Biotope planting—adding exotics to native vegetation

The idea of adding spice to pre-existing native vegetation is an old one, and was the core idea of William Robinson’s (1870) The Wild Garden’ (Robinson 1870). Whilst some in the ‘nativist’ lobby may find the idea appalling, it is a recognition that local floras do not always have the aesthetic appeal that we might want, and can be visually enhanced by the strategic addition of species whose impact or length of seasonal interest generates public interest and support. This type of planting tends to be based upon recognisable native structural plant community types (biotopes), such as meadows and woodlands (and, therefore, has a philosophical connection to native landscapes), but may be considerably altered in terms of its species composition to include non-natives from similar habitats in different regions of the world. Of course, a full consideration of context is vital here. Those who advocate the inclusion of exotics in native-type vegetations generally do so in relation to urban parks and private gardens and not in the open countryside or ecologically-sensitive sites.

Strictly speaking, this style of planting is the most commonly practised of ‘ecological’ approaches. Every native woodland that is underplanted with exotics in a garden or park is essentially a replacement of one, or two, layers of native vegetation in a multi-layered native-dominated community. This ‘woodland garden’ has been much developed in Britain and in the US, although the number of practitioners who are conscious of the possibilities of creating a genuinely self-sustaining plant community remains limited. Attempts at the naturalisation of exotics in open, non-woodland, habitats have been much fewer, as the problems of establishment are much greater. Nevertheless, this is arguably a key area in the development of a planting style for new public landscapes. Before proceeding further, however, we must examine the arguments for and against the inclusion of non-natives in ecological/naturalistic plantings a little further (see also Chapter 1).