Pacific Island Ecosystems at Risk (PIER)


Santalum album


RISK ASSESSMENT RESULTS: Low risk, score: -3


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment
  Santalum album (Indian sandalwood) Santalaceae.  Synonyms:  Amaryllis candida Lindl.; Atamosco candida (Lindl.) Small Answer Score
1.01 Is the species highly domesticated? y=-3, n=0 n 0
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 y 1
2.04 Native or naturalized in regions with tropical or subtropical climates y=1, n=0 y 1
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 -2
3.02 Garden/amenity/disturbance weed                              y = 1*multiplier (see Append 2) n=0 n 0
3.03 Agricultural/forestry/horticultural weed                         y = 2*multiplier (see Append 2) n=0 n 0
3.04 Environmental weed                                                     y = 2*multiplier (see Append 2) n=0 n 0
3.05 Congeneric weed                                                          y = 1*multiplier (see Append 2) n=0 n 0
4.01 Produces spines, thorns or burrs y=1, n=0 n 0
4.02 Allelopathic y=1, n=0 n 0
4.03 Parasitic y=1, n=0 y 1
4.04 Unpalatable to grazing animals y=1, n=-1 n -1
4.05 Toxic to animals y=1, n=0 n 0
4.06 Host for recognized pests and pathogens y=1, n=0 n 0
4.07 Causes allergies or is otherwise toxic to humans y=1, n=0 n 0
4.08 Creates a fire hazard in natural ecosystems y=1, n=0    
4.09 Is a shade tolerant plant at some stage of its life cycle y=1, n=0 y 1
4.1 Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) y=1, n=0 y 1
4.11 Climbing or smothering growth habit y=1, n=0 n 0
4.12 Forms dense thickets y=1, n=0 n 0
5.01 Aquatic y=5, n=0 n 0
5.02 Grass y=1, n=0 n 0
5.03 Nitrogen fixing woody plant y=1, n=0 n 0
5.04 Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) y=1, n=0 n 0
6.01 Evidence of substantial reproductive failure in native habitat y=1, n=0 n 0
6.02 Produces viable seed. y=1, n=-1 y 1
6.03 Hybridizes naturally y=1, n=-1 n -1
6.04 Self-compatible or apomictic y=1, n=-1 n -1
6.05 Requires specialist pollinators y=-1, n=0 y -1
6.06 Reproduction by vegetative fragmentation y=1, n=-1 y 1
6.07 Minimum generative time (years)                 1 year = 1, 2 or 3 years = 0, 4+ years = -1 See left 2 0
7.01 Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) y=1, n=-1 n -1
7.02 Propagules dispersed intentionally by people y=1, n=-1 y 1
7.03 Propagules likely to disperse as a produce contaminant y=1, n=-1 n -1
7.04 Propagules adapted to wind dispersal y=1, n=-1 n -1
7.05 Propagules water dispersed y=1, n=-1 n -1
7.06 Propagules bird dispersed y=1, n=-1 y 1
7.07 Propagules dispersed by other animals (externally) y=1, n=-1 n -1
7.08 Propagules survive passage through the gut y=1, n=-1 y 1
8.01 Prolific seed production (>1000/m2) y=1, n=-1 n -1
8.02 Evidence that a persistent propagule bank is formed (>1 yr) y=1, n=-1    
8.03 Well controlled by herbicides y=-1, n=1    
8.04 Tolerates, or benefits from, mutilation, cultivation, or fire y=1, n=-1 n -1
8.05 Effective natural enemies present locally (e.g. introduced biocontrol agents) y=-1, n=1    
  Total score:     -3

Supporting data:

  Notes Source
1.01 Although cultivated in India, Indonesia and elsewhere, no evidence that the cultivated speceis are different from the wild. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
1.02 No evidence of naturalization in the introduced range.  
1.03 No evidence  
2.01 The natural distribution of S. album is in the tropical belt of the Indian peninsula, up to an elevation of 1200 m (Rai, 1990), in the highland regions of eastern Indonesia, primarily on the islands of Nusa Tenggara Timur, up to an elevation of 2000 m (Harisetijono and Suriamihardja, 1993), and the coastal areas of northern Australia, near Darwin (Barrett and Fox, 1995). S. album is considered indigenous along the southern islands of the Indonesian archipelago to eastern Java (Harisetijono and Suriamihardja, 1993). The origin of S. album is disputed, and it has been hypothesized that S. album was introduced to India from West Timor (Brand, 1994). However, references to sandalwood utilisation from natural stands in India can be traced back to 2300 years ago (Srinivasan et al., 1992).' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
2.02    
2.03 (1)Altitude range: 0 - 2000 m
Mean annual rainfall: 400 - 3000 mm
Rainfall regime: summer
Dry season duration: 6 - 7 months
Mean annual temperature: 19 - 32ºC
Mean maximum temperature of hottest month: 21 - 37ºC
Mean minimum temperature of coldest month: 13 - 25ºC
Absolute minimum temperature: 1 - 4ºC  (2) 'Hardiness: USDA Zone 10a: to -1.1°C (30° F).
CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
2.04 The natural distribution of S. album is in the tropical belt of the Indian peninsula, up to an elevation of 1200 m (Rai, 1990), in the highland regions of eastern Indonesia, primarily on the islands of Nusa Tenggara Timur, up to an elevation of 2000 m (Harisetijono and Suriamihardja, 1993), and the coastal areas of northern Australia, near Darwin (Barrett and Fox, 1995). S. album is considered indigenous along the southern islands of the Indonesian archipelago to eastern Java (Harisetijono and Suriamihardja, 1993). The origin of S. album is disputed, and it has been hypothesized that S. album was introduced to India from West Timor (Brand, 1994). However, references to sandalwood utilisation from natural stands in India can be traced back to 2300 years ago (Srinivasan et al., 1992).' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
2.05 Experimental introductions have been made in China (Li and Yu, 1984), Fiji (Bulai, 1995), New Caledonia (Chauvin, 1988), Hawaii (Merlin and VanRavensway, 1990), Tonga (Kaufusi, 1995), Papua New Guinea (Paul, 1990), Nepal (Neil, 1990), Sri Lanka (Tennakoon, personal communication), East Indonesia (Harisetijono and Suriamihardja, 1993) and North Queensland, Australia (Keenan, personal communication). Commercial irrigated plantations are currently being established near Kununurra, northern Western Australia (Radomiljac et al., 1998a).' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
3.01 No evidence of naturalization in the introduced range. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
3.02 No evidence  
3.03 No evidence  
3.04 No evidence  
3.05 No evidence  
4.01 No evidence of such structures. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.02 No evidence  
4.03  ' A wide range of plant species is parasitized by S. album. Under natural conditions S. album preferentially parasitizes nitrogen-fixing species (Rai, 1990). Under plantation conditions S. album growth is greater when parasitising leguminous species than non-leguminous species (Radomiljac et al., 1998c).' 'Due to its hemi-parasitic nature S. album grows best in association with, but not dominated by other tree species. Sandalwood requires a host which is neither too vigorous and out competes the tree, nor too weak so that the host is exhausted.'  'The long term host, which must persist as final host for the entire rotation length (25-30 years), is planted up to four metres from the S. album and pot host combination. This is to avoid obstruction of the growth of the S. album as both S. album and long term hosts have large crowns. An intermediate host is planted between the S. album and long term host seedling. The intermediate host is parasitized for about 4-5 years, until it dies (Radomiljac et al., 1998a). Ideal intermediate hosts are fast-growing, short lived leguminous trees. Once parasitism is initiated S. album remains highly heterotrophic and this sequence of hosts is required to maintain high plantation productivity.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.04 Young trees are sensitive to fire (Singh, 1995) and grazing animals. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.05 No evidence  
4.06 (1)The following fungi species were listed to be associated with Santalum album: Ascochyta santali: India - 6558
Asterina congesta: India - 7983 , 37308
Capnodiastrum santali: India - 6558
Cladosporium herbarum: India - 5834
Colletotrichum gloeosporioides: China - 36727 ; India - 5834 , 6558
Fusicoccum indicum: India - 5834 , 6558
Gloeosporium sp.: India - 6558
Oidium santalacearum: India - 36795
Oidium sp.: India - 7190
Phytophthora arecae: India - 30294
Phytophthora palmivora: India - 7983
Phytophthora palmivora var. palmivora: India - 30294
Sphaceloma santali: India - 6558 , 7983
(2)No evidence that the above are recognized pests that are relatively specific in their host range].
(1)http://nt.ars-grin.gov/fungaldatabases/index.cfm  (2)http://www.aphis.usda.gov/cgi-bin/htsearch?config=htdig&restrict=&exclude=&words=Asterina+congesta&x=15&y=9
4.07 No evidence  
4.08 An evergreen tree found in mostly in dry deciduous and scrub forests in the native range. [Not sufficient evidence to determine if it is a fire hazard] http://www.worldagroforestrycentre.org/sea/Products/
AFDbases/AF/asp/SpeciesInfo.asp?SpID=1481
4.09  'It grows well in early stages under partial shade but at the middle and later stages shows intolerance to heavy overhead shade.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.1  'Site specificity of S. album is highly variable (Jain, 1968), and it is capable of growing on a range of soil types from laterite, loam, sand, clay and black cotton soils. The most common soil type in India is the red ferruginous loam, with underlying gneiss (Luna, 1996). The red ferruginous loam nutrient status is poor (Rangaswamy et al., 1986a). It is able to tolerate soils with a pH up to 9.0 but is unable to tolerate waterlogged sites. ' Soil types: alfisols; alkaline soils; vertisols; clay soils; granite soils; red soils; sandy soils CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.11  'A tree to 15-18 m in height, typically with a straight stem and a high bushy crown when grown in dense shade. ' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
4.12 No evidence  
5.01 A tree 15 to 18 m in height. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
5.02    
5.03    
5.04    
6.01  'Flowering and fruiting seasons vary depending on locality. In India flowering begins in May (end of the dry season in India) with fruit maturity commencing in September (end of the wet season) (Srimathi and Nagaveni, 1995). A second flowering commences in November with fruit maturity commencing in February. Most trees usually flower and fruit twice a year, however some have been observed to flower once a year and others throughout the year.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
6.02  'Seed germination has been extensively studied.' 'In India direct sowing seeds under potential hosts plants is commonly practised.'  CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
6.03 The possibility of producing interspecific and intraspecific hybrids of Santalum album and S. spicatum was investigated. A study of the reproductive biology of the species showed that both S. album and S. spicatum are obligate out-crossing species, with pre-and post-fertilization barriers preventing self pollination and interspecific pollination. Initial fruit set was low with 70-100% fruit abscission. Reasons for failure of fruit set included lack of fertilization, lack of embryo sacs and failure of endosperm development. An in vitro culture technique was developed which could induce embryogenesis and thus 'rescue' embryos of intraspecific crosses at the age of 3.5-6 months, but not from putative interspecific hybrid fruit, which abscised at the age of 1-3 months. Putrescine spray increased fruit set and delayed fruit abscission for both intra- and interspecific crosses. However, only a few putative hybrid fruits were retained until 4 months after pollination; they were not harvested for ovary culture, but allowed to develop to maturity. These mature putative hybrid seeds did not germinate, but their endosperms were confirmed to be hybrid by RAPD analysis.' [No evidence of hybridization under natural conditions]. Interspecific hybridisation between Santalum album and S. spicatum . By: McComb, J. A.;  ACIAR Proceedings Series (84), 1998, p.36-41 (Conference paper) (Journal article)
6.04  (1)'Although the flower structure is designed for self-pollination S. album is a predominantly outbreeding species.'  (2)'The possibility of producing interspecific and intraspecific hybrids of Santalum album and S. spicatum was investigated. A study of the reproductive biology of the species showed that both S. album and S. spicatum are obligate out-crossing species, with pre-and post-fertilization barriers preventing self pollination and interspecific pollination. Initial fruit set was low with 70-100% fruit abscission. Reasons for failure of fruit set included lack of fertilization, lack of embryo sacs and failure of endosperm development. An in vitro culture technique was developed which could induce embryogenesis and thus 'rescue' embryos of intraspecific crosses at the age of 3.5-6 months, but not from putative interspecific hybrid fruit, which abscised at the age of 1-3 months. Putrescine spray increased fruit set and delayed fruit abscission for both intra- and interspecific crosses. However, only a few putative hybrid fruits were retained until 4 months after pollination; they were not harvested for ovary culture, but allowed to develop to maturity. These mature putative hybrid seeds did not germinate, but their endosperms were confirmed to be hybrid by RAPD analysis.' (1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)Interspecific hybridisation between Santalum album and S. spicatum . By: McComb, J. A.;  ACIAR Proceedings Series (84), 1998, p.36-41 (Conference paper) (Journal article).
6.05  'Pollinating agents are bees, butterflies and beetles.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
6.06 Ability to sucker. 'Natural regeneration can be profuse, through both seed germination and root-suckers …' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
6.07 Fruiting begins around 2 to 3 years of age. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.01 No evidence that the propagules have means of attachment.  
7.02 Sandalwood is the highly valued aromatic heartwood from most species of the Santalum genus. Sandalwood has significant cultural, medicinal and commercial importance in Asian, Middle East and Pacific Island countries.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.03 Probably not - relatively large seeds - 'Drupe globose, the size of a small cherry, dark red, purple to black when ripe, single-seeded. The drupe is 7 to 8 mm in diameter.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.04 Probably not - No evidence that the seeds are adapted for wind dispersal. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.05 Probably not - relatively large seeds - 'Drupe globose, the size of a small cherry, dark red, purple to black when ripe, single-seeded. The drupe is 7 to 8 mm in diameter.' CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.06 Natural regeneration is via bird dispersal of seeds, and root suckers. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.07 Probably not - no evidence that the propagules have any means of attachment. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
7.08  'Drupe globose, the size of a small cherry, dark red, purple to black when ripe, single-seeded (Doran and Turnbull, 1997). ... The drupe is 7 to 8 mm in diameter. The mesocarp is creamy yellow, endocarp more or less spherical, up to about 6 to 8 mm diameter and smooth. The kernel is firm and white.' [Probably yes as the fruit is a small fleshy drupe]. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
8.01  'Drupe globose, the size of a small cherry, dark red, purple to black when ripe, single-seeded (Doran and Turnbull, 1997). ... The drupe is 7 to 8 mm in diameter. The mesocarp is creamy yellow, endocarp more or less spherical, up to about 6 to 8 mm diameter and smooth. The kernel is firm and white.' [Probably not - relatively large seeds]. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
8.02  Seed storage orthodox. [No evidence of seed viability under natural conditions]. CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
8.03 No evidence that the species is being controlled for.  
8.04  'S. album has good coppicing ability at an early age, however this capacity decreases with increasing age. Young trees are sensitive to fire (Singh, 1995) and grazing animals (Doran and Turnbull, 1997). CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.
8.05 Don’t know.  

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