Rangewide adaptive plasticity in trees provides resilience to climate change

Abstract Ecosystem restoration is a critical strategy for addressing the global challenges of biodiversity loss, ecosystem degradation and climate change. Where seeds should be sourced for restoration plantings remains intensely debated. Climate-adjusted provenancing – sourcing seed from populations already experiencing the climatic conditions expected at future restoration sites – has been proposed as a proactive strategy to enhance the resilience of restoration plantings under climate change. However, the benefits of climate-adjusted provenancing over alternative strategies, such as local provenancing, remain largely untested. To address this, we established 30 large provenance trials with multiple species, locations, years, and substrates, with seeds sourced from 20 provenances across a 400 km climate gradient where mean annual rainfall doubles. Despite harsh environmental conditions, we found no clear relationship between climate at the provenance and seedling survival or growth. Occasional provenance effects were observed but were inconsistent across trials. We show that neither climate-adjusted nor local provenancing provided a predictable benefit or disadvantage. We hypothesise that the similar tolerance to a wide range of environmental stressors reflects range-wide adaptive plasticity. Such plasticity likely evolved in these ancient lineages on old landscapes in response to a long history of climatic oscillations, increasing aridity, and frequent fire.