Browsing impacts on seedling survival of Black Box (Eucalyptus largiflorens)

Abstract

Black Box (Eucalyptus largiflorens F. Muell) is a dominant floodplain tree across the Murray-Darling Basin. At Hattah-Kulkyne National Park (northwest Victoria), historical changes in the hydrological regime and land use have degraded Black Box populations, with the majority of trees in poor health and with limited recruitment. To mitigate this threat, environmental watering has been implemented to improve condition, but successful regeneration has been limited. A 17-month trial (April 2021 to September 2022) was undertaken to evaluate the effectiveness of different management techniques in promoting Black Box regeneration (natural regeneration, seed-scattering, tube stock and browsing control: guarded and unguarded tube stock). At the end of the trial, only four of the initial 63 seedlings remained alive (two guarded tube stock and two natural regeneration). Most seedling death was attributed to browsing (likely kangaroos), which was evident in the first three months, with unguarded plants heavily impacted. No germinants were recorded in the seed—scattering plots. Our findings of high browsing impacts on Black Box seedling survival, corroborates existing data on browsers (abundance levels and management thresholds) and emphasises the importance of incorporating herbivore browsing management in floodplain vegetation management strategies that aim to promote regeneration within Hattah-Kulkyne National Park.