Protection of the existing landscapes and mature vegetation is of critical importance because of the long-time scales required to establish landscapes that are able to support a variety of plants and animals and to allow planted vegetation to mature. Mature vegetation and existing habitats, where possible should be retained.
There are a number of solutions that can be implemented both pre and during the construction process to protect existing landscapes and habitats.
Buffer Zones are a well-established method for protecting existing landscapes and habitats. They often contain mature planting therefore have the ability to separate conflicting land uses as well as provide attractive boundaries or ‘edges’. They can also be used to avoid disturbance of existing features during construction and operational lifetime as even temporary disturbance can cause permanent damage to existing landscapes.
Buffer zones can also reduce the potential for future conflicts with residents due to reduced security from houses which abut woodland, heavy shading from trees, potential for tree roots to cause subsidence and/or perceived danger from veteran trees. Where watercourses or other sensitive landscape features are located on site, a buffer zone will be required to protect it during construction and operation.
To be effective buffer zone widths should be a minimum of:
- Ten metres from rivers
- Eight metres from smaller watercourses and ponds
- 20 metres from woodland to the edge of residential gardens and other property boundaries.
Buffer zones were used in The Staithes case study, where the development footprint was pulled back from the river to minimise the impact on a valuable site for wading birds.
Exclusion zones are buffer zones which have additional restrictions on their use. Mitigation involving exclusion zones must be considered at the design stage, to ensure that the zone is feasible and viable in terms of practical working area and implemented and maintained in accordance with the approved plans.
Protective fencing is essential for ensuring contractors and others are aware of areas of landscape value which are vulnerable to damage on site. Breakdowns in communication are frequently responsible for irreversible errors on construction sites.
Where development will disturb a habitat, a habitat protection scheme must be in place. If protected species are present then a scheme of habitat fencing and supporting specification, including licenses will be required before work starts on site.
Habitat protection schemes may include fencing vegetation to preserve or reduce the adverse effects such as trampling. Fencing of buffer strips abutting watercourses is desirable in rural areas to reduce poaching from livestock.
Features such as trees that are proposed to be retained or removed must be clearly identifiable on site by spraying with brightly coloured paint. The project manager and contractor must also have the most up-to-date, approved plan of features being retained and those to be removed.
New landforms such as earth bunds can be an effective way of screening existing landscapes and habitats from adverse noise and visual effects. The M25 Widening Scheme case study below is an example of how this can be achieved.
Timing and phasing
Timing and phasing are important ways of minimising adverse effects of development on wildlife and existing habitats. Works must be phased and carried out with regard to seasonal patterns such as nesting, mating and hibernation. It is important that advanced planning of development schemes is carried out in order to maximise the effectiveness of development schemes.
Monitoring of a development, particularly during the construction phase, is critically important. This will ensure that a development is not having unanticipated adverse effects including; dust, noise, unauthorised vegetation clearance, inappropriate materials storage, night lighting and polluted runoff, on the biodiversity values on a site and the surrounding area.
Active and regular monitoring in a timely manner helps ensure that mitigation measures can be provided where necessary e.g. constructing bunds to catch runoff before it enters a watercourse.