Old forest, new perspectives—Insights from the Mountain Ash forests of the Central Highlands of Victoria, south-eastern Australia

Abstract

Old growth forest has become a major and increasingly prevalent research topic over the past two decades. However, there is no generic definition that can be applied uncritically to all forest types. This is because a precise definition of old growth is ecologically meaningful only when it is applied to a specific vegetation type. This is demonstrated in this paper using the Mountain Ash ( Eucalyptus regnans) forests of the Central Highlands of Victoria, south-eastern Australia as a case study. These forests have been the target of extensive and intensive research over the past 25 years. That work has shown that a number of attributes of stand structure and composition can be crudely used to distinguish old growth forest from other age cohorts of Mountain Ash forest. However, it is not unusual for some of these characteristics also to be recorded in regrowth stands. A key feature of stands of old growth Mountain Ash forest was that the overstorey was rarely even aged. Rather, there was strong evidence of at least two cohorts of overstorey trees in old growth stands. This highlighted the existence of multiple disturbance pathways. Thus, although an absence of disturbance is typically one of the criteria for defining old growth forest, extensive evidence was found to suggest that most stands of old growth Mountain Ash have been subject to several previous natural disturbance events. Current management policies in Mountain Ash forests preclude the harvesting of old growth stands. The ecological importance of living and dead biological legacies for many elements of biodiversity in Mountain Ash forests indicates that naturally disturbed old growth stands also should be exempt from salvage logging, particularly salvage logging using traditional clearfelling methods.