增温和光周期变化对温带典型木本植物展叶始期的影响

厘清驱动植物物候变化的气候因子对评估全球变化对生态系统的影响具有重要意义。针对欧洲与北美地区木本植物的控制实验表明春季物候变化主要受冷激、驱动温度和光周期影响,但这3个气候因子是否对东亚地区木本植物的春季物候存在相似的作用仍需验证。论文选取了5种典型木本植物(迎春Jasminum nudiflorum、连翘Forsythia suspensa、荚蒾Viburnum dilatatum、玉兰Yulania denudata与东京樱花Cerasus yedoensis),利用生长箱对冬季休眠枝条的展叶过程开展了控制实验。实验设置了3种驱动温度(12 ℃、15 ℃、18 ℃)、3种冷激(3 d、38 d、59 d)以及2种光周期(10 h、14 h)处理,并利用分层贝叶斯模型建立了展叶始期与各影响因子间的关系。结果表明,驱动温度每升高1 ℃导致展叶始期提前2.6 ~ 9.0 d,但展叶始期的温度敏感度随温度和冷激天数的增加而减弱。冷激也是影响木本植物展叶始期的重要因子。与冷激处理3 d相比,冷激处理59 d使展叶始期提前20.3 ~ 66.6 d,但随冷激天数增加,展叶始期对冷激响应的敏感度减弱。光周期延长对展叶始期具有提前效应,但总体小于驱动温度与冷激的影响。光周期由10 h延长至14 h后,展叶始期提前0.3 ~ 12.9 d,且在低冷激处理时光周期的效应更明显。这些结果为理解近几十年来春季物候变化及其对增温的响应提供了科学依据。

Effects of warming and photoperiod changes on the leaf-out date of typical temperate woody plants

Clarifying the climatic factors driving plant phenological changes is vital for assessing the effects of global change on the ecosystem. The previous controlled experiments on European and North American woody plants demonstrated that spring phenological changes were mainly affected by chilling, forcing temperature, and photoperiod. However, it was unclear whether these three climatic factors have similar effects on the spring phenology of East Asian woody plants. In this study, we selected five typical woody plants (Jasminum nudiflorum, Forsythia suspensa, Viburnum dilatatum, Yulania denudata and Cerasus yedoensis) to investigate the leaf-out date of their dormant twigs in growth chambers with controlled environments. We set three forcing temperature treatments (12 ℃, 15 ℃, and 18 ℃), three chilling treatments (3 d, 38 d, and 59 d), and two photoperiod treatments (10 h and 14 h) and monitored the leaf-out date in each treatment. Finally, we established the relationship between the leaf-out dates and the climatic factors using the hierarchical Bayesian model. The results show that 1 ℃ warming in forcing temperature advanced the leaf-out dates by 2.6-9.0 d, but the temperature sensitivity of the leaf-out dates decreased with the increase in forcing temperature and chilling days. Chilling is also an important factor affecting the leaf-out dates of woody plants. Compared with 3 d chilling treatment, 59 chilling days advanced the leaf-out dates by 20.3-66.6 d. However, the sensitivity of leaf-out dates on chilling decreased with the increase in chilling days. Longer photoperiod caused earlier leaf-out dates, but the effect of photoperiod was smaller than that of forcing temperature and chilling. When the photoperiod was extended from 10 h to 14 h, the leaf-out dates were advanced by 0.3-12.9 d, and the effect of photoperiod was more significant in lower chilling treatment. These results provide a scientific basis for understanding spring phenological changes in responses to climate warming over the past decades.