Research Branch

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Partial cutting and helicopter yarding on environmentally sensitive floodplains in old-growth hemlock/spruce forests

Author(s) or contact(s): K. Moore
Source: Research Branch
Subject: Logging Techniques
Series: FRDA Report
Other details:  Published 1991. Hardcopy is available.


This study describes the development of partial cutting and yarding system using a helicopter to remove old-growth Sitka spruce, western hemlock, and western redcedar from environmentally sensitive floodplain sites on the Queen Charlotte Islands, BC.

At Naden Harbour on the Queen Charlotte Islands, B.C., partial cutting and yarding with a Sikorsky S 64-E Sky-Crane helicopter has been used to remove old-growth Sitka spruce, western hemlock, and western redcedar from environmentally sensitive floodplain sites. Between 1986 and 1989, 67 600 m3 of timber was logged from 141 ha in 14 partially cut blocks.

A retrospective study of the development of these partial cutting operations was conducted. Four case studies are presented to describe the type of floodplain sites on which partial cutting has been used. Various forestry concerns about partial cutting are reviewed, including the silvicultural implications, the damage to residual trees, blowdown following cutting, and the protection of important fish habitats. The procedures used to select appropriate sites mark individual trees, and conduct falling, yarding, and post-logging clean-up are described.

The partial cutting and helicopter yarding at Naden Harbour has been successful in meeting the objectives of (1) harvesting a previously inaccessible volume of timber and (2) protecting environmentally sensitive fish habitats. The methods and procedures developed here for partial cutting and helicopter yarding may be appropriate on a variety of other sites in coastal British Columbia where objectives such as protecting wildlife habitats, retaining aesthetic values, or maintaining the stability of steep slopes require or favour partial cutting over conventional clearcutting and cable yarding.

Most of the silvicultural concerns for partial cutting in old-growth coastal forests have been overcome at Naden Harbour. Most blocks are expected to be windfirm and will become fully stocked uneven-aged stands that will support another harvest before the normal rotation period. Procedures for improving the condition of the residual stand are identified in this report. As well, recommendations are made to ensure that the silvicultural objectives for the residual partially cut stand are set before tree marking and cutting begin.

FRDA Research Report 166 (3657 KB)

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Updated July 24, 2015