Daily Bulletin


The Conversation

  • Written by The Conversation
imageIt may look attractive, but Lantana has crowded out native plants. mehrishi/Flickr, CC BY-SA

Think of a weed and that annoyingly stubborn plant you can never quite rid from the veggie patch inevitably springs to mind. We are accustomed to viewing weeds as the ultimate pests of the plant word, apparently existing only to give gardeners and conservationists a headache. It may even be tempting to distinguish between native plants and weeds as a simple case of good versus bad.

But is this distinction accurate, or even useful? A look at the complex nature of weeds can shed some light on this issue.

imageNative fauna, like the blue wren, rely on weeds such as blackberry to provide food and habitat.Kathryn Lambert, Author provided

The lowdown on weeds

A weed is typically a plant that inhabits and endures in an ecosystem where it did not occur before. It can be either native or exotic, and generally moves into new habitats when it has an advantage over resident plants.

Weeds commonly produce a large number of seeds and they reproduce and survive well in environments as diverse as cities, deserts, farmland, bushland and gardens. They succeed in a range of temperatures and climates.

A native weed you may be familiar with in Australia is the Cootamundra wattle (Acacia baileyana), which has established itself outside its natural range. This species flowers profusely and as a result has been planted in a variety of gardens.

It is also used as a food source by ants and birds, which then transport the seeds to different areas. Because these seeds remain viable for decades and germinate quickly after fire, this species can take over some habitats and gardens.

imageThe Cootamundra wattle is considered a weed in Victoria, where it out-competes native local species.momentaryglimpse/flickr, CC BY-NC-ND

Are weeds bad for the environment?

It is important first to recognise that species classified as native do not always have positive effects on the local environment. The native Christmas beetle, for example, is suspected of killing multiple broad-leaf peppermint gums (Eucalyptus dives) in Australia. Similarly, categorising flora according to how long these have occupied an ecosystem does not tell us much about a plant’s role in that habitat.

Nevertheless, the underlying assumption for conservation and restoration remains that non-native species offer little by way of ecological benefits. But this is not necessarily the case.

The devil’s claw plant (Martynia annua) was brought to Australia from Mexico in the 19th century as a garden plant, like many weeds now present here. This plant has been removed by hand for the past 20 years in Gregory National Park in the Northern Territory.

However, there is little evidence to suggest this species has negatively changed this ecosystem by increasing nitrogen or reducing biodiversity. Instead, native birds and insects gather nectar and pollen from the devil’s claw, so its removal could be detrimental to the native fauna that regularly feed on it.

Blackberry is another exotic weed, introduced for its fruit, which has spread over more than 8.8 million hectares in Australia. It has reduced the productivity of primary industries, restricting access to land and water as it forms large thickets and overgrown shrubs.

But despite its negative influence on farmland and bushland, this species also provides benefits for fruit and honey production, fodder for browsing animals and food and habitat for some native fauna species, including bandicoots and blue wrens. So its removal, like many other weeds, could be detrimental to the survival of native fauna.

The case of Lantana

My research has focused on another prominent weed known as Lantana (Lantana camara). It is admired for its mass of pink, yellow and red flowers, but also derided for its negative environmental impacts.

After beginning as a humble garden plant, Lantana unfortunately escaped and has been spread by birds and small mammals that feed on its seeds and fruits. This species has changed soil nutrient characteristics by increasing nitrogen, which can cause stress and even death in forest trees. It has been blamed for the death of thousands of eucalypts in northern New South Wales.

imageA native bush rat caught in Lantana.Kathryn Lambert, Author provided

Lantana is so invasive that it is now illegal to sell it in nurseries or even grow it in your garden. Any plant is a potential seed bank for more invasion.

But what if, despite all the negative influences of this species on floral diversity, the removal of Lantana actually harms native fauna? Our research at the University of New England’s Avian Behavioural Ecology Lab shows that this might indeed be the case in forested areas in NSW.

When Lantana in this area began dying after an eradication program, we noticed a fall in the numbers of certain species such as Antechinus and bush rats. It turns out that this weed provides invaluable habitat for these small native mammals.

So it seems that at least some native species are starting to adapt to, and even rely on, weeds as a food source and habitat. What would happen if, in the name of conservation, we completely removed them from these areas and even our own backyards?

As we’ve seen, the answers aren’t always straightforward, and there’s a chance it could end up doing more harm than good.

Kathryn Teare Ada Lambert does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Authors: The Conversation

Read more http://theconversation.com/hold-the-spray-some-garden-weeds-are-helping-native-wildlife-47848

Writers Wanted

Why a carbon price alone won't be enough to drive down New Zealand's emissions

arrow_forward

At last, health, aged care and quarantine workers get the right masks to protect against airborne coronavirus

arrow_forward

NZ’s clean car discount is a turn in the right direction, but how much will it drive consumer demand?

arrow_forward

The Conversation
INTERWEBS DIGITAL AGENCY

Politics

Prime Minister interview with Karl Stefanovic and Allison Langdon

Karl Stefanovic: PM, good morning to you. Do you have blood on your hands?   PRIME MINISTER: No, it's obviously absurd. What we're doing here is we've got a temporary pause in place because we'v...

Karl Stefanovic and Allison Langdon - avatar Karl Stefanovic and Allison Langdon

Prime Minister Scott Morrison delivered Keynote Address at AFR Business Summit

Well, thank you all for the opportunity to come and be with you here today. Can I also acknowledge the Gadigal people, the Eora Nation, the elders past and present and future. Can I also acknowled...

Scott Morrison - avatar Scott Morrison

Morrison Government commits record $9B to social security safety net

The Morrison Government is enhancing our social security safety net by increasing support for unemployed Australians while strengthening their obligations to search for work.   From March the ...

Scott Morrison - avatar Scott Morrison

Business News

Boom in Aussies buying up restaurants, pubs, hotels and bars in regional centres

With international borders closed, regional Australia is seeing a dramatic surge in popularity as people move out of the cities and into their quaint communities. City slickers are looking for new...

Tess Sanders Lazarus - avatar Tess Sanders Lazarus

5 Signs Your Business Needs Onboarding Software

Onboarding software is the technology that automates a smooth transition for new hires from before the interview to the first day on the job. High-quality onboarding platforms feature a digital da...

Onboarded - avatar Onboarded

What Is COVID 19 Risk Assessment for Vulnerable Workers and Why Your Business Needs it

During the height of the COVID-19 pandemic, governments strongly advised people to just stay at home as a critical effort to stop the spread of the virus. This led to many businesses temporarily s...

NewsServices.com - avatar NewsServices.com