Two Hundred Years of Land Use and Vegetation Change in a Remnant Coastal Woodland in Southern Australia

Abstract

Post-settlement changes in vegetation and land use were examined in a reputedly undisturbed woodland remnant at Ocean Grove, southern Victoria, the site of earlier ecological studies. The vegetation has passed through at least three structural phases since European colonisation: an open grassy woodland dominated by Allocasuarina and Eucalyptus species and Banksia marginata Cav. with few shrubs; an open scrub of Acacia pycnantha Benth.; and a closed scrub of Allocasuarina littoralis (Salisb.) L.A.S.Johnson, which now dominates the reserve. Tree and shrub density has progressively increased, from perhaps less than 20 trees ha^–1 in the early 1800s, to over 3000 trees ha^–1 in 1996. Most large Allocasuarina trees established in the late 1930s or early 1940s, and Allocasuarina littoralis appears to have invaded rapidly thereafter. Surprisingly, A. littoralis was not recorded in an 1894 plant census, and might have been locally rare last century. Vegetation changes over the past 200 years can be attributed to the long-term absence of fire. The abundant recruitment of Acacia species in the mid- to late-1800s may have been a rapid response to the curtailment of Aboriginal burning, and the more recent invasion of A. littoralis a longer-term response to fire exclusion. The importance of active vegetation management for biodiversity conservation in the future is stressed.