New Zealand Journal of Forestry (1977) 22(1): 81–100
©New Zealand Institute of Forestry
A selective logging trial in dense podocarp forest in the central North Island
J. Herbert and A.E. Beveridge
This paper reports a first attempt at selective logging in dense podocarp forest (mean merchantable volume 555 m3/ha), with tree marking based on silvicultural and ecological principles.
Three trial blocks were established, one being an unlogged control. In the second block 20 trees/ha were logged to remove 183 mi/ha, amounting to 30% of the merchantable volume, and in the third block 29 trees/ha were logged to remove 266 m3/ ha, amounting to 55% of the volume.
An important objective was to remove small, discrete groups of trees, leaving other groups intact. In marking trees for removal or retention emphasis was on the condition and structure of the residual crop rather than on the quality of extracted timber.
The early impact of logging was assessed by recording the degree of damage sustained by residual trees and the nature and degree of ground disturbance. In general it was found that the heavier logging (55%) did not result in more extensive or superior sites for regeneration than the 30% logging, and that in the 55% block the residual forest structure, condition, stability, and appearance were substantially inferior.
Long-term results will be assessed in the future by recording windfall, vigour of residual trees, and natural regeneration trends.