Increasing fragmentation of the wildland–urban interface as it expands across China’s dryland landscape from 1990 to 2020

Abstract

Context: The wildland–urban interface (WUI) is a landscape where buildings and wildland vegetation meet or mix, and is usually regarded as a high risk region because of the high impact of human activities. The expansion of the wildland–urban interface (WUI) could exacerbate environmental risks such as wildfire risk at the landscape scale. China’s dryland landscape provides an ideal case study for assessing WUI dynamics, as they are experiencing rapid urbanization and increasing vegetation cover. However, the morphological features, which is essential in landscape planning, are few recorded in the rapid increase in WUI landscape in China’s dryland. Methods: We produced a set of WUI datasets for the five-year period of 1990–2020 in the drylands of China, and introduced landscape configuration metrics, such as Landscape Shape Index (LSI), Largest Patch Index (LPI), to analyze morphological changes in four WUI types across China’s dryland from 1990 to 2020, and correlated them with population and Gross Domestic Product (GDP) among 486 counties. Results: We identified the WUI area in China’s dryland was spatially accounted for approximately one-tenth of the total area and was concentrated around big cities, exhibited a growth rate of 15% during the 30 years. WUI landscape heterogeneity showed substantial increases, with the LSI increased by 81.1%, and LPI decreased by 38.3%. The WUI area changes were significantly correlated with GDP and population changes; while some landscape configuration metrics showed significant correlations with GDP, but none with population. Conclusions: The WUI fragmentation tendency implies greater exposure of homes and infrastructure to wildfire-prone areas and harder efforts on controlled burns and firefighting in dryland landscape management, especially around big cities. Furthermore, GDP growth may correspond to continued WUI expansion and fragmentation, even if population urbanization will be stagnating.