The role of trees in public spaces in Spanish cities. Past and future

The article makes a brief historical review of urban trees, from the Enlightenment to the present. It focuses on the analysis of a case study, the city of Valladolid (Spain), where different periods can be established. The first one (mid-18th century - mid-20th century), has two distinct stages, the Enlightenment and Hygienism, and in them the planting of trees is more or less widespread. In the second one, which covers the second half of 20th century, it can be documented the disappearance of many of these historical trees. In the current one, the renaturation of cities is considered as part of the solution to environmental problems