Contents lists available at ScienceDirect Ecological Indicators journal homepage: www.elsevier.com/locate/ecolind Study on hierarchical transformation mechanisms of regional ecological vulnerability and its applicability Kang Hou a , Wendong Tao b, ⁎ , Liming Wang a , Xuxiang Li c a School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an 710048, China b Department of Environmental Resources Engineering, College of Environmental Science and Forestry, State University of New York, 1 Forestry Drive, Syracuse, NY 13210, USA c School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China ARTICLEINFO Keywords: Ecological vulnerability classification Ecological vulnerability index Fuzzy analytic hierarchy process Spatial distribution Vulnerability level transformation Weihe Plain ABSTRACT This study analyzed hierarchical change patterns of regional ecological vulnerability by coupling GIS data and fuzzy analytic hierarchy process. It identified the spatiotemporal features of eco-environment and major en- vironmental problems in Weihe Plain, a typical urban agglomeration in China. Previous studies on regional ecological vulnerability have been focusing on evaluating ecological vulnerability status and developing as- sessment methods, while ignoring the mechanisms of vulnerability transformation from one to another level. This study further proposed a subjective evaluation model for ecological vulnerability classification and trans- formation analysis in a multi-index hierarchical evaluation system. The results indicated that ecological vul- nerability index was higher in the urban areas than the surrounding counties from 2000 to 2012, which had a great relationship with the impacts of urbanization on ecological vulnerability. The light ecological vulnerability level was found to be relatively variable over the years and have the greatest impact on the change of regional ecological environment. Analysis with the transformation matrix model found that the degree of regional eco- logical environment stability was regulated by two mechanisms: 1) The proportion of the constant ecological vulnerability level is essential for maintaining the stability of ecological environment; and 2) the difference between the area percentages of decreased and increased vulnerability determines the trend of ecological vul- nerability changes. As verified by applications to two nearby regions, this ecological vulnerability transforma- tion model can be used to monitor the dynamics of ecological vulnerability and identify the leading ecological vulnerability level in other large geographical areas. 1. Introduction Ecological vulnerability is a specific attribute of ecosystems, which indicates the resistance and resilience of an ecosystem to external dis- turbances within a certain region (Beroya-Eitner, 2016). Due to the differences in the degree of internal material, overall structure and external interference of ecosystems, there are certain differences in the characteristics of regional ecological vulnerability (Song et al., 2010). Ecological vulnerability assessment is a necessary means to present the differences. It can not only master the vulnerable state and spatial distribution characteristics of regional habitats, but also promote ef- fective utilization of resources, which is pragmatic for maintaining sustainable development of ecosystems. The evolution of ecological vulnerability directly affects the stability of regional ecological en- vironment and is important for sustainable development (Holden and Linnerud, 2007; Barbier and Burgess, 2017). Therefore, delineation of ecologically vulnerable areas can affect regional human socio-economic activities and ecological environment restoration processes through environmental policies (Hou et al., 2016b). With population increase and accelerated urbanization, the resource and environmental carrying capacities of ecologically vulnerable areas are approaching their limits. The Weihe Plain is a typical, ecologically vulnerable area in northern China. From 2000 to 2012, the urbaniza- tion rate increased from 49.56% in 2000 to 50.02% in 2012, during which the highest urbanization rate reached 53.47% (Shaanxi Provincial Bureau of Statistics, http://www.shaanxitj.gov.cn/).Itisone of the areas that suffer severe soil erosion in the Loess Plateau. Subsequently, the stability of its ecological environment is susceptible to social and economic activities. Rapid urbanization is encroaching the natural environment and disrupting the balance of the ecosystem itself (Wei and Ye, 2014). Because of the frequent interactions between human and land, it is necessary to monitor spatiotemporal variations of https://doi.org/10.1016/j.ecolind.2020.106343 Received 15 December 2018; Received in revised form 9 June 2019; Accepted 24 March 2020 ⁎ Corresponding author. E-mail address: wtao@esf.edu (W. Tao). Ecological Indicators 114 (2020) 106343 1470-160X/ © 2020 Elsevier Ltd. All rights reserved. T