Pacific Island Ecosystems at Risk (PIER)


Adansonia digitata


RISK ASSESSMENT RESULTS: Low risk, score: -6


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.

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

Adansonia digitata (Baobab, upside down tree, dead rat 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

n

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

n

3.02

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

n=0

n

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

n

3.05

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

n=0

n

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

n

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

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

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

n

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

6.05

Requires specialist pollinators

y=-1, n=0

y

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

8

7.01

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

y=1, n=-1

n

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

n

7.05

Propagules water dispersed

y=1, n=-1

n

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

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

8.02

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

y=1, n=-1

y

8.03

Well controlled by herbicides

y=-1, n=1

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

Total score:

-6

Supporting data:

Source

Notes

1.01

No evidence

1.02

No evidence of naturalization

1.03

No evidence

2.01

Country of Origin: Trop. Africa

http://florawww.eeb.uconn.edu/acc_num/199200321.html

2.02

Native range and regions where it is planted are well known.

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

2.03

(1) Climate descriptors
- Altitude range: 200 - 1300 m
- Mean annual rainfall: 90 - 1500 mm
- Rainfall regime: summer; winter
- Dry season duration: 4 - 10 months
- Mean annual temperature: 19 - 23ºC
- Mean maximum temperature of hottest month: 27 - 32ºC
- Mean minimum temperature of coldest month: 4 - 9ºC
- Absolute minimum temperature: > -10ºC
(2) Hardiness range 10A - 11. (3)Prefers arid areas and well-drained sandy sites between 450 and 600 m above sea level, with a rainfall of 300 to 500 mm per year (Palmer and Pitman 1972). (4)found in the savannas of African and India, mostly around the equator. (5)Habitat = dry coastal regions and open savanna forest of Africa [Savanna environment]

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.hortpix.com/pc163.htm (3)http://www.fao.org/docrep/X5327e/x5327e0g.htm (4)http://www.blueplanetbiomes.org/baobab.htm (5)Irvine, F.R. 1961. Woody plants of Ghana. Oxford University Press

2.04

Country of Origin: Trop. Africa

http://florawww.eeb.uconn.edu/acc_num/199200321.html

2.05

Introduced to several countries.

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

3.01

No evidence of naturalization

3.02

No evidence

3.03

No evidence

3.04

No evidence

3.05

No evidence

4.01

No evidence

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

4.02

No evidence

4.03

No evidence

4.04

Young trees are rarely found. Reasons may be due to the intensive browsing of young plants by livestock and the excessive use of leaves for food by people (don Maydell 1986). Elephants find the whole tree palatable up to 3 years of age.

http://www.fao.org/docrep/X5327e/x5327e0g.htm

4.05

The leaves, flowers, fruits and the bark make good fodder.

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

4.06

(1) 'Baobabs are alternative, although insignificant, hosts of cotton and cocoa pests.' Pests recorded
Insect pests:
Kerria fici
Parasitic plants:
Loranthus mechowii
(2)Susceptible to:
Cacao swollen shoot badnavirus [see (4)]
Cacao yellow mosaic tymovirus
Cassava brown streak-associated (?) carlavirus
Okra mosaic tymovirus
(3)The following pathogens: Bipolaris sp., Cercospora sp., Leveillula taurica, Peltula corticola, were found to be associated with A. digitata.
(4)Theobroma cacao - interveinal chlorosis, swollen stems and roots caused by many strains, a few cause root swelling only, and some cause no symptoms.
(5) Susceptible host range of Cacao yellow mosaic virus include: Susceptible host species
Adansonia digitata
Beta vulgaris
Catharanthus roseus
Ceiba pentandra
Chenopodium amaranticolor
Chenopodium quinoa
Cucumis melo
Cucurbita pepo
Nicandra physalodes
Nicotiana clevelandii
Nicotiana tabacum
Tetragonia tetragonioides
Theobroma cacao
Vigna unguiculata [HU

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://image.fs.uidaho.edu/vide/famly025.htm (3)http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm (4)http://image.fs.uidaho.edu/vide/descr129.htm (5)http://image.fs.uidaho.edu/vide/descr130.htm

4.07

No evidence

4.08

(1) the species occurs in savannah habitats and is leafless for about nine months of the year. (2) 'The trunk of a baobab stores water, and its size may vary from season to season, as it uses water or stores it.'
(3)'Adaptation to dry climate …' [a large single trunked tree]

(1)http://www.blueplanetbiomes.org/baobab.htm (2)http://www.icogitate.com/~tree/baobab.w31.htm (3)Neal, M. 191965. In Gardens of Hawaii. Bishop museum press. Honolulu.

4.09

(1)Light Requirements: Strongly demanding. (2)Full sun.

(1)http://www.fao.org/docrep/X5327e/x5327e0g.htm (2)http://www.succulents.co.za/swollen/baobab/adansonia_digitata.html

4.1

(1)There are no particular soil requirements, but it does appear to fare well on calcareous soils. (2) Soil range: Sand to Sandy Loam and pH range: 6.5 to 07 (3)Prefers sandy topsoil over loams, but can tolerate poorly drained heavily-textured soils. Does not occur on deep sands. Tolerates both acid and calcareous soils (FAO 1988).

(1)http://edcsnw3.cr.usgs.gov/senegal/veg4.html (2)http://www.neoflora.com/cgi-bin/plant_profile.cgi?plant_sid=500234 (3)http://www.fao.org/docrep/X5327e/x5327e0g.htm

4.11

Probably not - not a vine.

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

4.12

Found as isolated trees only

http://www.fao.org/docrep/X5327e/x5327e0g.htm

5.01

A medium height deciduous tree with an enormous trunk in Bombacaceae family.

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

5.02

5.03

5.04

6.01

'…and in Africa …Flowers six inches in diameter hang by long, thick stems, have five white ….'

6.02

'Trees germinate easily from seed and …'

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

6.03

Don’t know.

6.04

Don’t know.

6.05

(1)This tree has beautiful creamy white flowers that hang down and are pollinated by bats. (2)(2)The flowers emit a scent that attracts the bats. The scent is described as resembling carrion (i.e. a sour smell). Bats swoop down on the flowers to seek the nectar secreted on the inner basal part of the sepals from secretory hairs. Visits are for seconds only and bat claws cling to and damage both corolla and staminal tube of the flowers. Bats have also been thought to eat some pollen (Wickens, 1982).Suggestions that wind pollination could occur (Jaeger, 1945; Wickens, 1982) or that ant pollination is possible (Humphries, 1982) are discounted by Baum (1995 a), although the suggestion that bush babies (Otolemur crussicaudatus and Galago senegalensis), known to feed on the flowers, play a pollinating role (Coe and Isaac, 1965) is not discounted; nevertheless they probably only play a minor role. The sour scent of the flowers also attracts certain flies and nocturnal moths as well as several species of bollworms th

(1)http://www.tfts.org/adansonia_digitata.htm (2)http://www.baobabfruitco.com/PDF/MonographySotonLight.pdf

6.06

(1)Propagation by seed. (2)Attempts to propagate vegetatively are reported to have failed

(1)http://www.desert-tropicals.com/Plants/Bombacaceae/Adansonia_digitata.html (2)http://www.fao.org/docrep/X5327e/x5327e0g.htm

6.07

Fruit is produced from 8 to 23 years onward (FAO 1988).

http://www.fao.org/docrep/X5327e/x5327e0g.htm

7.01

No evidence that the seeds have any means of attachment. No evidence that the pulp surrounding the seeds is sticky.

7.02

'The fruit and leaves are edible and it is planted as an ornamental and shade tree.'

http://www.ecoport.org/EP.exe$EntPage?ID=2807

7.03

Probably not seeds relatively larger and embedded in a pulp. 'The long oval woolly fruit, to 12 by 4 inches, has given rise to the name 'dead rat tree'. The fruit contains mealy, acid tasting pulp, eaten both by people and cattle. As the pulp contains about 30 seeds, the fruit is sometimes called "judas bad."

Neal, M. 191965. In Gardens of Hawaii. Bishop museum press. Honolulu.

7.04

Probably not - the seeds are embedded in a fleshy pulp.

http://www.icogitate.com/~tree/baobab.w31.htm

7.05

Probably not - the species is adapted to dry habitat.

7.06

No evidence

7.07

Seeds embedded in a pulp but no evidence that the pulp is sticky.

7.08

No evidence [hard seeds embedded in pulp and consumed by large ungulates; assumed to survive ingestion]

8.01

(1) 'The long oval woolly fruit, to 12 by 4 inches, has given rise to the name 'dead rat tree'. The fruit contains mealy, acid tasting pulp, eaten both by people and cattle. As the pulp contains about 30 seeds, the fruit is sometimes called "judas bad." (2)Each pod contains about 100 seeds with a thick, hard coat.

(1)Neal, M. 191965. In Gardens of Hawaii. Bishop museum press. Honolulu. (2)http://www.fao.org/docrep/X5327e/x5327e0g.htm

8.02

(1)Dormancy in seeds of Adansonia digitata (L.) can be attributed partly to the testa and partly to the pulp. (2)The only effective pretreatment is to crack the seed coat;Other recommended methods are to immerse seed in boiling water, remove immediately and let cool, or boil in water for 5 to 7 minutes; Seeds apparently keep their viability for years if stored in a cool dry place (Palmer and Pitman 1972).

(1)ESENOWO-G-J. 1991. STUDIES ON GERMINATION OF ADANSONIA-DIGITATA SEEDS. Journal-of-Agricultural-Science. 117 (1): 81-84. (2)http://www.fao.org/docrep/X5327e/x5327e0g.htm

8.03

No evidence of the species being controlled for.

8.04

(1)'Ability to regenerate rapidly; suited for coppicing; suited for pollarding.' (2)fire resistant.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.fao.org/docrep/X5327e/x5327e0g.htm

8.05

Don’t know.


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