Читать книгу Collins Complete Guide to British Trees: A Photographic Guide to every common species - Paul Sterry - Страница 23

Although Sessile Oak often grows alongside its Pedunculate cousin, its requirements for optimum growth are subtly different and it predominates in upland and western parts of the region where rainfall is highest. Often the best remaining tracts of Sessile Oak woodland are on steep slopes, in part because the trees are less easy to fell there; in such circumstances they are often referred to as ‘hanging oak woodlands’. Try to negotiate the broken ground and slippery roots of one of these woodlands and it is not hard to see why.

Although the wildlife that Sessile Oak is capable of supporting is broadly similar to that of a Pedunculate Oak, in reality there are subtle differences. In part this may be a reflection of the generally harsher climatic conditions that it favours, although the history of land use by man sometimes plays a part too.

In lowland oak woods that have an understorey of Hazel, grazing animals were typically excluded in the past, or at the very least discouraged on account of the damage they might do to growing shoots. By contrast, many hanging woods of Sessile Oak are freely grazed by sheep and cattle with the consequence that the shrub layer is considerably reduced. Bluebells and other flowers of the woodland floor are common, but what strikes most visitors is often the abundance of ferns, mosses and liverworts. In part this is a result of an absence of competition from more palatable (in grazing animal terms) flowering plants, but the humidity of the regions where Sessile Oaks grow also plays a part. Hence the abundance of epiphytic mosses and liverworts in particular, often festooning trunks and branches well off the ground. Sessile Oak woodlands are the classic domain of nesting Pied Flycatchers and Redstarts.

Hanging Sessile Oak woodland.

Sessile Oak woodland cloaking steep hillsides on Exmoor.

In the British Isles, Pied Flycatchers reach their highest breeding densities in Sessile Oak woodlands.

Tree Lungwort.