SFF Project Summary
||Developing and managing farm-grown totara forests for high-value timber
|Name of Applicant Group:
||Northland Totara Working Group
||76 Mangamanihi Road
||09 405 0052
|Total Project Funding:
|Proposed Start Date:
|Proposed Finish Date:
Last udpated: August 2013
The project is the five year re-measurement and analysis of a large silvicultural trial involving regenerating totara trees on farms. It will provide essential base information on growth-rates, potential harvest yields, carbon and management regimes for the developing ‘farm-totara’ resource on private land.
Totara is abundant in many pastoral areas from Northland to Southland, where reversion of marginal hill country is occurring. Considerable potential for management of this species as a future long-term high-value specialty timber has been identified. Development of an industry based on this sustainable land-use option is the vision.
This could complement existing pastoral land-use, improve farm resilience and bring multiple wider environmental and local economic gains. Therefore the Northland Totara Working Group promotes the management of naturally regenerating totara trees on farms for both timber-production and for environmental benefits.
Research projects to date have all returned very encouraging results regarding this potential. However better information on growth rates and management is still required.
This project will provide tangible outcomes in the form of:
- The most up-to-date published information on the early performance of thinned and pruned naturally regenerating pole-stands of totara on farms.
- The essential base data for analysis for more accurate projections for harvest, yields, time-frames, and carbon sequestration.
- The re-measurement data will help refine practical silvicultural management options and prescriptions (i.e. Optimal time and relative intensities of thinning and pruning etc).
- The above information will enable land-owners to better consider the business-case for this sustainable land-use option.
This will also be extremely useful information for private forest owners and land-owners considering this land-use option and equally so for MAF in administering Part 3A of the Forests Act, particularly in the Northland area.
Five years ago, some 40 permanent sample plots (PSPs) were established by Scion Scientist Dr David Bergin for the Northland Totara Working Group (NTWG). These were in naturally regenerating totara pole-stands on 10 farms around Northland. The purpose is to determine how far both growth-rates and tree-form (log quality) can be improved by silvicultural management (thinning and pruning).
Early performance of thinned stands compared to control was very encouraging. However, that data is only for the first two years following silviculture. It is now critical that these stands are re-measured after a five year period and that that data is made available for the development of more accurate and refined growth and yield models and for carbon estimates. This re-measurement was always intended with establishment of these permanent sample plots (PSPs). The full-value of this established silvicultural trial is only realised by such periodic re-measurement.
The project has several core components:
- Measurement of 40 silvicultural plots established at least five years ago in representative naturally regenerating totara pole stands in three Northland areas – Herekino, Kaeo, Glenbervie.
- Review, analysis and interpretation of the data to determine improvement in growth and tree form, considering implications for silvicultural management regimes, developing growth models, as well as providing projections of volumes at harvest at selected rotation lengths.
- Completion of several publications for nationwide dissemination and promotion.
- Undertake maintenance, further thinning and extension of plot network as required and where resources permit.
A preliminary analysis of the data from the re-measured totara stands shows the following main points:
- The diameter increments of the trees in the thinned stands are still double the rate of the un-thinned stands. This increase in growth-rate was recorded at the first re-measurement (one year after thinning) and has been maintained over the 5 year period.
- There is still significant variance in mean growth-rates between different sites.
- To interpret these results, a Stand Density Index (SDI) for totara has been derived. This size/density chart will be useful to assist with decisions regarding the timing and intensity of thinning operations in natural pole-stands of totara on farms.
- An SDI analysis of the results shows that the un-thinned plots are mostly above the 55% max SDI line, which indicates that when tree diameters appear to increase, this is invariably accompanied by mortality.
- The thinned plots lie mostly between the 25% and the 55% SDI lines. A desirable target line for thinning for this species may be 25%. Therefore this suggests that our previous thinnings carried out in 2007 was overly conservative. A more aggressive thinning intervention may produce yet better growth responses.
This information makes it possible to begin developing models for predicting growth responses in managed and unmanaged stands of totara on farms.