The temperature sensitivity (S_T) of the vegetation greenup onset date (VGD) is critical for the assessment and prediction of phenological response to climate warming. Spatial variations in S_T, though well documented based on satellite observations in recent studies, have remained largely under-explained. We determined VGD from satellite observation of the normalized difference vegetation index over the period 2000–2018 and showed that S_T is substantially smaller in areas with stronger temperature seasonality (i.e. the multiyear mean of standard deviations of monthly mean temperature over a 12-month period). Spatially, S_T averaged over each 2 °C bin of temperature seasonality increased from about −10.0 days K⁻¹ in areas with temperature seasonality of about 3.5 °C to about −3.3 to −2.3 days K⁻¹ in areas with temperature seasonality between 15.0 and 22.3 °C. Statistical analyses suggest that this pattern was not related with spatial variations in the length of chilling exposure, spring frost risk, inter-annual variability of spring temperature, or photoperiod. Rather, it may occur because areas with stronger temperature seasonality have stronger pre-VGD constraints because of a lower temperature and a faster temperature increase from the onset of greenup to summer, which could result in faster leaf development rates and thus higher speeds of completion of leaf development. Our results also show that the greater S_T associated with higher mean annual temperature and multiyear mean VGD across the northern middle and high latitudes observed in previous studies is probably caused by temperature seasonality. This study deepens our understanding of the spatial variation in the temperature sensitivity of vegetation spring leafing phenology in the Northern Hemisphere.

的温度敏感性（小号_Ť植被返青发病日期（VGD）的）可以对气候变暖候响应的评估和预测的关键。S _{T 的}空间变化，尽管在最近的研究中根据卫星观测得到了很好的记录，但在很大程度上仍未得到充分解释。我们确定VGD从在此期间2000至2018年的归一化植被指数的卫星观测，并表明小号_Ť与更强的温度季节性区域小得多（即月平均温度的标准偏差的平均值多年在12个月期间）。在空间上，小号_ŧ在温度季节性约为 3.5 °C 的地区，每个 2 °C 温度季节性区间的平均值从约 -10.0 天 K ^{- 1}增加到约 -3.3 至 -2.3 天 K ^{- 1}在温度季节性在 15.0 至 22.3 °C 之间的地区。统计分析表明，这种模式与寒冷暴露时间、春季霜冻风险、春季温度的年际变化或光周期的空间变化无关​​。相反，它可能发生是因为温度季节性较强的区域具有更强的 VGD 前约束，因为从绿化开始到夏季温度较低且温度升高更快，这可能导致更快的叶片发育速度，从而更高的完成速度叶发育。我们的结果还表明，越大的S _T与先前研究中观察到的北部中高纬度地区较高的年平均温度和多年平均 VGD 相关，可能是由温度季节性引起的。这项研究加深了我们对北半球植被春季生叶物候温度敏感性空间变化的理解。