Assessing the comprehensive impacts of different urbanization process on vegetation net primary productivity in Wuhan, China, from 1990 to 2020

Urban expansion has complicated impacts on vegetation coverage and growth, including direct impact caused by the conversion of productive land to non-productive impervious surfaces and indirect impact due to urbanization effects on plant growth. Vegetation improves the urban environment and enhances residents' quality of life, yet our understanding of impacts on vegetation under rapid urbanization remains limited. We proposed an improved framework to explore the dynamic comprehensive impacts of urbanization on vegetation net primary productivity (NPP) and further analyzed these impact characteristics in different expansion patterns in Wuhan during 1990-2020. The results showed 3378.92 g C m- 2 yr-1, 3453.56 g C m- 2 yr- 1 and 4090.82 g C m- 2 yr-1 of NPP loss caused by direct impact during 1990-2000, 2000-2010 and 2010-2020, respectively, while NPP increased by 811.33 g C m- 2 yr-1, 2435.91 g C m- 2 yr-1 and 4640.42 g C m- 2 yr- 1 due to indirect impact, during the same time periods. The indirect impact offset approximately 24.01%, 70.53% and 113.43% of NPP loss during the three periods. Direct loss and indirect impact strengthened as the urban expansion intensity (UEI) gradient increased, and the compensation of indirect impact to direct impact was more obvious when the UEI reached less than 20%. Compensation increased more steadily in the compact urban pattern. This study provides fundamental support for forecasting the ecological consequences of future urbanization as well as local ecological policy decision-making.