Mechanised steep slope felling and bunching (FFR)


  • Harvesting costs on steep slopes have continued to increase.
  • The proportion of harvest on steep slopes will increase as the harvest from ‘non corporate’ forests increases over the next decade.
  • Conventional harvesting practices with manual felling and breaking out are physically demanding and hazardous with 3-4 fatalities on average each year and many serious lost time injury accidents.
  • Skilled labour will become increasingly difficult to attract to these operations as the industry will require approximately one additional new hauler crew every month for the next 10 years.
  • Traditional North American suppliers of haulers and yarders have closed operations so productivity improvements will require local innovations and development.

Potential benefits

Eliminating lost time accidents from the felling and extraction phase of steep slope harvesting.

Improving productivity of steep slope harvesting to achieve a 25% reduction ($8 per tonne) in harvesting costs.


Research commenced in 2010 to assist Trinder Engineering/Kelly Logging with development of a beta prototype steep slope harvester that is capable of felling and bunching under a grapple system.

Evaluating and monitoring the productivity benefits of the mechanised felling and bunching system compared to conventional manual felling and breaking out.


The Beta prototype has been successfully commissioned and has completed 1500 hours of operations of felling for both conventional breaking out and grapple systems.

An innovative winch control system and stability blade have been developed.

Felling of 800 tonnes of a wood a day has been achieved on slopes exceeding 35 degrees.

Productivity improvements of up to 40% were achieved in initial trials of the alpha prototype machine.

Trinder have sold the first commercial model to a North Island contractor – currently being commissioned.

Use of cable-secured machines have been incorporated into the revised approved code of practice for harvesting.


Without the support of the industry/PGP programme the commercialisation of the steep slope harvester would not have occurred.

Early trials of the prototype machines in conjunction with grapple extraction systems show that significant productivity improvements that will drive cost reductions in harvesting are achievable.

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