Woodland encompasses a rich and diverse range of habitats for plants and animals, some of which require management for their creation and maintenance.
Woodland is composed of the full range of plant types including trees and shrubs, climbers, perennial herbs, bulbs, grasses, sedges, mosses and lichens. No other habitat contains such a diverse range of plants. Nearly every plant species has its own invertebrate fauna which feeds on it more or less exclusively. Other animals depend on these invertebrates, building the complex web of organisms which make up the woodland community. Deadwood supports a huge range of invertebrates and other organisms.
In its natural state woodland is very varied. Old and dying trees make up a large component of the woodland, with fallen trees creating gaps where regeneration occurs. Glades and other open spaces are maintained by grazing animals, and areas which are too wet, steep or rocky for tree growth create further diverse habitats. From earliest times domestic animals have been grazed in woodlands, replacing the wild grazing animals and maintaining the wood-pasture habitat. In managed woodlands where animals are excluded, rides, tracks and verges can be mown to mimic the glades created by grazing animals. The importance of grazing animals has been recognised and some areas are now reintroducing cattle or ponies as grazers in old wood-pastures. Deer and rabbits can be important in maintaining open areas, but have a damaging effect on regeneration. In coppice woodland, artificial variety produced by management partly compensates for the loss of structural variation in wildwood, but with a loss of deadwood habitats.
New woodlands can be designed and planted to encourage diversity of habitats and diversity of plant and animal species. Plantations, or woodlands suffering from neglect can be improved by increasing their range of habitats, by widening rides, creating and clearing glades, creating ponds and other management work.
Any changes though to existing woodland must be done with caution, as diversification nearly always requires clearance of woody growth, which itself will have wildlife value. Clearance should only be done if the habitat created is likely to be of higher value, or will have significant advantages for amenity or recreation. Site surveys should be undertaken to ensure that valuable habitats are not lost. Recording of invertebrates is difficult and specialised, but a single visit on a sunny day when the hawthorn is in flower should give a good indication of the wood’s value (Kirby, 1992).
Invertebrates in particular move slowly and are very site specific. Woods with a long history are often isolated, and if the invertebrate habitat is lost, for example by the loss of deadwood or old trees, the chances of recolonisation are small. Management of old woodland should be done only with great caution.