Tree growth response and adaptation to climate change and climate extremes: From canopy to stem.

Ongoing climate warming has altered precipitation patterns and increased the frequency and intensity of climate extremes such as droughts, heatwaves, floods, and frosts. These changes have significantly influenced tree growth and development processes, including canopy phenology, intra-annual wood formation dynamics, and annual stem growth. However, these processes are affected by various climatic factors, and their responses are highly species-specific and vary across temporal and spatial scales. Beyond these rapid growth responses, trees may also undergo long-term genetic adaptation to climate change. This review synthesizes how canopy phenology, intra-annual wood formation dynamics, and annual stem growth respond to climate change and climate extremes. We summarize the response and adaptation of these growth processes to various climatic drivers and highlight the interactions among them in determining tree growth. Concepts and mechanisms of rapid response and heritable genetic adaptation in trees under climate change are also reviewed. We identify the key knowledge gaps in tree growth response and adaptation, such as integrative multiple organ and growth process monitoring and genetic-level studies, which are critical to further improve our understanding of tree growth to support sustainable forest management and enhance forest carbon storage under ongoing climate warming.