THE SCOURGE OF ACACIA ELATA IN BETTY’S BAY

Article compiled for the Kogelberg Branch of the BotSoc by Dr Allan Heydorn

Originating in south-eastern Australia, the Peppertree wattle, Acacia elata, is an invasive species causing increasing concern in the Western Cape. As with other invasive Acacia species, it displaces indigenous fynbos vegetation, lowers groundwater levels and poses a serious hazard during wildfires. It spreads rapidly through prolific seed production and dispersion. A. elata is listed under the National Environmental Management Biodiversity Act (NEMBA) as Category 1b. Its removal is therefore enforceable by law.

Unfortunately, A. elata is also spreading rapidly in Betty’s Bay. In some areas prolific stands of adult A. elata trees and their saplings occur in the immediate vicinity of the Kogelberg Biosphere Reserve (KBR). It therefore represents a serious threat to this internationally recognised conservation area.

The smallish leaves of A. elata are very similar to those of the indigenous Keurboom (Virgilia oroboides) but can be distinguished by the pointed bipinnate leaves of the former versus the rounded tripinnate leaves of the latter. This characteristic enables accurate identification of even small saplings. Furthermore, the flowers of the two species are notably different. Flowering seasons also differ with V. oroboides flowering from January to April while A. elata flowers in November and December.

The rapid growth and decorative leaves of A.elata make this species popular as an ornamental shrub.  However, the shrubs grow to become trees of over 20 m in height with massive trunks and root systems and, together with their dense clusters of saplings, they are exceedingly difficult to remove. As can be seen in the photograph above (taken near the Disa Jeugkamp on the border of the core zone of the KBR), the clusters of saplings become very dense and this characteristic drastically enhances the danger they represent during wildfires. The Betty’s Bay Hack Group and especially hack convenor, Ed Silberbauer, have waged an unremitting battle for years to keep the spread of A. elata saplings at bay – especially in the immediate vicinity of the Disa Jeugkamp and its neighbouring properties on the border of the core zone of the KBR. During a hack which took place here in October 2014, it became clear once again that the removal of saplings is an impossible task as long as large numbers of mature trees remain standing. Earlier during the same month, a wildfire driven by a powerful NW gale had destroyed several houses in Betty’s Bay. Had this fire been driven into the vicinity of the Disa Jeugkamp and set the dense clusters of A. elata saplings and mature trees alight, the entire camp as well as properties in its vicinity – including the Harold Porter National Botanical Garden – would have been placed at severe risk.

This catastrophic fire attracted the attention of the responsible authorities, especially the Bio-Security Directorate of the Department of Environment Affairs (DEA), who conducted an inspection of Betty’s Bay on 17 December 2014. Amongst others, they visited the Disa Jeugkamp and neighbouring properties. It was encouraging that one owner had already removed the bulk of A. elata from his property at substantial cost.

Following the inspection, Mr Pagel Haefele, manager of the Disa Jeugkamp, drew up a plan for the systematic removal of A. elata from the camp terrain for submission to the DEA. Furthermore, both SANBI and the City of Cape Town have Invasive Species Programmes (ISP) and Early Detection and Rapid Response Units (EDRR), both of which are deeply concerned with the removal of A. elata (as far as this is possible), from the Metropolitan Area of Cape Town and adjacent regions. In this context, Virgil Jacobs who heads the SANBI ISP convened a meeting at the Disa Jeugkamp on 10 February 2015. In attendance were:

Virgil Jacobs                            (SANBI ISP)

Ulrike Irlich                             (City of Cape Town EDRR)

Jane Forrester                         (SANBI HPNBG)

Pagel Haefele                         (Disa Jeugkamp)

Hannes Botha & Colleagues   (Disa Jeugkamp Management)

Tracy Sampson                        (Working for Water: DEA/OM)

Edward Silberbauer                (Hack Convenor, Kogelberg BotSoc)

Allan Heydorn                         (Coastal & Marine Ecologist)

The following main points emanated from this meeting:

a. The management plan for systematic removal of large elata trees on the Jeugkamp terrain was received with appreciation. This is the plan which was requested by the Bio-security Directorate of the DEA, following their inspection on 17 December 2014.

b. It was agreed, however, that because elata has already spread so widely in Betty’s Bay, a further management plan is required incorporating a far wider area in the township. It was recommended that this requirement be discussed with the Kogelberg Branch of the BotSoc, SANBI/HPNBG, the Betty’s Bay Ratepayers Association and Overstrand Municipality. This will require involvement of all owners of private properties where the species now occurs.

c. Because of the substantial cost of felling large elata trees, funding for this purpose needs to be found for the Jeugkamp which is run on a charitable basis. Note was taken of this by the SANBI ISP.

The Kogelberg Branch of the BotSoc is closely involved. Current action by the Branch includes:

• Ed Silberbauer and other BotSoc members did a survey of the occurrence of elata in a wider area in Betty’s Bay and this information was conveyed to the Bio-Security Directorate of DEA, who will conduct a follow-up inspection in December 2015.
• SANBI ISP is in the process of obtaining bids for removal of the mature elata on the Disa Jeugkamp terrain. This will place sharper focus on the funding required.
• The current article was prepared for publication in the newsletter of the Kogelberg Branch of BotSoc. However, as all Betty’s Bay residents are not BotSoc members, the threat which the spread of elata is posing needs to be brought to the attention of a wider audience. The article will therefore also be submitted to ‘The Buzz’, the newsletter of the Betty’s Bay Ratepayers Association.
• All home owners in Betty’s Bay are asked to check whether elata occurs on their properties and to cooperate in the urgent removal of these aliens.

The ‘Acacia elata Battle’ in Betty’s Bay is therefore in full swing. Although good progress has been made, the battle has by no means been won. The assistance of each and every one of us is required.

This article is a general information sheet and should not be used or relied on as professional advice. No liability can be accepted for any errors or omissions nor for any loss or damage arising from reliance upon any information herein. Errors and omission excepted. (E&OE)