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Acacia cyclops

Evergreen shrub or small tree, with yellow spherical flower heads, usually found in sand dunes.

Scientific name: Acacia cyclops A. Cunn. ex G. Don

Common name: coastal wattle

Family: Fabaceae (Leguminosae)

Status in Portugal: invasive species

Risk Assessment score: (in development)

Synonymy: Acacia cyclopis A.H. Mackay ex Loudon, A. cyclopis F. Muell., A. cyclopis Sweet, A. eglandulosa DC., A. mirbeli Dehnh., ortho. var., A. mirbelii Dehnh., Racosperma glandulosum (DC.) Pedley

Last update: 30/06/2014

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How to recognise it

Shrub or small tree up to 4m, prostrate, with a fissured rhytidome.

Leaves: evergreen, reduced to phyllodes, with 4-9 x 0,6-1,2 cm, linearoblong to oblanceolate, sometimes falcate, with 3-5 longitudinal veins.

Flowers: yellow and arranged in globular flower heads 4-6-mm wide; solitary or in groups of 2 or 3.

Fruits: compressed pods, undulate or contorted, reddish-brown; seeds completely surrounded by a scarlet funicle.

Flowering: March to October.

 

Similar species

Acacia longifolia (Sydney golden wattle) is similar, but it has flowers arranged in spikes, the pod is cylindrical and the funicle is much shorter and whiter. Acacia melanoxylon (Australian blackwood) is also similar but it is a tree of larger dimension and has yellow flowers, but more pale, and the seeds are encircled by an orange funicle.

  

Characteristics that aid invasion

It reproduces by seed; it produces many seeds that accumulate in numerous seed banks and remain viable in the ground for many years. The seeds are dispersed by animals, mainly birds, ants and small vertebrates. Germination is stimulated by fire.

Native distribution area

Southeast Australia.

 

Distribution in Portugal

Mainland Portugal (Beira Litoral, Beira Alta, Estremadura, Baixo Alentejo).

A.cyclops

Geographic areas where there are records of Acacia cyclops

Other places where the species is invasive

Europe (Spain), South Africa, western USA (California).

 

Introduction reasons

For ornamental purposes, having also been planted for erosion control in coastal dunes.

 

Preferential invasion environments

Coastal dunes and maritime calcareous rocks.

It prefers sandy, quartzite or calcareous soils. It tolerates salt spray, winds, salinity and moderate frost.

It doesn’t develop well in the shade.

Even though it’s not legally considered an invasive plant in Portugal, its shows invasive behaviour in some locations.

Impacts on ecossystems

It forms very dense thickets, inhibiting the development of native vegetation and reducing the diversity of species.

It produces a lot of nitrogen-rich litter, which promotes soil change.

It has allelopathic effects, inhibiting the development of other species.

 

Economic impacts

It has potential expensive control measures.

 

Natura 2000 network habitats more subject to impacts

– Shifting dunes along the shoreline with Ammophila arenaria («white dunes») (2120);
– Fixed coastal dunes with herbaceous vegetation («grey dunes») (2130);
– Atlantic decalcified fixed dunes (Calluno-Ulicetea) (2150);
Malcolmietalia dune grasslands (2230);
– Coastal dunes with Juniperus spp. (2250);
Cisto-Lavenduletalia dune sclerophyllous scrubs (2260).

 

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Acacia cyclops include:

 

Physical control

Hand pulling: preferential methodology for seedlings and small plants. In compacted substrates, hand pulling should be made during the rainy season as to facilitate the removal of the root system.

Cutting: preferential methodology for adult plants. Cut should be made as close to the ground as possible by using manual and/or mechanical equipment. It should be done before seed maturation.

 

Biological control

The weevil Melanterius servulus Pascoe (Coleoptera: Curcullonidae), that causes the destruction has been used, since 1991, very successfully in the control of Acacia cyclops in South Africa.

The wasp  Dasineura dielsi Rübsaamen (Diptera: Cecidomyiidae), used since 2002, has also had considerable results in controlling A. cyclops in South Africa. This species forms galls in the floral shoots of A. cyclops inhibiting seed formation.

These agents have not yet been tested in Portugal as to verify their harmlessness to native species, so its use is not yet an option in our country.

 

Prescribed fire

It may be strategically used to favour germination of the seed bank, e.g., after the control of adult individuals (with the adequate management of the resulting biomass) and the subsequent elimination of seedlings. This method provides an advantageous reduction of the seed bank, both by destroying part of the seeds or by stimulating the germination of the remainders.

 

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

Adair RJ (2005) The biology of Dasineura dielsi Rübsaamen (Diptera: Cecidomyiidae) in relation to the biological control of Acacia cyclops (Mimosaceae) in South Africa. Australian Journal of Entomology 44: 446-456.

Agricultural Research Council – Plant Protection Research Institute – Weed Research Division (2014) Management of invasive alien plants: A list of biocontrol agents released against invasive alien plants in South Africa. Available: http://www.arc.agric.za/arc-ppri/Documents/WebAgentsreleased.pdf [Retrieved 28/02/2014].

CABI (2012) Acacia cyclops. In: Invasive Species Compendium. Wallingford, UK: CAB International. Available: http://www.cabi.org/isc/ [Retrieved 06/11/2012].

DAISIE European Invasive Alien Species Gateway (2012) Acacia cyclops. Available: http://www.europe-aliens.org/speciesFactsheet.do?speciesId=12740 [Retrieved 06/11/2012].

Dufour-Dror J-M (2012) Alien invasive plants in Israel. The Middle East Nature Conservation Promotion Association, Ahva, Jerusalem, 213pp.

Impson FAC, Moran VC, Hoffmann JH (2004) Biological control of an alien tree, Acacia cyclops, in South Africa: impact and dispersal of a seed-feeding weevil, Melanterius servulus. Biological Control 29: 375-381.

Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.

Verloove F, Reyes-Betancort JA (2011) Additions to the flora of Tenerife (Canary Islands, Spain). Collectanea Botanica 30: 63-78.

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