Identifying climate refugia for Australian rainforest plant species: from the Last Glacial Maximum to 2070

Historically, climate refugia – areas that have remained suitable for species during periods of climate disruption – have played an important role in species persistence. Identifying and protecting climate refugia is a key climate change adaptation approach for conservation planning. This study aims to identify climate refugia for Australian rainforest flora, from the Last Glacial Maximum to 2070. Models of habitat suitability for 30 plant species were calibrated using Maxent, and projected onto climate data for the Last Glacial Maximum (LGM, ~22,000 ybp), mid-Holocene (MH, ~6,000 ybp), current period and 2070. The intersection of suitable habitat over consecutive periods was assessed, identifying a) paleo refugia (LGM – MH – Current), b) future refugia (Current – Future) and c) High Value Refugia (HVR, suitable over all four periods). Centres of refugia (regions suitable for multiple species) were identified. Predictive performance of models was acceptable, with maps of current suitable habitat verified by experts. Generally, habitat suitability spans the greatest extent now compared to past or future time periods. Four centres of paleo refugia were located in the Wet Tropics, Central Mackay Coast, South Eastern Queensland and North Coast of New South Wales bioregions. Ranges for most species were projected to decline by 2070 (mean = 52%, SD = 22%). HVR were identified for all species to at least 2070, although these occupy, on average, 16% of current habitat (SD = 11%). Future refugia were projected to occur elsewhere for all species, but may be well beyond species’ dispersal ranges. HVR are likely to be highly important for the conservation of these rainforest species, given generation times, limited dispersal capabilities and anthropogenic barriers to movement. This study may assist in understanding long-term spatial shifts in rainforest flora in response to climate change, and for designing future conservation strategies.