The largest part of the Laaer Berg was originally largely forest-free and was home to a Pannonian flora that is unique in Vienna. Due to the juxtaposition of dry grassland and wet locations, there was an extraordinary wealth of species. As early as 1905, when Vienna's green belt was being planned, the intention was to reforest 234 hectares of forest on the Laaer Berg. However, this project was only started in 1953 with a delay of around 50 years on an area of 40 hectares. Due to the geological condition and dryness of the gravel soil, however, there were severe failures and after three years only a tenth of the trees that had been raised were still alive. As a result, the city, which did not want to be dissuaded from the project, had large trenches dug with excavators, filled with earth and the trees planted there artificially watered at great expense. From 1956 to 1970, over 270,000 trees and bushes were reforested here. It was only in 1982 that the now well-grown forest was made accessible to the public. From today's nature conservation point of view, the then well-intentioned afforestation and destruction of the unique dry vegetation is consistently viewed negatively.