Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

When plants turn bad

Understanding how and why plants make the transition to weedy species, often after long lag times, is one of the aims of an ambitious new research project.

Lincoln-based researchers Peter Heenan and Gary Houliston want to address the significant information gap on the lag phase – often 20, 40 or even 100 years – from the time that plants are first recorded to their becoming fully established weeds.

‘Much of the research in New Zealand is based on current weeds – ones that have been around for a long time, but there is little knowledge about changes that occur to newly naturalised plants after we first record them in the Allan Herbarium here at Lincoln until they’re considered a “weed”,’ Dr Heenan says.

This research will allow better decisions about what plants to let into the country as well as improve biosecurity and management of naturalised plants.

Dr Houliston says that the ability to identify certain plant attributes, along with a better understanding of plant biology, could potentially lead to local authorities acting earlier and more cost effectively to eradicate weeds. He also wants to know what triggers the plants to become weeds, with many people suggesting it could be the plants building up critical mass or adapting to local conditions.

‘So, we’re studying three Australian species that are becoming weedy in New Zealand – a Banksia and two Acacia (wattle).

‘We want to get their genetic profiles from where they’re growing naturally in Australia and compare these to the profiles of the same species being sold and planted in New Zealand. We can then compare these with profiles of the seedlings that are weedy to better understand the process.

‘We can then look at variation in the native range, how much is being sold here commercially, how much is being planted out and then how much of that is actually self-establishing. Molecular tests will then determine if the self-establishing trees are a subset of the genetic range in Australia or a subset of what’s been introduced here. Likewise, it’ll show if they’re novel new genotypes that have arisen only in New Zealand,’ Dr Houliston says.

If successful the information could be replicated to other species and provide significant advances in the ongoing battle against weeds.

Dr Gary Houliston

Dr Peter Heenan

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