A network-based framework for characterizing urban carbon metabolism associated with land use changes: A case of Beijing city, China

Abstract

Land use and cover changes associated with urbanization is an important source of the global carbon emissions. Understanding of the driving mechanism of the LUCC-related carbon emissions is of great significance to enhance the benefit of reducing anthropogenic emissions, estimate land use-carbon flow feedbacks, and formulate climate policies. In the present study, we established a network-based framework integrated with ecological network analysis (ENA) and patch-generating land use simulation (PLUS) models to quantify the LUCC impacts on carbon flow variabilities during 1990–2018, using Beijing, China as a target case. Results showed that the total carbon emissions increased from 1990 (10.69 Mt C yr−1) to 2010 (20.61 Mt C yr−1), followed with steady decease to 2018 (18.63 Mt C yr−1), which predominated over total carbon sequestrations with a factor of 28.5 times in 1990 to 48.5 times in 2018. Both the net carbon source and carbon sink associated with land use changes showed decreasing trends over time, with decreasing rates at 5.5% and 4.6%, respectively. Most of this decrease in net carbon source was attributed to emission intensity decline of transportation and industrial land. The decrease of net carbon sink was attributed to slower urban land shrinkage rate and recover of green space. The simulated decarbonization paths suggests there is still a great potential for carbon emission reduction in the city. Carbon emission reduction of different scenario ranged from 19% to 44%, among which 96.1%–97.5% was contributed by decline of emission intensities and 2.4%–3.9% was resulted from recovery of carbon sink land. Moreover, the additional land use adjustment caused extra 6.1%–9.4% carbon emission reduction and 2.2%–5.2% carbon sequestration growth comparing the situation in 2018, which mainly attributed to carbon emission intensities decline and reforest. Overall, our results provide insights into the key carbon flow paths that are necessary for making land use policy towards a more sustainable urban metabolism.