Polgar Caroline A, Primack Richard B, Dukes Jeffrey S, Schaaf Crystal, Wang Zhuosen, Hoeppner Susanne S
Boston University, Boston, MA, 02215, USA,
Int J Biometeorol. 2014 Aug;58(6):1251-7. doi: 10.1007/s00484-013-0718-z. Epub 2013 Sep 1.
Leaf out time is a widely used indicator of climate change and represents a critical transition point of annual seasonality in most temperate ecosystems. We compared three sources of data to determine the effect of spring temperature on tree leaf out: field observations, remotely sensed satellite data, and experimental warming. All three methods recorded earlier leaf out with warmer spring temperatures. However, leaf out timing was more than twice as sensitive to temperature in the field study (advancing at a rate of 6.1 days/°C), as under experimental warming (2.1 days/°C), with remote sensing intermediate (3.7 days/°C). Researchers need to be aware of the currently unexplained differences among methodologies when using phenological data to parameterize or benchmark models that represent ecosystem processes. The mechanisms behind these discrepancies must be better understood if we are to confidently predict responses of leaf out timing to future climates.
展叶时间是一种广泛使用的气候变化指标，代表了大多数温带生态系统年度季节性的关键转变点。我们比较了三种数据来源，以确定春季温度对树木展叶的影响：实地观测、遥感卫星数据和实验性增温。所有这三种方法都记录到随着春季温度升高展叶提前。然而，在实地研究中展叶时间对温度的敏感度是实验性增温条件下（2.1天/°C）的两倍多（以6.1天/°C的速率提前），遥感数据的敏感度处于中间水平（3.7天/°C）。研究人员在使用物候数据为代表生态系统过程的模型进行参数化或设定基准时，需要意识到目前方法之间存在的无法解释的差异。如果我们要自信地预测展叶时间对未来气候的响应，就必须更好地理解这些差异背后的机制。
