Hotspots from Nelson fire remain as crews race to salvage blackened forests

Tuesday, 9 April 2019

Hotspots remain two months after the Pigeon Valley wildfire started as forestry crews race to salvage trees in the blackened forests.

Tasman Pine Forests chief operating officer Steve Chandler said its priority was harvesting what could be salvaged, clearing out the rest, and replanting burnt forestry blocks.

He said the salvage operation was 'a race against time' before borer bugs like huhu beetles infested the wood.

Boring insects weren't a concern when harvesting healthy trees, Chandler said, but the fire meant they were harvesting dead or dying fire-damaged trees.

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'As soon as the trees get stressed these beetles move in, they can smell it a mile away,' he said.

The Pigeon Valley wildfire started on February 5 and spread over 2343 hectares of mainly pine plantation to become one of the country's biggest blazes. Up to 23 helicopters and 150 firefighters were on the fire ground at its peak. 

Tasman Pine Forests, which owned much of the affected plantations, has five logging crews salvaging as much as they can from the older forestry blocks. Chandler said the fire had burned some trees and left others untouched, but even the burnt trees could be salvaged.

'Generally in most forest fires it's only the bark that gets burned, unless the whole tree is incinerated. It kills the tree, but it doesn't tend to burn too far into the wood.'

He said the blocks which were over 20 years old were still saleable, but any trees younger than that were not mature enough for market. The salvaged wood would also likely be sold for lower prices than they would normally fetch.

Salvaging is just the first step in the recovery for the Tasman forestry industry, however. Chandler said for Tasman Pine it would be an estimated three-year project to clear and replant all the fire-damaged land.

'We'll never quite get back to normal because that's a lot of years of growth that have been lost.'

While work has already begun to harvest what can be saved, clear the rest and replant the land, several hotspots are still burning in the land consumed by the wildfire.

Chandler said there were about eight to 10 hotspots on Tasman Pine land and he was working with Fire and Emergency (FENZ) to manage them.

Principal rural fire officer Ian Reade said they were still finding new hotspots, particularly on skid sites, where trees are brought for initial processing after harvest, and in old 'bark dump-sites'.

'It can keep burning, a deep fire underground like this one can keep ticking over for months and months,' Reade said.

'There's a lot of work going on with re-establishment, replanting and harvesting … those people are on site keeping an eye on things. We're using thermal imaging to find some, and with the cold winter mornings the hot-spots can make themselves known with columns of steam.'

He said without proper management, the underground fires could 'pop up' again unexpectedly, but there was little danger of that with FENZ and forestry working together to dig up potentially dangerous hot-spots to extinguish or burn them out, and leaving minor ones to extinguish over winter.

Reade warned that conditions were still right for fires to start.

'We've had two calls where people have lit fires in the wrong locations and it's got into scrub. You've got to be aware of the location, things like if it's near a slope, the grass might look green but on a clear day like today it'll still burn, anywhere near scrub - that's what's caught out the two callouts we had.'