Spatial differentiation of heritage trees in the rapidly-urbanizing city of Shenzhen, China

•Synoptic heritage-tree conditions in mainland China was reviewed via >300 articles.•We studied remnant heritage trees in the large new city of Shenzhen in south China.•Tree density and diversity are notably higher in the oldest and youngest districts.•Village and forest habitats are more amenable to tree conservation in urban areas.•Policies for town-plan layout and urban tree management determine tree conservation.