Revising Yield and Equivalence Factors of Ecological Footprints Based on Land-Use Conversion

In the current ecological footprint (EF) calculations, the parameters of built-up land are set as equal to those of cropland, based on the assumption that built-up land is totally converted from cropland. However, built-up land may be derived from other types of land use. With the expansion of built-up area as a result of urbanization, the yield and equivalence factors of built-up land are becoming increasingly important in the EF calculation. The objective of this study was to evaluate the influence of this assumption on EF calculation. In this study, the proportions of different land types converted into built-up land were evaluated based on actual land-use conversion in two urbanized areas of Yunnan Province and Kunming City from 1980 to 2010 in the ArcGIS platform. Then, the parameters of built-up land were calculated by an area-weighting approach with the proportions. The results showed the following: (1) In both cases, the EF of Yunnan Province and Kunming City were greater than their biocapacities ( BC ), indicating that they were in unsustainable states. (2) The EF and BC of the two studied cases were reduced to varying degrees because the yield and equivalence factors of built-up land from land-use conversion are less than cropland factors. As the proportion of the built-up land area in Kunming City was larger than that in Yunnan Province, the reduced proportion of the EF and BC of Kunming City is greater than that of Yunnan Province. (3) The proportion of built-up land converted from cropland has a significantly positive correlation with EF and BC . Therefore, it is of great significance to revise the yield and equivalence factors of built-up land using actual land-use conversions in highly urbanized areas.