Assessing Efficiency of Urban Land Utilisation under Environmental Constraints in Yangtze River Delta, China

Future carbon storages of ecosystem based on land use change and carbon sequestration practices in a large economic belt

Assessments of ecosystem carbon storage are needed to form the scientific basis for carbon policies. Due to lack of data, there are few accurate, large-scale, and long-term predictions of ecosystem carbon storage. This study used the Distributed Land-Use Change Prediction (DLUCP) model with ten socioeconomic and two climate change scenarios for a total of 20 combinations that take into account population increase, technology innovation, climate change, and Grain for Green Project to make high-resolution predictions of land use change in the Yangtze River Economic Belt. Low and high carbon sequestration practices were considered to predict future carbon densities. Land use change data, carbon densities data, and the InVEST model were used to predict changes in ecosystem carbon storage from now to 2070. The results show a slight increase (1.88-4.17%) in carbon storage in the study area only based on land use change. Grain for Green Project has the largest impact on carbon storage among population increase, technology innovation, climate scenarios, and Grain for Green Project, which increases carbon storage by 4.17%. After the implementation of carbon sequestration practices, there is an increase in carbon storages from 28.51 to 56.77% in the study area from now to 2070, and increasing carbon storages of forest in each stream and carbon storage of cropland in downstream are efficient ways to achieve carbon neutralization.

Using Systems Thinking and Modelling: Ecological Land Utilisation Efficiency in the Yangtze Delta in China

Ecological land has two definitions: the broad category and the narrow category. This paper studied the narrow category, which refers to the land whose main purpose is to provide ecological services, such as environmental regulation and biological conservation. Ecological land areas are likely to decrease with the development of urbanisation all over the world, which poses potential risks to the environment, society, and public health, and low utilisation efficiency of ecological land will exacerbate this risk. Based on the actual input–output situation of ecological land utilisation, we constructed an index system in the Yangtze Delta to measure the ecological land utilisation efficiency with a Slack-Based Model (SBM) in the data envelopment analysis (DEA). The results revealed that the comprehensive efficiency exhibited an increasing trend from 2012 to 2020, and more high-efficiency cities appeared in the areas closer to Shanghai. Both the technical efficiency and scale efficiency increased over the research period. The technical efficiencies in most cities were efficient and equal to the scale efficiencies. Among the remaining cities, the technical efficiencies and scale efficiencies were inefficient and not synchronous. In addition, we found that the that poor efficiencies of some cities can mainly be attributed to low-technology, an unsuited-scale, or a combination of these. In the future, improvement should be focused on the economical and intensive use of ecological land, technical innovations, and the optimal scale. The present results can provide references for making scientific decisions regarding the efficient utilisation of ecological land in the Yangtze Delta and other similar rapid-urbanization areas.