The distribution of selected vegetation types on the Yanakie Isthmus, Wilson's Promontory National
Park, was mapped from aerial photographs from 1941, 1972 and 1987. The main changes in the
vegetation dynamics were: (1) an expansion of Leptospevmum laevigatum into grasslands and into
Banksia integrifolia woodlands with herbaceous understoreys, and (2) a stabilisation of dunes by shmbs
dominated by Leptospennum laevigatum. The total area of L. laevigatum shrubland and scrub increased
from 2179 ha in 1941 to 3436 ha in 1972 and 4516 ha in 1987. Land-use changes in this period
included the exclusion of fire in the early 1970s, after a history of regular burning, and an increase in
grazing pressure primarily due to population expansions of the rabbit and the eastern grey kangaroo.
Fire was not a prerequisite of the L. laevigatum expansion on the Isthmus because the spread continued
after fire was excluded; nor was fire the primary cause of the expansion because the percentage yearly
increase in the area of L. laevigatum was, on average, similar before and after 1972. An increase in
grazing pressure was identified as the probable cause of the L. laevigatum expansion due to: (1) the
exposure of bare ground, and (2) the restriction of the feeding range of cattle (known to graze both
L. laevigatum and Acacia sophorae on the Isthmus).