Meitan xuebao (Jul 2023)
Observational study on the change of vegetation carbon sink in cities with depleted coal resources in transition: Xuzhou as an example
Abstract
In the context of the national strategy of “carbon peak and carbon neutrality”, ecological restoration in resource-depleted cities is becoming an important way to carbon sequestration and sinks. The quantitative evaluation of carbon sequestration and sink capacity using long time series observation data will provide valuable references for designing ecological restoration methods in resource-depleted cities. Taking Xuzhou, a typical resource-depleted transformation city in eastern China, as the research area, the temporal and spatial variation characteristics of Gross Primary Productivity (GPP) were observed and analyzed by “Eddy Covariance” and “satellite remote sensing”. The results show that: ① MODIS satellite remote sensing underestimates GPP during the growing season when vegetation is actively growing, because the Light Use Efficiency model sets the maximum Light Use Efficiency of the same vegetation as a constant value, which does not reflect the influence of vegetation growth state, thus increasing the uncertainty of estimating Light Use Efficiency. However, the MODIS GPP and the GPP measured by Eddy Covariance flux tower have the same trend and strong correlation (R2=0.587, P=0), so the MODIS GPP data can be used for the analysis of the GPP change characteristics before and after ecological restoration in the Xuzhou mining area. ② From 2005 to 2011, the coal mining severely damaged the ecological environment in the Xuzhou mining area, and the carbon sequestration capacity continued to weaken. After 2011, the Xuzhou area adopted ecological restoration measures, and the GPP increased significantly and reached the highest value in 2015 (0.878 kgC/(m2·a)), and the change of GPP tended to be stabilized between 2016 and 2020 (0.85 kgC/(m2·a) or so). ③ A series of ecological restoration measures such as mine closure, coal gangue backfill and ecological park construction adopted by Xuzhou have improved the carbon sequestration and sink capacity of the original mine area and formed a self-stabilizing ecosystem, and there is still a trend of improvement in the future, proving that the ecological restoration of coal depleted cities can effectively improve the local ecological environment and rapidly enhance the local carbon sequestration capacity of vegetation within 5 to 10 years, providing a reference for the ecological restoration of other coal depleted cities.
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