Rebuilding a threatened plant population

Biodiversity Specialist-Plants Anita Benbrook says Wellington city has 42 species that are listed as Critical, Endangered, or Declining, plus many more that are becoming very uncommon.

A working group has been looking at how to bring many of these species back from the brink, with habitat loss, pest plants, and browsing pest animals the key issues.

Anita says a recent discovery has boosted the local matagouri (Discaria toumatou) population.

“A curious enigma, matagouri can be a curse to many farmers in the South Island, where populations are in slow decline. However it’s a different situation in the North Island.

“The plant numbers in the North Island are so seriously Critical, they are unlikely to be able to survive without intervention.”

Matagouri is a thorny shrub that can grow up to six metres high. It has spines up to 5cm long with very fragrant small white flowers.

Anita says these plants are beneficial as they can fix atmospheric nitrogen, which helps other plants.

“Old plant records suggest matagouri may once have been a common sight amongst the grey scrub, from Miramar to Mt Victoria and around the south coast.

“One of the many benefits of Predator Free Wellington's Miramar eradication is the increased access to many of the areas of land not previously visited.”

While checking one of these traplines, Predator Free Wellington’s Community Engagement and Field Officer Joakim Liman recognised the significance of coming across some previously undiscovered plants of matagouri.

He contacted Anita right away, and the collaborative approach to threatened plants means these plants have now boosted the Wellington population as they are healthy and fruiting.

Manager of Council's Urban Ecology Team, Daniela Biaggio says Predator Free Wellington has done a great job employing staff who are not only passionate about the eradication of predators, but also knowledgeable and passionate about plants and our other environmental taonga.

"This finding was an awesome consequence of having people like Joakim exploring new grounds," Daniela says.

Anita says Gary James from the Community Forest and Bird Nursery has gathered over 300 seed off the plants, more than the usual 20 or 30 seed from previous years from the only other known plants in Wellington.

“These new plants are healthy and are substantial shrubs, unlike the trailing small relic shrubs we have been trying to protect.”

Anita says once the seed has germinated and some healthy new plants are produced, they can form the basis of a new population in one of Wellington's coastal reserves.

“Thanks to this discovery, we can start the journey of rebuilding this population once more.”