A need for more resilient forests
The pictures from Tolaga Bay this week were alarming. We saw forestry debris piled up against a bridge, surrounding an isolated house and stranded across muddy fields. This was the disastrous consequence of heavy rainfall in a forest environment affected by clear-felling.
As has become commonplace, we quickly calculate the financial cost of the disaster. Cleaning up will cost $10 million, according to reports, and Gisborne Mayor Meng Foon expects the forestry sector to cover some of the bill.
But behind these immediate questions, there are greater concerns about the sustainability of clear-felling. There were similar scenes four months ago near Nelson, in the wake of ex-cyclone Gita. Both disasters might suggest the need for a rethink.
David Hall, an Auckland University of Technology senior researcher who wrote the Pure Advantage report Our Forest Future, argues persuasively that both show how much is at stake as we prepare to plant one billion trees. With climate change expected to produce greater and more frequent storms, ‘‘it is critical that we don’t plant one billion of the wrong trees in the wrong place with the wrong management system’’.
The deep question we face is how to balance commercial return with environmental sustainability, while minimising future disasters. In New Zealand, clear-felling still dominates. Large swaths of forests are cleared and replanted at once, creating ugly, denuded tracts of land. But it is not just aesthetic. Clear-felling also creates ‘‘a window of vulnerability’’ when land is at an increased risk of erosion and degradation.
The technical term for forestry waste left behind after large-scale felling is ‘‘slash’’. It was slash that we saw this week in Tolaga Bay.
Rather than planting and clearing, Hall argues for continuous cover forestry. Trees are harvested incrementally, not en masse. This is a common practice in parts of Europe, where it also protects wildlife that would be threatened by clear-felling.
The conventional wisdom is that clear-feeling is more financially viable. But Hall cites a recent announcement from the European Investment Bank (EIB), which is putting €12.5m (NZ$20.8M) into the Irish Continuous Cover Forestry Initiative. The EIB said that, while Irish commercial forests are among the world’s most productive, ‘‘the new investment will demonstrate how best practice in Ireland’s world-class forestry industry can take better account of the need to safeguard biodiversity, soils and landscapes, and help resist the threats associated with climate change’’, according to Andrew Mcdowell, EIB vicepresident responsible for Ireland.
The EIB announcement goes on to say that ‘‘continuous cover forestry also enables productive forests which are more resilient to pests and diseases, as well as avoiding the negative impacts on soil and water resources of conventional practices’’.
The twist is that incremental harvesting can also have financial rewards. Hall reports that EIB’S modelling is based on a rate of return of 6 per cent. While that is lower than the 8 or 9 per cent that forestry operators expect in New Zealand, it avoids the clean-up costs that will hit all of us harder as climate change worsens.