图5. 贵阳(a、b)、西安(c、d)和牡丹江(e、f)垂柳和榆树开花始期的积温需求与冷激日数的关系 注:slope1、slope2和slope3分别为GDD、GDDS和GDH算法的积温需求变化趋势。
Fig. 5. Relationship between the thermal requirements and chilling days for the first flowering dates of Salix babylonica and Ulmus pumila in Guiyang (a, b), Xi'an (c, d) and Mudanjiang (e, f)