This report is based upon the National Vegetation Classification (NVC), which provides general descriptions of the floristics of woodland and scrub plant communities occurring in London. Our operational definitions of woodland and scrub are the NVC communities included within volume 1 of the NVC^a. The NVC descriptions are confirmed by the audit of data from London in the following sections of this report. The NVC sampled few woods in London, but the areas around London were well-sampled. This means that most of the more widespread and interesting woodland types of London are described adequately by the NVC, but there are problems with woodlands of recent origin on typically urban sites.

Climate is probably the largest natural influence on London’s woodlands, as London lies near the extreme of three national trends:

In combination, these climatic effects lead to several woodland species being concentrated in the lowland south or east of the UK. Among the canopy species these are: hornbeam, field maple, beech, yew and small-leaved lime. Shrubs include: buckthorn, wayfaring-tree, spindle and dogwood, and in the ground flora we find wood spurge, yellow archangel, early dog-violet and Lords-and-Ladies.

These have been listed in approximate order of decreasing concentration in and around London, but there is no single species that is widespread in London and not elsewhere; even hornbeam is widespread as a native tree in the counties adjoining London to the north, south and east.

Past coppice management has favoured species such as ash, field maple, hornbeam, beech, sweet chestnut and hazel over oak, birch, elm, rowan, holly and sycamore. In this regard many of London’s recent secondary woodlands may have a more natural canopy than those with a history of traditional management.

Many of London’s larger woodlands are accessible to the public and so have suffered from trampling, eutrophication and the clearance of the shrub layer to improve sightlines. In the extreme these woodlands have been degraded to mown grasslands with bare pathways and scattered trees. Conversely, many of the smaller woodlands are of recent origin through ecological succession on inaccessible land and suffer no such problems.

Finally, the absence of significant grazing and browsing in many of London’s woodlands has favoured species such as holly and ivy.

The classification in the table below is designed to provide somewhat more friendly labels for the NVC woodland and scrub communities of London than those of the NVC itself.

In Table 3, the columns summarise the soil types on which the communities are found. The base rich soils (rendzinas and brown calcareous earths) in London occur on the chalk, but also on Boulder Clay and on the London Clay in places. The more neutral soils (brown earths of low base status) occur widely on the clays, and on the recent sands, gravels and alluvium. The acid soils (rankers, brown podsolic soils and podsols) occur on the older leached sands and gravels. The rows relate mainly to drainage and soil development, but also to succession in the case of scrub. At one extreme, the yew woodlands are on steep, thin soils over chalk, and at the other, the willow and alder woodlands have a permanently wet or water-logged soil. Beech tends to occur on better drained soils than do oak, ash and maple, although some regard beech woodland as a later successional stage to the other three trees, even in moister soils.

The NVC does not place London’s hornbeam-dominated woodlands, into one community. Despite their ground flora being generally poor, they are seen as the product of historic management of ash-maple and oak-honeysuckle woods, but largely the latter. The many sycamore-dominated, recent, secondary woodlands in London span a wide range of soil types, but are mainly on the soils that would otherwise have ash-maple woodland.

The amount of each woodland and scrub type in London is summarised in Figure 1, to which the following accounts refer. More detailed information is given in Table 1, which gives the approximate amount of each type in each of the woodlands included within London’s Sites of Metropolitan Importance for nature conservation. There are about 7300 ha of woodland in London, a half of which is included within Sites of Metropolitan Importance for nature conservation. The distribution of this across the boroughs is given in Table 2.

Much of the information used to determine the community types in these woodlands was collected before the NVC methodology was available precluding many precise identifications of the communities, and some well-described woods did not appear to fit the classification very well. For these reasons some broad categories were employed, ranging from woodlands where no sensible community identification could be made, to some which appeared to be a mosaic of two or more types, or to fall between their communities.