The legacy of pasture improvement causes recruitment failure in grassy eucalypt woodland conservation reserves in the Midlands of Tasmania

Abstract

Australia’s most fragmented and least reserved landscapes are the grassy eucalypt woodlands of the south-east. Two hundred years of agricultural disruption have transformed these landscapes, and agricultural enterprises continue to expand and develop, meaning the threats to these landscapes have not abated. The Tasmanian Midlands is primarily privately owned, with very little area devoted to conservation of biodiversity. In this landscape, conservation covenants have been enacted on many private properties with the intention of encouraging tree recruitment and conservation of threatened plant communities and rare species. Evidence of the effectiveness of these covenants in protecting overstorey tree population health is lacking. This study compared the demographic structures of overstorey Eucalyptus species and midstorey tree genera on public and private properties with contrasting land use histories. Reserves on private lands had little tree recruitment, probably because exotic pasture species were common, whereas tree recruitment was abundant in public reserves, where pasture improvement has not occurred. Active measures are needed to restore ecological structure and function in grassy woodland conservation reserves on private land by encouraging regeneration of Eucalyptus and Acacia species as well as returning the ground layer to a functionally native state. This will entail reinstating fire disturbance, reducing exotic pasture species cover and managing domesticated, feral and native herbivores.