The Widely Increasing Sensitivity of Vegetation Productivity to Phenology in Northern Middle and High Latitudes

Although vegetation phenology generally alters productivity, spatiotemporal variations in this effect and its potential drivers remain unclear. We used satellite-based vegetation phenology and gross primary productivity (GPP) data sets to analyze trends in the sensitivity of spring GPP to spring phenology (spring S_GP) and autumn GPP to autumn phenology (autumn S_GP). We also explored potential drivers across the northern middle and high latitudes (>30°N) from 2001 to 2019. Our analysis revealed significant increases in spring and autumn S_GP (P < 0.05), with pronounced increases in boreal forests and tundra biomes. In contrast, spring S_GP significantly declined in deserts and xeric shrublands (P < 0.05). Spring temperatures and leaf area index (LAI) were key factors influencing spring S_GP, while autumn LAI and downward surface solar radiation drove the variation in autumn S_GP. Our findings highlight the critical role of phenology-productivity interactions in achieving carbon goals and the need for future research on climate feedback mechanisms.