Large, near-term increases in climate-induced tree growth may help offset impacts of increasing disturbance across Canadian boreal forest

Large projected increases in forest disturbance pose a major threat to future wood fibre supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem 1–4. Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics 5–8. Here we apply a novel machine-learning algorithm to an unprecedented network of over 1 million tree growth records from 18,715 permanent sample plots distributed across both Canada and the US, spanning a 16.5°C climatic gradient, and project the near-term (2050s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 40-52% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests warming-induced growth increases should no longer be considered marginal, but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.