Analysis of the indicators between urban metabolism and land use change in Guangzhou
The study on the interaction between land use change and urban metabolism, which is the core of Global Change Programme, has currently come into lively discussion in the field of ecological research. On the whole ecologic-economic-social system of Guangzhou, this paper analyzes the emergy-based urban metabolism in the past 17 years with reference to the resource flows from 1990 to 2006 and investigates this interaction of the metabolism and land-change of Guangzhou. It finds out the truth that various types of land-use changes had remarkable influence on the material and energy flows during the metabolic course, especially the fast rise of the construction land. The more construction land the city increases, the more total solar emergy it consumes, which makes a decline in the emergy sustainable indices. The per unit area energy consumption also increases in the process of urban expansion with a large amount of depletion of minerals, fuels and building resources. Because of the growing environmental load, the emergy yield ratio is decreasing year by year. At the same time, the emergy efficiency of farmland has been enhanced while there has been a decrease in the amount of farmland and a downward trend of emergy density since 1990. The results can provide an important basis and new ideas for the land planning and management of Guangzhou.