Abstract: Taking the built-up areas of Wulingyuan District,Zhangjiajie as the research subject,this study employs fractal theory and equal-sector analysis based on Landsat remote sensing image data in 2000,2005,2010,2015,and 2022 to quantitatively analyze the spatiotemporal characteristics of urban spatial expansion and the evolution of spatial form of the built-up areas in Wulingyuan.Results indicate that from 2000 to 2022,the built-up area expansion exhibited distinct phased characteristics,progressing through four stages:"moderate speed,low intensity","low speed,low intensity","moderate speed,moderate intensity",and "high speed,high intensity".The period from 2015 to 2022 represented the peak phase of expansion.The expansion exhibited pronounced anisotropy,unfolding as an east-west ribbon pattern.The expansion progressed through four phases:slow wing-fan expansion,slow dendritic expansion,rapid wing expansion,and rapid axial expansion.The compactness index of the urban spatial form exhibited a V-shaped pattern,reaching its lowest point in 2015;while the fractal dimension continued to decline.The urban spatial expansion pattern shifted from outward expansion to internal infill,with the strip-like spatial form tending to be stable.Based on these findings,several recommendations are proposed for the urbanization development of Wulingyuan District.

Key words: urban spatial form, spatial extension, fractal theory, small tourist city, Wulingyuan District