Warm-dry climate narrowed the difference between vegetation greenness and photosynthetic phenology periods in the Yellow River Basin, China

China has got a great achievement on ecological restoration in the Yellow River basin (YRB), which owned an extremely frail ecosystem in history. Nowadays, warm and dry climate has threatened the ecosystem there. Change of vegetation phenology act as an effective indicator for ecosystem balance against climate change. Thus, the periods of two vegetation phenology, vegetation green phenology periods (VGPPs) and vegetation photosynthetic phenology periods (VPPPs), were gained and compared here to identify the response of vegetation ecosystem to warm and dry climate in YRB. Sun-induced chlorophyll fluorescence (SIF) and NDVI were used to gain the two VGPPs with SG-filtering and dynamic thresholding method. The results showed that: 1) the differences between VGPPs and VPPPs gradually reduced with the warm-dry climate in the YRB from 2001 to 2022. Specifically, the growing season length (GSL) of VGPPs was shortened by 5 days, while VPPPs was lengthened by 11 days from 2001 to 2022. Thus, the difference between the duration of VGPPs and that of VPPPs was reduced from 40 d to 24 d, with an obviously declined trend (k = −0.74); 2) the start of growing season (SOS) appeared earlier in the southern and southeastern regions, while it occurred later in the western and northern regions. The end of growing season (EOS) showed the opposite pattern compared to SOS; 3) for VGPPs and VPPPs, temperature was the dominated factor for SOS, soil water was the dominated factor for EOS. Besides that, VPPPs were more sensitive than VGPPs to temperature, soil water (SW), precipitation and photosynthetically active radiation (PAR).