Invasion Biology

Saturday, July 15, 2006

SOME POTENTIAL “WEEDS” WE RECENTLY GAVE TO AUSTRALIA

We all know about Rooikrans (Acacia Cyclops) and Port Jackson (Acacia saligna) originating from Australia that have invaded many areas in the Cape Floristic Region. Many South African plants have however also become invasive in Australia. Some are even threatened species in their natural habitat in South Africa, but have become a pest in Australia. One such example is the yellow wild iris (Dietes bicolour). South African plants that have long been declared pests in Australia are for example our bitou (Chrysanthemoides monilifera) and arum lily (Zantedeschia aethiopica).

New introductions of potential weeds is however an ongoing problem. Recent South African introductions (between 1971-1995) in Australia that have already become locally naturalized are amongst others the green ixia (Ixia viridiflora), the blouooguintjie (Moraea aristata), a gladiolus from Kwazulu-Natal (Gladiolus natalensis) and a chasmanthe (Chasmanthe bicolour). Yet three of these species are red data species in South Africa! All of the above mentioned plants were introduced as ornamental garden plants but have since escaped from urban gardens and have become naturalized. (read more here)

Up until 2004 non-South African resident members of the Botanical Society of South Africa could make use of the “free seed benefit”. This meant that as members they could order a certain amount of seeds from South African indigenous plants for free on a yearly basis. This was discontinued at the end of 2004. One of the reasons was to stop the spread of potentially alien invasive weeds to other countries.

Australia now has very strict legislation to try and prevent further introductions of potentially invasive species. However, as long as there are obsessed plant collectors willing to pay, seeds and plants will find their way into other countries …


Further reading:

March 2006 issue of Veld & Flora, the Journal of the Botanical Society of South Africa.

South African Red Data List (can be downloaded at the following link: http://www.sanbi.org/frames/infofram.htm )


Karen Marais
BCB Hons NISL student
University of the Western Cape
Private Bag X17
Bellville

E-mail 2657211@uwc.ac.za

Web http://brit-journal.com/karen2006bcbnisl/

NEWLANDS FOREST

A recent research article in Biological Conservation 132 ( 2006 ) 183 –198 by Alston KP and Richardson DM deals with alien invasive plants in Newlands Forest, Cape Town. The “edge effect” of an urban/wildland interface was studied. They found a significant correlation between the distance from supposed source populations (mainly sub-urban gardens) and alien species richness in different habitats of Newlands Forest as well as a significant correlation between alien species richness and the level of disturbance.

To read more follow the link http://academic.sun.ac.za/cib/publications2006.htm


Karen Marais
BCB Hons NISL student
University of the Western Cape
Private Bag X17
Bellville

E-mail 2657211@uwc.ac.za

Web http://brit-journal.com/karen2006bcbnisl/

CENTRE OF EXCELLENCE FOR INVASION BIOLOGY

If Invasion Biology interests you, visit the website of the Centre of Excellence for Invasion Biology based at the University of Stellenbosch. I have found this website very informative. There are also links to other sites as well as to recent publications regarding Invasion Biology. Make sure to visit the “Of interest” section for some relevant and interesting recent news in this field.

http://academic.sun.ac.za/cib/



Karen Marais
BCB Hons NISL student
University of the Western Cape
Private Bag X17
Bellville

E-mail 2657211@uwc.ac.za

Web http://brit-journal.com/karen2006bcbnisl/