African olive (Olea europaea ssp. africana)

Present distribution

Scientific name:	Olea europaea ssp. africana Mill.
Common name(s):	African olive, Wild olive

This weed is not known to be naturalised in Victoria

Habitat:

Present in forest and woodland from coastal to montane, including riverine (Muyt 2001 and Tesfaye, Teketay & Fetene 2002). Can invade heath if fire is suppressed until able to reach maturity between 4 and 12 years (Manders & Richardson 1992 and von Richter, Little & Benson. 2005). Constant grazing can prevent establishment in grassland, however under intermittent the species can establish (von Richter, Little & Benson. 2005).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Forest private plantation; forest public plantation; horticulture;

Broad vegetation types
Coastal scrubs and grassland; coastal grassy woodland; heathy woodland; lowland forest; heath; box ironbark forest; inland slopes woodland; sedge rich woodland; dry foothills forest; moist foothills forest; montane dry woodland; montane moist forest; sub-alpine woodland; grassland; plains grassy woodland; valley grassy forest; herb-rich woodland; sub-alpine grassy woodland; montane grassy woodland; riverine grassy woodland; riparian forest; rainshadow woodland; mallee; mallee heath; boinka-raak; mallee woodland; wimmera / mallee woodland

Colours indicate possibility of Olea europaea ssp. africana infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

map showing the potential distribution of the african olive

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Can form dense clumps and invade riverine environments ( Muyt 2001 and vonRichter, Little & Benson 2005)	mh	mh
2. Reduce tourism?	No reported cases of this, however being a shrub it would be obvious.	m	l
3. Injurious to people?	No reports of this.	l	m
4. Damage to cultural sites?	May have some visual impact, being able to form dense clumps (vonRichter, Little & Benson 2005).	ml	m
Abiotic
5. Impact flow?	Terrestrial species with only minor tolerance of waterlogging (Morettini 1968).	l	mh
6. Impact water quality?	Terrestrial species.	l	mh
7. Increase soil erosion?	No reports of use for erosion control, is a densely growing shrub/tree (vonRichter, Little & Benson 2005). Would have some soil holding capacity.	ml	m
8. Reduce biomass?	Can from dense clumps of vegetation in woodland and grassland (vonRichter, Little & Benson 2005). This would be a biomass increase.	l	mh
9. Change fire regime?	When invading an area requires fire at intervals longer than it takes to grow to maturity which can vary between 4 and 12 years (Manders & Richardson 1992 and vonRichter, Little & Benson 2005). Mature plants suppress undergrowth therefore can alter fuel loads decreasing ground fuel and increasing raised fuel. Therefore has some effect of the fire regime while also potentially requiring an outside influence to suppress fire for a time so it can invade areas where it’s presence would have the most change (Manders & Richardson 1992).	m	m
Community Habitat
10. Impact on composition (a) high value EVC	EVC= Plains Grassy Woodland (E); CMA= North Central; Bioreg= Goldfields; VH CLIMATE potential. Can become dominant species within shrub layer (Manders & Richardson 1992).	mh	h
(b) medium value EVC	EVC= Box Ironbark Forest (D); CMA= North Central; Bioreg= Goldfields; VH CLIMATE potential. Can become dominant species within shrub layer (Manders & Richardson 1992).	mh	h
(c) low value EVC	EVC= Heathy Dry Forest (LC); CMA= North Central; Bioreg= Goldfields; VH CLIMATE potential. Can become dominant species within shrub layer (Manders & Richardson 1992).	mh	mh
11. Impact on structure?	Often creates a middle stratum or increases its density, altering ground flora through suppression and shading (Manders & Richardson 1992). Can also prevent the regeneration of overstory species (vonRichter, Little & Benson 2005).	mh	h
12. Effect on threatened flora?	Capable of suppressing and shading out ground flora (vonRichter, Little & Benson 2005).	mh	m
Fauna
13. Effect on threatened fauna?	Can significantly alter habitat (vonRichter, Little & Benson 2005).	mh	m
14. Effect on non-threatened fauna?	Alters habitat, often creating a dense middle stratum (vonRichter, Little & Benson 2005). Therefore may change the suite of species inhabiting an area.	m	m
15. Benefits fauna?	Creating a dense middle stratum and providing a fruit crop rich in fats can be significant for many small bird and mammal species. Species reported eating the fruit and dispersing the seed include emu, currawong, wombat and silvereye (Spennemann & Allen 2000).	ml	h
16. Injurious to fauna?	None reported.	l	m
Pest Animal
17. Food source to pests?	Fruit eaten by foxes, rabbits, pigs, goats and many introduced bird species (Spennemann & Allen 2000). Foxes reported dispersing between 1 and 6 seeds at a time (Spennemann & Allen 2000).	h	mh
18. Provides harbor?	Evidence of this not reported, however it is a densely clumping species.	m	l
Agriculture
19. Impact yield?	No evidence of this.	l	m
20. Impact quality?	No evidence of this.	l	m
21. Affect land value?	No evidence of this.	l	m
22. Change land use?	No evidence of this.	l	m
23. Increase harvest costs?	No evidence of this. However O.e.africana can harbour pests and diseases of O.e.europaea steps would need to be taken to negate this impact.	m	l
24. Disease host/vector?	Within the same species as O.e.europaea and therefore could harbour pests and diseases that inflict it however this is not reported. At the very least could increase bird populations surrounding olive groves increasing fruit predation.	m	l

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Predominantly an autumn germinator (Spennemann & Allen 2000).	mh	h
2. Establishment requirements?	Known to shade out undergrowth except its own seedlings which can persist until there is a break in the canopy (vonRichter, Little & Benson 2005). Forming what has been termed seedling banks as opposed to seed banks (Teketay & Granstrom 1997). Therefore seedlings can establish under a canopy that suppresses the majority of other growth and then waits for space in the canopy to open up.	h	mh
3. How much disturbance is required?	Can establish in fynbos (Heathland) however persistence requires fire to be suppressed until some individual can reach maturity (Manders & Richardson 1992)	h	h
Growth/Competitive
4. Life form?	Shrub to medium sized tree (other) (Spennemann & Allen 2000).	l	h
5. Allelopathic properties?	No specific allelopathic effect described, however mature trees have been described as being able to suppress the growth of other species, while allowing its own seedlings to establish (Spennemann & Allen 2000).	m	l
6. Tolerates herb pressure?	Seedlings can be removed by constant grazing, mature trees will aggressively coppice (vonRichter, Little & Benson 2005).	mh	mh
7. Normal growth rate?	Seedlings have been described as having a moderate growth through winter and can grow to maturity in 4 years (Spennemann & Allen 2000). The strategy of establishing seedling banks allows them a head start when favourable conditions present themselves (Teketay & Granstrom 1997). It is a competitive species unkown if growth rate will exceed that of most other species.	mh	mh
8. Stress tolerance to frost, drought, w/logg, sal. etc?	Fire will kill plants with a stem diameter of less than 20 mm, more mature trees will regrow/resprout (vonRichter, Little & Benson 2005) Can survive through periods of low rainfall, however this can effect fruiting capacity (Spennemann & Allen 2000). While there is reported to be variation between cultivars of O.e.europaea and O.e.africana is recognised as a different subspecies, O.e.africana is still the same species as O.e.europaea and therefore for our purposes be similar in tolerance. Damage to O.e.europaea can occur at temperatures of -10C and below (Bartolozzi & Fontanazza 1999). O.e.europaea is described as being moderately salt tolerant (Chartzoulakis 2005). O.e.europaea trees will recover after being inundated for a period of 36 days if the normal drainage returns after this. Individuals can show higher tolerance including recovering by producing suckers after 100 days of inundation (Morettini 1968).	h	mh
Reproduction
9. Reproductive system	Produces a single seeded dupe and is capable of vegetative spread however vegetative spread is reportably very slow (Spennemann & Allen 2000).	h	h
10. Number of propagules produced?	The European variety is grown for its fruit crop, and untended trees produce larger crops with smaller dupes (Spennemann & Allen 2000). Therefore wild olive trees are capable of high fruit yields.	h	mh
11. Propagule longevity?	Viable after four years, unknown after that. However has a life strategy of forming seedling banks rather than seed banks (Teketay & Granstrom 1997)	l	mh
12. Reproductive period?	In the wild life expectancy is believed to be between 40 and 50 years (Spennemann & Allen 2000).	h	h
13. Time to reproductive maturity?	In higher rainfall areas, or under irrigation can set fruit after 4-5 years otherwise can take 10-12 years (Spennemann & Allen 2000).	ml	h
Dispersal
14. Number of mechanisms?	Fruit eaten by birds including emus and highly mobile animals including foxes (Spennemann & Allen 2000).	h	h
15. How far do they disperse?	Individual emus may disperse in excess of 50 seeds at a time more than 50 km. Individual foxes may disperse up to 6 seeds at a time 5 km (Spennemann & Allen 2000).	h	h

References

Bartolozzi. F. & Fontanazza. G. (1999) Assessment of frost tolerance in olive (Olea europaea L.). Scientia Horticulturae. 81: 309-319.

Chartzoulakis. K.S. (2005) Salinity and olive: Growth, salt tolerance, photosynthesis and yield. Agricultural Water Management. 78: 108-121.

Manders. P.T. & Richardson. D.M. (1992) Colonization of Cape fynbos communities by forest species. Forest Ecology and Management. 48: 277-293

Mathooko. J.M & Kariuki. S.T. (2000) Disturbances and species distribution of the riparian vegetation of a Rift Valley stream. African Journal of Ecology. 38: 123-129.

Morettini. A. (1968) Studies on the resistance of olive trees to waterlogging. Italian agriculture. 105: 791-801.

Muyt. A. (2001) Bush invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South-East
Australia. R.G. and F.J. Richardson. Meredith.

von Richter. L., Little. D. & Benson. D. (2005) Effects of low intensity fire on the resprouting of the weed African Olive (Oliea europaea subsp. Cuspidata) in Cumberland Plain Woodland, western Sydney. Ecological Management & Restoration. 6: 230-232.

Spennemann. D.H.R. & Allen. L.R. (2000) Feral olives (Oliea europaea) as future woody weeds in Australia: a review. Australian Journal of
Experimental Agriculture. 40: 889-901.

Tesfaye. G., Teketay. D. & Fetene. M. (2002) Regeneration of fourteen tree species in Harenna forest, southeastern Ethiopia. Flora. 197: 461-474.

Teketay. D. & Granstrom. A. (1997) Seed viability of Afromontane tree species in forest soils. Journal of Tropical Ecology. 13: 81-95.

Global present distribution data references

Australian National Herbarium (ANH) 2006, Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, viewed 24 Nov 2006 , http://www.anbg.gov.au/avh/

Global Biodiversity Information Facility (GBIF) 2006, Global biodiversity information facility: Prototype data portal, viewed 23 Nov 2006, http://www.gbif.org/

Mathooko. J.M & Kariuki. S.T. (2000) Disturbances and species distribution of the riparian vegetation of a Rift Valley stream. African Journal of Ecology. 38: 123-129.

Missouri Botanical Gardens (MBG) 2006, w3TROPICOS, Missouri Botanical Gardens Database, viewed 22 Nov 2006, http://mobot.mobot.org/W3T/Search/vast.html

Tesfaye. G., Teketay. D. & Fetene. M. (2002) Regeneration of fourteen tree species in Harenna forest, southeastern Ethiopia. Flora. 197: 461-474

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