Guiding landscape transition for climatic change: planning in the Royal Botanic Gardens Victoria, Australia

Melbourne Gardens comprises of 38 ha of living plant collections containing 48,000 specimens from 8,400 taxa originating from a broad geographical distribution across the globe. The plant collections provide conservation, reference, research, interpretation, education and aesthetic outcomes in what is a heritage and picturesque landscape. Melbourne's climatic predictions for 2090 indicate significantly hotter and drier conditions, with increased frequency of extreme events, particularly heat waves and flooding. In response to these threats and to manage the risk of diminishing water supplies and an aging plant population, a Landscape Succession Strategy (LSS) has been developed to transition the existing landscape towards the projected climate of 2090, whilst retaining heritage character, plant species diversity and recreational green space for future generations. Development of the LSS included assessment of landscape microclimates, auditing of living plant collections against future climates, and implementation of more efficient irrigation using soil moisture sensing technologies. While outcomes of the LSS are still emerging, early results are encouraging. A mean cooling effect of 1-2°C (up to 6°C on certain days) in some zones of the landscape has been identified; about 65% of the 5,000 plant taxa reviewed are potentially 'suitable' for 2090 climate conditions, although gaps in plant distribution and climate data have hampered this, and landscape water use research has informed water use efficiency. The long life spans of living assets and projected climatic changes require well-directed plant selection towards achieving an effective vegetation succession. Therefore, the LSS is a valuable planning framework to integrate the protection of the urban landscape against key climatic risks and provides a reference for other botanical gardens to consider as a climate adaption template to manage landscapes into the future.