Project Overview
Michael Bergin measuring in a Permanent Sample Plot (PSP).This project was undertaken by Tāne’s Tree Trust on behalf of the Northland Tōtara Working Group. It involved the remeasurement of the tōtara silviculture trial plots established by the Northland Tōtara Working Group since 2007 across a range of pole and semi-mature regenerating totara dominant forest. Data from 50 Permanent Sample Plots (PSPs) yields valuable information on growth rates, carbon sequestration, and management prescriptions for timber production. It also includes some implications for effects on indigenous biodiversity associated with silvicultural interventions in pole-stands of regenerating tōtara.
This Tāne’s Tree Trust project was co-funded by Te Uru Rakau.
Project term
It was a two-year project completed 30 June 2022.
Background
Anna Manning remeasuring a tōtara tree in a sample plot.The results of this project complement and support other initiatives endeavouring to start a new regional industry based on the sustainable management of tōtara forests on private and Maori land.
While focused on naturally regenerating stands, the results of this project also indicate what may be possible from plantation tōtara forests too. Tōtara is the most common high native tree species planted nationwide.
Key Results
Control plot (no thinning) with no grazing. Photo credit: Michael Bergin
The thinned plot of the pair with no grazing five years after thinning. Photo credit: Michael Bergin.Highlights of the results include:
- Thinning induced a genuine diameter growth response in the residual trees of thinned PSPs compared to the unthinned controls.
- Annual increments in stem volume and carbon per hectare were both significantly higher in the thinned plots than in the control plots.
- Understory development and biodiversity scores were significantly higher in the thinned than in the unthinned control Plots, and significantly higher in plots with no evidence of grazing or browsing compared with those with evidence of grazing.
- A revised thinning schedule was produced based on the results of a Stand Density Index analysis.
The full results are set out in the project report on the Tāne’s Tree Trust website (see link under Outputs below).
Outputs
Kimberley, M.; Quinlan, P,; Bergin, M. 2022: Results of the 2020 Remeasurement of Tōtara PSPs (PDF, 2.19 MB) (PDF, 2.19 MB). Tane’s Tree Trust. Unpubl. 16p.
Contacts for this project
- Project Manager, Paul Quinlan
- TTT Executive Officer: [Enable JavaScript to view protected content]