One of the small (0.5ha) islands from the Variable Retention Harvesting Experiment.


This project was set up in 2003 to investigate the silvicultural method of retention harvesting.  Retention harvesting involves retaining patches or islands of standing, unharvested trees within the boundary of a traditional clearfell logging coupe.  The assumption being that retaining some standing trees within the coupe area will have a positive influence on biodiversity compared to the traditional large clearfelled area.

 We setup 24 treatments, blocked into groups of 4.  Each coupe in a block had either:

  • A large 1.5 ha island
  • 3 x smaller 0.5 ha islands
  • No islands in traditional clearfell coupe
  • A control site in unharvested forest of similar age

 Birds, Vegetation and small mammals were surveyed at each site.  We still continue the bird surveys and vegetation surveys to date, as the regrowth in the surrounding coupes continue to develop.