Long-term consequences of single tree and small group harvesting of podocarps
Operational research project code: SUS 703
Work being undertaken under PGSF funding by Landcare Research in the Urewera podocarp tawa forest seeks to establish requirements for podocarp regeneration, survival and growth in mixed podocarp-tawa forest, subjected to previous selective harvesting for podocarps in the 1960’s. The Landcare study area is Maori land subject to a sustainable forest management plan (Tuawhenua Trust). This current work addresses short to medium term regeneration success/failure.
Work undertaken in Fiordland (Waitutu terraces) in pure rimu and mixed rimu – beech forest is being parameterised for analysis by a sophisticated model to model long-term ecological change and species’ ecological requirements for successful regeneration and survival, under the impacts of animal browsing and testing such things as continued expansion and infilling of beech into Southland hitherto podocarp-broadleaf dominated forests (beech has only been present in much of Southland’s forests for less than 2000 years).
The model, which requires extremely large computing capacity, has inbuilt ability to model long term, under a range of light and nutrient status levels, competition between species in the forest understorey and can be used to test the capability of podocarps to replace themselves in these forests under a range of harvest scenarios over 500 to 1000 years.
Key questions (already asked by some scientists and practitioners) are:
- Is single tree/small group harvesting of podocarps as required by the Forests Act appropriate in mixed beech-podocarp forest to ensure podocarp replacement?
- Are these Southland forests “beech saturated” or is beech still displacing other species, including podocarps?
- Will podocarps retain their presence in these forests without large scale disturbance?
This is at the root of the sustainable forest management prescriptions in Part IIIA of the Forests Act. Results may call into question the efficacy of single tree and small group management of podocarps in forests and lead to review of management prescriptions and guidelines for their management.
Contact:
Alan Griffiths
Tel: 03 379 1986
Email: alan.griffiths@maf.govt.nz
Contact for Enquiries
Manager, Innovation Policy
Ministry of Agriculture and Forestry
MAF Policy
PO Box 2526
Wellington
New Zealand
Tel:+64 4 894 0618
Fax:+64 4 894 0741
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