Grazed, burnt and cleared: how ecologists have studied century-scale vegetation changes in Australia.

Ecological studies of century-scale vegetation changes in Australia were quantitatively reviewed by assessing relevant papers according to a range of methodological and environmental attributes. In general, century-scale vegetation dynamics are rarely studied by Australian ecologists. Most studies of century-scale changes are short-term studies with one sampling period, and few long-term experimental studies exist. Century-scale changes are well documented in open forests, grassy woodlands, tussock grasslands and rainforests, but little information is available from lowland heathlands, herblands or hummock grasslands. Tall open forests and rainforests have received the most comprehensive attention. Five major genres of research were recognised from a multivariate analysis of methodological attributes: (1) single-species tree-ring and fire-scar studies; (2) forest dynamics and age-structure studies; (3) floristic degradation studies (usually caused by stock grazing); (4) archival benchmarking studies; and (5) palynological research. These genres tend to focus on different ecosystems and ecosystem attributes, giving incomplete pictures of vegetation changes even in some well-studied ecosystems. In all genres other than forest dynamics studies, century-scale changes are commonly described by comparing present conditions with a pre-European reference point, and few studies have documented successive vegetation changes within the period of European occupation. Considerable opportunity exists to document long-term ecosystem responses to successive disturbances resulting from European disturbance regimes.