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

Tamarix aphylla; Athel tamarisk

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

y

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

y

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

y

3.05

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

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

y

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

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

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

3

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

y

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

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

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

y

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:

13

Source

Notes

1.01

no evidence

1.02

AB: Exotic tamarisk trees have become established along several hundred kilometres of the Finke River, the largest river system in arid central Australia. Sources of infestation were plantings at homesteads near the River, and establishment appears to have taken place after heavy flooding dispersed seeds downstream and tore out eucalypt trees which usually dominate. In addition, flushes of saline water which have entered the Finke River from adjacent palaeodrainage systems probably favoured tamarisks at the expense of less tolerant eucalypts. Displacement of eucalypts by tamarisks has resulted in dominance of ground vegetation by relatively few species of introduced or salt-tolerant plants, and in reduction in numbers of indigenous birds and reptiles, thereby reducing pastoral and conservation value of the Finke River. The conditions allowing tamarisk establishment are uncommon but recurrent, and unless positive steps are taken to inhibit their spread they will probably invade other river systems in inland A

1.03

no evidence

2.01

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

Review of natural distribution
The native range of T. aphylla extends over the Middle East, North, East and Central Africa, and parts of West and South Asia (Brandis, 1924; Bailey, 1960). The species is thought to have originated in the Central Sahara, from where it spread to Pakistan, India, Afghanistan, the Middle East, Egypt and North Africa, as well as to Eritrea, Somalia, Kenya and Ethiopia (National Academy of Sciences, 1980; Qaiser 1981).
Natural latitude range
Approximate limits north to south: 35°N to 0°N
Vegetation types: deserts; dry forests; dunes
List of countries with natural populations
Asia: Afghanistan, Gaza, India, Chandigarh, Delhi, Haryana, Indian Punjab, Rajasthan, Uttar Pradesh, Iran, Iraq, Jordan, Kuwait, Oman, Pakistan, Qatar, Saudi Arabia, Syria, Yemen
Africa: Algeria, Egypt, Eritrea, Ethiopia, Kenya, Libya, Morocco, Senegal, Somalia, South Africa,  Sudan, Tunisia, Western Sahara

2.02

2.03

(1)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html (2)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

(1) Where established outside of cultivation, Athel tamarisk commonly occurs on salt flats, springs, and other saline habitats especially along streams and rivers (2) XEROPHYTIC
The native range of T. aphylla extends over the Middle East, North, East and Central Africa, and parts of West and South Asia (Brandis, 1924; Bailey, 1960). The species is thought to have originated in the Central Sahara, from where it spread to Pakistan, India, Afghanistan, the Middle East, Egypt and North Africa, as well as to Eritrea, Somalia, Kenya and Ethiopia (National Academy of Sciences, 1980; Qaiser 1981).
Natural latitude range
Approximate limits north to south: 35°N to 0°N
Climate T. aphylla is generally found in arid subtropical and desert regions in ravine thorn scrub forests, desert dune scrub forests and in Salvadora scrub forests. It tolerates temperatures from -10 from to 50°C and frequent droughts (National Academy of Sciences, 1980). It survives in areas with annual rainfall of 75-100 mm, but for optimum growth

2.04

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

Review of natural distribution
The native range of T. aphylla extends over the Middle East, North, East and Central Africa, and parts of West and South Asia (Brandis, 1924; Bailey, 1960). The species is thought to have originated in the Central Sahara, from where it spread to Pakistan, India, Afghanistan, the Middle East, Egypt and North Africa, as well as to Eritrea, Somalia, Kenya and Ethiopia (National Academy of Sciences, 1980; Qaiser 1981).
Natural latitude range
Approximate limits north to south: 35°N to 0°N
Vegetation types: deserts; dry forests; dunes
List of countries with natural populations
Asia: Afghanistan, Gaza, India, Chandigarh, Delhi, Haryana, Indian Punjab, Rajasthan, Uttar Pradesh, Iran, Iraq, Jordan, Kuwait, Oman, Pakistan, Qatar, Saudi Arabia, Syria, Yemen
Africa: Algeria, Egypt, Eritrea, Ethiopia, Kenya, Libya, Morocco, Senegal, Somalia, South Africa,  Sudan, Tunisia, Western Sahara

2.05

(1) CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.
(2) USDA, NRCS. 2001. The PLANTS Database, Version 3.1 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

(1) Location of introductions T. aphylla has been introduced to some sites in central Australia; since its introduction it has aggressively spread along the Finke River (Griffin et al., 1989). The species has also been introduced on an experimental scale in the semi-arid lowlands of Cyprus.
(2) Present in USA: Arizona, California, Nevada, Puerto Rico, Texas, Utah

3.01

Griffin, G. F.; Smith, D. M. S.; Morton, S. R.; Allan, G. E.; Masters, K. A.; Preece, N. (1989) Status and implications of the invasion of tamarisk (Tamarix aphylla ) on the Finke River, Northern Territory, Australia. Journal of Environmental Management, 1989, Vol.29, No.4, pp.297-315, 25 ref.

AB: Exotic tamarisk trees have become established along several hundred kilometres of the Finke River, the largest river system in arid central Australia. Sources of infestation were plantings at homesteads near the River, and establishment appears to have taken place after heavy flooding dispersed seeds downstream and tore out eucalypt trees which usually dominate. In addition, flushes of saline water which have entered the Finke River from adjacent palaeodrainage systems probably favoured tamarisks at the expense of less tolerant eucalypts. Displacement of eucalypts by tamarisks has resulted in dominance of ground vegetation by relatively few species of introduced or salt-tolerant plants, and in reduction in numbers of indigenous birds and reptiles, thereby reducing pastoral and conservation value of the Finke River. The conditions allowing tamarisk establishment are uncommon but recurrent, and unless positive steps are taken to inhibit their spread they will probably invade other river systems in inland A

3.02

no evidence

3.03

no evidence

3.04

(1) Sainty, G. (1995) Streambank weeds. Better planning for better weed management. Proceedings of the 8th biennial noxious weeds conference, Goulburn, NSW, Australia, Tanner, L.; Nolan, P. Editors. 19-21 September 1995: volume 1., 1995, pp.85-86
(2) Groves, R. H. (1990) Weed control in conservation and amenity areas of Australia. Proceedings of the 9th Australian Weeds Conference., 1990, pp.97-102, 30 ref. (3)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

(1) AB: The control of streambank weeds in Australia is reviewed. Topics discussed include: the need to control exotic plants; problems of erosion as a consequence; a case study example of Salix spp. on the Nambucca River, New South Wales; problems caused by invasion of camphor laurel [Cinnamomum camphora ], Gleditsia tri[a]canthos, Erythrina crista-galli, Tamarix aphylla and Rubus discolor ; and an outline of management methods.
(2) AB: Case histories for the control of different weeds (Rubus fruticosus [blackberries], Chrysanthemoides moniliferum subsp. rotundata and moniliferum, Mimosa pigra and Tamarix aphylla ) in different regions of Australia are presented. A review of these case histories shows that control programmes combining prescription burning, biological control and active revegetation may be ecologically more appropriate and acceptable to users for weed control in conservation and amenity areas than ones relying solely on chemical methods. (3)Unlike the deciduous Tamarix spp., which have b

3.05

(1) Sobhian, R.; Fornasari, L.; Rodier, J. S.; Agret, S. (1998) Field evaluation of natural enemies of Tamarix spp. in southern France. Biological Control, 1998, Vol.12, No.3, pp.164-170, 36 ref. (2)DeLoach, C. J. (1990) Prospects for biological control of saltcedar (Tamarix spp.) in riparian habitats of the southwestern United States. Proceedings of the VII International Symposium on Biological Control of Weeds., 1990, pp.307-314, 41 ref.

(1) AB: "Species of saltcedar or tamarisk (Tamarix spp.) have been classified among the 10 worst noxious weeds in the USA. Field."
(2) AB: Deciduous saltcedars (Tamarix ramosissima [T. chinensis], T. chinensis and T. parviflora ) introduced from southwestern Asia have invaded and replaced most of the native vegetation on 500000 ha of wildlife and agricultural land in riparian ecosystems of the western USA. Saltcedar is little eaten by birds, wild mammals or livestock and provides a poor habitat for most wildlife species. Conventional control methods can destroy wildlife habitats and tend to be costly. The evergreen athel (T. aphylla ) is less widely distributed and seldom invasive; it is used for shade trees, windbreaks, and for honeytrees. Several species of insects from the eastern Mediterranean and Pakistan attack saltcedar but not athel. Such insects, if introduced, could achieve most objectives and avoid most of the ecological disadvantages of conventional control methods.

4.01

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

"T. aphylla is a small to moderate-size evergreen tree which is quite beautiful in appearance. It has feathery foliage, an erect tapering trunk and rough grey bark. It looks like a conifer and is easily mistaken for Casuarina. It generally attains small height and large girth. A variable height of the tree has been reported in the literature; 8-12 m (National Academy of Sciences, 1980) and 18 m height and girth of 1.8-2.1 m, occasionally attaining 3-3.5 m girth (Troup, 1921; Brandis, 1924). The tree is not very long-lived. It tapers rapidly and is heavily branched, but its crown does not spread widely.
It has slender, cylindric, jointed branches which are articulate at the base of the sheath and slender twigs are often hoary with deep punctate glands that produce a saline efflorescence. The salty 'tears' drip in the night and the soil beneath trees is generally covered with a salt layer (Troup, 1921; National Academy of Sciences, 1980).
The bark of the branchlets is smooth, reddish brown or light grey; th

4.02

The allelopathic effects of plant residues on some weed plants.
AU: Al-Juboory, B. A.; Ahmad, M. M.
SO: Arab Journal of Plant Protection, 1994, Vol.12, No.1, pp.3-10

AB: The allelopathic effects of 2.5-5.0 kg/ha fresh wt. leaf residues of Nerium oleander, Schanginia [Suaeda ] aegyptiaca, Tamarex articulata [Tamarix aphylla ], lucerne, liquorice, sunflowers and Eucalyptus camaldulensis , and stem residues of S. aegyptiaca and lucerne were compared with the effects of 2 kg/ha glyphosate on weed growth (particularly in Sorghum halepense, Cyperus rotundus, Convolvulus arvensis and Lagonychium farctum ) under field conditions at Baghdad, Iraq. Results indicated that residues from different plants reduced either broad-leaved and/or grassy weed growth, in some cases as or more effectively than glyphosate. It was noted that time of incorporation and rate of application were critical. [due to salt???]

4.03

no evidence

4.04

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

"The leaf fodder of T. aphylla is of poor quality."

4.05

no evidence

4.06

no evidence

4.07

no evidence

4.08

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

T. aphylla is fire-hardy (National Academy of Sciences, 1980) and is a useful species to plant as a firebreak. The salt drip from branches becomes moist due to its hygroscopic nature and suppresses other inflammable vegetation. Moreover, the leaf litter is too saline to burn. It can be grown in 30-m wide strips to check the spread of wildfires common in dry regions.

4.09

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

"It is a light-demander and does not tolerate shade. "

4.1

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

Soil and physiography
The best growth of T. aphylla is in loamy soil, but it is also found on sand as well as on stiff clay and on alkaline, saline and seasonally waterlogged soils (National Academy of Sciences, 1980). It is considered to grow more vigorously on land subjected to occasional flooding as compared with land which is never flooded. It also grows well on the tops of sand dunes in subtropical regions receiving 250-500 mm of annual rainfall. T. aphylla produces salty 'tears' which cover the soil beneath trees with a salt layer (Troup, 1921; National Academy of Sciences, 1980), thus increasing soil surface salinity.
Descriptors
- Soil texture: light
- Soil drainage: free
- Soil reaction: neutral
- Special soil tolerances: sodic; saline
- Soil types: alkaline soils; alluvial soils; arid soils; clay soils; saline soils; sandy soils; silty soils; subtropical soils

4.11

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

4.12

no evidence

5.01

terrestrial

5.02

tree; Tamaricaceae

5.03

no evidence

5.04

tree

6.01

no evidence

6.02

Teissier du Cros, E. (1973) The germination of Tamarix aphylla. Bulletin d'Information, Institut National de Recherches Forestieres, Tunisia, 1973, No.16, pp.19-23

AB: T. aphylla [T. articulata], widely used in windbreaks in parts of Tunisia with a water table near the surface, sets little seed and is usually propagated vegetatively. Propagation by seed could afford opportunities for tree improvement. The author descrbies the flowers and seeds, discusses the best method of collecting and testing the seed, and gives results of an attempt to raise seedlings by sowing a small quantity of fresh seed (tested and found to be viable) in pots of sand in a greenhouse. The seed germinated, but the seedlings died soon after they were pricked out, a fortnight later, into pots containing a 50% mixture of soil and sand and stood in the open. Seed collected in Oct. 1970 and stored in paper sacks at normal temperature was no longer viable in Jan. 1971. It is suggested that seedlings might be successfully raised by sowing seed direct into pots containing a fertile medium, thus avoiding the need for pricking out.

6.03

no evidence

6.04

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

"The flowers are loosely arranged on the slender spikes. They are small, whitish-pink or pink, unisexual or bisexual, monoecious or dioecious, sessile and delicate. "

6.05

(1)http://plants.gardenbed.com/67/6658_flo.asp (2)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

(1)insects are responsible for pollinating (2)an important source of pollen for the European honeybee

6.06

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

(1)" Ability to sucker; regenerate rapidly; suited for coppicing; suited for pollarding" (2) Its main method of propagation is vegetative. It sprouts from the root crown or forms adventitous roots from submerged, broken or buried stems

6.07

R. Criley, UH Department of Horticulture, personal communication

7.01

no evidence

7.02

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

"T. aphylla is a highly useful tree. Being xerophytic in nature, it is widely planted in arid areas in many countries of Africa and Asia."

7.03

no evidence

7.04

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

"Fruit is small, sessile, capsule-like, and ripens in the cold season. The capsules contain minute seeds with tufts of long, soft, woolly hairs. Ripe capsules turn brown and open up gradually to allow the minute seeds be dispersed by the wind."

7.05

http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

it can colonize disturbed areas by broken limbs carried by water

7.06

no evidence

7.07

no evidence

7.08

no evidence

8.01

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

(1)T. aphylla produces a large number of seeds, i.e. about 500,000 seeds/year from a single tree (National Academy of Sciences, 1980; Sheikh, 1993). The seeds are minute, about 1000 per gram. Under natural conditions, germination is generally good and natural regeneration is fairly plentiful. The seedlings establish themselves as a jungle-like growth of wildings in low-lying areas or hollows where rainwater collects. These can be transplanted into new areas. (2)Athel tamarisk flowers and produces many seeds, but most of the seeds are sterile

8.02

(1) CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.
(2) Teissier du Cros, E. (1973) The germination of Tamarix aphylla. Bulletin d'Information, Institut National de Recherches Forestieres, Tunisia, 1973, No.16, pp.19-23

(1) The seed loses viability in a few days if stored at ambient temperature.
(2) AB: T. aphylla [T. articulata], widely used in windbreaks in parts of Tunisia with a water table near the surface, sets little seed and is usually propagated vegetatively. Propagation by seed could afford opportunities for tree improvement. The author descrbies the flowers and seeds, discusses the best method of collecting and testing the seed, and gives results of an attempt to raise seedlings by sowing a small quantity of fresh seed (tested and found to be viable) in pots of sand in a greenhouse. The seed germinated, but the seedlings died soon after they were pricked out, a fortnight later, into pots containing a 50% mixture of soil and sand and stood in the open. Seed collected in Oct. 1970 and stored in paper sacks at normal temperature was no longer viable in Jan. 1971. It is suggested that seedlings might be successfully raised by sowing seed direct into pots containing a fertile medium, thus avoiding the need for prickin

8.03

http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

Athel tamairsk can be controlled by cutting stumps and applying the herbicide Kuron

8.04

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.fs.fed.us/database/feis/plants/tree/tamaph/all.html

(1)" Ability to sucker; regenerate rapidly; suited for coppicing; suited for pollarding" (2)Athel tamarisk sprouts from the root crown after fire

8.05

no evidence