Differences in Tree Seedling and Adult Responses to Climatic Stressors

Predictions of forest responses to climate change often use whole-system flux data, while most experiments focus only on seedlings. Both approaches overlook differences in responses throughout tree development that are critical for forecasting forest dynamics. We synthesize evidence on how tree responses to elevated CO 2 , drought, and warming differ between seedlings and adult trees, combining a qualitative review of mechanistic differences with a quantitative meta-analysis across 15 widely studied species. Seedlings face unique vulnerabilities due to shallow roots and lower energy reserves, while adults are buffered by deeper roots and greater storage but show limited plasticity. Despite contrasts, growth responses were surprisingly similar across stages: CO 2 increased growth, drought reduced it, and temperature effects were variable. Yet these similar responses mask key differences: Identical growth reductions can be lethal for seedlings but temporary for adults. To accurately predict forest composition and ecosystem function under climate change, vegetation models must incorporate these developmental differences.