This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Mākaka (native broom) and kōwhai seeds might be able to survive the heat of fires, new research shows. Scientists heated native and exotic seeds in a lab oven to temperatures they may face in the soil during a fire, expecting only the exotics—which often experience fires in their homelands—to survive.
However, mākaka and kōwhai seeds survived up to 80°C, and mākaka seeds even sprouted in response. Māhoe, tī kōuka (cabbage tree) and matagouri seeds died after heating, while invasive gorse survived 100°C and sprouted. As fires get more common in NZ, it's important to understand if any native seeds could survive and grow back, the researchers say.
Lead author of the paper Dr. Sarah Wyse, senior lecturer in forest ecology at the School of Forestry, University of Canterbury, comments, "In our study, we looked at the ability of seeds of some of our native species to tolerate high temperatures in a laboratory setting, relative to exotic species that have frequent fires in their native range (and which we would therefore expect to be more tolerant of being heated in a soil seed bank than our native species). "Interestingly, we found that the native broom species we looked at (Carmichaelia australis) is able to tolerate temperatures of 80°C (176°F), and that those temperatures even stimulated the seeds to germinate.
Kōwhai was also able to tolerate these temperatures, but heating did not break the physical seed dormancy of this species. "In comparison, gorse could tolerate heating to 100°C (212°F) (the highest temperature we looked at), and all temperatures of 60°C (140°F) and higher broke seed dormancy and stimulated germination—explaining why gorse comes up after a fire! Seeds of species like māhoe, cabbage tree and matagouri were killed by high temperatures.
So if a fire goes through an area, we might expect it to kill seeds of these species in a soil seed bank, while encouraging all the gorse to come up." The work is published in the New Zealand Journal of Botany. Wyse et al, New Zealand Seed Ecology in the Pyrocene: Testing Seed Responses to High Temperatures Under Laboratory Conditions, New Zealand Journal of Botany (2026). DOI: 10.1002/nzb2.70159 MA in English, copy editor since 2021 with experience in higher education and health content.
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