This study experimentally investigates the effects of global warming on the phenology of Quercus serrata under elevated temperatures and CO2 conditions. The experiment was conducted for two years under five treatments: ambient temperature and CO2 (control), + 2 ℃ (T2) and + 4 ℃ (T4) with ambient CO2, and + 2 ℃ (CT2) and + 4℃ (CT4) warming combined with 1.8-fold elevated CO2. Seeds of Q. serrata were sown under each condition, and primary shoot emergence (PSE), first budbreak (FBB), growing-season budbreak (GSB), and leaf abscission (LA) were recorded as day of year (DOY). Warming advanced spring phenological events but delayed summer processes. In the first-year experiment, PSE occurred at DOY 101.2 ± 3.5 (control), 92.1 ± 0.7 (T2), and 76.7 ± 3.4 (T4), corresponding to an advancement of 12.3 days (d) per 1 ℃ increase. Under combined warming and elevated CO2, PSE occurred at DOY 83.3 ± 4.0 (CT2) and 80.8 ± 3.7 (CT4), equivalent to 10.2 d earlier per 1 ℃ increase. LA occurred at DOY 348.0 ± 1.7 (control), 359.0 ± 6.0 (T2), and 365.0 ± 6.0 (T4), indicating an 8.5 d delay per 1 ℃ increase. Under elevated CO2, LA occurred at DOY 360.0 ± 7.5 (CT2) and 363.0 ± 3.5 (CT4), representing a delay of 7.5 d per 1℃ increase. Consequently, the growing period increased by 20.8 d under warming alone and by 17.7 d under combined warming and elevated CO2 per 1℃ increase. Similar patterns were observed in the second-year: the growth period was 223.4 ± 3.7 d (control), 254.0 ± 1.6 d (T4), and 257.8 ± 0.3 d (CT4), reflecting extension of 15.3 d and 12.6 d per 1℃ increase, respectively. CO2 enrichment did not significantly alter phenological responses, as shown by the similarity between T4 and CT4 conditions. The timing gap between the control and warmed conditions widened as growth progressed. All treatments exhibited frequent GSB events up to the fourth occurrence, but warmed conditions showed higher frequencies of later season. Q. serrata observed in this study indicates that a warming of approximately + 4 °C did not reduce chilling enough to impede budbreak. Overall, elevated temperature strongly influenced phenology, whereas CO2 enrichment had minimal impacts. The extended growing period and increased GSB frequency under global warming suggest potentially positive impacts on the growth and productivity of Q. serrata. Phenological shifts in Q. serrata may further biomass accumulation, species interactions, and community dynamics.

Phenological responses of Quercus serrata under the elevated CO₂ and temperature

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发表日期：

2026年3月5日

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Jae Seok Lee

摘要

This study experimentally investigates the effects of global warming on the phenology of Quercus serrata under elevated temperatures and CO₂ conditions. The experiment was conducted for two years under five treatments: ambient temperature and CO₂ (control), + 2 ℃ (T2) and + 4 ℃ (T4) with ambient CO₂, and + 2 ℃ (CT2) and + 4℃ (CT4) warming combined with 1.8-fold elevated CO₂. Seeds of Q. serrata were sown under each condition, and primary shoot emergence (PSE), first budbreak (FBB), growing-season budbreak (GSB), and leaf abscission (LA) were recorded as day of year (DOY). Warming advanced spring phenological events but delayed summer processes. In the first-year experiment, PSE occurred at DOY 101.2 ± 3.5 (control), 92.1 ± 0.7 (T2), and 76.7 ± 3.4 (T4), corresponding to an advancement of 12.3 days (d) per 1 ℃ increase. Under combined warming and elevated CO₂, PSE occurred at DOY 83.3 ± 4.0 (CT2) and 80.8 ± 3.7 (CT4), equivalent to 10.2 d earlier per 1 ℃ increase. LA occurred at DOY 348.0 ± 1.7 (control), 359.0 ± 6.0 (T2), and 365.0 ± 6.0 (T4), indicating an 8.5 d delay per 1 ℃ increase. Under elevated CO₂, LA occurred at DOY 360.0 ± 7.5 (CT2) and 363.0 ± 3.5 (CT4), representing a delay of 7.5 d per 1℃ increase. Consequently, the growing period increased by 20.8 d under warming alone and by 17.7 d under combined warming and elevated CO₂ per 1℃ increase. Similar patterns were observed in the second-year: the growth period was 223.4 ± 3.7 d (control), 254.0 ± 1.6 d (T4), and 257.8 ± 0.3 d (CT4), reflecting extension of 15.3 d and 12.6 d per 1℃ increase, respectively. CO₂ enrichment did not significantly alter phenological responses, as shown by the similarity between T4 and CT4 conditions. The timing gap between the control and warmed conditions widened as growth progressed. All treatments exhibited frequent GSB events up to the fourth occurrence, but warmed conditions showed higher frequencies of later season. Q. serrata observed in this study indicates that a warming of approximately + 4 °C did not reduce chilling enough to impede budbreak. Overall, elevated temperature strongly influenced phenology, whereas CO₂ enrichment had minimal impacts. The extended growing period and increased GSB frequency under global warming suggest potentially positive impacts on the growth and productivity of Q. serrata. Phenological shifts in Q. serrata may further biomass accumulation, species interactions, and community dynamics.

Phenological responses of Quercus serrata under the elevated CO2 and temperature

摘要

Phenological responses of Quercus serrata under the elevated CO₂ and temperature