A synthesis of outcomes from the Warra Silvicultural Systems Trial, Tasmania: Safety, timber production, economics, biodiversity, silviculture and social acceptability

Summary The Warra Silvicultural Systems Trial was established in southern Tasmania from 1998 to 2007 in tall wet Eucalyptus obliqua forest to compare seven alternatives to the traditional clear-fell, burn and sow (CBS) harvesting method. The alternatives included CBS with understorey islands, patch-fell, strip-fell, dispersed retention, aggregated retention, single-tree/small-group selection and group selection. The effects of the treatments were compared at age three years against six criteria: safety for harvesting crews, rate of timber recovery, economic returns to the forest owner, old-growth biodiversity, regeneration and growth of eucalypts (silviculture), and social acceptability. Combining all criteria, aggregated retention performed best, and is suggested to be the most suitable alternative for routine use in wet eucalypt forests if a management objective is to maintain old-growth structures and biodiversity at the stand (coupe) level. Aggregated retention presented no novel safety issues even th...