Scotland's Native Trees and Shrubs
Selecting native tree species by design
In 1991, a total of 25 natural communities of woodland and scrub were characterised in 'Natural Vegetation Classification' (NVC). They are described in 'British Plant Communities', by JS Rodwell. The NVC should form the basis of any native plant selection. This data should not, however, obviate the need for personal observation and study of the site nor should it be taken too literally or be more than a guide. The NVC has been derived from statistically analysed samples. But other species occur from time to time in most of the assemblages and intermediate communities exist. It is the attention to this level of detail that gives landscape particularity and offers the opportunity to add distinction to design.
Badly conceived design, that is design with insufficient intellectual input, for example, limited to plants selected from the NVC data alone, without knowledge of what communities exist in the area already, will not be acceptable to the Scottish Executive.
The CEL:LFN Procedural Inspection is an important check to ensure that attention to this level of detail is not overlooked. Designers are required to submit survey notes, site sketches, photographs and other site investigation records during the Scottish Executive's design approval procedure.
Gean or wild cherry ( Prunus avium) will grow into a tall tree within a semi-natural woodland. It develops a massive, relatively shallow fibrous root system that anchors the tree. The tree can become a menace where the roots can penetrate adjacent built structures.
Detailed observation of a site, coupled with an understanding of the reasons why and how natural plant communities develop, is considered to be essential to enable designers to match the best selection of species to a specific site. The process is as follows:
- establish which of the 25 woodland communities is right for the site in question bearing in mind that 10 woodland types do not occur in Scotland at all and several other types (associated with fertile or calcareous soils) are rare. The type is determined by examining any remnants of ancient woodland that may exist in the vicinity and the relationship of geography and ground conditions. Alternatively, guidance may be sought from the Forestry Commission 'Bulletin 112: Creating New Native Woodlands', Appendix 1 of CEL:LFN or the Postcode Plants Database produced by the Natural History Museum.
- develop the species mix from the NVC type, selecting the best plant associations for the ground conditions and design objectives. Guidance is available in CEL:LFN Appendix 1 and Forestry Commission 'Bulletin 112 Creating New Native Woodlands'. It is at this stage that the choice of species can be refined to maximise design and biological value - leaf cover or flowering time may be extended, colours contrasted or complemented, or provision made for specific insects or animal life, for example, bees or pine martens.
Upland oakwoods dominate the wetter west-side of the country from Galloway to Sutherland and readily define the NVC woodland type there. Be sure to observe how the different species relate to one another and consider how and why they grow there.