Soil temperature remains isothermal at 0 °C and water shifts to a liquid phase during soil thawing. Vegetation may receive this process as a signal and a key to restore physiological activity. We aimed to show the relationship between the timing of soil thawing and the spring growth onset. We estimated the delay between the soil thawing and the spring growth onset in 78 sites of the FLUXNET network. We built a soil thawing map derived from modeling for the northern hemisphere and related it to the greenness onset estimated with satellite imagery. Spring onset estimated with GPP time series occurred shortly after soil surface thawing in tundra (1.1 ± 3.5 days) and alpine grasslands (16.6 ± 5.8 days). The association was weaker for deciduous forests (40.3 ± 4.2 days), especially where soils freeze infrequently. Needleleaved forests tended to start the growing season before the end of thawing (−17.4 ± 3.6 days), although observations from remote sensing (MODIS Land Cover Dynamics) indicated that the onset of greenness started after the thawing period (26.8 ± 3.2 days). This study highlights the role of soil temperature at the spring growth onset at high latitudes. Soil thawing becomes less relevant in temperate forests, where soil is occasionally frozen and other climate factors become more important.

土壤温度在0°C时保持等温，并且在土壤解冻过程中水变为液相。植被可能会将此过程作为信号和恢复生理活动的关键。我们旨在显示土壤解冻时间与春季生长开始之间的关系。我们估计了FLUXNET网络中78个站点的土壤解冻和春季生长开始之间的延迟。我们建立了从北半球模型获得的土壤解冻图，并将其与卫星图像估计的绿色开始联系起来。用GPP时间序列估算的春季发作发生在苔原（1.1±3.5天）和高山草原（16.6±5.8天）的土壤表层融化之后不久。落叶林的关联性较弱（40.3±4.2天），尤其是在土壤不经常冻结的地方。针叶林倾向于在融化结束之前开始生长季节（−17.4±3.6天），尽管遥感（MODIS土地覆被动力学）的观察结果表明，绿化的开始是在融化时期（26.8±3.2天）之后。这项研究突出了土壤温度在高纬度春季生长开始时的作用。在温带森林中，土壤解冻变得不那么重要了，在温带森林中，土壤偶尔会被冻结，而其他气候因素变得更加重要。