Impacts of urban expansion on vegetation in drylands: A multiscale analysis based on the vegetation disturbance index

The rapid urban expansion in drylands has threatened local fragile vegetation in recent years. Evaluating the urban expansion impacts on local vegetation in drylands effectively is crucial for promoting regional urban sustainability. Taking the Hohhot-Baotou-Ordos-Yulin (HBOY) urban agglomeration in China as a case, we quantitatively evaluated the positive and negative urban expansion impacts on vegetation using the vegetation disturbance index. The results indicated that HBOY experienced significant urban expansion from 2000 to 2020. The urban land in HBOY expanded from 242 km2 to 1276 km2, an expansion of 1034 km2, with an annual growth rate of 8.7 %. The negative urban expansion impacts on vegetation far exceeded the positive impacts. Urban expansion negatively and positively affected 404 km2 and 169 km2 of vegetation, respectively. The former was 2.4 times that of the latter. The negative impacts on vegetation are mainly caused by the loss of cropland and grassland. Such negative impacts further affected more than 80 % of the threatened species in HBOY. Therefore, cities in drylands should balance urban development and vegetation conservation by strictly controlling cropland and grassland occupancy and promoting intelligent urban growth.