Athel pine (Tamarix aphylla) NT Weed Risk Assessment Technical

www.nt.gov.au/weeds

Athel pine (Tamarix aphylla)

NT Weed Risk Assessment Technical Report

January 2014

Athel pine

Tamarix aphylla

2 www.nt.gov.au/weeds

Please cite this report as:

Department of Land Resource Management (2014). Athel pine (Tamarix aphylla) NT Weed

Risk Assessment Technical Report, Department of Land Resource Management, Darwin.

ISBN: 978-1-74350-050-7

Acknowledgments

The NT Weed Risk Management (WRM) System was jointly developed by Charles Darwin

University (CDU) and the Weed Management Branch, Department of Land Resource

Management (DLRM); our thanks to Samantha Setterfield, Natalie Rossiter-Rachor and

Michael Douglas at CDU. Project funding for the development of the NT WRM System,

obtained by Keith Ferdinands and Samantha Setterfield, came from the Natural Heritage Trust.

Our thanks to the NT WRM Reference Group for their assistance in building the NT WRM

System and the NT WRM Committee for their role in building the system and their ongoing

role in weed risk assessments.

Cover photo (top): Cultivated athel pines growing near buildings.

Cover photo (bottom): Athel pine infestation along the Finke River, NT.

Final report compiled January 2014.

Edited by Louis Elliott, Department of Land Resource Management.

NOTE: Online resources are available at https://nt.gov.au/environment/weeds/list-of-

declared-weeds-in-the-nt/athel-pine which provide information about the NT Weed Risk

Management System including an explanation of the scoring system, a fact sheet and user

guide, a map of the NT weed management regions and FAQs.

Weed Management Branch contacts

For more information or advice in relation to the identification, management or monitoring of

weeds please contact the Weed Management Branch:

Phone: (08) 8999 4567

Email: w[email protected]

Website: http://www.nt.gov.au/weeds

The NT Herbarium can also provide plant identification advice

Phone: (08) 8999 4516

Rangelands Division

Department of Land Resource Management

PO Box 496

Palmerston NT 0831

This product and all material forming part of it is copyright belonging to the Northern Territory

of Australia. You may use this material for your personal, non-commercial use or use it with

your organisation for non-commercial purposes provided that an appropriate

acknowledgement is made and the material is not altered in any way. Subject to the fair dealing

provisions of the Copyright Act 1968 you must not make any other use of this product

(including copying or reproducing it or part of it in any way) unless you have the written

permission of the Northern Territory of Australia to do so.

Athel pine

Tamarix aphylla

www.nt.gov.au/weeds

Weed risk and Feasibility of Control results

Table 1. Weed Risk and Feasibility of Control (FOC) results for athel pine (Tamarix aphylla).

Weed Risk is calculated for the whole of the Northern Territory; FOC is calculated by Weed

Management Region. Maximum score for Weed Risk and FOC is 1000. Each has three

sections (A, B, C), with section scores expressed as a percentage.

Weed Risk (NT)

Band

Very high

Note: For an explanation of how the Weed Risk and

Feasibility of Control scores and bands are calculated,

and for the Northern Territory Weed Management

Regions, refer to www.nt.gov.au/weeds/risk.

Score

412

A. Invasiveness (%)

B. Impacts (%)

C. Potential distribution (%)

Feasibility of Control (by region)

Weed Management Region

Darwin

Katherine

Tennant Creek

Alice Springs

Band

High

Medium

Score

251

125

Control costs (%)

Current distribution (%)

100

C. Persistence (%)

# A high score indicates low control costs and contributes to a high Feasibility of Control. ## A

high score indicates a restricted distribution and contributes to a high Feasibility of Control.

Table 2. Broad management response recommended for athel pine (Tamarix aphylla) by

Weed Management Region, according to Weed Risk and Feasibility of Control assessments.

Feasibility of Control

Very high–High

Medium–Low

Very high

Prevent movement; regional eradication;

contain regional spread; protect priority sites

Targeted control (including biocontrol)/protect

priority sites

High

Medium

Prevent movement; contain regional spread;

protect priority sites

Targeted control

Improve general weed management

Targeted control; improve general weed

management; monitor; protect priority sites

Low

Monitor; assist interested parties

Assist interested parties

Tennant Creek Region

Alice Springs Region

Athel pine

Tamarix aphylla

4 www.nt.gov.au/weeds

Background information

Taxon Tamarix aphylla

Synonyms Tamarix articulata, Thuja aphylla

Common name Athel pine

Other names Tamarisk, saltcedar, athel tree

Family Tamaricaceae (tamarisk family)

Lifeform Tree

Environment Terrestrial

Origin Northern Africa, the Arabian Peninsular,

Iran and India.

Legislation Declared in all other Australian states and territories.

Declared Class A and Class B in different parts of the Northern Territory.

The NT declaration zones for athel pine are available at:

www.nt.gov.au/weeds/find/athelpine.

Description

Large, spreading tree up to 15 m tall. Athel pine is not a true conifer or pine, but its pendulous

needles and branches give it the appearance of one. Salt secreting glands in the needles

create a whitish coating giving the tree foliage a silvery grey appearance. Small, white and

pink flowers occur in dense racemes. Habitat

Dominates sandy riparian habitats in the arid zone. In the Northern Territory, it forms

monospecific stands along rivers and adjacent fringing woodlands in the arid zone. It is spread

by wind and floodwaters, and is able to establish on sandy soils free of other vegetation.

Distribution

There are large infestations present in South Australia, New South Wales, Queensland and

Western Australia. In the Northern Territory athel pine is mainly found in the central region,

where it was extensively planted in Aboriginal communities and at homesteads, bores and

roadhouses as far north as the Barkly region. Extensive stands of athel pine are found on the

Finke River system south of Alice Springs. Other

Athel pine is recognised as a Weed of National Significance.

Athel pine is also a significant invasive species in southern USA.

Current situation in the NT

In the Northern Territory (NT) athel pine is well established in the Finke River, this being

the largest naturalised infestation in Australia. Infestations outside this core area, such as

those found in Walker and Karinga Creeks, are smaller and of lower density, and as such

have been prioritised for management. Historical and amenity plantings of athel pine are

found throughout the southern region of the Territory. As these present potential for spread,

their control and removal is also considered a management priority.

Athel pine

Tamarix aphylla

www.nt.gov.au/weeds

Summary of Weed Risk and Feasibility of Control

Weed RIsk

A. Invasiveness:

Intentionally introduced into Australia and widely planted for shade. Current infestations

originate from trees planted around homesteads and communities. Seed viability is moderate

(c. 22%), but a single tree is capable of producing enormous quantities of tiny seed (c. 500

000) which are principally spread by floodwaters. A major dispersal event occurred in the NT

with the flood of 1974, with floods in later years aiding further establishment. It is also able to

spread vegetatively—broken stem fragments can take root and are also spread by floods.

People may continue to accidentally spread athel pine with heavy machinary such as graders.

B. Impact:

Forms monocultures which displace native vegetation, particularly the iconic river red gums

(Eucalyptus camuldulensis) and coolibah (Eucalyptus microtheca) in central Australia. Athel

pine extracts salt from the soil, causing salination affecting plant growth up to 50 m away. It

lowers the water table, dry up waterholes, adds to sedimentation rates and can change the

course of rivers. Only salt-tolerant herbs or grasses can grow under athel pine, so it reduces

grazing area. Native birds, reptiles and insects are negatively impacted—athel pine flowers

have no nectar, the trees do not provide hollows for nesting, and it is a poor source of food for

invertebrates. A threatened species of brushtail possum is impacted. C. Potential distribution:

Wide native and introduced range throughout arid and semi-arid zone, surviving in areas with

rainfall as low as 100 mm/year. The climate for optimum growth is probably 350–500 mm/year.

Particularly suitable vegetation types in the NT are arid and semi-arid riparian and wetland

areas, due to dispersal by floodwaters and the close proximity of groundwater.

Feasibility of Control

A. Control costs

Moderate. Athel pine is readily identifiable and infestations are generally accessible for

treatment. However, the tree does not translocate chemical well. Chemical and labour costs

are very high, especially for large infestations.

B. Current distribution (NT)

Large stands of athel pine exist on the Finke River system in the Alice Springs Region. In other

parts of the arid and semi-arid NT, infestations tend to isolated. In these areas, isolated trees

planted for amenity purposes continue to exist.

C. Persistence

Moderate. Seeds remain viable for a only a few weeks. However vegetative propagules can

propagate even when there is no seed. The tree can live for at least several decades.

General Management Recommendations

Refer to the Weed Management Plan for Athel Pine (Tamarix aphylla). This can be found at

www.nt.gov.au/weeds/find/athelpine.

Athel pine

Tamarix aphylla

6 www.lrm.nt.gov.au

Weed Risk Assessment - Determinations

A. INVASIVENESS

A1. What is the ability of the plant to establish amongst intact native

Determination

environments? Very high

A2. What is the reproductive ability of the plant?

a) Time to seeding

b) Annual production of viable seed per sq m or /plant

c) Vegetative reproduction

A3. Do propagules of the plant have properties that allow them to be dispersed

long-distance by natural means?

a) Flying animals (birds, bats)

b) Other wild animals

c) Water

d) Wind

A4. How likely is long-distance dispersal by human means?

a) Deliberate spread by people

b) Accidentally by people and vehicles

c) Contaminated produce

d) Domestic/farm animals

B. IMPACTS

B1. What is the plants competitive potential? High

B2. What is the plant’s potential to modify the existing fire behaviour and

alter the fire regime? Some potential

B3. What is the plant’s potential to restrict the physical movement of people,

animals, vehicles, machinery and/or water? High

B4. What is the plant’s potential to negatively affect the health of animals

and/or people? None

B5. Does the plant potentially have negative effects on natural and cultural values?

a) reducing habitat quality for native animals

b) threatened species or communities

c) sites of natural significance

B6. Is the plant presumed to have negative effects on environmental health?

a) soil chemistry/stability

b) water quality

c) hydrology

C. POTENTIAL DISTRIBUTION

C1. What is the CLIMATE suitability score (which indicates the proportion of

the NT environment that is suitable for the plant)? 8.8

C2. How many broad habitat types in the NT will the plant potentially

naturalise in (up to 5) ? Two

C3. What is the potential of the plant to occur throughout its favoured

habitat in the NT (from those identified in question 2)? Some

2-3 years

High

Frequent

Don't know

Yes

Unlikely

Occasional

Unlikely

Occasional

High

One

More than 1

Yes

www.nt.gov.au/weeds

Feasibility Of Control - Determinations

A. CONTROL COSTS Darwin Region Katherine Region Tennant Ck Region Alice Springs Region

A1. How detectable is the weed?

a) Distinguishing features

b) Active growth period

c) Height at maturity

A2. What is general accessibility of infestations at the optimum treatment time?

A3. How expensive is control of the weed in the first year of targeted control, for an infestation that has reached maximum

weed density?

a) Chemical cost

b) Labour costs

c) Equipment costs

A4. What is the general community perception of this week within the region?

B. CURRENT DISTRIBUTION

B1. What is the current pattern of the weed’s distribution across the weed's range in the NT?

C. PERSISTENCE

C1. How long will it take to reach the maintenance period? The maintenance period is reached when there is no further

recruitment from the original infestation, although monitoring and follow up may still be required.

C2. What is the minimum time period for reproduction of sexual or vegetative propagules?

C3. What is the maximum longevity of sexual or vegetative propagules?

C4. What is the threat of reinfestation from outside the region?

a) Long-distance dispersal by natural means

b) Long-distance dispersal by human means

Always distinct

4-8 months

> 2 m

Medium

Very High

Low

High

Restricted

Medium

<1 year

>5 years

Frequent

Occasional

Athel pine

Tamarix aphylla

8 www.nt.gov.au/weeds

Figure 1. Global records of athel pine (Tamarix aphylla). Source: Global Biodiversity

Information Facility and Australian Virtual Herbarium (2007).

Figure 2. Potential distribution of athel pine (Tamarix aphylla) in Australia using CLIMATCH.

Areas of suitable climate are indicated by a climatic suitability score of 7 or above out of 10.

Source: NT Weed Management Branch 2010.

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

www.nt.gov.au/weeds 9

A INVASIVENESS

A1 What is the ability of the plant to establish amongst intact native environments?

The established trees [on the Finke River] now tend to form dense, almost

monospecific stands, which appear to displace the native river gum (Eucalyptus

camaldulensis) from parts of the river.

Griffin et al. (1989)

Dominates sandy riparian habitats in arid areas such as Finke River and

excludes all other vegetation. In places, river red gums (Eucalyptus

camuldulensis) an icon of central Australia, have been replaced by Athel Pine.

Csurhes (2008)

In the Finke River, the infestation of Athel pine ..extends into the dense

fringing Coolabah woodlands. The infestation has now reached the Finke

Floodout forest; an area of very dense Coolabah (Eucalyptus coolabah

subsp. arida) and Cooba (Acacia salicina) woodland/forest.

Duguid et al. (2002)

Along the Finke River it has formed many monospecific stands at the expense

of the river red gum, Eucalyptus camaldulensis Dehnh., and the coolibah,

Eucalyptus microtheca F. Muell., considerably reducing the available grazing

area.

Parsons & Cuthbertson

(1992)

Over the past 18 years Athel pine has become established along several hundred

kilometres of the Finke River in the NT.

Fuller (1993b)

Seedlings seem only to establish on sandy soils that are free of vegetation.

Csurhes (2008)

In the Lake Mead recreational area (Nevada, USA) Tamarix aphylla has spread

from 4 large trees in 1982 to over >5000 individuals in the same area of the

park in 2006.

Walker et al. (2006)

A2a Reproductive ability: Time to seeding?

The first flowers appear in about the third year, and annually thereafter, in Parsons & Cuthbertson

summer. (1992)

A2b Reproductive ability: Annual production of viable seed per square meter or per plant?

Athel pine flowers and produces many seeds, but most of the seeds are sterile.

Tesky (1992)

Seed viability is moderate (ca. 22% under best conditions) and seed

production period [in America] is fairly restricted, but because millions of

seeds can be produced, under the right conditions the potential for invasion is

theoretically very high

Dudley (2004)

T. aphylla produces a large number of seeds, i.e. about 500,000 seeds/year from

a single tree. The seeds are minute, about 1000 per gram.

500,000 seeds per year from a single tree X 22% viability = 11,0000 viable seeds

per year from a single tree.

A2c Reproductive ability: Vegetative reproduction?

CAB International (2000)

In their native habitat, propagation is assumed to be mostly vegetative, although

establishment from seeds after summer rains has been reported.

Griffin et al. (1989)

Its main method of propagation is vegetative. It sprouts from the root crown or

forms adventitious roots from submerged, broken or buried stems.

Tesky (1992)

Athel pine reproduces from broken stem fragments as well as from seeds.

Vegetative reproduction is particularly successful when branches are broken up

by floodwaters and carried downstream.

Csurhes (2008)

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

10 www.nt.gov.au/weeds

A3a Propagule dispersal: Flying animals (birds, bats)

Seeds are spread . . . by birds.

A3b Propagule dispersal: Other wild animals

Parsons & Cuthbertson

(1992)

Seeds are spread . . . by animals.

A3c Propagule dispersal: Water

Parsons & Cuthbertson

(1992)

Major flows in the Finke River in 1974 dispersed seed along its entire length,

and the wet conditions that followed were ideal for seed establishment.

Further floods in 1983 and 1984 enabled more Athel pine to establish, from

seed and vegetable matter, probably from those trees established in the 1974

floods.

Fuller (1993b)

Seeds are spread principally by floodwaters . . .

Parsons & Cuthbertson

(1992)

It can colonise disturbed areas by broken limbs carried by water.

A3d Propagule dispersal: Wind

Tesky (1992)

The minute seeds [of Tamarix aphylla] are furnished with a pappus, making them

fit for long distance dissemination.

Waisel (1960)

Seeds are small enough to be carried over short distances by the wind.

Csurhes (2008)

Seeds have a pappus, making them suitable for wind transportation, but they are

viable for only a few weeks.

Griffin et al. (1989)

Fruit is small, sessile, capsule like and ripens in the cold season. The capsules

contain minute seeds. Ripe capsules turn brown and open up gradually to allow

the minute seeds to be dispersed by the wind.

A4a Human dispersal: Deliberate spread by people

CAB International (2000)

Athel pine was introduced into Australia to provide shelter against wind and

sun and for use as an ornamental in the arid and semi-arid zone. It was

planted extensively around Broken Hill and Whyalla in the 1930’s and 40’s and

soon after in other states, particularly around homesteads, stock yards, bores

and other hot, exposed sites on grazing properties and towns.

Csurhes (2008)

All infestations originated from trees planted around homesteads and communities

for shade.

A4b Human dispersal: Accidentally by people and vehicles

Fuller (1993b)

There is evidence to suggest that Athel Pine is spread accidentally by people,

particularly via vegetative material adhering to heavy machinery such as earth

moving equipment, road graders etc.

A4c Human dispersal: Contaminated produce

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

It would not be spread by contaminated produce. C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

www.nt.gov.au/weeds 11

A4d Human dispersal: Domestic/farm animals

It is possible that it could be spread by domestic and feral herbivores.

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

IMPACTS

What is the plant's competitive potential?

Dominates sandy riparian habitats in arid areas such as Finke River and excludes

all other vegetation.

Csurhes (2008)

Along the Finke River it has formed many monospecific stands at the expense

of the river red gum (Eucalyptus camaldulensis Dehnh.), and the coolibah

(Eucalyptus microtheca F. Muell), considerably reducing the available grazing

area.

Parsons & Cuthbertson

(1992)

Few native herbs persist under the dense infestations.

Fuller (1993b)

B2 What is the plant's potential to modify the existing fire behaviour and alter the fire regime?

Because they are drought tolerant and fire resistant, athel pines decrease the

frequency of fires and alter vegetation structure.

Commonwealth

Department of

Environment and Heritage

(2003)

Athel pines do not allow fire to pass through an area and as a consequence

natural fire regimes are altered. This can affect the regeneration of many native

plant species.

Csurhes (2008)

T. aphylla is fire-hardy 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.

CAB International (2000)

T. aphylla is not known to increase fire risks.

Dudley (2004)

The high ash (30-40%) and salt content of its foliage make it hard to burn even

when dry.

Tesky (1992)

B3 What is the plant's potential to restrict the physical movement of people, animals, vehicles,

machinery and/or water?

Presence of the trees may alter the course of rivers.

Fuller (1993b)

Athel pine increases soil sedimentation in arid rivers systems.

Humphries et al. (1991)

Increases in the density of tamarisks may well alter the river’s course and

increase sedimentation rates by trapping and stabilising sediments during floods.

Griffin et al. (1989)

Extensive, old stands lower the water table and cause water holes to dry up.

Csurhes (2008)

B4 What is the plant's potential to negatively affect the health of animals and/or people?

Tamarix spp. are relatively unpalatable to most classes of livestock and Tesky (1992) wildlife.

Athel tamarisk foliage contains phenolic acids which may prevent herbivory.

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

12 www.nt.gov.au/weeds

B5a Natural & cultural values: Reducing habitat quality for native animals

Dominates sandy riparian habitats in arid areas such as Finke River and

excludes all other vegetation. In places, river red gums (Eucalyptus

camuldulensis) an icon of central Australia, have been replaced by Athel Pine.

Unlike eucalypts, athel pines do not provide nesting hollows or food for native

wildlife.

Csurhes (2008)

The displacement of eucalypts by tamarisks has resulted in dominance of the

ground vegetation by a relatively few species or introduced or salt-tolerant plants.

Griffin et al. (1989)

Fewer birds occurred in the area invaded by tamarisks. Birds could find

tamarisks unsuitable as they provide only tiny flowers which presumably

attract few insects and no nectarivorus birds; their foliage is devoid of

herbivorous species; and, tamarisks probably suppress ground-dwelling

insects because of depauperate litter fauna. Fewer herbs and forbs grow

through the litter to provide substrate for invertebrates. In addition,

holenesting birds probably decline in abundance near tamarisk infestations

during breeding periods, due to the absence of tree-hollows in tamarisk

stands.

Griffin et al. (1989)

Fewer reptiles occurred in the area invaded by tamarisks. Reptiles could find

tamarisks less suitable as: the litter beneath tamarisks appeared to contain

sparse populations of litter invertebrates; and tamarisk deposited few logs or

dead branches on the ground, and those on the ground did not have the same

thick persistent bark of the eucalypts that encourages colonization by reptiles.

B5b Natural & cultural values: Threatened species of communities

Griffin et al. (1989)

One threatened species affected, common brush tail possum.

J. Woinarski [NT

Biodiversity Conservation]

2007, pers. comm.

Athel Pine does have a significant impact on the natural values of inland

waterways such as the Finke River as it can dominate large sections of the river

channel excluding native river red gums and coolabahs. These inland riverine

areas form significant breeding and refuge areas for native wildlife.

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

In central Australia, the common brushtail possum now occupies riverine

habitat that is close to rocky outcrops and moist gullies within the ranges or

rocky slopes (Kerle et al. 1992). This habitat occurs on various geological

substrates but is characterized by a diverse association of fire-sensitive plant

species. Its former habitat in central Australia included river systems supporting

large eucalypts, coolibah claypans and spinifex grasslands with a shrubby

overstorey (Burbidge et al. 1988).

B5c Natural & cultural values: Sites of natural and cultural significance

Burbidge et al. (1988)

Kerle et al. (1992)

Pavey (2006)

The Finke and several other water courses are listed as nationally significant

wetlands and river red gums are characteristic of these sites.

B6a Environmental health: Soil chemistry/stability

Duguid et al. (2002)

J. Woinarski [NT

Biodiversity Conservation]

2007, pers. comm.

Their extensive roots also extract all soluble salts from the soil; these are

excreted through the glands in the leaves onto the top of the soil in the form of

litter or 'tears', thus causing salinisation of top soil even in non-saline areas,

reducing the growth of nearby plants up to a distance of 50 m.

CAB International (2006)

Athel pine tolerates saline water and exudes large quantities of salt through its

leaves, leading to increasing levels of salinity in surrounding soil.

Csurhes (2008)

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

www.nt.gov.au/weeds 13

Tamarisk tolerates saline water and exudes large quantities of salt through its

leaves; the salt concentration on the foliage may be up to 50 times that in the

root water supply.

Berry (1970)

Leaf litter from T. aphylla can significantly increase soluble salts in the soil

surface, with the mean values under the canopy about twice or three times as

high as out in the open.

Fig. 1 Mean of total soluble salts (in parts per million) in soil under the canopy

of Tamarix aphylla and in the open (from Litwak, 1957).

Depth Under canopy In open Difference

0 cm 1201 ± 345 480 ± 120 721*± 299

40 cm 1198 ± 216 512 ± 102 678**± 250

80 cm 859 ± 187 490 ± 78 368**± 57

* Significant at 0.05, ** Significant at 0.01

The change in soil composition was also affected by the age of the trees, with

total soluble salts highest under large mature trees.

Litwak (1957)

B6b Environmental health: Water quality

Presence of the trees may increase sedimentation rates.

Fuller (1993b)

Exotic tamarisk trees have become established along several hundred

kilometres of the Finke River, the largest river system in arid central Australia.

Establishment appears to have deposited large quantities of sediment on the

levees.

Griffin et al. (1989)

Athel pine increases soil sedimentation in arid rivers systems.

B6c Environmental health: Hydrology

Humphries et al. (1991)

Athel pine is a hydrophyte, which means it has specialised roots that draw water

from deep underground. It uses large quantities of water and dense stands can

have significant impacts on underground water tables.

Csurhes (2008)

Tamarix aphylla is known to lower ground water tables.

Csurhes & Edwards (1998)

Extensive, old stands lower the water table and cause water holes to dry up.

C POTENTIAL DISTRIBUTION

Csurhes (2008)

C1 What is the CLIMATE suitability score (which indicates the proportion of the NT environment

that is suitable for the plant)?

The native range of T. aphylla extends over the Middle East, North, East and

Central Africa, and parts of West and South Asia. 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.

CAB International (2000)

Tamarix aphylla has a very wide range of distribution in North Africa and in

Western Asia…It is assumed to be indigenous in Morocco, Algeria, Tunisia,

Central Sahara, Lybia, Egypt, Sudan, Israel, Trans-jordan, Syria, Iraq, Arabia,

Yeman, Iran, Baluchistan, Sind and Punjab.

Waisel (1960)

It is an aggressive, fast growing species which survives in areas where

annual rainfall is as low as 100 mm (optimum growth is probably 350-500 mm

per annum).

National Academy of

Sciences (1980)

The CLIMATE model used by the NT Weed Management Branch predicts that

88% of the NT is climatically suitable for athel pine (see Figure 1).

NT Weed Management

Branch (2007)

Athel pine

Tamarix aphylla

Weed Risk Assessment - Evidence Used

14 www.nt.gov.au/weeds

C2 How many broad vegetation types in the NT will the plant potentially naturalise in (up to 5) ?

The broad vegetation types that Tamarix aphylla will potentially naturalise in are:

• Arid and semi-arid wetlands

• Arid riparian

The favoured vegetation type is arid riparian.

NT Weed Risk

Management Committee

(2007)

Rossiter-Rachor (2012)

Vegetation types: deserts; dry forests; dunes

CAB International (2000)

C3 What is the potential of the plant to occur throughout its favoured habitat in the NT (identified

in question 2)?

Tamarix aphylla has the potential to occur through some of its favoured NT Weed Risk

habitat. Management Committee

(2007)

Athel pine

Tamarix aphylla

Feasibility of Control - Evidence Used

www.nt.gov.au/weeds 15

A CONTROL COSTS

A1a Distinguishing features

Tamarix aphylla (Athel pine) is a spreading tree reaching 10 m in height. The

leaves are blue green and are similar in appearance to pine needles. Flowers

are pinkish white and are arranged in racemes at the end of the branches.

Csurhes & Edwards (1998)

Always distinct.

A1b Active growth period

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Active growth period 4-8 months (spring/summer).

A1c Height at maturity

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

The height at maturity is >2m.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Tamarix aphylla (Athel pine) is a spreading tree reaching 10 m in height.

Csurhes & Edwards (1998)

A2 Is general accessibility of infestations at the optimum treatment time?

The general accessibility of infestations is Medium.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Medium (all work done with 4WD quadbikes).

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

A3a Chemical cost

Chemical Costs: Medium Category ($250-$500/Ha). C. Brown [NT Weed

Athel pine does not translocate chemical well

In the maximum density infestation of Athel pine (like has been on the Finke)

there would be large broken stems plants, as well as seedlings coming up.

Would need to use:

• 4-5 L of access of Garlon/ha @ $70/L = 280-350

• 1000L of diesel /ha @ $1.80/L

Therefore would cost $2080 - $2150 per hectare.

[Note: This would place Athel pine control in the Very High (>$500 /ha)

chemical costs category]

Management Branch, Alice

Springs] 2007, pers.

comm.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

A3b Labour costs

The labour costs for controlling a maximum density Athel pine infestation would

include people to do basal bark control, as well as spraying seedlings, and

someone operating the earthmoving equipment. [Note: This would place

Athel pine control in the Very high (>$500 /ha) labour costs category]

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Labour Costs: High ($200-$500).

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

Athel pine Tamarix

aphylla

Feasibility of Control - Evidence Used

16 www.nt.gov.au/weeds

A3c Equipment costs

Equipment Costs: High (for dense stands of mature trees as requires bulldozer).

A4 What is the general community perception of this weed within the re

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

gion?

The general community perception of Athel pine is High. Well known weed in P. Jeffery, M. Fuller & G.

the Alice Springs region. McSkimming [weed control

contractors] 2007, pers.

Comm.

B CURRENT DISTRIBUTION

B1 What is the current pattern of the weed's distribution across the weed's range?

C3 What is the maximum longevity of sexual or vegetative propagules?

Athel pine’s distribution in the Alice Springs region is Scattered.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

In the Northern Territory athel pine is mainly found in the central region of the

Northern Territory, where it has been extensively planted on Aboriginal

communities and at homesteads, bores and roadhouses as far north as the Barkly

region. Athel pine is well established in the Finke River.

C PERSISTENCE

Department of Land

Resource Management

(2014)

C1 How long will it take to reach the maintenance period?

Medium. It is likely to take 2-5 years to reach the maintence period.

C2 What is the minimum time period for reproduction of sexual or veget

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

ative propagules?

The minimum time for reproduction is within 1 year.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

The first flowers appear in about the third year, and annually thereafter, in summer.

Parsons & Cuthbertson

(1992)

Athel pine Tamarix

aphylla

Feasibility of Control - Evidence Used

www.nt.gov.au/weeds 17

Seed viability is moderate (ca. 22% under best conditions) and seed

production period [in America] is fairly restricted, but because millions of

seeds can be produced, under the right conditions the potential for invasion is

theoretically very high.

Dudley (2004)

Although a single tree can produced 500 000 seeds. The seed is short lived, lasting

only a few weeks.

Griffin et al. (1989)

About 60% of stem tissues produce new shoot/roots under greenhouse

conditions, while root cutting was less successful, producing only about 19% new

shoot growth. [Note that this paper only refers to Tamarix spp.]

Brock (1994)

T. aphylla cuttings lose their vitality after loosing one-third of their water content.

Waisel (1960)

Tamarix aphylla can reproduce by seed, but most spread is via broken living plants

that are transported in floodwaters.

Csurhes & Edwards (1998)

The maximum longevity of vegetative propagules is greater than five years.

C4a Long-distance dispersal by natural means

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Major flows in the Finke River in 1974 dispersed seed along its entire length,

and the wet conditions that followed were ideal for seed establishment.

Further floods in 1983 and 1984 enabled more Athel pine to establish, from

seed and vegetable matter, probably from those trees established in the 1974

floods.

Fuller (1993b)

Seeds are small enough to be carried over short distances by the wind.

Csurhes (2008)

It can colonise disturbed areas by broken limbs carried by water.

Tesky (1992)

Seeds are spread principally moved by floodwaters.

Parsons & Cuthbertson

(1992)

Seeds are spread . . . by animals

Parsons & Cuthbertson

(1992)

Long-distance dispersal of Athel pine by natural means is likely to be rare.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

T. aphylla can reproduce by seed, but most spread is via broken living plants that

are transported in floodwaters.

C4b Long-distance dispersal by human means

Csurhes & Edwards (1998)

It would not be spread by contaminated produce but there is the possibility that it

could be spread by domestic and feral herbivores.

Long-distance dispersal of Athel pine by human means is likely to be rare

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers.

comm.

P. Jeffery, M. Fuller & G.

McSkimming [weed control

contractors] 2007, pers.

Comm.

Athel pine

Tamarix aphylla

www.nt.gov.au/weeds 18

Athel pine was introduced into Australia to provide shelter against wind and

sun and for use as an ornamental in the arid and semi-arid zone. It was

planted extensively around Broken Hill and Whyalla in the 1930’s and 40’s and

soon after in other states, particularly around homesteads, stock yards, bores

and other hot, exposed sites on grazing properties and towns.

Csurhes (2008)

All infestations originated from trees planted around homesteads and communities

for shade.

Fuller (1993b)

There is evidence to suggest that Athel Pine is spread accidentally by people,

particularly via vegetative material adhering to heavy machinery such as earth

moving equipment, road graders etc.

C. Brown [NT Weed

Management Branch, Alice

Springs] 2007, pers. comm.

Athel pine

Tamarix aphylla

www.nt.gov.au/weeds 19

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