The sampling of woodland vegetation

Sampling woodland vegetation poses some particular problems. In the first place, woods are often a prominent feature of the landscape and tend to impress themselves upon us in their entirety. Some have a long-established integrity, enshrined in a name and witnessing to a complex history of economic and social recognition and use, but even those woods which are the product of more recent afforestation or neglect can demand attention as a whole. In fact, of course, individual stretches of wooded vegetation are often very varied internally. They can consist of a number of widely-differing woodland communities, and have scrub around their margins, on the edges of clearings and along rides, quite apart from including stands of bracken, heath and grassland, mires and swamps, and aquatic vegetation in pools and flooded ruts. It is very important, in the description and assessment of sites, to be sensitive to the frequently intimate ecological and historical relationships between the vegetation types that make up particular woods, but our priority here is to characterise woodland communities in the strict sense. This volume therefore includes just vegetation in which trees and/or shrubs are dominant, together with closely related underscrub, and readers will have to consult other parts of the work for full accounts of grasslands and heaths and so on which they might encounter within the boundaries of woods. At the same time, frequent reference is made here to such zonations and successions between the various vegetation types that are found in and around woods, and to the different kinds of wooded landscapes characteristic of Britain.

Within woodland communities, a second difficulty is that the range of size among the plants represented is very great, from hepatics, mosses and lichens that can be tiny, through herbs and ferns of various proportions, to shrubs and sometimes enormous trees. On entering a stretch of woodland, it may be clear enough that the plants are organised in a stratified arrangement of one sort or another, approximating to ground and field layers, understorey and canopy, or some variation on this theme, but it is often difficult to take in the extremes of this structural complexity at a single glance, or do ready justice to all its subtleties.