Extensive areas of the Blean are managed as coppice, the stems being cut down every 10-25 years, keeping the woodland in a permanently juvenile state. However, there are also large blocks which are managed far less intensively, if at all, where the trees (mainly oak, but also some beech, birch and hornbeam) are allowed to mature. These areas of older woodland are referred to by foresters as high forest, and are extremely important to a wide range of wildlife that cannot thrive in the more artificial coppice habitat.
Intensively managed coppice can be extremely uniform; high forest, by contrast, supports several species of trees of varying ages, which generally admit enough light to permit the development of an understorey (hazel, crab apple, holly, wild service and so on), as well as bramble, bracken, honeysuckle, grasses and, in some areas, spring flowers such as bluebells and wood anemones. So, high forest has far more inbuilt structure, but most importantly, it generally contains massively more dead wood, whether as dead standing or fallen trees, or rotting boughs that may be still attached to living trees or scattered across the woodland floor. A huge range of fungi feed on this dead wood, converting everything from oak trunks to twigs, leaves and acorns back into compost to enrich the soil. Decaying wood is colonised by numerous wood-boring insects, which in turn are preyed on by woodpeckers and nuthatches, while rotholes within standing trees may become nest sites for a range of birds such as tits and woodpeckers and, if large enough, may even be occupied by stock doves, jackdaws and tawny owls, as well as the ubiquitous grey squirrels.
Oak (mainly sessile, but with pedunculate on the more clayey soils in the valley floors) is the principal high forest tree in the Blean. Formerly felled for its timber at a relatively young age (around 60-100 years), oak can certainly live far longer than this. We don’t really know what their natural lifespan is on these acid soils, but it is certainly several hundred years. So, although individual trees may shed tens of thousands of acorns most autumns, there is actually no urgency for any of them to germinate in order to replace the parent tree.
Written by Michael Walter