Spatiotemporal analysis of ecological footprint and biological capacity of Gansu, China 1991–2015: Down from the environmental cliff

Abstract

Ecological footprint methodology, as an excellent educational tool applicable to global issues, is essential for quantifying humanity's consumption of natural capital, for overall assessments of human impact on earth as well as for planning for a sustainable future. At present, quantitative studies on the development trends of ecological footprint (EF) time series and biological capacity (BC) time series in a given region are still rare. In this paper, we present two quantitative estimate indices over time scale called the change rate and scissors difference, which describe quantitatively the development trends of EF and BC and the difference between both trends in a long time series. For a case study of Gansu province in western China, we calculated the change rates and scissors differences of per capita EF and BC from 1991 to 2015, analyzed the development trends in the past 13 years and predicted those in the following 12 years. We have, by using GIS and geostatistics, also produced a prediction map that contains 13 annual maps interpolated for the per capita ecological budget data of 87 counties in Gansu between 1991 and 2015. This map can reflect the spatiotemporal patterns and trends of ecological sustainability in spatiotemporal dimension, which coincide with the results from the time series using the two indices. As shown by our results, the negative change rates of per capita EF (1991–1993) indicate a descending trend of per capita EF and the positive change rates (1994–2015) indicate an ascending trend afterwards. The negative change rates of per capita BC (1991–2015) indicate a descending trend of per capita BC. The scissors difference growing from 1991 to 2015 shows that the difference between EF and BC is increasing rapidly. The state of ecological development has been unsustainable since 1998. The primary factor leading to the unsustainability is the increasing consumption of fossil energy, which has doubled in the past 13 years. The analysis suggests four strategies for the local governments. The purpose of our work is to point out the need for research into the development trends of EF and BC time series in spatiotemporal dimension.