Net primary productivity exhibits a stronger climatic response in planted versus natural forests

Compared to planted forest ecosystems (PFE), natural forest ecosystems (NFE) generally have a longer history and theoretically have stronger environmental adaptability. Changes in net primary productivity (NPP) due to global change have been studied for many forest types, yet the underlying mechanism remain poorly understood. Using 926 forest plots (including both PFE and NFE) established between 2005 and 2020 in China, we found that NPP exhibited stronger climate and soil nutrient responses, with greater environmental plasticity, in PFE versus NFE. Several functional traits (e.g., leaf area, leaf nitrogen and phosphorus content) differed between NFE and PFE, but only weakly predicted spatial variation in NPP, as compared to the environmental factors. Overall, NPP in both NFE and PFE showed consistent responses to climate and soil nutrient changes. These environmental responses were weaker in coniferous forests than broadleaved forests. Direct effects of climatic factors on NPP were stronger than indirect effects. Overall, the effects of functional traits on NPP were mediated by climatic and edaphic factors. These findings provide guidance for more reliable predictions of NPP and succession in NFE and PFE in the context of global warming.