Hänninen Heikki, Slaney Michelle, Linder Sune
Department of Biological and Environmental Sciences, Plant Biology, Plant Ecophysiology and Climate Change Group (PECC), P.O. Box 65, FI-00014 University of Helsinki, Finland.
Tree Physiol. 2007 Feb;27(2):291-300. doi: 10.1093/treephys/27.2.291.
Ecophysiological models predicting timing of bud burst were tested with data gathered from 40-year-old Norway spruce (Picea abies (L.) Karst.) trees growing in northern Sweden in whole-tree chambers under climatic conditions predicted to prevail in 2100. Norway spruce trees, with heights between 5 and 7 m, were enclosed in individual chambers that provided a factorial combination of ambient (365 micromol mol-1) or elevated (700 micromol mol-1) atmospheric CO2 concentration, [CO2], and ambient or elevated air temperature. Temperature elevation above ambient ranged from +2.8 degrees C in summer to +5.6 degrees C in winter. Compared with control trees, elevated air temperature hastened bud burst by 2 to 3 weeks, whereas elevated [CO2] had no effect on the timing of bud burst. A simple model based on the assumption that bud rest completion takes place on a fixed calendar day predicted timing of bud burst more accurately than two more complicated models in which bud rest completion is caused by accumulated chilling. Together with some recent studies, the results suggest that, in adult trees, some additional environmental cues besides chilling are required for bud rest completion. Although it appears that these additional factors will protect trees under predicted climatic warming conditions, increased risk of frost damage associated with earlier bud burst cannot be ruled out. Inconsistent and partially anomalous results obtained in the model fitting show that, in addition to phenological data gathered under field conditions, more specific data from growth chamber and greenhouse experiments are needed for further development and testing of the models.
利用在瑞典北部全树室中生长的40年生挪威云杉（Picea abies (L.) Karst.）树所收集的数据，对预测芽萌发时间的生态生理模型进行了测试，这些树生长在预计2100年将普遍存在的气候条件下。高度在5至7米之间的挪威云杉树被封闭在单独的室中，这些室提供了环境（365微摩尔/摩尔）或升高（700微摩尔/摩尔）的大气二氧化碳浓度[CO₂]以及环境或升高的气温的析因组合。气温比环境温度升高的范围从夏季的+2.8摄氏度到冬季的+5.6摄氏度。与对照树相比，气温升高使芽萌发提前了2至3周，而升高[CO₂]对芽萌发时间没有影响。一个基于芽休眠完成发生在固定日历日这一假设的简单模型，比另外两个更复杂的模型（其中芽休眠完成是由累积低温引起的）更准确地预测了芽萌发时间。与最近的一些研究一起，结果表明，在成年树中，芽休眠完成除了低温外还需要一些额外的环境线索。虽然看起来这些额外因素将在预测的气候变暖条件下保护树木，但与芽提前萌发相关的霜冻损害风险增加不能排除。模型拟合中获得的不一致和部分异常结果表明，除了在田间条件下收集的物候数据外，还需要来自生长室和温室实验的更具体数据，以进一步开发和测试这些模型。
