Within the agricultural sector the production of temperate perennial fruit faces unique challenges in adapting to climate change. The permanency and longevity of fruit trees means management decisions implemented now will persist into new climates. These attributes constrict flexibility in adaptation options with actions that seem minor, such as changing varieties, requiring substantial investment and can lock a grower into decadal scale commitment. Compounding this vulnerability, knowledge gaps in temperature-physiology relationships restrict the adequate construction of climate impact statements which inform adaptation.

An Australian-wide project has been conducted to begin to address key questions regarding climate risk and adaptive actions to secure the future of the Australian temperate fruit tree sector. Three key areas were investigated, sufficient accumulation of winter chill, flowering timing and extreme heat damage. The research involved taking field observations with coincident temperatures, applying mathematical models to interpret these relationships, projecting these relationships under future climate conditions (for 2030, 2050, 2090) and, where appropriate, evaluating the potential success of adaptive options. Presentation of results to assist converting the science into actionable knowledge was prioritised to assist with industry decision-making.

Results for winter chill focussed on variety and site sensitivities and showed for some sites, regardless of variety, little impact was expected. Conversely, other sites demonstrated considerable future risk as early as 2030. Modelling procedures for flowering timing focussed on application of the chill-overlap model. This model was found to be stable across Australian climates instilling greater confidence in its application to future climates. Little change or a delay in flowering was found under climate change for most Australian growing districts. Finally, extreme heat damage was observed under field conditions with and without over-tree netting. This allowed relationships for estimates of damage under future climates with and without adaptation (installation of netting) to be evaluated. A lowering of risk was found with netting, however for some sites this protection diminished as climate change progressed.

Although these results are specific to Australia, modelling processes should be applicable to France and indeed globally. This is currently being tested for flowering timing for a global apple dataset and initial insights will be presented, highlighting future research directions in adapting the fruit tree industry to climate change.

Rebecca Darbyshire

Faculty of Veterinary and Agricultural Sciences, the University of Melbourne, Australia.