It could take several days before the fire on the commercial forestry property was completely out.
Four helicopters, five water tankers, two other fire appliances and about 55 men were on site yesterday.
A command unit from Wellington was also brought in.
Mr Wishnowsky said one of the neighbouring landowners alerted the fire service to the blaze.
Incident control officer Pete Sainsbury of Juken New Zealand said the fire was in an area of forest that was in its second rotation.
That meant ground crews had the added difficulty of old logs and stumps to "mop up" as well as creating fire breaks.
Helicopters were dropping 800-litre buckets of water directly on to the flames.
The ground crew also included forestry workers and firefighters from Gisborne, Wainuiomata and Upper Hutt.
Mr Sainsbury said the forestry workers were trained to deal with fires and praised the work of those involved.
"We just couldn't do it without the people," he said.
He said the log supply to JNL would not be affected.
Forestry worker and rural firefighter Tyrone Ewington was one of the replacements for the men who worked through Wednesday night.
He said the fire was quite big, although this was not the first one he had faced.
It was unclear what had started the blaze and police were investigating. Nobody was injured in the incident.