Controlled experiments suggest that the seasonal build-up of nitrogen (N) limitation constrains the responses of forest autumn phenology to elevated temperatures. Therefore, rising soil N is expected to increase the delaying effects of elevated temperature on the end of the season, i.e., leaf senescence. However, the interactive effects of temperature, soil N, and aridity on xylem autumn phenology remain unknown. We conducted a wide spatial analysis from 75 conifer sites in the Northern Hemisphere and found that rising soil N increases the delaying effects of elevated temperature on the end of xylem cell wall thickening but reduced the delaying effects on the cessation of cell enlargement, especially in humid regions. The contrasting effects of elevated soil N on cell enlargement versus cell wall thickening could affect xylem cell anatomy, thereby induce changes in wood density, and induce a decoupling of stem size growth from photosynthate production. These analyses extend previous findings on forest autumn phenology by systematically investigating the spatial variation in the interactive effects of temperature and soil N on xylem autumn phenology at the cellular scale.

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.

Climate warming and subsequent drought are predicted to alter local forest production and carbon budgets, the sensitivity of which may be site- and species-specific. Although a warmer and drier climate often constrains tree growth, whether trees grown in cool, wet regions across the Siberian forest can in turn be promoted remains unknown. Here, we aimed to investigate the historical growth tendency of Siberian forests in the Sayan Mountain areas and to explore how climate interacts to regulate their growth. We used ring-width data from Siberian pine (Pinus sibirica Du Tour) sampled from three sites in this area to establish a regional chronology and calculate percentage growth change (%GC) over the past 250 years. Bootstrapped correlation analysis between the regional ring-width chronology and climatic factors indicates the mean air temperature, though not precipitation, is more often positively linked to the radial growth of Siberian pines. The %GC series shows that, from 1966 to 2006, the rising temperatures in May resulted in a significant increase in the radial-growth rate of Siberian pines (r = 0.47, p < 0.05). Our study suggests that the positive growth rate anomaly is more likely to occur as temperatures rise in Southern Siberia.