Medieval cities had little vegetation, because land within city walls was so scarce and so expensive. As artillery improved and the practice of siege warfare declined, private gardens and public parks became thinkable. In the nineteenth century they became popular, as did coal fires. The latter transformed rain into dilute sulphuric acid, which dissolved all but the toughest vegetation. There was also a shortage of firewood, which put trees at risk. It was only in the twentieth century that cities became richly vegetated. This process can be seen in the illustrations of Edinburgh (Figure 8.4a and 8.4b). My guess is that if another photograph is taken in AD 2050, the process will have gone further.
As it was the public park and the private garden that created space for ornamental vegetation in cities, the vegetation was managed in a gardenesque way. It was not countryside. Park managers aimed for three categories of vegetation: clear-stemmed trees, mown grass and ornamental beds From a sustainability viewpoint, this was improvident. Heavy resource inputs are required for park maintenance, as fuel, fertilizer, pesticide, herbicide and irrigation. These inputs produce wastes: air pollution, soil pollution, water pollution and noise pollution. They also destroy wildlife habitats. Is it possible to strike a compromise between garden exotica and nature conservation? Yes. Small areas of garden, maintained by hand with loving care, are a delightful luxury. Large areas of semi-natural habitat, maintained by adaptations of natural processes, provide a good environment for man. But it is time to do away with the middle landscape of "amenity grass' and "amenity shrubs', where the "amenity' in question is gardenesque in the sense of "like a garden'
Medieval cities, like Old Prague, had little space for vegetation.
Future cities will be much more vegetated than old cities
Fig 8.4a Central Edinburgh in 1830 - with few trees
Fig 8.4b Central Edinburgh in 2005 - with many more trees. The Castle (right) and the dome of Register House (left) are visible in both illustrations.
A plan for creating new habitats in Holland