La Trobe botanist helps shed light on invasive plant species (Issue 4, 2011)

20110217_Botany-picAustralia is home to many unique species of flora and fauna. As a result, keeping Australia free from diseases and pests that might harm our ecosystems is serious business.

While we often think about the effects of introduced threats to Australia’s wildlife, those that affect the land are just as serious. Invasive plants cause extensive environmental, economic and social problems. They lead to loss of native biodiversity and damage the functioning of ecosystem, such as the recycling of nutrients.  With climate change, gaining knowledge about plant spread and behaviour has become more urgent.

To further investigate exactly why invasive species can take such a strangle-hold on an environment, a team of 36 scientists, including La Trobe University botanist Dr John Morgan, have carried out research on this ecological phenomenon.

As part of its research the team of scientists carried out a ‘Home and Away’ study where 26 species were grown at 39 locations on four continents.

The study found little difference between plant numbers in their introduced environments and their native ranges.

'We discovered that increases in species abundance are, in fact, unusual,' says Dr Morgan.

These results shot holes in one of the most common theories about how invasive species establish themselves at the expense of native plants.

Dr Morgan explains that previously, predicting the success of invading species has always relied on the assumption that these plants are more abundant in their new settings than they are in their native communities because they behave in a special way.

An example is the highly invasive weed English Broom which has infested large parts of eastern Australia and New Zealand. It was thought the absence of natural enemies that kept the species in check in Europe, combined with its ability to fix its own nitrogen, gave it competitive advantages over the native species in its new range.

However, this new research has found that the abundance of invasive species in new environments is more to do with the plants own ability to spread rather than the lack of natural enemies.

'Success of a plant on its native range can probably be used to predict its spread at introduced sites – a criterion which currently is not included in biosecurity screening programs,' says Dr Morgan.

Dr Morgan's field study was carried out in alpine grasslands at Falls Creek in Victoria and was the only Australian field site in the global initiative. The study was carried out by the Nutrient Network, with funds from the US National Science Foundation's Division of Environmental Biology.


La Trobe University offers a range of undergraduate and postgraduate courses in biological sciences. For more information go to our international coursefinder.