides. A survey of invasive plants in South Africa called it a potential landscape transformer. It recruits large numbers of seedlings. Also invasive in Western Australia (outside its native range of South Australia). See link to CABI datasheet in Evaluation Notes.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

Queensland Government (2011). Weeds of Australia Biosecurity Queensland Edition.

4. Is the species (or cultivar or variety) noted as being invasive in the US or world in a similar climate?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

Invasive in South Africa, where it is a Category 2 listed invasive plant and invades fynbos (shrubland), forest gaps, plantations, watercourses and roadsides. A survey of invasive plants in South Africa called it a potential landscape transformer. It recruits large numbers of seedlings. Mostly in the Western Cape of South Africa, which has a similar climate to California.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

-IPC, C. (2016). Cal-IPC global map of climate areas matching California.

[Anonymous] (2012). Invasive Species South Africa.

5. Are other species of the same genus (or closely related genera) invasive in a similar climate?

Yes or No:

Yes

Points:

Confidence Level:

High

Answer / Justification:

Eucalyptus globulus and E. camaldulensis are invasive in California (both rated Limited on Cal-IPC Inventory). Six species of Eucalyptus are regulated in South Africa and must be removed when they are in protected areas (parks) or riparian areas - see link in Notes.

Reference(s):

Cal-IPC (0). California Invasive Plant Inventory.

[Anonymous] (2012). Invasive Species South Africa.

6. Is the species (or cultivar or variety) found predominately in a climate matching the region of concern?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

Although the species occurs naturally in a winter rainfall, mediterranean-type climate, Poynton (1979) reported that its use in afforestation in South Africa extends to parts of the Cape Province with uniform and summer rainfall. - see CABI datasheet. See information above on where it has naturalized above. Most of the naturalized areas and native range are similar to California. GBIF map = http://www.gbif.org/species/3176313

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

-IPC, C. (2016). Cal-IPC global map of climate areas matching California.

GBIF (0). Global Biodiversity Information Facility (GBIF).

Impact on Native Plants and Animals

7. Does this plant displace native plants and dominate (overtop or smother) the plant community in areas where it has established?

Yes or No:

Yes

Points:

Confidence Level:

High

Answer / Justification:

Its rapid growth and high seedling recruitment allow it to outcompete native species and change the botanical composition of an area. Has a spreading and competitive root system.

Reference(s):

Weber, E.. (2003). Invasive Plant Species of the World. 548.

[Anonymous] (2007). CABI Invasive Species Compendium.

8. Is the plant noted as promoting fire and/or changing fire regimes?

Yes or No:

Yes

Points:

Confidence Level:

Medium

Answer / Justification:

The canopy of mature E. cladocalyx also recovers more quickly than the native species after fire and it would appear that the species is therefore at a competitive advantage in areas where bush fires occur regularly (Ruthrof et al., 2003). - However, I'm not sure if it actually changes the fire regime or simply benefits from fire. Many eucalyptus species contain aromatic oils and increase crown fires, so it is possible this species influences fires. Answering yes but with medium confidence due to lack of specific information on this species.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

9. Is the plant a health risk to humans or animals/fish? Has the species been noted as impacting grazing systems?

Yes or No:

Points:

Confidence Level:

Medium

Answer / Justification:

The leaves are poisonous, producing prussic acid, but I don't know how likely it it that they would be eaten. No mention of impacts to grazing.

Reference(s):

[Anonymous] (2012). Invasive Species South Africa.

10. Does the plant produce impenetrable thickets, blocking or slowing movement of animals, livestock, or humans?

Yes or No:

Points:

Confidence Level:

Very Low

Answer / Justification:

While it is invasive, I could not find information on how densely E. cladocalyx grows in its invasive range of South Africa.

Reference(s):

Reproductive Strategies

11. Does this species (or cultivar or variety) reproduce and spread vegetatively?

Yes or No:

Points:

Confidence Level:

High

Answer / Justification:

Propagated by seeds. Other species of Eucalyptus produce stem sprouts but the references on this species don't mention that.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

12. If naturally detached fragments from this plant are capable of producing new plants, is this a common method of reproduction for the plant?

Yes or No:

Points:

Confidence Level:

High

Answer / Justification:

Seems unlikely because it is a tree.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

13. Does the species (or cultivar or variety) commonly produce viable seed?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

There are approximately 120,000 viable seed per kilogram of seed and chaff mix.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

14. Does this plant produce copious viable seeds each year (> 1000)?

Yes or No:

Yes

Points:

Confidence Level:

Medium

Answer / Justification:

There are approximately 120,000 viable seed per kilogram of seed and chaff mix. I found articles on E. cladocalyx breeding systems but nothing that gave a clear number of seeds produced. Given the number above and the fact that this is a large tree, I am assuming yes.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

15. Is there significant germination (>25%) of seeds the next growing season, with no requirement of an infrequent environmental condition for seeds to germinate (i.e. fire) or long dormancy period?

Yes or No:

Points:

Confidence Level:

Medium

Answer / Justification:

E. cladocalyx has large seedling recruitment after fire. Eucalyptus species in general have very low seedling survival when they germinate between fires. Although I could not find a clear statement that fire is required for germination, it appears to greatly stimulate germination and help seedling survival.

Reference(s):

Ruthrof, K. X., Loneragan W. A., & Yates C. J. (2003). Comparative Population Dynamics of Eucalyptus cladocalyx in Its Native Habitat and as an Invasive Species in an Urban Bushland in South-Western Australia. Diversity and Distributions. 9, 469–483.

16. Does this plant produce viable seed within the first three years (for an herbaceous species) to five years (for a woody species) after germination?

Yes or No:

Points:

Confidence Level:

Very Low

Answer / Justification:

Although I found several articles on E. cladocalyx breeding systems, I could not find a clear answer on when seeds are first produced.

Reference(s):

17. Does this plant continuously produce seed for >3 months each year or does seed production occur more than once a year?

Yes or No:

Yes

Points:

Confidence Level:

Medium

Answer / Justification:

Flowering occurs January to April in Australia, with mature seed available for collection about 12 months later. In South Africa, flowers from October to May. Based on the longer flowering period in South Africa, I am extrapolating to >3 months of seed production.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

[Anonymous] (2012). Invasive Species South Africa.

Dispersal

18. Are the plant’s propagules frequently dispersed long distance (>100 m) by mammals or birds or via domestic animals?

Yes or No:

Points:

Confidence Level:

High

Answer / Justification:

Tiny seeds are dispersed by wind and that sounds like the main form of dispersal.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

19. Are the plant’s propagules frequently dispersed long distance (>100 m) by wind or water?

Yes or No:

Yes

Points:

Confidence Level:

Very High

Answer / Justification:

Has tiny seeds that are dispersed by wind.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

20. Are the plant’s propagules frequently dispersed via contaminated seed (agriculture or wildflower packets), equipment, vehicles, boats or clothing/shoes?

Yes or No:

Points:

Confidence Level:

High

Answer / Justification:

Wind appears to be the main form of dispersal.

Reference(s):

[Anonymous] (2007). CABI Invasive Species Compendium.

Evaluation Notes

USDA: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=15530

Jepson: http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=25260

GBIF: http://www.gbif.org/species/3176313