Warming NZ climate ignites forest fire risk

A warming New Zealand could help our pine forests grow — but not without extreme fire risk almost doubling by the end of the century.

Scion researchers have modelled what climate change will mean for plantation forests, taking into account everything from growth gains to risk from pests, disease and wind.

The modelling suggested changing climatic conditions — notably higher temperatures and changes in rainfall — would bring few gains in productivity for our main commercial forest species, radiata pine.

But when the photosynthetic effects from increasing carbon dioxide were factored in, the researchers estimated productivity gains of around 10 per cent by 2040, and double that by 2090.

The study’s lead author, Dr Michael Watt, said some other positives emerged from the projections. More growth would mean greater uptake of CO2 which could further offset New Zealand’s carbon emissions.

And two key pine needle diseases, dothistroma and cyclaneusma, didn’t appear to become more damaging under climate change.

But Watt said the increased productivity would bring marked increases in wind risk, due to trees becoming taller and more slender.

The average season length with “very high and extreme” climatic fire risk could almost double under climate change by 2090.

Rural fires already cost the economy around $67 million each year, although they generally tended to be smaller, and not on the scale of monster blazes seen in dry places like Australia.