« Previous | Contents | Next »
Listen
Scotland's Native Trees and Shrubs
General
The most important criteria for the selection of any tree or shrub must be that it is fit for purpose; it must grow well and fulfil its design objective. CEL:LFN requires that 'native species shall be selected wherever they can effectively perform the requirements of the design'.
'Bottom Dead Centre' design from 'Cost Effective Landscape: Learning from Nature' publication
The use of native species is also encouraged by the application of 'the 'Bottom dead centre' approach to design advocated in CEL:LFN. This is based on the premise that the closer to the natural state a landscape is the more sustainable and valuable it becomes biologically. No more than casual observation will confirm that large natural ecosystems are pretty good at looking after themselves. The aim of designers should be to achieve design objectives that are as close to the natural state as is possible. The operative words being 'as close to the natural state as is possible'. Seldom do the design objectives offer the opportunity to design natural landscape in its purest state. Most road landscape design objectives require semi-natural solutions at best. The most common exception being natural colonisation in remote areas. This was, for example, the design solution selected for the re-vegetation of the disturbed ground associated with the new section of A86 road that passes through the National Nature Reserve at Craig Meagaidh.
This is not to suggest that using highly decorative, ornamental planting in creating arresting gateway features to towns and villages or completely free expression on roundabouts is inappropriate or bereft of any value to wildlife. All soft landscape, whether semi-natural or completely artificial, has the potential to provide agreeable habitation for some form of life. As discussed earlier, non-native species can make a valuable contribution to road landscape design and biological diversity - just not as valuable as all native habitat creation in terms of species diversity.
Landscape can be natural or artificial and all shades between. The time, money and resources required to maintain landscape increases the further the design is from its natural state. This can be likened to a pendulum. Bottom dead centre is the state of rest that represents the natural self-reliant landscape and the displacement from bottom dead centre represents the degree of artificiality. Both the pendulum and the landscape will begin to revert to their natural state or bottom dead centre if the energy input declines. CEL:LFN requires the design to achieve its objectives and be as close to 'Bottom Dead Centre' as is possible.
|
Natural regeneration of a rock cutting on the A9 at Drumossie. | The colourful, ornamental varieties of willow and dogwood against an evergreen back-cloth can draw attention to roundabouts and help to reduce vehicle overrunning. In this instance on the A9 at Tor the 'doughnut design' makes efficient and wise use of resources - the centre of the roundabout inside the ring of planting is left unplanted. Willow and dogwood used for this purpose must be pruned annually to maintain their colour but have the advantage that if they are overrun by vehicles the supple form of the shrubs helps to arrest the vehicle without doing too much damage to either. The cuttings can be recycled. |
« Previous | Contents | Next »