Pinehaven’s Pines: Time for the Chop?
The common pine tree, Pinus radiata, is a native of Monterey, California. It does not naturally grow large or live to very old ages. Californian radiata forests are subject to frequent forest-destroying fires and storms, after which new forest regenerates.
In New Zealand, rainfall is higher and wild fires are rare. Pine trees grow larger and live longer. As they grow old, however, they become unstable because they are not deep rooted (unlike naturally long-lived species such as redwood, totara and kahikatea). Pine trees over 45 years old are regarded as “over-mature”. Old pines, be they in forests or as individual trees, are vulnerable to falling in high winds. This is exacerbated when some trees are removed from a mature stand, exposing trees that were formerly sheltered by their neighbours to the full force of the wind.
The vulnerability of over-mature pines was spectacularly demonstrated at Tinakori Hill in 2004. That forest was planted in the 1930s and never tended. In February 2004, after days of heavy rain (which saturated the soil beneath the trees) severe gales brought large swathes of trees crashing down in tangled heaps. The trees that landed on top of the pile slid down over the logs beneath and ended up in the back of properties on Tinakori Road. The fallen trees that remained on the hillside posed a significant threat and had to be removed. The timber was recovered using a heavy lift helicopter (the largest in New Zealand), but not before the root plates that had been pulled from the ground by the falling trees had been secured to the ground with steel cables (Mike Oates, Wellington City Council, pers. comm.). The operation was difficult, dangerous and cost the Wellington City Council $5M. Had the forest been properly managed it would have been much less costly, possibly unnecessary.
The PPA is concerned that the large pines above houses on Elmslie Road, Pinehaven Road, Blue Mountains Road, Jocelyn Cres and Wyndham Road pose a significant risk to properties on those roads, and that that risk will increase as the trees age. Like the Tinakori Hill stands, the Pinehaven stands have never been tended and they are now beyond the 45 year old “over-maturity” mark. The same storm that brought down the Tinakori Hill trees also brought down a number of pines in Pinehaven, including one that went through the middle of a house’s roof. The PPA is concerned that if the trees are left to their own devices then Pinehaven may one day face a catastrophic event like the one on Tinakori Hill. If that happened, how many homes would be hit? Who would clear up the mess? Who would have to pay? And would landowners be liable for damage caused by their trees falling onto neighbours’ properties?
The PPA suggests that the best option would probably be to sell all the trees to a logging contractor so that they can be felled systematically, and the sale of timber used to offset the cost of removal. If properly planned it is likely that the work could be done without cost to residents, and may even yield a small financial gain to residents with trees on their properties. In any case, having the risk taken away at no cost would be preferable to having to pay (either directly or through rates increases) for a Tinakori Hill style clean up if the worst should happen.
The situation in Pinehaven is complicated by the pattern of land ownership which divides the forest into many small parcels, each belonging to the relevant home owner(s). Agreement between all owners would be needed so that any logging operation could be conducted systematically and safely. Cutting out most of the forest while leaving isolated stands on individual properties would be unwise because the remaining trees would be extremely vulnerable to wind throw. Several instances of such exposed trees being blown down across property boundaries were recorded in Pinehaven in February 2004.
After the pines were removed the land could either be replanted in plantation or left to revert to native. There are good examples above Pinehaven, Elmslie and Wyndham roads of properties from which the pines have been cleared in the past, making way for regenerating native. The mature pines currently have a vigorous native understorey that would respond quickly to logging, producing a healthy native cover within a relatively short time. Just look at Tinakori Hill eight years on.
A logging operation on steep slopes above a residential area would have to be well-planned so as to minimise the risks of slipping and sediment runoff. Forest harvest planning is a professional discipline that addresses such risks. An option may be to fell the forest as a series of smaller areas over several years, giving each area time to recover before the next is cleared, as has been done with the Guildford forest above Pinehaven and Elmslie roads. Other risks would relate to logging traffic (which would probably use Blue Mountains and Avro roads because of the lack of access to the forest from below).
Note that, in our view, the greatest risk is likely to come from doing nothing, leaving the trees to grow ever larger and more unstable.
Where to from here?
The PPA believes that the Pinehaven community needs to start talking about this issue. We are holding a community meeting [details to be added]
Assuming there is broad community support, we will approach the Upper Hutt City Council to request that the Council engages a forest consultant to assess the forest and, if appropriate, prepare a harvest plan that addresses the concerns of residents.
Or PPA could independently engage a forest consultant?