Spatiotemporal changes in ecologically functional land in China: A quantity-quality coupled perspective

摘要

Finding ways to identify the coupled relationship between changes in the quantity and quality of ecologically functional land (EFL) is essential for sustainable ecosystem management. However, this coupled relationship has been ignored in the literature. This paper proposes a quality-based quantity (QBQ) method to evaluate the spatiotemporal change in EFL in China. Three Landsat images spanning 20 years were used to investigate the gains and losses of EFL. We compared the differences and linkages between the net change and QBQ change of EFL at the county scale. Continuous EFL loss and growing fragmentation were observed in China. From 1995 to 2015, the main cause of EFL loss was desertification, followed by farmland occupation and construction land consolidation. It should be noted that the EFL loss from 2005 to 2015 was much higher than that from 1995 to 2005. The main gain in EFL was from desert land exploitation, followed by farmland return and construction land consolidation. In particular, grassland degradation was the most severe ecological problem in western China. The QBQ change in EFL showed a more severe situation than did the quantity change. The dynamic processes associated with quantity change and their effects on landscape were well reflected in the QBQ change. These results indicated that the EFL degraded in both quantity and quality in China between 1995 and 2015. EFL conservation policies should focus not only on the dynamic losses and gains in quantity but also on the changes in quality linked to landscape patterns. (C) 2019 Elsevier Ltd. All rights reserved.