WOODLAND STRUCTURE

The complex structure of semi-natural broadleaved woodland offer a great diversity of habitats in which plants and animals can live. Like other aspects of the woodland environment, structural features are impermanent and ever-changing. One of the main aims of woodland management is to create, maintain or restore structural diversity where it has been lost or where, without management, it would decline.

Woodland structure can be seen both vertically and laterally. Often, three layers of vegetation can be seen beneath the tree canopy: a shrub layer, field layer and ground layer.

The field layer may develop two sub-divisions: a layer of tall herbs and undershrubs, and a layer of low herbs. Trees of the canopy and shrub layers may consist of plants of a single species, but of different ages and sizes, or they may be of different species which reach varying heights when mature. In a mixed wood, typical mergent species may include elm or beech, with oak or ash as dominants and crab apple, wild cherry, holly, rowan or field maple forming the understorey. The shrub layer may include hazel, hawthorn or blackthorn. Bracken (Pteridium aqualinum), rose-bay, willow-herb (Epilogium angustifolium) and bramble (Rubus spp) may form a tall herb layer with bluebells (endymion non-scripta), dog’s mercury (Mercuralis perennis), ramsons (Allium ursinium) and smaller ferns among the low herbs. The ground layer would consist of mosses and liverworts, plus the seedlings of the plants of the taller layers. Where the woods are coppiced , the lower layers are likely to include coppiced shoots of the canopy species.

Coppiced woods are often especially diverse because at any given time they are likely to contain some coupes which have recently been cut over, some where the the coppice has created a dense shrub layer and others where the coppice has matured into an understorey with standards as canopy dominants.