The Variable Retention Harvest System and its implications for biodiversity in the Mountain Ash forests of the Central Highlands in Victoria

Ecologically sustainable forest management (ESFM) is, in part, predicated on the assumption that
harvesting activities undertaken within the forest will not lead to species decline or loss or the
impairment of key ecological processes. Timber harvesting and subsequent regeneration of
forests must therefore be conducted in ways that do not diminish opportunities for forest
dependent species to persist within forest landscapes.
Victoria’s forests, including the Mountain Ash forests of the Central Highlands of Victoria, are
managed for a variety of purposes including timber production, catchment protection and
biodiversity conservation. Mountain Ash forests are significant for a range of species including
endangered ones like Leadbeater’s Possum that occur virtually nowhere else. Mountain Ash
forests also support important populations of many other species of mammals as well as
populations of a range of bird, reptile, frog and plant taxa.
Although a relatively small percentage of the overall Mountain Ash forest estate is subjected to
timber harvesting each year, the community perception is that these activities may be
incompatible with biodiversity conservation. However, improvements in silviculture and an
adaptive management approach have the potential to deliver positive outcomes for both timber
production and biodiversity conservation. If such improvements in timber harvesting activities
are embraced in the Mountain Ash forests of the Central Highlands of Victoria, they offer the
potential to become one of very few examples of demonstrated ecologically sustainable forest
management in Australia and indeed around the world.
Forms of silviculture that are currently widely applied in Mountain Ash forests, such as
clearfelling, are proven methods of timber harvesting and are relatively straightforward and
efficient to apply. However, extensive clearfelling without adequate retention of structural
elements can have significant negative effects on other values demanded from multiple-use
forests, such as biodiversity conservation. In particular, they can substantially alter levels and
spatial patterns of stand structural complexity on which many elements of forest biota depend.
Alternative forms of logging such as the Variable Retention Harvest System (VRHS) that retain
key structural elements of native forests can, in turn, promote the conservation of structure
dependent biota in wood production forests