Native planting needs fire-smart approach
New research into native planting damaged by the 2024 Port Hills wildfire suggests plant selection, weed control and design could all play an important role in creating more fire-resilient landscapes
Some young native trees and shrubs can recover after being badly damaged by wildfire – but what is planted around them could determine whether that recovery succeeds.
That’s one of the findings from Te Whare Wānanga o Waitaha | University of Canterbury (UC) research examining native restoration planting affected by the February 2024 Port Hills wildfire.
Researchers studied native woody plants for 17 months after fire swept through a restoration site at Mt Ada on 14 February 2024. The area had previously burned during the major 2017 Port Hills wildfire and was subsequently replanted.
The study found significant differences in the ability of species to recover. Broad-leaved Coprosma performed particularly well: 16 of 17 monitored plants initially resprouted, with 15 still showing basal resprouting at 17 months.
Other species showed much lower recovery rates. Three of four monitored tī kōuka/cabbage trees resprouted, as did three of six Olearia avicenniifolia and four of 11 five-finger. Young kānuka, akeake, Hebe, korokio and tōtara did not resprout during the 17-month monitoring period.
The researchers caution that the results are not a definitive ranking of fire resistance. The plants were less than seven years old and, as some species mature, increasing size and bark thickness can improve their ability to survive fire and resprout. Griselinia littoralis illustrates the point: only one of 15 young plants resprouted at Mt Ada, while previous studies of older plants recorded much higher recovery rates.
How the natives fared
Basal resprouting recorded 17 months after the February 2024 Mt Ada wildfire:
Species | Plants resprouting |
Coprosma spp. | 15/17 – 88% |
Cordyline australis – tī kōuka/cabbage tree | 3/4 – 75%* |
Olearia avicenniifolia | 3/6 – 50% |
Pseudopanax arboreus – five-finger | 4/11 – 36% |
Hoheria angustifolia – houhere | 2/9 – 22% |
Sophora microphylla – kōwhai | 2/9 – 22% |
Pseudopanax crassifolius – horoeka/lancewood | 1/6 – 16% |
Griselinia littoralis – broadleaf/kāpuka | 1/15 – 7% |
Pittosporum tenuifolium – kōhūhū | 1/20 – 5% |
Olearia paniculata | 0/8 |
Podocarpus totara – tōtara | 0/10 |
Kunzea robusta – kānuka | 0/15 |
Hebe spp. | 0/6 |
Dodonaea viscosa – akeake | 0/10 |
Corokia cotoneaster – korokio | 0/5 |
*One of five initially tagged Cordyline australis plants could not be located after nine months. Source: Clemens, J. and Jameson, P.E. (2026), Forests 17, 999, Table 2.
However, researchers say plant selection is only part of the equation.
Breaking the ‘fire trap’
Highly flammable non-native grass had grown densely through the restoration site before the 2024 fire and quickly re-established afterwards.
UC School of Biological Sciences researcher Professor Emerita Paula Jameson says this can create what ecologists call a ‘fire trap’, where repeated fires prevent regenerating native vegetation from reaching maturity.
“You can plant native trees and shrubs but if highly flammable grasses and weeds remain around them, fire can keep setting that regeneration back before it has the chance to develop into mature forest.”
Co-author Dr John Clemens says the research provides further information about which native plants may be better placed to survive wildfire, although species alone does not determine the outcome.
“Age and size matter, as do fire intensity and the conditions around each plant. This research gives us another piece of the puzzle about how we might design restoration plantings and protect naturally regenerating areas with wildfire in mind.”
Designing for resilience
The researchers say greater consideration could be given to ‘green firebreaks’ – strategically planted areas containing lower-flammability species that may help protect regenerating native bush.
Used alongside native species capable of resprouting after fire, the approach could help improve the speed of recovery following a wildfire.
Drawing on the Mt Ada results and earlier New Zealand research, the paper identifies Griselinia littoralis, Fuchsia excorticata, Melicytus ramiflorus (māhoe) and Carpodetus serratus (putaputawētā) as potential green-firebreak candidates because they combine relatively low flammability with an ability to resprout.
Jameson and Clemens are also members of the Summit Road Society, which has three reserves on the Port Hills. One, Ohinetahi Reserve, was burned in both 2017 and 2024. Volunteers have recently planted a green firebreak where fire twice crossed into the reserve, but Jameson says keeping grass and other flammable weeds down around the new planting will be critical to preventing another fire from resetting the return to less fire-prone native bush.
Active management is also important. Jameson and Clemens say controlling highly flammable weeds and grasses, alongside planting natives in ways that encourage faster canopy closure, could reduce the risk of restoration sites becoming caught in a cycle of repeated fires.
The findings provide a key consideration for landscapers involved in native restoration and revegetation projects, particularly in areas exposed to increasing wildfire risk – creating resilient landscapes depends as much on which species are planted as how the entire site is designed, established and maintained.
