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

Swietenia macrophylla; Honduras mahogany, large-leaf mahogany

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

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

y

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

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

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

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

y

6.04

Self-compatible or apomictic

y=1, n=-1

y

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

12

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

y

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

n

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

n

8.03

Well controlled by herbicides

y=-1, n=1

8.04

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

y=1, n=-1

8.05

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

y=-1, n=1

Total score:

-2

Source

Notes

1.01

no evidence

1.02

http://rathbun.si.edu/botany/pacificislandbiodiversity/hawaiianflora/ManualSupplement2.3.pdf

apparently locally naturalized in Hawaii

1.03

no evidence

2.01

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

Review of natural distribution
The genus Swietenia has a natural distribution from 20°N to 18°S in tropical America. S. macrophylla is the most widely distributed species occurring from the Atlantic regions of south-east Mexico, through Central America (Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Panama), northern South America (Colombia, Venezuela, Ecuador, Peru) and in an arc across the southern Amazon Basin, in Bolivia and Brazil (Lamb, 1966; Styles, 1981).

2.02

2.03

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

The species has a very wide altitude range from near sea-level to 1500 m in Bolivia and Peru (Lamb, 1966). The wide geographical range and the ecological tolerance of S. macrophylla indicate that a number of biotype groups have developed taking advantages of a variety of habitats and changing environmental conditions (Lamb, 1966). Optimum conditions for the species appear to be an average annual rainfall of approximatley 2000-4000 mm which may be uniformly distributed or with a dry season of up to four months, and a mean annual temperature range from 24-28°C (Ehrhart, 1992; Chaplin, 1993; Lamb, 1966).

2.04

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

Review of natural distribution
The genus Swietenia has a natural distribution from 20°N to 18°S in tropical America. S. macrophylla is the most widely distributed species occurring from the Atlantic regions of south-east Mexico, through Central America (Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Panama), northern South America (Colombia, Venezuela, Ecuador, Peru) and in an arc across the southern Amazon Basin, in Bolivia and Brazil (Lamb, 1966; Styles, 1981).

2.05

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

Location of introductions
S. macrophylla has been cultivated throughout the lowland humid and sub-humid tropics. The species has been widely planted in south and south-east Asia, the Pacific Islands, the Caribbean and tropical Africa (Streets, 1962; Evans, 1982, Ehrhart, 1992; Thaman and Whistler, 1996). Substantial areas of plantation have been established in Indonesia, Fiji and parts of Central America.

3.01

http://rathbun.si.edu/botany/pacificislandbiodiversity/hawaiianflora/ManualSupplement2.3.pdf

apparently locally naturalized in Hawaii

3.02

no evidence

3.03

Holm, Geographic Atlas of Weeds

listed as "present" in Honduras (native range), not an economic weed

3.04

(1)www.bangor.ac.uk/~afs101/iwpt/web1-99.doc (2)Zoysa, N. D. de; Gunatilleke, C. V. S.; Gunatilleke, I. A. U. N. 1986. Vegetation studies of a skid-trail planted with mahogany in Sinharaja. Sri Lanka Forester 17:142-156.

(1)listed as "possibly invasive" [source is probably ref. 2] (2)The danger of mahogany suppressing the forest species which are now establishing themselves is discussed in the context of the desire to maintain natural floristic diversity in this reserve; means of controlling mahogany are described. [found at trail edges, near plantations][See also comments by M. Rejmanek 2002 published in Environmental Conservation 29:266 -- not considered invasive in Sri Lanka]

3.05

no evidence

4.01

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

no description of these traits

4.02

no evidence

4.03

no evidence

4.04

http://www.uog.edu/cals/PEOPLE/Pubs/Agrofors/Multspec.pdf

not listed as being used for fodder

4.05

no evidence

4.06

no evidence

4.07

no evidence

4.08

no evidence

4.09

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

S. macrophylla is a light-demanding species (Lamb, 1966), and seedlings do not survive long under the shady conditions of the forest understorey or in felling gaps (Snook and MacLellen, 1996).

4.1

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

Soil and physiography
S. macrophylla grows on a variety of soils which are well drained or at times subject to inundation (Pennington et al., 1981; Snook and MacLellen, 1996). Within its natural range the species is found growing on alluvial soils of considerable fertility, and soils derived from limestone, granite, andesite and other sedimentary, igneous or metamorphic rock formation (Lamb, 1966). It tolerates soils ranging from deep, poorly drained, acid clays of the wooded swamps, to the well drained alkaline soils of the limestone uplands (Lamb, 1966; Chaplin, 1993). While maximum development is attained on deep, fertile, moist, well-drained, neutral to mildly alkaline soils (Lamb, 1966; Ehrhart, 1992). The species may also become successfully established on rather poor soil conditions in Java, Fiji and tropical America.
Descriptors
- Soil texture: medium; heavy
- Soil drainage: free; impeded; seasonally waterlogged
- Soil reaction: acid; neutral; alkaline
- Special soil tolerances:
- Soil t

4.11

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

S. macrophylla is an evergreen tree up to approximately 30-45 m, infrequently attaining a height of 50 m and d.b.h. of 2 m.

4.12

no evidence

5.01

terrestrial

5.02

tree; Meliaceae

5.03

no evidence

5.04

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

S. macrophylla is an evergreen tree up to approximately 30-45 m, infrequently attaining a height of 50 m and d.b.h. of 2 m.

6.01

no evidence

6.02

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

The seed should be stored at 3-7% moisture content at low temperatures (3°C ±2°C). Untreated seed is sown in a germination bed or in pots inside a lightly shaded germination house. Under favourable conditions of moisture supply, temperature, and available oxygen, seed germination starts within 10 days of planting and continues for approximately 20 days.

6.03

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

Interspecific hybridization with S. mahoganii and S. humilis has also added to observed levels of variation in morphological traits and those of economic importance. Hybrid zones between S. macrophylla and S. humilis are thought to occur in native stands in Costa Rica, Guatemala and Mexico (Whitmore and Hinojosa, 1977; Styles, 1981), and such hybrid zones are likely to contain high levels of diversity (Helgason et al., 1996).

6.04

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

Whilst Swietenia are known to be monoecious, with separate male and female flowers, little is known about their incompatibility systems other than that they are generally outbreeding, with the possibility of self-pollination (Styles and Khosla, 1976).

6.05

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

Pollination is by insects, bees and moths (Styles and Khosla, 1976); in case species are grown together hybridization is frequent.

6.06

http://www.pcarrd.dost.gov.ph/division/FERD/MAHOGANY_profile.html

Mahogany is propagated from seeds

6.07

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

" S. macrophylla trees may flower and start to produce seed after 12 years growth. "

7.01

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

no evidence; Seeds are large, chestnut coloured and 7.5-12 cm in length

7.02

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

Location of introductions
S. macrophylla has been cultivated throughout the lowland humid and sub-humid tropics. The species has been widely planted in south and south-east Asia, the Pacific Islands, the Caribbean and tropical Africa (Streets, 1962; Evans, 1982, Ehrhart, 1992; Thaman and Whistler, 1996). Substantial areas of plantation have been established in Indonesia, Fiji and parts of Central America.

7.03

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

no evidence; Seeds are large, chestnut coloured and 7.5-12 cm in length

7.04

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

"The centre of the fruit is a thick, woody 5 angled columella extending to the apex from which the seeds hang pendulous by their wing, leaving conspicuous seed scars after their release."

7.05

no evidence

7.06

no evidence

7.07

no evidence

7.08

no evidence that it is swallowed whole -- a very large seed that could not be swallowed by most animals.

8.01

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

'The fruits are large (12-15 x 6-8 cm)"; "There are usually about 35-45 winged seeds per fruit (Ehrhart, 1992). Seeds are chestnut coloured and 7.5-12 cm in length (Pennington et al., 1981)".[ 22.2 to 28.6 fruits to reach a density larger than 1000 seeds/m2; which is not likely with its large fruits.]

8.02

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.pcarrd.dost.gov.ph/division/FERD/MAHOGANY_profile.html

(1)Mahogany seeds do not retain their viability beyond any rainy season and there is no soil seed bank. (2)Seeds can be stored for 2 - 3 months beyond this germination is zero.

8.03

no evidence

8.04

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

Young mahogany are very sensitive to fire. Mature trees are more fire resistant and control burning may be used to reduce competing vegetation and create conditions favourable for natural reproduction (Lamb, 1966).

8.05

http://www.foresters.org/fiu/2001/22.htm

seeds consumed by rats