A bridal creeper research site along the Gaidner River in the Fitzgerald National Park, Western Australia. The photos were taken one year apart.

Dead or alive – bridal creeper is bad for environment

Reference: 07/187

Bridal creeper, a native of southern Africa, is an attractive plant once much loved by gardeners. Now it is one of southern Australia’s worst environmental weeds. It smothers native vegetation and its huge tuber mats prevent germination of native plants.

• 19 September 2007

This invasive plant has been successfully targeted by biological control programs across Australia with control of up to 95 per cent, but until now little has been known about what happens after the weed is controlled or killed. The assumption has been that the native bush would regenerate.

New research has shown that this is not necessarily so. Instead, restoration and revegetation projects need to manage the lingering environmental changes associated with weed invasion.

At the 9th International Conference on the Ecology and Management of Alien Plant Invasions in Perth 17 - 21 September, researcher Peter Turner will present the results of his PhD research on the ecological effects of bridal creeper invasion and its removal.

“Generally native plants are adapted to low nutrient soils while exotic invasive species prefer more fertile soils,” Mr Turner says. “But bridal creeper has no problem invading low nutrient soils and taking over.

“Our research has shown that once bridal creeper is removed it leaves behind more fertile soil than when it first invaded and these changes in soil nutrients could favour invasion by other weeds rather than the regeneration of the native bush.

“We have shown that soil in areas invaded by this weed in south west Australia have higher levels of available nutrients than nearby weed free areas.”

A bridal creeper invasion replaces native woody shrubs and increases the rate of nutrient cycling. It is deciduous at the end of spring and as its foliage contains higher phosphorous and nitrogen levels than natives, the decaying foliage adds these nutrients to the soil. Its tuberous root mat then traps these nutrients.

“One important finding of our research is that restoration and regeneration work at sites freed from bridal creeper need to take into account the increased soil fertility or it could just be a case of exchanging one weed for another,” Mr Turner says. “Sites with high conservation value need to be identified so that the biological control actions can be used in conjunction with other restoration techniques.”

Mr Turner is completing his PhD at the University of Western Australia and CSIRO Entomology. The research was part of the Cooperative Research Centre for Australian Weed Management. He has recently moved to Sydney to develop a national plan aimed at reducing the impacts to native biodiversity caused by another serious environmental weed, Lantana camara.

Download images at: Dead or alive – bridal creeper is bad for environment.

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