Sessile oak and its close relative English/Pedunculate oak are the two native oaks in Britain. Both have iconic status in British culture and have had significant impact on our history particularly the building of the early navies. They are large trees with a substantial impact on the landscape and host to many thousand species of native flora and fauna.
Sessile oak is prominent in the west of England, Cornwall, Wales, Scotland, and Ireland with English oak dominant in the south, east and central England. The ranges overlap and there is a recognised hybrid between the two species: Quercus x rosacea. The hybrid is widely distributed in Britain and has characteristics of both parents which can cause issues in identification. In Cornwall Sessile oak is known as the Cornish oak derowen Kernow, and there would have once been continuous Cornish oak forest from Cornwall into Somerset & Dorset. But in Cornwall this species is becoming rarer.
Sessile oak is a native tree categorised as a Principal tree species. These are tree species where silvicultural knowledge provides confidence to enable successful deployment across Britain. The species are either already widely used or are increasing in usage. They will continue to be important unless affected by a new pest or disease or become adversely affected by climate change.
Native to the British Isles and to much of western, central, and eastern Europe. In Britain it tends to have a more westerly and upland distribution than English oak, but the natural distribution has been much influenced by plantations in previous centuries. Provenances from selected British or north-west European seed stands are to be preferred.
Sessile oak is cold hardy and generally windfirm but can be damaged by late spring frosts. Tolerant of exposure but will develop poor form; for timber production should be planted in sheltered sites. A species of intermediate shade tolerance which can grow well on mineral soils of poor or medium nutrient status. Will tolerate slightly drier soils than pedunculate oak and is not suited to compacted or wet soils.
Sessile oak is a light-demanding species, with a deep rooting system which makes it very wind-firm. It lacks apical dominance and will tend towards a bushy appearance if open grown. It is a species that coppices well.
When planting protection from herbivores is essential. This can be in the form of fencing, but oaks will respond well to growing in tubes. On heavy soils ground preparation may be required. Plants should be sturdy with a good root/shoot ratio and can be established satisfactorily with bare root or containerised plants. Good weeding and follow-up care are essential. Plants that develop poor form can be revitalised by stumping back with subsequent singling.
The poor apical dominance of sessile oak suggests higher densities at planting than would normally be financially acceptable (6000 + stems per hectare). To reduce costs, oak can be grown successfully with a nurse species to encourage straight growth. This can be achieved by group / nest planting or by planting in rows. Mixed broadleaves dominated by shade tolerant species can be planted as a matrix around groups. Suitable species for mixtures if planting in rows is western red-cedar (Thuja plicata), Norway spruce (Picea abies), Larch spp. (Larix spp.) or Scots pine (Pinus sylvestris).
To produce a quality saw log early formative pruning is essential to ensure single leaders and to remove larger side branches. This should start soon after establishment and continue until a single straight stem is achieved. Subsequent management if growing in mixture may require follow-up pruning to maintain stem quality to a minimum of 6 m height on the stem. Aim to manage 300 to 400 trees/ha as potential final crop.
Thinning should be frequent and light with the aim of keeping healthy balanced crowns, but keeping enough shade to reduce epicormic growth. Thinning should continue with the aim of leaving c.100 trees/ha as the final crop. Yield class ranges for oak are from 2 to 8 with an average around 4, but this is dependent on-site conditions. Rotations can be from 130 to 160 years with oak grown under specific management conditions producing sawlogs as early as 100 years.
