Invasive species are one of the biggest threats to indigenous biodiversity. Another new weed for Aotearoa New Zealand has been reported by Botany Curator Leon Perrie and Geneticist Lara Shepherd. They ask whether we are doing enough to identify and control new weeds.
Weed species – exotic plants that have been recorded as self-propagating – now outnumber indigenous species in Aotearoa New Zealand among vascular plants (principally flowering plants, conifers, and ferns). Indeed, New Zealand’s North and South Islands are some of the weediest islands in the world. And the list of weeds continues to grow at a frightening rate.
Our recent publication in Te Papa’s journal Tuhinga adds another weed for Aotearoa New Zealand, documenting the establishment of the Australian tree Lomatia fraseri.
Our paper is freely accessible here.
Lomatia fraseri in New Zealand
A ridge overlooking Wainuiomata is infested with thousands of individuals of Lomatia fraseri. This was first brought to our attention in July 2019. But it is clear that Lomatia fraseri has been establishing at this site for much longer, given that there are many individuals and some of them are big.
Self-sown individuals have also been reported from elsewhere in the Wellington region and near Christchurch.
Lomatia fraseri has a fairly wide indigenous distribution in mainland Australia. This indicates it can thrive across different environments.
In Aotearoa New Zealand, Lomatia fraseri has demonstrated its ability to both dominate suitable sites and disperse reasonable distances.
Nevertheless, weed management authorities are not controlling the Wainuiomata infestation because it is not in a so-called “Key Native Ecosystem”. KNEs are those that are “the best and most threatened examples of our native ecosystems”. However, several KNEs are within only 4 kilometres.
It might turn out that Lomatia fraseri is largely restricted to regenerating mānuka forest. Even disregarding the natural values of mānuka forest, there is the potential for Lomatia fraseri to impede what is now a lucrative honey industry.
What you can do
Adults and saplings of Lomatia fraseri are very distinctive. If you see plants outside cultivation, please report them to your local council, and record them in the public domain with the likes of the iNaturalist website. Leave a comment below if you’d like me to help with identification.
Additionally, given that Aotearoa New Zealand’s indigenous species and ecosystems are being overrun by weeds, you might like to ask your local council to do more.
You can learn how to recognise and control the worst of our weeds on the excellent Weedbuster’s website.
How many weeds are on your whenua (land)?
The bigger picture
It’s concerning that such a distinctive weed has been able to establish so intensively and for so long within a major suburb of Aotearoa New Zealand’s capital city. Is the country doing enough to spot newly establishing weeds and pests?
Furthermore, even when we are spotting new weeds and pests, is enough being done to stop them? Lomatia fraseri has already shown it can invade and spread.
As we write in our paper, “We fear that by leaving yet another exotic species to establish itself in New Zealand, we (the New Zealand of 2021) will be shown to have been negligent in our kaitiakitanga (caretaking) of the taonga (treasures) that are the indigenous plants, animals, fungi and other biota of Aotearoa.”
A native we don’t like? Like spur-winged plovers.
A wind-blown native we like? Orchids.
Kia ora Robert.
Lomatia fraseri is native to mainland Australia. It is not native to New Zealand. But it has been introduced to New Zealand and cultivated here, presumably as an ornamental.
It’s estimated that some 20000-30000 exotic plant species are cultivated in New Zealand (compared with c. 2500 native vascular plant species). Exotic plants originally cultivated in New Zealand are steadily becoming naturalised (i.e., going weedy) here – Lomatia fraseri is another one of these.
Ngā mihi, Leon
A large part of the problem is, I think, that there is a very limited number of people who have an interest in and knowledge of weed species. This means that early and potentially controllable infestations are missed with the result that large sums of money are spent on well established infestations. Such efforts are often futile. There is no easy solution.
Kia ora Mike,
I agree about the lack of interest/knowledge. Which is why MPI’s strategy of relying on public surveillance seems ambitious/misguided. The solutions aren’t easy, but maybe involve greater active surveillance by biosecurity agencies and greater education for the public about identifying/recognising biodiversity. As you know, iNaturalist can play a part in both of these, but maybe more so the latter.
Kind regards, Leon