The Recovery of Timber from Storm-damaged Native Forest on the West Coast.
by Ian James, Okarito
Cyclone Ita caused catastrophic damage to West Coast forests. Plantation radiata forest suffered terribly while native forests withstood the gales much better, however, significant areas of rimu and beech forest were flattened. Given the likelihood of an increased frequency and severity of such climatic events, forest blowdowns may become more frequent. Fortunately our native forests have tremendous regenerative capacity and they will adjust to the changing climate maybe with some structural and species changes.
Windfalls are a completely natural occurrence in native forests but the difference this time is the scale of damage. For those living on the Coast the spectacle of thousands of rimu trees lying on the ground raised the obvious question of why not use some of the heartwood logs on stewardship conservation lands? This is not a debate about logging live trees. Rather it is about recovery of logs using the techniques available that minimise any physical impact. There are two aspects to the answer, one ecological and the other commercial.
Only the heartwood butt of large rimu trees will prove economical to remove. What proportion that constitutes of the total biomass is difficult to estimate as the forest is so variable. But in rimu/kamahi dominant forest it will be way less than 10%. Remember that the blowdowns include the biomass of many other species such as miro, kamahi, rata, quintinia, many small shrubs and ferns. Rimu heartwood contains the least nutrients compared to the rest and is also the slowest to rot and release nutrients. Old rimu butt logs remain for over 100 years on the forest floor. Most nutrients are in the bark, small branches, leaves and fibrous roots.
Realistically, the one-off impact from the heartwood removal to the overall ecosystem will be imperceptible and the forest will easily adjust by regrowing the lost biomass in a few years. Photos of seedlings growing on logs is misleading because few ever reach maturity. However, planting rimu seedlings where the removed log lay is a good idea.
The real ecological impact will be how the trees are removed. If heavy ground based machinery is used the impact will be severe because skidders and bulldozers crush seedlings, damage remaining trees and destroy the natural soil profiles. They also often introduce weeds such as gorse into the forest. They have no place in our native forests. The only acceptable method that should be permitted is logging by heavy-lift helicopters
Then there are the birds, lizards and invertebrates to consider but to say they will suffer harm is nonsense. Sadly, the native fauna in West Coast forests are so depleted by possums, stoats rats and mice that they are not playing their normal function in the ecosystem. Lack of habitat is not the problem, it is the predators. But they will benefit if DOC spends the revenue they gain on additional predator control.
On the commercial side, there are several issues. Health and safety is a big one and nobody disputes that cutting up windfall logs is skilled work. There are people from the previous era who can train new native loggers. Timberlands had an exemplary safety record with helicopter logging, apart from the tragic crash of the Mil 8 caused by pilot error. Today DOC workers are safely cutting up hundreds of windfalls that fell along roads, tracks and cycleways in the Doc estate.
The resources to transport and process the logs still exist and several local companies have held up their hand for the logs. Given the job losses in the mining industry, locals will welcome new jobs.
The final question is whether there are markets for the wood? First NZder’s should acknowledge that we are using substantial volumes of tropical timbers that come from dubious sources. We should not be contributing to the loss of tropical forests when we have an alternative source of sustainable specialty timber at home.
Comment has been made that the extra timber will the destroy market for private operators. The current dwindling private supply is too small for any viable industry to develop. An increase in supply would revitalise NZ furniture makers, many of whose livelihood disappeared when adequate native timber became unavailable. That should raise prices for all.
Native timber was given such bad press during the 1990’s forest campaigns by activists in F&B. It is time to move on from the past and allow utilisation of a small amount of windfall timber. It is surely sustainable, the revenue is going to DOC, and rural people will benefit both in processing the timber plus the extra jobs in killing predators funded by the revenue. If all NZ got behind this proposal a market would appear overnight.
Background: My 40 year career in science was entirely spent in the study of NZ alpine and lowland native forests. I was fortunate to have spent the majority of those years in the forest on a daily basis rather than desk-bound in a University or Research Institute. My major achievement was working with a Timberlands team to develop world-recognised systems for the sustainable management of podocarp and beech forests. Those systems were rejected when the Labour government ended all native logging 13 years ago but have been the basis for a small ongoing private industry.