In Japan, the geographical distribution of the first date of flowering (FFD) of Yoshino cherry trees ( Cerasus × yedoensis ) in 2020, a year when temperatures were mild during the previous December and March, was different from the average FFD, which progresses northward along a latitudinal gradient. We hypothesized that global warming may have changed the average geographical pattern of the FFD. To test this hypothesis, we examined the relationship between the observed FFD and latitude at 42 sites during the period 1953–2020. We found that the correlation between FFD and latitude had decreased since 1980. This decrease may have been caused by a rise of temperatures in winter that delayed dormancy release and the subsequent FFD in areas where the annual mean temperature is high. Our results suggest that the correlation between FFD and latitude will decrease further as the climate warms in the future.

中文翻译：

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全球变暖是否会降低日本樱花开花日期与纬度之间的相关性？

在日本，2020年吉野樱（Cerasus × yedoensis）的初花期（FFD）地理分布与去年12月和3月气温温和的年份不同，平均FFD向北推进沿纬度梯度。我们假设全球变暖可能改变了 FFD 的平均地理格局。为了验证这一假设，我们检查了 1953 年至 2020 年期间 42 个地点观测到的 FFD 与纬度之间的关系。我们发现 FFD 与纬度之间的相关性自 1980 年以来有所下降。这种下降可能是由于冬季气温升高延迟了休眠释放，随后在年平均气温较高的地区进行了 FFD。