Climate warming strengthened but droughts eliminated the coupling between productivity and tree growth in semi-arid plantations

Forest carbon sequestration depends on how trees allocate carbon between canopy productivity and stem growth, yet these processes may respond differently to climate change, creating uncertainty in estimates of plantation carbon uptake. Here, we combined tree-ring measurements with satellite observations of canopy productivity from 2000 to 2018 to examine the relationship between radial growth and canopy productivity in the four most widely planted tree species across northern China, and to assess their responses to extreme droughts in 2008–2009 and 2014–2015. We found that radial growth and canopy productivity remained broadly coupled across plantations, with stronger temporal coherence in conifers and increasing coherence in broadleaved species. Both processes showed similar climatic sensitivity, but radial growth recovered more rapidly after droughts, whereas canopy productivity recovered more slowly and often incompletely. These results suggest that plantations may regain wood production earlier than canopy productivity, with important implications for evaluating forest recovery and carbon sequestration under increasing drought stress. Canopy productivity and radial growth remain strongly coupled in major plantations across northern China, yet droughts create asynchronies, with faster post-drought growth recovery, based on radial-growth records and MODIS data from 2000 to 2018.