From horse to helicopter: Logging at Tikitapu, Rotorua
Stands of the mighty Douglas fir are a feature of the area of the Whakarewarewa Forest that lies between Rotorua’s Blue and Green Lakes (Tikitapu and Rotokakahi). Planting of these trees started in 1905 and, as the forest has matured over the past century, these magnificent trees have had to be thinned – first by horse logging; most recently by helicopter.
Native forest and scrub around Tikitapu were destroyed in the <>1886 Tarawera eruption and the natural forest regeneration that followed had little value except for its scenery and the stability it provided for the terrain. Except for one or two pockets of native bush, the area was bare of trees and was coated in tussock, with an abundance of flax and fern and smatterings of manuka and coprosmas.
As European settlement increased so did the demand for timber. Not only was kauri ideal for ships’ masts, but timber was also in high demand for building. Consequently extensive areas of native forest were felled, for the timber and to clear the land for agriculture.
Realising that New Zealand’s slow-growing indigenous forests were becoming exhausted, Government anticipated a shortage of building timber and in 1897 established an exotic plant nursery at Whakarewarewa to determine which tree species had commercial potential in the Bay of Plenty.
One of the earliest of the exotic forest trials was in the Tokorangi triangle, within Whakarewarewa Forest, where 170 species were introduced, the two most significant of which proved to be the Californian Monterey Pine (Pinus radiata) and the slower-growing North American Douglas-fir. It was noted that these exotics grew significantly more vigorously here than they did in their native environment. Later, in the Depression years relief workers were used to plant vast areas across the country of radiata pine, the greatest being the 188,000-hectare Kaingaroa Forest, reputedly the largest plantation forest in the world. Nowadays radiata pine accounts for 90% of our plantation forests.
Whakarewarewa Forest was one of the first plantations to be established at the end of the 19th century. The Tikitapu Douglas-fir stand was planted in it in 1913. This was considered a high-value timber, stronger for construction purposes than radiata pine but slower growing – while pines are optimally harvested at 35 years, sometimes even at 25 years, this Douglas-fir plantation still stands tall and continues to mature even as the stand hits its hundredth year in 2013.
The Douglas-fir stand was therefore established, and has been managed, as a long term crop – a ‘landbank’ investment. Trees were spaced for optimum growth from both rainfall and soil, the soil being now layered with Rotomahana mud and scoria, deposited during that 1886 eruption on top of deep pumice through which roots can penetrate in search of nutrients.
Thinning is an essential part of dense forest management. The Tikitapu Douglas-firs have been thinned four times already. The first, mainly by horse logging, took place over a decade from the mid-1940s when the trees were around 30 years old.
Logging tracks were determined by topography and used the natural contours of the land to best advantage – especially so when horses were involved. Forest roads giving truck access to felling sites were located at the foot of the hillsides, and tracks through the forest to the landings were designed so that the horses pulled the logs easily downhill, using gravity, to the landing where they were loaded onto trucks – but the horses still had to walk back uphill for their next load, requiring reasonable gradients that did not exhaust the horses.
While all the less steep areas around Tikitapu were thinned with horses, the animals could not be used on the steeper slopes, which also needed thinning. The American cable logging systems, common in New Zealand for clearfelling, were unsuitable for thinning and so in 1953 a Swiss cable crane system was trialled promising more precision and, following the trial, the second thinning was undertaken.
The Swiss method used a wire rope skyline supported by upper and lower stations where a hanger slung between two trees held the skyline well above the ground. On undulating terrain an intermediate hanger was required to ensure the logs in motion were kept clear of the ground. Both ends of this fixed skyline were anchored to stumps. Within the forest the trees were felled in a herringbone pattern to facilitate the extraction of the logs.
The operating mainline was wound on and off the single drum cable hauler stationed at the top and pulled a carriage up the skyline to a stop device set on the skyline and locked to it. The mainline was fed out through a pulley in the carriage into the bush and attached to the logs. The machine operator then reversed the drum and pulled the load in and up to the carriage where the load locked to it, releasing the carriage from its stop. The load was then lowered to the landing using gravity.
While this Wyssen cable system proved satisfactory in that it caused very little collateral damage to the trees left standing, it was an expensive, time-consuming operation as the cable had to be repositioned regularly in 100-metre steps into each new strip to be thinned. In those days this was a complicated five-day process and consequently the system was used only on the steep section of Tikitapu. The lower slopes were harvested at that time by tractor. Some tractor-based thinning also occurred on the slopes round Rotokakahi in the 1970s, using the existing roads and some new, but small, skids.
By the mid-1980s the forest need attention again. By then technology had advanced and in 1984 the third thinning took place – by helicopter. At a cost estimated to be in excess of $2000/hr, this was an expensive exercise, requiring careful time management. Trees were felled into a clearing over which the helicopter hovered while lowering a rope to which the men on the ground hitched a bundle of up to five logs. These were lifted clear of the residual trees and flown to a nearby landing. Easier terrain was thinned with a log skidder.
The most recent thinning – again by helicopter – took place in 2008 amid public disquiet, reflecting an increase in the general public’s environmental concern while also illustrating the misunderstandings of many would-be conservationists.
Forest management at this time focused on selective logging aimed at taking out small groups, or strips, of trees. Also, trees round the edges of Lake Rotokakahi had over the years been dropping into the lake and the Maori owners asked that they be removed. The trees were lifted out by excavator with no damage to the lake edge.
As helicopter hireage was enormously expensive the aircraft were used for short runs only. Logs were transported to a large landing between Tikitapu and Rotokakahi which was probably extended for the first helicopter thinning in the mid-1980s.
This landing, and the roads too, date back to the 1940s for that first thinning by horse logging and were again used by tractors on the lower slopes during the cable logging days of the 1950s and ’60s. In several places along the Blue Lake walking track there are indications today of log skids that would have been constructed some couple of metres above the bank and from which logs would have been rolled onto the back of a truck.
Located on a slight ridge that ensured rainwater run-off, the helicopter landing was sited in the lowest position possible, at the crossroads where this Blue Lake walkway meets the track to the Green Lake and intersects the forest road to Waipa Mill.
Even today in its overgrown state the landing seems excessively spacious. However, safety issues were paramount: helicopters needed room to hover above while delivering their load, which involved lowering the logs and releasing the stop catch just as they hit the ground so that they all fell in the same direction. The several men below needed space to sort and stack the incoming logs in preparation for loading onto the trucks destined for the mill – and to stand out of harm’s way when the logs were delivered.
Today the Tikitapu Douglas-fir plantation is a valuable asset.
Although the harvesting of these blocks of Whakarewarewa Forest have been very high-cost logging operations with both the Wyssen Skyline and the helicopters, the cost has been offset to some extent by the high quality timber extracted, and by the forest’s proximity to Waipa and Rotorua mills which has kept down transport costs.
These Douglas-fir stands around both lakes not only grow high quality wood and provide superior recreational and scenic values, but they also prominently demonstrate that forests can be managed for multiple use without damage to the environment.
Observers can readily note the contrast between the flourishing Douglas-fir stands and the stunted natural native forest that clothes the rest of the perimeter of both lakes and which started regenerating after the 1886 Tarawera eruption – 20 years or more before the Douglas-firs were planted!
About the author.
After a decade of writing features and news stories, truncating press releases, and proofreading for a community newspaper, Alison Brown cut loose.
Now her proofreading, editing and rewriting services earn her bread’n’butter, while her cake’n’cappuccinos come from writing about older folk who modestly consider themselves 'ordinary'.
She notes: “They seldom are ‘just’ ordinary. Many have led colourful lives and are still doing extraordinary things in their golden years. I feel privileged that these ageless characters allow me to rake through their memories. I see them as colourful role models and I am honoured to be the chronicler of their tales.”
The Founding Years in Rotorua, Don Stafford, Chapter 15, Forest and Farm; Rotorua District Council, Destinations; http://www.wyssen.com for detail and illustrations outlining the workings of the Wyssen Skyline Crane.
Jim Spiers, retired logging superintendent, New Zealand Forest Service; Rex King, harvest planning, Timberlands.