Historical vegetation change in relation to forest management in the Pilliga State Forests of northern NSW, Australia

Timber harvesting and increasing woody vegetation density have been responsible for structural changes in Australian remnant native vegetation, but the magnitude and geographic extent of changes are poorly understood. Knowledge of past management and its effects on vegetation change would help guide future management. This study therefore aimed to quantify vegetation change in the controversial Pilliga State Forests, to describe their forest management history in detail and to tease out the relative effects of forest harvesting practices and increased vegetation density in causing structural changes since the 1940s.Pilliga management history was related to regional and global forest history via a six-phase global paradigm-shift model� described in literature, from exploitation to Sustainable Forest Management (SFM). To facilitate the comparison of individual forest management histories worldwide, the original global paradigm-shift model was extended to encompass common trends in several facets of forest-level management. Models showed considerable agreement with a detailed history constructed for the Pilliga. Key factors causing deviations appeared to include local environmental factors, changes in world timber demand, and the social value of regional jobs. Vegetation changes were quantified using 1940s forest inventory records. Resurvey of selected sites in 2005 showed an approximate 3-fold density increase, not only as expected for Callitris glaucophylla but also two other species studied, Eucalyptus crebra and Allocasuarina luehmannii. Conspecific overstorey density was negatively correlated with subsequent C. glaucophylla regeneration.