Totara – a growing resource
Dave Cown, David Bergin and Paul Quinlan, New Zealand Tree Grower November 2009.
Totara is widely distributed throughout New Zealand, from sea level to over 500 metres, on well drained flood plains and drought prone hills, and on clay to volcanic soils. Totara was highly prized by Maori due to its availability as large trees, the ease of splitting and natural durability, and for carving.
The species now regenerates prolifically in marginal pastoral hill country in some regions where there is now a considerable resource, with the potential to be managed as a future long-term supply of specialty timber. Young totara can grow rapidly and develop straight trunks of several metres length in a few decades, if conditions are suitable. In many cases, logs with large diameters of between 50 cm and 80 cm can be found aged 80 to 150 years, often with heavily branched crowns.
Under current law, the timber can only be milled and sold from indigenous forests which are sustainably managed. In the case of regenerating totara, not enough is yet known about selection, management practices and sustainable logging options, and a market for the young timber has not been developed.
A programme of work has been undertaken over the past few years by the Northland Totara Working Group (NTWG).The aim is to look at sustainable management options for wood production from naturally regenerating stands of totara on farmland.
Open-grown totara usually develop a large crown with multiple leaders. However an investigation of naturally regenerating totara-dominant stands on farmland showed that they can develop into pole and semi-mature stands which are relatively uniform as natural thinning occurs. Naturally regenerating stands may appear to grow slowly, but research indicates that improved growth rates can be achieved by timely thinning. A total of 38 permanent sample plots have now been established on nine farms in three districts in Northland.
Research into the early growth response of naturally regenerating totara and plantation totara to various thinning and pruning regimes has now been completed. Result show that, for example, mean diameter growth rate of residual trees in thinned stands has been shown to increase by a factor of two to four compared to non-thinned control plots. Naturally regenerating totara trees on farms could therefore be a sustainable wood resource.
Under management for wood production, the saplings and poles with the best form and spacing could be selected and lower branches removed to make knot free logs.Totara could be a special opportunity for sustainable management on working farms, even in the presence of grazing.
Uses of totara
The focus is now shifting to wood use. Information from farmers and local handcraft workers indicates that young totara has a range of excellent qualities, but is rarely used as a specialty timber because of lack of a regular supply.
In 2009, wood quality studies by NTWG involved felling naturally regenerating stands at Kawakawa north of Whangarei. Based on a preliminary grading of a sample of logs with an average diameter of 50 cm and length of 4.4 metres, a considerable proportion of the wood appeared to be heartwood. Even poor logs produced a significant amount of valuable timber.
Amongst a number of initiatives this project involves the evaluation of the wood properties as a key to a sustainable market of high value applications for totara. This could have economic, social and environmental sustainability benefits. Indications so far are that the wood from regenerating stands of totara on farmland, while not as durable, has many of the properties of old growth crops. There are likely to be high value uses for the wood from relatively fast growing trees.
In conjunction with the use studies, a full assessment of the thinned and control plots is planned over the next three years to see what the growth response is to silviculture treatments five years after the trials were established. Recommendations for further work include an evaluation of the response of pole totara to fertiliser, and finding out more about local knowledge on the uses and properties of farm grown totara.
The long term results will benefit farmers throughout New Zealand by using an existing resource that at the moment has minimal or low economic value. Naturally regenerated totara has many environmental benefits such as the reduction of hill slope erosion, enhancement of water quality and increase of biodiversity.
Regenerating totara often grows on less productive steep slopes that continue to be grazed, or within riparian zones that are increasingly being fenced off. Therefore management of the species as a long term timber crop offers opportunities to enhance existing landscapes. Combined with the timber and carbon sequestration, this has a unique blend of production, environmental benefits and sustainability.
Northland Totara Working Group
The initial trial work was funded by the MAF Sustainable Farming Fund. Additional money was provided by the Scion Diverse Forestry Programme. Direct or in-kind additional contributions came from the NZ Landcare Trust, Northland Regional Council, Far North District Council, iwi, landowners, wood millers and Tane’s Tree Trust.