A variety of approaches to the use of ecologically-informed vegetation and plant communities may be taken when designing landscapes. Along a continuum, which goes from the most conservative (i. e. the most like currently-practiced traditional approaches) to the most complete departure from them, the following steps can be identified:
– substitution of native species for traditionally used exotics
– diversification of ground layer plantings
– stylisation/abstraction of native plant communities.
Substitution
This term implies a traditional approach to plant placement, i. e. forming spaces with plants and meeting functional criteria such as shading, windbreaking or the screening of views. But instead of selecting individual plant species almost solely on the basis of size, form, colour, and texture, one selects from an appropriate native community of plants those which can be expected to meet the aesthetic and/or functional criteria that have been established.
For most situations, there are native species that meet such criteria. Further, because plants of a particular plant community grow in association with each other in nature, they tend to appear harmonious when they are placed together in a designed landscape. Perhaps most importantly, they provide a link with the natural history of a site, and perpetuate or even intensify the local or regional identity, thereby counteracting the ‘place-less’ syndrome that has afflicted so many designed landscapes in US cities and suburbs.
The application of a ‘substitution’ approach on an upland site in the southeastern US Piedmont could draw on the upland Piedmont slope forest community for plants in a variety of sizes and forms. For example, the evergreen, low-growing herb, green-and – gold (Chrysogonum virginianum) could be used as a ground cover in a semi-shady area, instead of the commonly used, exotic, periwinkle. Shadblow (Amelanchier arborea), redbud (Cercis canadensis), flowering dogwood (Cornus florida), and sourwood (Oxydendrum arboreum) could make up the subcanopy layer. Shrubs such as sparkleberry (Vaccinium arboreum), sweetshrub (Calycanthus floridus) and maple-leaved viburnum (Viburnum acerifolium), could make up much of the shrub layer under a canopy of white oak (Quercus alba), black gum (Nyssa sylvatica), mockernut hickory (Carya tomentosa) and American beech (Fagus grandifolia). As suggested above, the arrangement or placement of plants using the ‘substitution’ approach is not necessarily different from that in traditional design and, hence, may range from formal geometric arrangements to more informal, organic ones.
