Hard questions ahead for East Coast forestry
Forest harvesting on hillsides prone to erosion resulted in an environmental disaster of debris and fast-moving water. Esther Taunton reports.
Clear-felling of pine trees should never have been allowed on the steep, unstable slopes of Tairā whiti, a scientist says.
On Thursday, the Government announced a ministerial inquiry into forestry slash and land use on the East Coast. Slash, the scrap timber, branches and offcuts left behind when pine plantations are harvested, has been blamed for exacerbating flood damage during recent severe weather events, including Cyclone Gabrielle.
The announcement coincided with the evacuation of 64 homes in Tokomaru Bay amid fears a debris dam in a river above the town could fail.
While the public will have the chance to provide feedback to the inquiry panel, some scientists have already weighed in on the problem and possible solutions.
Dr Nathanael Melia, senior research fellow at Victoria University of Wellington’s Climate Change Research Institute, said the cause was simple: ‘‘All was calm when the catchments contained only standing forest in the decades following Cyclone Bola, then came the clear-fell harvest.
‘‘The situation with the forestry slash in Tairā whiti has proven to be a lethal environmental disaster that has plagued iwi, hapā , and local communities.
‘‘I have said for years that clear-fell harvesting is an inappropriate land-use practice for the slopes and soils of
Tairā whiti.’’
Clear-fell harvesting and leaving slash to replenish nutrients was a valid practice on the relatively stable slopes of the central North Island, but should never have been applied to the East Coast, Melia said.
His preference was for pine species to be selectively harvested, which would allow natives growing under them to be nurtured to maturity.
‘‘This would need the backing of local and national governments and could provide ample transitional employment opportunities beyond just the current short harvesting cycle.’’
Climate Sigma managing director Belinda Storey said
difficult questions needed to be asked about whether harvesting forestry was a reasonable activity in Tairā whiti. The region had some of the most erodable soils in the world and was exposed to extreme events.
‘‘The long-term response in these locations is likely to be permanent native forestry,’’ she said. ‘‘I recognise that forestry is a significant employer in the region, so if we move to permanent native forests, =we need to think about what a just transition for those communities would be.’’
Storey, who is also manager of the Whakahura: Extreme Events and the Emergence of Climate Change Programme, said
Tairā whiti had always been exposed to the weather, but the situation had been made worse by clearing the land for farmland and again when forests were harvested.
Trees were generally able to hold rain and trap it, and when hillsides were covered in trees, there tended to be less flooding further down, she said.
‘‘If you cut down those trees and get an extreme event, debris from that harvesting gets mobile, and that water is not held in the hillside, it moves much faster because the hillside is bare.’’
Private businesses were financially rewarded for growing trees quickly, sequestering carbon in the short-term, and then cutting the trees down, Storey said. ‘‘All the incentives are to plant pine trees. But if we accounted for all the costs of a disaster, I suggest native forest blocks would start to pay off.’’
Dr Tim Payn, a member of the Forest Owners Association environment committee and principal scientist at Scion, said the Crown research institute’s Resilient Forests research programme was designed to ensure the long-term economic, environmental and social sustainability of forestry.
Research trials were under way to identify forest management practices that could future-proof the industry’s productivity. However, it was also recognised that some regions would require bespoke systems.
Solutions could include retreating forestry from risky sites while supporting the industry to remain productive and generate value from slash and woody debris .