Planning for Fire-Resilience

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. 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.

Breaking the ‘Fire Trap’

Researchers say plant selection is only part of the equation.

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.”

Basal resprouting recorded 17 months after the February 2024 Mt Ada wildfire

Species	Resprouted
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 Cordyline australis plants could not be located after nine months. Source: Clemens, J. and Jameson, P.E. (2026), Forests 17, 999, Table 2.