In a global warming context, analyses of historic temperature records are essential to understand the potential impacts of climate change on spring phenology. To estimate flowering trends over recent decades, we analyzed long-term temperature and phenology records of eleven local apple cultivars in Asturias (northwestern Spain) in a temperate oceanic climate. Our results show that, over a period of 30 years, bloom dates of the local cultivars have experienced relatively minor changes, considering that temperatures increased strongly since 1978, by 0.30 °C per decade. An explanation for this weak phenological response to warming may be that these temperature changes only had a small effect on overall chill accumulation, but possibly delayed the onset date of endodormancy, which may have counteracted phenology-advancing effects of warming in spring. At present, chill accumulation in this area is high, at an average of 96 Chill Portions from November to March, which indicates that chill is not currently a limiting factor for the quality of flowering and fruiting in the study area. We used Partial Least Squares (PLS) regression to delineate an effective chilling period between November 12th and February 9th and effective heat accumulation between March 15th and May 4th. While these periods appear plausible, we noticed that this approach was unable to identify well-known differences in chilling requirements among many of the cultivars, with similar chill needs determined for many of them. This observation may be explained by inaccurate expectations about cultivars’ climatic needs, by inaccuracy of the chill (and possibly heat) model or, most concerning, by inability of the PLS approach to correctly identify the chilling periods of apple cultivars in this region. Bloom dates were similarly responsive to mean temperature during the chill and the heat accumulation phases, indicating that both processes need to be considered when predicting future phenology.

在全球变暖的背景下，对历史温度记录进行分析对于了解气候变化对春季物候的潜在影响至关重要。为了估计近几十年来的开花趋势，我们分析了在温带海洋气候下阿斯图里亚斯（西班牙西北部）的11个当地苹果品种的长期温度和物候记录。我们的结果表明，在30年的时间里，考虑到自1978年以来温度急剧上升，每十年增加0.30°C，当地品种的开花日期发生了相对较小的变化。这种对变暖的较弱的物候响应的解释可能是，这些温度变化仅对总体寒气积聚产生了很小的影响，但可能延迟了内吸味的发作日期，这可能抵消了春季变暖的物候推进作用。目前，该地区的寒冷积聚很高，从11月到3月，平均有96个寒冷部分，这表明寒冷不是当前限制该研究区开花和结果质量的因素。我们使用偏最小二乘（PLS）回归来描述11月12日至2月9日之间的有效冷却期以及3月15日至5月4日之间的有效热量积累。尽管这些时期似乎是合理的，但我们注意到，这种方法无法确定许多品种之间在冷藏需求方面的众所周知的差异，其中许多品种都确定了相似的冷藏需求。对观测者对气候需求的不正确预期，对冷（或可能为热）模式的不准确，或者最令人担忧的是，可能解释了这一观察结果。PLS方法无法正确识别该地区苹果品种的冷藏期。寒潮期和蓄热期的开花日期对平均温度的响应类似，表明预测未来物候时需要同时考虑这两个过程。