When degraded rivers are mentioned, the impact of plantation forestry is often part of the conversation. Is the criticism justified? Bill Moore asks the industry and the watchdogs.
Nobody denies that forestry has harmed many New Zealand rivers. The good news is that there's an improvement.
Many anglers claim that forestry has "stuffed" rivers. There's evidence that the effects of harvesting - not just the "slash" left behind to wash downhill, but the run-off from new roads and skid sites - can be catastrophic for otherwise healthy waterways.
The Motueka River, internationally famed for its bounteous brown trout, took a very visible hit when the loggers swung into action some years ago. Neither the fish population nor the river's reputation have recovered - but the experts, as opposed to the riverbank critics - believe that frequent big floods are responsible for most of the losses. The aftermath of logging is a factor, but not the main cause, they say.
Nelson City Council has its own small forest in the Maitai River catchment, 172.8 hectares, managed for it by one of the big foresters, P F Olsen.
The New Zealand wing of the giant multi-national Hancock Forest Management has a further 2000ha in the catchment, with just under 25,000ha in the wider Nelson region.
Hancock's Maitai forest is under Crown forest licence and the land under the Hira forest will transfer to Ngati Koata on August 1, part of the top of the south iwi settlements.
A public meeting the council held three months ago heard complaints from residents about some forestry practices. But Forest and Bird national advocacy manager Kevin Hackwell, who grew up in Nelson and campaigned unsuccessfully against the Maitai plantings in the 1980s, says the industry as a whole works constructively to minimise environmental damage.
Still lamenting the Maitai pines - " left alone that would be 30 years now of regeneration back to native bush" - he is working with Fish and Game's Nelson-Marlborough regional manager Neil Deans on New Zealand-wide forestry standards under the Resource Management Act, consulting with forest companies, regional councils and the Ministry for Primary Industries.
"To be fair, I think most of the big forestry companies in New Zealand, Hancock included, are pretty alert to the environmental issues," Hackwell says.
"Everybody knows the big risks are at the time of logging and the immediate post-logging period. The industry is putting a lot of effort into that."
But then come events like the weather bomb that brought devastation to coastal parts of Golden Bay in December 2011, with forest "slash" bearing some of the blame.
"It's that sort of stuff which is the most dangerous - getting through that harvesting and immediate post-harvesting period without having a major weather event."
Hackwell is advocating riparian buffers or setbacks, so that commercial forests aren't planted closer than 10 metres to the banks of waterways. That creates wildlife corridors and lessens the visual impact if native plantings are in-between.
"Yes, the Forest Service planted right down to the stream edges in the 1980s; this time around we need full setbacks, a new buffer."
He thinks New Zealand is already close to international best practice in plantation forestry management but says councils are responsible for monitoring conditions, and their performance varies greatly and "isn't very good at times".
"Some councils see it as a very important issue and others either don't, or don't have the resources to do it properly. Locals are really important in this stuff - they're the ones seeing machinery in the rivers or stuff dragged across streams when it shouldn't be."
He says performance isn't perfect "by any stretch", but compared to some primary sector groups, the forestry industry is "one of the more switched on".
Forest and Bird and other environmental groups signed the Forest Accord in 1991, and had experienced a constructive relationship with the plantation forestry industry since.
"They are a very unified sector and they have done a lot of work on getting their own industry standards up." Deans largely echoes Hackwell's view of the industry.
"They've got some things that they do well. They're largely the employees of large corporates, they're technically competent, they know what the issues are - but they're lean mean operators in the sense that they don't have a lot of resources at their disposal."
He says sediment is a major contaminant of waterways and over a 30-year forestry cycle there's often less than from farming.
"For 25 of that 30 years there may be next to nothing coming off, but then in a short period, if you get the combination of opening up the roads again, reopening the landings, doing all the work and then getting high intensity rainfall, you can get disaster wrought on the land, which then runs off into the river."
He has some sympathy for the forestry sector because it's often unfairly blamed for problems, Deans says.
"Having said that, and having been to other parts of the world where forestry is a major issue, we put trees in this country on steeper slopes, in tougher country, and then we have much larger coup sizes [areas cut down in one go] than they would ever allow in Sweden or North America."
Hancock southern area manager John Moorhead says parts of the Maitai catchment are "particularly challenging" to harvest, with steep slopes dropping directly to the river and trees planted to the edge. To add to the challenge, some of the area being cut was wind-damaged.
"The area has been cable-logged using the most up-to-date equipment available for harvesting this topography," Moorhead says. "We have used a harvesting machine tethered by cable to a winch at the top of the slope, a system developed by harvesting contractors in the Nelson area."
The main driver was to increase safety, but the system provided environmental benefits by giving greater control over trees as they were felled, stopping them toppling into the river.
All potentially unstable woody material was pulled to the top of the slope to avoid future risk of rain shifting the wood into the river, and the logging was done without the need for any earthworks on the slopes above the river.
Operations are consented by the city council, and monitored by its staff, Moorhead says. Hancock has taken Friends of the Maitai members on a field trip and engages with iwi, the council and others. The company intends to harvest 30ha in the Maitai catchment over the next 12 months.
It isn't practical to leave a strip of radiate pine along the edge of the river as these will end up toppling in, causing much more damage than controlled harvesting, he says. It is better to harvest the current crop, minimising impacts, then introduce a set-back strip when replanting.
On the wider issues, Moorhead says Hancock, certified by the international Forest Stewardship Council, is using best practice to minimise impact on New Zealand waterways, with maintaining and improving water quality a key management objective.
"Clear-cut areas in New Zealand plantations are comparable to those in other countries that operate similar plantation forestry systems, such as Australia, Southern USA and Chile. In some parts of the world clear cuts are limited to smaller areas, but this is typically in native forest harvesting."
The city council told the Nelson Mail that all forestry earthworks require a consent covering sediment control and skid sites, monitored by contractor Environmental Inspections Ltd, with industry best practice guidelines adhered to.
Harvest is timed around international wood prices and the council's forest isn't a money-spinner at the moment. Its forestry account recorded a $284,000 deficit last year. The deficit is projected to drop to $23,000 for 2013-14.
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