Impacts of land cover changes on summer surface ozone in China during 2000-2019

China implemented continuous forestation and experienced significant greening tendency in the past several decades. While the ecological project brings benefits to regional carbon assimilation, it also affects surface ozone (O₃) pollution level through perturbations in biogenic emissions and dry deposition. Here, we use a coupled chemistry-vegetation model to assess the impacts of land use and land cover change (LULCC) on summertime surface O₃ in China during 2000-2019. The LULCC is found to enhance O₃ by 1-2 ppbv in already-polluted areas. In contrast, moderate reductions of -0.4 to -0.8 ppbv are predicted in southern China where the largest forest cover changes locate. Such inconsistency is attributed to the background chemical regimes with positive O₃ changes over VOC-limited regions but negative changes in NO_x-limited regions. The net contribution of LULCC to O₃ budget in China is 24.17 Kg/s, in which the positive contribution by more isoprene emissions almost triples the negative effects by the increased dry deposition. Although the LULCC-induced O₃ perturbation is much lower than the effects of anthropogenic emissions, forest expansion has exacerbated regional O₃ pollution in North China Plain and is expected to further enhance surface O₃ with continuous forestation in the future.