Fires ravage Port Hills
Firefighters have spent much of the week battling fires on Christchurch's Port Hills, which have forces families out of their homes.
Two fires started in separate locations on Monday evening, but by Thursday they had merged into one fire encompassing an estimated 1800 hectares.
The resulting cloud of smoke has been visible from space - pictured above is the view on Thursday from the CawthronEye.
University of Auckland ecologist Professor George Perry said the vegetation on much of the Port Hills was extremely flammable, especially in areas with abundant gorse. "The dry and windy conditions in Canterbury have led to conditions conducive to fire spread as fuels are dried and the flaming front pushed by the wind."
Lincoln University ecologist Dr Tim Curran said that fuel was a key determinant of fire behaviour, but that not all plant species are equal when it comes to fire. Biomass, arrangement and flammability all affected the behaviour of a given fire.
"The Port Hills and Banks Peninsula have large tracts of continuous, highly flammable vegetation. This includes scrub dominated by gorse, pine and eucalypt plantations of shelter belts, pastures and grasslands, and native regrowth dominated by kanuka."
"When combined with hot, dry and windy weather, such vegetation fuels the intense and extensive fires like those we are currently experiencing on the Port Hills."
Prof Perry said a key question in the longer term was "what vegetation will replace that which has burned?"
"Those species that appear in the aftermath of fire tend to be highly flammable so there is the potential for a feedback loop in which ‘fire begets fire’, a dynamic that may be exacerbated in a drier, warmer future," he said.
"It is important for New Zealanders to consider how best we might ‘fire-proof’ our landscapes by, for example, using tools such as ‘green firebreaks’. "