Sisal (Agave sisalana)

Present distribution

Scientific name:	Agave sisalana Perrine
Common name(s):	sisal

This weed is not known to be naturalised in Victoria

Habitat:

It is not known from the wild but is thought to have originated from Mexico. Grows in sandy places along roadsides and in hammocks (FNA 2008), calcareous soils on coastal belts (Lock 1962), coastal shrub and grassland (Ewusie, Ghatak 1972), can be an understorey plant (Brown 2002). Its invaded habitats include grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) and inselbergs (Porembski 2000). Rainfall range: 1000-1500 mm per year (Brown 2002).

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:
Forestry; horticulture perennial; pasture dryland

Ecological Vegetation Divisions
Coastal; heathland; grassy/heathy dry forest; lowland forest; foothills forest; forby forest; damp forest; granitic hillslopes; rocky outcrop shrubland; western plains woodland; basalt grassland; alluvial plains grassland; semi-arid woodland; alluvial plains woodland; ironbark/box; chenopod shrubland; chenopod mallee; hummock-grass mallee; lowan mallee; broombush whipstick

Colours indicate possibility of Agave sisalana infesting these areas.

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

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

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Grows to 1.5 m (Lock 1962) and has been reported to form a monoculture (Brown 2002) – likely to have a high nuisance value. People and vehicles access with difficulty	mh	m
2. Reduce tourism?	Grows to 1.5 m (Lock 1962) and has been reported to form a monoculture (Brown 2002). It is invasive in grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) – impact on aesthetics	ml	m
3. Injurious to people?	Leaves lanceolate with margins sometimes with teeth single prickles (FNA 2008) – may cause irritation	ml	m
4. Damage to cultural sites?	Grows to 1.5 m (Lock 1962) and has been reported to form a monoculture (Brown 2002). It is invasive in grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) – moderate visual effect on important natural cultural sites	ml	m
Abiotic
5. Impact flow?	Not stated to grow on or near water (Lock 1962: Brown 2002: Weber 2003) – little or negligible impact on water flow	l	mh
6. Impact water quality?	Not stated to grow on or near water (Lock 1962: Brown 2002: Weber 2003) – no noticeable effect on dissolved oxygen or light levels	l	mh
7. Increase soil erosion?	Although “the topsoil becomes matted with tough fibrous roots” (Lock 1962). Spaan et al (2005) found that soil loss was reduced (compared to the control – bare soil) by 56% in Agave sisalana plots, however for natural vegetation and Andropogan gayanus (perennial grass) the soil loss was reduced by 71% and 93%, respectively. Hence A. sisalana was identified as a “less effective” barrier. It is invasive in grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) – in some environments there may be a moderate probability of large scale soil movements	ml	mh
8. Reduce biomass?	It invades grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) and grows to 1.5 m (Lock 1962) and has been reported to form a monoculture (Brown 2002) – may slightly decrease biomass in forest ecosystems	mh	mh
9. Change fire regime?	Invaded habitats include grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003) and inselbergs (Porembski 2000) – as it would change the vegetation type Agave sisalana is likely to cause a moderate change to both frequency and intensity of fire risk	mh	m
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Plains Grassland (E); CMA = North Central; Bioregion = Victorian Riverina; M CLIMATE potential. “The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Agaves (including A. sisalana) have been found to have a higher invasive potential in sandy soils due increasing clonal production and higher establishment rates than in clay soils (Badano, Pugnaire 2004) – Monoculture within a specific layer	h	h
(b) medium value EVC	EVC = Rocky Outcrop Shrubland (R); CMA = East Gippsland; Bioregion = East Gippsland Lowlands; M CLIMATE potential. “The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Agaves (including A. sisalana) have been found to have a higher invasive potential in sandy soils due increasing clonal production and higher establishment rates than in clay soils (Badano, Pugnaire 2004) – Monoculture within a specific layer	h	h
(c) low value EVC	EVC = Sandstone Ridge Shrubland (LC); CMA = Wimmera; Bioregion = Goldfields; M CLIMATE potential. “The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Agaves (including A. sisalana) have been found to have a higher invasive potential in sandy soils due increasing clonal production and higher establishment rates than in clay soils (Badano, Pugnaire 2004) – Monoculture within a specific layer	h	h
11. Impact on structure?	“The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Agaves (including A. sisalana) have been found to have a higher invasive potential in sandy soils due increasing clonal production and higher establishment rates than in clay soils (Badano, Pugnaire 2004) Has been reported to form a monoculture (Brown 2002).	h	mh
12. Effect on threatened flora?	“The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Has been reported to form a monoculture (Brown 2002) – as it is likely to replace vegetation in areas it involves, A. sisalana is likely to replace threatened flora – however, this is not yet determined.	mh	l
Fauna
13. Effect on threatened fauna?	“The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Has been reported to form a monoculture (Brown 2002) – likely to form a reduction of habitat for threatened fauna – however, this is not yet determined.	mh	l
14. Effect on non-threatened fauna?	“The weedy behaviour is due to vegetative growth, allowing the species to colonise large areas and replace the native vegetation with its rosettes” (Weber 2003). Has been reported to form a monoculture (Brown 2002) – likely to change habitat dramatically, leading to the possible extinction of non-threatened fauna	h	m
15. Benefits fauna?	Although the leaves are unpalatable (Spaan et al 2005) the pollen is the “single most important food source for Pteropus rufus” (Old World fruit bats) which are endemic to Madagascar (Long, Racey 2007) – the pollen is likely to provide some assistance as a food source to desirable species	mh	mh
16. Injurious to fauna?	Not documented to be injurious to fauna (Lock 1962: Weber 2003)	l	mh
Pest Animal
17. Food source to pests?	Although the leaves are unpalatable (Spaan et al 2005) the pollen is the “single most important food source for Pteropus rufus” (Old World fruit bats) which are endemic to Madagascar (Long, Racey 2007) – likely to supply food for one or more minor environmental pest species, such as European bees	ml	m
18. Provides harbor?	A. sisalana colonises large areas (Weber 2003), has been reported to form a monoculture (Brown 2002) and grows to 1.5 m (Lock 1962) – capacity to provide harbor and permanent warrens for foxes and rabbits throughout the year	h	mh
Agriculture
19. Impact yield?	As this is an agricultural plant in many Africa and Central and South America there does not appear to be information on the potential of this plant to be a weed of agriculture itself, however it has been recorded as an agricultural weed in Australia (Randall 2007). It is also known to invade forests and grassland (Weber 2003) and is also unpalatable (Spaan et al 2005). Therefore it may have potential to be a weed of forestry and pasture land however the effect on quantity of produce is unknown	m	l
20. Impact quality?	A. sisalana has been recorded as an agricultural weed in Australia (Randall 2007) and has been identified as an emerging weed of significance to the grazing industry in Australia (Barker et al 2006) – however, to what extent has not been determined	m	l
21. Affect land value?	A. sisalana has been recorded as an agricultural weed in Australia (Randall 2007) and has been identified as an emerging weed of significance to the grazing industry in Australia (Barker et al 2006) – however, to what extent has not been determined	m	l
22. Change land use?	A. sisalana has been recorded as an agricultural weed in Australia (Randall 2007) and has been identified as an emerging weed of significance to the grazing industry in Australia (Barker et al 2006) – however, to what extent has not been determined	m	l
23. Increase harvest costs?	A. sisalana has been recorded as an agricultural weed in Australia (Randall 2007) and has been identified as an emerging weed of significance to the grazing industry in Australia (Barker et al 2006) – however, to what extent has not been determined	m	l
24. Disease host/vector?	Host of Hendersonula toruloidea which affects fig, grapevine, walnut, apple, grapefruit, mulberry, stone fruit, mandarin, organge, poplar, Cavendish banana, yam and potato plants. Although it is not known to occur in Australia (Punithalingam, Waterston 1970) – has the capacity to be a host vector, but this extent is unknown in Australia	m	l

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	“Sucker production is usually greatest on calcareous soils in the coastal belt, whereas it may be inhibited on hard, compacted sandy clays or heavier kinds of soil… During a drought bulbils shrivel up… although dehydrated, they will soon strike root upon being watered after planting… Field sisal will pole sporadically throughout the year.” (Lock 1962) – opportunistic germinator, can set root at any time whenever water is available	h	mh
2. Establishment requirements?	Although Lock (1962) states that it “must grow in full sunlight, otherwise its leaves become flaccid, lack bloom, and develop weak fibres,” it has been found as an understorey plant with Casuarina equisetifolia as the canopy species in Florida (Brown 2002) – can establish under moderate canopy/litter cover	mh	m
3. How much disturbance is required?	Sandy places along roadsides and in hammocks (FNA 2008). Invaded habitats: Grass and heathland, forests, rock outcrops, coastal beaches (Weber 2003). In Madagascar it has “invaded inselbergs” (Porembski 2000) – establishes in relatively intact ecosystems	mh	mh
Growth/Competitive
4. Life form?	“commonly suckering with elongate rhizomes” (FNA 2008)	ml	m
5. Allelopathic properties?	Not said to have allelopathic properties in the literature (Brown 2002: Lock 1962)	l	m
6. Tolerates herb pressure?	“unpalatable species” (Spaan et al 2005) – favoured by heavy grazing pressure as not eaten by animals/insects and not under a biological control program	h	h
7. Normal growth rate?	Produces higher leaf yield when plants are closer together (DAT 1948) – grows better with competition – moderate growth rate that will equal competitive species of the same life form	mh	m
8. Stress tolerance to frost, drought, w/logg, sal. etc?	“It is drought tolerant and withstands waterlogging” (Weber 2003) although Lock (1962) states that it is “extremely sensitive to water-logging” Although a “natural” saline environment causes height reduction, A. sisalana was salinity tolerant to 8000 ppm (El-Bagoury et al 1993) Night temperatures of -5˚C “often cause leaf burn and dieback” (Brown 2002) – susceptible to frost Destroyed after fire (Brown 2002) – susceptible to fire	mh	m
Reproduction
9. Reproductive system	Vegetative, “seeds unknown” (FNA 2008) by bulbils and suckers (Lock 1962)	mh	m
10. Number of propagules produced?	“A plant may produce about twenty suckers during its life” and “a massive sisal pole with many flowering branches will bear from two to three thousand bulbils of various sizes” (Lock 1962)	h	mh
11. Propagule longevity?	Vegetatively reproduces (Lock 1962)	l	mh
12. Reproductive period?	Can live for 20 years and has been reported to form a monoculture (Brown 2002)	h	mh
13. Time to reproductive maturity?	“Normally, suckers do not appear in a field of sisal until it is about one year old, after which they are produced fairly prolifically, especially during the second and third years.” (Lock 1962)	mh	mh
Dispersal
14. Number of mechanisms?	“may be propagated vegetatively by means of suckers… short sections of rhizome, each with a bud, will also develop into plants if grown in a suitable rooting mechanism.” (Lock 1962) – spread by both accidental and deliberate human dispersal	mh	m
15. How far do they disperse?	“may be propagated vegetatively by means of suckers… short sections of rhizome, each with a bud, will also develop into plants if grown in a suitable rooting mechanism.” (Lock 1962) – likely that humans will disperse this greater than one kilometre	h	m

References

Badano EI, Pugnaire FI (2004) Invasion of Agave species (Agavaveae) in south-east Spain: invader demographic parameters and impacts on native species. Diversity and Distributions 10, 493-500

Barker J, Randall R, Grice T (2006) Weeds of the future? Threats to Australia’s grazing industries by garden plants. Meat & Livestock Australia. Available at
http://www.mla.com.au/NR/rdonlyres/075176BC-1E50-4D6D-BD9A-C3EE0091F132/0/WEEDSofSIGNIFNBP35720060720FinalReport.pdf (verified 24 September 2008)

Department of Agriculture Tanganyika (DAT) (1948) Annual Report of Department of Agriculture Tanganyika. Annual Report of Department of Agriculture Tanganyika, 194: 147

El-Bagoury OH, El-Agroudy MH, Shenouda MA (1993) Effect of salinity levels on growth of six plant species. Egyptian Journal of Agronomy 18(1/2), 129-143

Ewusie JY, Ghatak J (1972) Studies on reproduction and cytology of sisal (Agave sisalana Perrine ex Engelm.). Ghana Journal of Science 12(1), 42-50

Flora of North America (FNA) (2008) Agave sisalana FNA Vol. 26 pp. 443-455. Available at http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200028033 (verified 5 September 2008)

Lock GW (1962) Sisal; Twenty-five years sisal research. Tropical Science Series. Longmans.

Long E, Racey PA (2007) An exotic plantation crop as a keystone resource for an endemic megachiropteran, Pteropus rufus, in Madagascar. Journal of Tropical Ecology 23. 397-407

Porembski S (2000) The invasibility of tropical granite outcrops (‘inselbergs’) by exotic weeds. Journal of the Royal Society of Western Australia 83, 131-137. Available at http://www.ecu.edu.au/pa/rswa/content/work/journals/PDF/83(3)/v83(3)porembski.pdf (verified 10 September 2008)

Punithalingam E, Waterston JM (1970) Hendersonula toruloidea. IMI Descriptions of Fungi and Bacteria. CAB International, Wallingford, UK, 28, Sheet 274

Randall RP (2007) The introduced flora of Australia and its weed status. CRC for Weed Management, Adelaide. Available at http://www.weedscrc.org.au/documents/intro_flora_australia.pdf (verified 24 September 2008)

Spaan WP, Sikking AFS, Hoogmoed WB (2005) Vegetation barrier and tillage effects on runoff and sediment in an alley crop system on a Luvisol in Burkina Faso. Soil and Tillage Research 83, 194-203

Weber E (2003) Invasive plant species of the world; a reference guide to environmental weeds. CAB International, Oxon, UK

Global present distribution data references

Australian National Herbarium (ANH) (2008) Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, Available at
http://www.anbg.gov.au/avh/ (verified 19 September 2008).

Global Biodiversity Information Facility (GBIF) (2008) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 19 September 2008).

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