Multi-decadal increases in shrub abundance in non-riverine red gum (Eucalyptus camaldulensis) woodlands occur during a period of complex land-use history

The history of land-use was examined in Eucalyptus camaldulensis Dehnh. woodland in the Victoria Valley of the Grampians National Park, south-eastern Australia, to help interpret changes in vegetation there during the last 50 years. We used aerial photography and dendrochronological data to quantify the amount of, and the rate of change in, the woody-vegetation cover between 1948 and 1997, and historical data to document land-use changes during this time. Aerial photographs indicated that in 1948, 56% of study area had <50% cover of woody plants. By 1997, 90% of the study area had >50% woody-plant cover. The native shrub Leptospermum scoparium J.R. Forst & G. Forst (Myrtaceae) was predominantly responsible for the increases in cover. Demographic analyses indicated that recruitment has been ongoing rather than episodic; large numbers of shrubs, however, have recruited since 1994. We hypothesise that the vegetation changes observed are likely a response to changes in land-use that have occurred since European occupation. Increased woody-plant cover followed the removal of sheep grazing in the long-term absence of fire. It is very likely that the long history of stock grazing, coupled with selective logging and associated soil disturbance, initiated a change in understorey vegetation by reducing competitive native tussock grasses and fuel loads to carry fires and this reduction was initially responsible for the encroachment of shrubs into the woodland. Recruitment has been ongoing in the absence of any recent land-use changes (most utilisation ceasing after the declaration of National Park status in 1984) and hence, this transformation from species-rich herbaceous woodland to shrubby woodland is expected to continue in the future.