Management specifications for hedges on or bordering development sites
Please note: All views and opinions expressed in this article are purely those of the author. The content cannot necessarily be taken to represent the specific policy of any of JP Associates’ developer clients.
The importance of hedges within the landscape is now universally accepted: in 1997 the Hedgerow Regulations were drawn up to protect important hedges. JP Associates’ hedge management methods are designed to recognise the importance of hedgerows and ensure their continued status within the landscape. Within a development context, the retention and management of existing hedges is particularly important as the pattern of land use changes.
The question of ownership of a hedge forming property or site boundaries often complicates its management. For the purpose of this guide we’ll assume an ideal situation where the hedge is owned or controlled by one party. In many property boundaries, ownership of the hedge is divided between the neighbouring properties and any management will require negotiations between the different owners.
In the interests of good neighbour relations, even where one party owns the whole hedge, operations such as laying should be carried out only after consultation with the neighbouring property owners and/or tenants. In some circumstances more drastic work can be carried out in phases over a number of years to reduce the initial impact on the landscape. Apart from small-scale, delicate, operations, effective hedge management can only be achieved when work can be carried out to both sides of the hedge at the same time.
Hedges differ in terms of the species present, the condition of the individual trees and in the variety of woody and woodland plants present. They are rich natural ecosystems, providing habitats for a multitude of species of flora and fauna including lower plants and many different trees, woody and woodland species. Communities of mammals, birds and invertebrates also interact and depend on each other and the floral communities and hedges frequently provide habitats for protected species. If protected species have been identified or are expected to be present in hedges that are due to be managed, further professional advice will need to be sought from a qualified ecologist (please also refer to the section on other professional disciplines below).
As with all ecosystems, hedges naturally change and develop as their environment changes through the natural processes of succession and as human influence effects change. Hedges are able to respond to environmental change as long as the rate of change does not exceed the rate at which the habitats can adapt. Thus, while the recognised practice of hedgelaying will remove the majority of the leaf area and will destroy certain habitats, the operation should be timed to reduce the immediate environmental impact and is designed not to damage the base of the plant where more sensitive habitats are often found. All hedgerow management tasks should be undertaken in a way that does not exceed the hedge's ability to respond to those changes.
Maintaining the integrity of hedge banks by adding earth/material should be carried out periodically in order to prevent the erosion of the hedge bank and, therefore, a deterioration of the ecosystem. Material should be added slowly so as not to exceed the rate of change that the hedge can cope with. Traditionally, material was placed on top of the bank at the time when the hedge was layed, every five years or so. If this has not been done for some time the bank will have naturally reduced in height but the ecosystem will have responded to this change in environment. Making a major alteration to bank height/condition in one operation may cause an environment change that the hedge cannot cope with. This may then result in a drastic change to the ecosystem and an unacceptably level of habitat loss.
Traditional field hedges often have ditches that run along one, or sometimes both, sides of their banks. These ditches often form an integral part of any existing land drainage/storm water management network. In a development context the existing land drainage infrastructure may or may not be incorporated into the drainage system for any development. If the hedges have not been closely managed for some time, the existing ditches may well have become silted and will have to be cleaned out and incorporated into the revised storm water management infrastructure.
Where ditches have to be brought back into management, any growth encroaching over the ditches will need to be cleared back to the hedge bank. Material removed from the ditches would traditionally have been put back on top of the hedge banks. In some circumstances this may be the best solution, as long as the volume of material added back to the bank is not excessive (as suggested above).
Where the hedge growth includes individual standard trees growing on the banks, the root systems may well extend beyond the hedge bank, across any adjacent ditches and into the adjacent site/land. To reduce any impact on the retained larger trees’ root systems, ditch cleaning operations may have to be reduced, carried out using hand tools only, or be supervised.
Traditional hedge management techniques vary across the country and have also changed in line with changes to the pattern of land management. While techniques may have altered, the underlying principles remain. In most cases hedges will need to be brought back into closer management following periods of reduced management. As a result the level of work necessary will often be significant and may remove up to 80 per cent of the existing growth. While this may seem a drastic step, the resulting regrowth will be vigorous and swiftly replace the removed growth.
Hedgelaying (in the vernacular style) remains the most appropriate way to manage hedge growth: suitable growth of less than 75mm diameter should be laid over and the majority of larger growth coppiced. The process is quite a personal one and no two people will lay a hedge in exactly the same way. One of the ways in which the management of hedges on development sites differs from agricultural hedge management is that stakes or pegs should be used to hold the laid stems in place (baler twine is not a suitable alternative for development site hedges). The use of stakes or pegs will also help to create a more substantial barrier without having to use supplementary fencing.
Any accumulated debris and old fencing materials should be removed. Traditional hedgelaying usually involves removing most of the existing growth and gaps will often be exposed. Any significant gaps should be replanted with suitable species (blackthorn, hawthorn, hazel, field maple, oak, and ash) using bare rooted whips (either 45–60cm or 60–90cm) planted in a double-staggered row at six plants per linear metre.
Stems left to grow on as hedgerow standards should be selected from tree species rather than shrubs.
Where the Local Planning Authority (LPA) is due to adopt Public Open Spaces (POS) or other areas, the department responsible for the future management will need to be consulted on their particular requirements and policies.
On development sites the management of existing hedges is often subject to a planning condition and the LPA will need to be consulted so that the finished hedges can be inspected and any conditions discharged.
In most development contexts the management of retained hedges (and any adjacent ditches) is discussed and agreed by the development design team. The design team will include several professional disciplines including ecologists and landscape designers as well as layout designers, architects and engineers. The precise management work carried out will need to be agreed by the wider design team to ensure that it does not contradict other professional input.
There are various management operations for different types of hedge, classed according to the different circumstances.
In all cases the exact work details will be subject to negotiation.
Hedges between private residences
The primary function of hedges between private residences is as a screen and private boundary so that properties enjoy both privacy and security without creating heavy overshadowing. Keeping the boundaries (and gardens) tidy is also important. In order to ensure the long-term efficiency of the hedges as screens it may be necessary to lay the hedge and allow the re-growth to form a thicker, more effective screen. Hedgelaying can cause a short-term decrease in the level of screening but as the re-growth is often more vigorous than the usual annual growth, the loss of screening should be quickly redressed.
Hedges bordering POS
The primary function of POS hedges is similar to that of private dwelling hedges except that the degree of screening can be reduced. There remains a distinct need to maintain the integrity of the hedges to prevent further erosion of the banks and habitat loss.
Within a POS the shading provided by mature trees is probably an advantage so more stems can be retained to grow on as hedgerow standards. Larger species such as oak, ash, beech and sycamore can be retained as their larger potential size can often be accommodated without compromising the amenity interests of the residential properties. Varying the appearance of the hedges will provide contrast to the development and add interest to the POS areas.
Hedges forming site boundaries
The primary function of site boundary hedges is to form a screen for/to the site, providing both security and privacy. The integrity of the screen must be ensured so that the screening effect is maximised. As with the other hedges it may well be necessary to carry out some fairly drastic operations to ensure the long-term effectiveness of the screen. As even a short-term reduction of the screen may be unacceptable to all concerned, the erection of a temporary screen fence may be needed. Site boundary management will usually only be able to proceed following agreement with the neighbouring properties or landowners and it may be necessary to phase certain more drastic operations over a number of years. If agreement over the hedge management can’t be negotiated with adjacent land owners, the scope of the work undertaken may be significantly reduced.