Pacific Island Ecosystems at Risk (PIER)


Khaya anthotheca


RISK ASSESSMENT RESULTS: Low risk, score: -1


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment
  Khaya nyasica (East African Mahogany)- Meliaceae Answer Score
1.01 Is the species highly domesticated? n 0
1.02 Has the species become naturalized where grown? y  
1.03 Does the species have weedy races? 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” 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
2.04 Native or naturalized in regions with tropical or subtropical climates y 1
2.05 Does the species have a history of repeated introductions outside its natural range?  y=-2 y  
3.01 Naturalized beyond native range         y = 1*multiplier (see Append 2), n= question 2.05 y 2
3.02 Garden/amenity/disturbance weed                              y = 1*multiplier (see Append 2) n 0
3.03 Agricultural/forestry/horticultural weed                         y = 2*multiplier (see Append 2) n 0
3.04 Environmental weed                                                     y = 2*multiplier (see Append 2) n 0
3.05 Congeneric weed                                                          y = 1*multiplier (see Append 2) n 0
4.01 Produces spines, thorns or burrs n 0
4.02 Allelopathic n 0
4.03 Parasitic n 0
4.04 Unpalatable to grazing animals n -1
4.05 Toxic to animals n 0
4.06 Host for recognized pests and pathogens n 0
4.07 Causes allergies or is otherwise toxic to humans n 0
4.08 Creates a fire hazard in natural ecosystems n 0
4.09 Is a shade tolerant plant at some stage of its life cycle y 1
4.1 Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) y 1
4.11 Climbing or smothering growth habit n 0
4.12 Forms dense thickets n 0
5.01 Aquatic n 0
5.02 Grass n 0
5.03 Nitrogen fixing woody plant n 0
5.04 Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) n 0
6.01 Evidence of substantial reproductive failure in native habitat n 0
6.02 Produces viable seed. y 1
6.03 Hybridizes naturally    
6.04 Self-compatible or apomictic n -1
6.05 Requires specialist pollinators n 0
6.06 Reproduction by vegetative fragmentation n -1
6.07 Minimum generative time (years)                 1 year = 1, 2 or 3 years = 0, 4+ years = -1 2 0
7.01 Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) n -1
7.02 Propagules dispersed intentionally by people y 1
7.03 Propagules likely to disperse as a produce contaminant n -1
7.04 Propagules adapted to wind dispersal y 1
7.05 Propagules water dispersed n -1
7.06 Propagules bird dispersed n -1
7.07 Propagules dispersed by other animals (externally) n -1
7.08 Propagules survive passage through the gut n -1
8.01 Prolific seed production (>1000/m2) n -1
8.02 Evidence that a persistent propagule bank is formed (>1 yr) n -1
8.03 Well controlled by herbicides    
8.04 Tolerates, or benefits from, mutilation, cultivation, or fire y 1
8.05 Effective natural enemies present locally (e.g. introduced biocontrol agents)    
  Total score:   -1

Supporting data:

   Notes Reference
1.01 No evidence  
1.02 Naturalized in Puerto Rico. http://www.fao.org/docrep/006/j1583e/J1583E10.htm
1.03 No evidence  
2.01 (1)Natural populaitions occur in Arica. (2)Khaya nyasica grows in central, eastern and southern Africa, including Malawi, Mozambique, South Africa, Tanzania, Zaire, Zambia and Zimbabwe.  (3)Origin - tropical Africa. (1)Forestry Compendium [Online]. © CAB International, Wallingford, UK, 2005.  (2)http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file  (3)http://www.hear.org/gcw/html/autogend/species/10794.HTM
2.02 (1)Natural populaitions occur in Arica. (2)Khaya nyasica grows in central, eastern and southern Africa, including Malawi, Mozambique, South Africa, Tanzania, Zaire, Zambia and Zimbabwe.  (3)Origin - tropical Africa. (1)Forestry Compendium [Online]. © CAB International, Wallingford, UK, 2005.  (2)http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file  (3)http://www.hear.org/gcw/html/autogend/species/10794.HTM
2.03  'The species grows from near sea level to 1400 m with the optimum elevation lying between 700 and 1000 m'. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
2.04 (1)Natural populaitions occur in Arica. (2)Khaya nyasica grows in central, eastern and southern Africa, including Malawi, Mozambique, South Africa, Tanzania, Zaire, Zambia and Zimbabwe.  (3)Origin - tropical Africa. (1)Forestry Compendium [Online]. © CAB International, Wallingford, UK, 2005.  (2)http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file  (3)http://www.hear.org/gcw/html/autogend/species/10794.HTM
2.05 Plantations of this species were tried in Cuba, Florida, Puerto Rico, and Nicaragua. http://www.fao.org/docrep/006/j1583e/J1583E10.htm
3.01 Naturalized in Puerto Rico. http://www.fao.org/docrep/006/j1583e/J1583E10.htm
3.02 No evidence  
3.03 No evidence  
3.04 No evidence  
3.05 No evidence  
4.01 No evidence of the presence of such structures.  
4.02 No evidence  
4.03 No evidence  
4.04 Browsing animals and rodents can destroy new production and set back development of sapling stands if not controlled.' http://www.worldagroforestry.org/sea/Products/AFDbases/af/asp/SpeciesInfo.asp?SpID=1026
4.05 No evidence  
4.06 It is resistant to termite attack but is very susceptible to short-boxer attack (Hysipyla spp) which causes dieback and multiple leaders. [No evidence of being associated with economic pests]. http://archive.idrc.ca/library/document/074940/chap34_e.html
4.07 Probably not - 'In its native range, bark preparations are said to cure colds and the seed oil is used to fight head lice.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
4.08 Probably not - "This is found along stream banks and moist areas of lower mountains and plateaus." http://archive.idrc.ca/library/document/074940/chap34_e.html
4.09  'To avoid problems with shootborers and sun scorch, this shade-tolerant tree should be planted in small forest clearings or interplanted withh fast-growing speceis.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
4.1  'Suitable soils include clay to sandy loam with a pH from 7 to less than 4. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
4.11 A tall tree. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
4.12 No evidence  
5.01 Khaya nyasica is an evergreen ot semideciduous tree that occasionally attains 60 m height and 4.5 m dbh. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
5.02    
5.03    
5.04    
6.01 In South Africa, the fruits from the previous year’s flowers ripen between March and July and even later. ' http://www.worldagroforestry.org/sea/Products/AFDbases/af/asp/SpeciesInfo.asp?SpID=1026
6.02  'Germination is cryptocotylar and takes place in 1 to 4 weeks with averge germiantion of 30 to 70 percent and sometimes almost 100 percent.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
6.03 The geographical distribution, climatic and soil requirements, growth characteristics and timber quality of K. nyasica and K. senegalensis are described. On good deep soils in the African tropics both species often reach heights of 35 mm and diameters of 0.70-1.20 m, while K. senegalensis will also tolerate dry savanna soils. On deep soils in Cuba growth of both species is excellent; a tree of K. nyasica measured at 38 years old was 35 m high and 1.20 m in diam. K. nyasica is affected in Cuba by a disfiguring bark gall which, however, does not damage the wood; some trees show resistance to this disease. K. senegalensis is unaffected by bark gall. Possibilities of genetic improvement of K. nyasica by using resistant trees and raising K. nyasica X K. senegalensis hybrids are being studied.' [Dont know if it hybridizes naturally].  
6.04 Probably not - unisexual flowers. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
6.05  ' The flowers are known to be insect pollinated.' http://www.worldagroforestry.org/sea/Products/AFDbases/af/asp/SpeciesInfo.asp?SpID=1026
6.06 No evidence of vegetative spread in the wild.  
6.07  'In Puerto Rico, the trees can produce these four or five part, unisexual flowers at 24 years.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
7.01 Probably not - no evidence that the propagules have any means of attachment.  
7.02  'Khaya nyasica is grown as an ornamental and as a shade tree in coffee plantations.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
7.03 Probably not - No evidence that the species grows or is planted near crops fields.  
7.04  'The four or five valved capsule opens from the top to release the pale- to reddish brown narrowly winged seeds, which measure about 2 to 2.5 by 2.5 to 5 cm. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
7.05  'The four or five valved capsule opens from the top to release the pale- to reddish brown narrowly winged seeds, which measure about 2 to 2.5 by 2.5 to 5 cm. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
7.06  'The four or five valved capsule opens from the top to release the pale- to reddish brown narrowly winged seeds, which measure about 2 to 2.5 by 2.5 to 5 cm. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
7.07 No evidence that the propagules have any means of attachment.  
7.08 No evidence of ingestion by animals.  
8.01  'The globe shaped gray-brown fruits are erect, woody, septifragal capsules up to 8 cm in diameter. When the fruits ripen in spring or early summer they release 20 to 60 seeds.' [Probably not - the size of each seeds is relatively large]. http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
8.02  'Because seeds are vialble for less than 3 months and are attacked by insects, they must be stored in sealed containers in a refrigerator or sown fresh.' http://www.rngr.net/Publications/ttsm/Folder.2003-07-11.4726/PDF.2004-03-15.0458/file
8.03 No evidence that the speceis  is being controlled for.  
8.04  'The species was genrally not attacked by H. robusta but has a strong tendency to develop multiple leaders and heavy branching while still young, requiring heavy and frequent pruning.' http://www.aciar.gov.au/web.nsf/att/JFRN-6BN982/$file/pr97chapter1.pdf#search=%22%22khaya%20nyasica%22%20coppice%22
8.05 Don’t know.  

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This page created 23 December 2006