It is clear from the examples given in this chapter that the practice of phytogeographic or plant geographical, physiognomic and ecological planting gradually merged and partially overlapped as ecological science and political and social movements developed. This type of planting arises out of the Enlightenment, which had encouraged a different perception of the concept of nature. The first examples of plant geographical planting date from the beginning of the nineteenth century, being concentrated mainly in botanical gardens, where this was considered the best and most instructive way of exhibiting plants. It never became a mainstream movement however, even after the idea of ecology was developed and promoted in the early part of the twentieth century. The second major wave of ecological gardens set out to educate the general public whilst others saw it as an economic and more sustainable manner to generate a planting scheme. With the progress of ecological science, another group—the scientific researchers—saw ecological planting as an opportunity to test ecological theory.
In some cases, ecological planting was used to reinforce nationalism and, as a result, fell out of favour in the decade after the Second World War. It is noticeable that there are strong parallels between the USA and Germany, not only in reinforcing a nationalist ideology, but also in the development of a strong research base for ecological restoration with Ttixen and Leopold. In the Netherlands, Sweden and Great Britain there has generally been a more liberal understanding of ecology and how this knowledge might inform new planting. During the post-war era, debates with regard to the use of ecological planting have concentrated mainly on management and maintenance issues, as well as integrity with respect to native and exotic species. It is clear that the practice of ecological planting has been important in defining the concept of nature. As with everything else, this notion of nature is subject to fashion and the development of scientific understanding.
As a result, as with other landscape design styles, it is possible to distinguish distinct types of ecological planting in different eras. In 1935, the landscape architect Marjorie Cautley observed:
In nature plants are grouped according to ecology, or adaptability to their environment. In landscape work, plant groups seem to depend upon fashions and styles. It is often possible to ascertain the decade in which a garden was laid out by the type of plants that were in vogue at the time.
This clearly is also the case with various types of ecological planting, where there are distinct developments and changes of emphasis, with nowadays a greater emphasis on artistic outcomes (particularly where these principles are applied to garden plantings), whereas historically ecological principles were mainly thought of in connection with a scientific approach. However, aesthetic considerations have always had a special significance, often aiming to challenge perceived notions of what garden planting is supposed to look like. Scientific approaches remain the dominant emphasis in largerscale work, with the latest projects concerned primarily about restarting natural processes, and natural recolonisation. In time, even this will be shown to have a period feel. This is even more evident for the whole series of artistic approaches stimulated by the ecological ideal that developed in the later decades of the twentieth century.