Helen Elizabeth Kuumbi |Artist| Cornwall
Ancient woodlands in the UK
If a woodland shows centauries of continuity on largely undisturbed soils it is considered ancient. This woodland type can encompass semi-natural woodland and plantation. At least 50% of ancient woodlands have been cleared and replanted, they are what is considered a Plantation on ancient woodland site (PAWs).
Woodland is ancient if it has existed since 1600, the woods that existed at this time are assumed to be remnants of the last of the primary forest. Tree planting did not occur in earlier centuries, and grazing pressure would have usually prevented the regeneration of secondary woodland.
Just 2.5% of the UK land is covered in ancient woodland (609,990 hectares).
Ancient woodland is the most complex and biodiverse terrestrial habitat in the UK.
A history of UK Woodland
The last truly natural woodland (i.e. without human disturbance) to develop in Britain followed the last glacial retreat. When looking at our native vegetation today, we consider those that colonised Britain from around 11,000BC as these have ecological continuity with today’s woodland. In this post glacial period a climax vegetation of continuous forest, the wildwood, developed from tundra and heath through a series of waves of colonisation from Europe until the land bridge stop further species migrating north.
Ancient woodland and Carbon capture
Ancient woodland makes up 25% of all UK woodland, but it holds 37% of all the carbon stored in woods and trees – without taking into account the carbon storage in the soils which would increase this. The mass ratio of trees continues to increase each year, even after the tree has reached a mature age. Generally, the older the tree, the more carbon dioxide it will capture from the atmosphere to continue to grow.
However, eventually its growth slows down as it enters over-maturity. It, therefore, spends a lot of energy maintaining its structure and, in turn, has limited energy to produce new wood and capture carbon.
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Soil is importmant
The soil determines the wider woodland health, it is the medium that plants grow in and older than the trees .Within the soil are symbiotic relationships such as between tree roots and mycorrhizae, chemistry and profile, and latent plant materials.
The centuries or millennia that ancient woodland soils have taken to form and their relative lack of disturbance means they are hugely complex and diverse: structurally and biotically. Soils house a significant amount of the earth’s biodiversity, and deliver a sizeable percentage of ecosystem services through their soils’ biotic community; such as carbon sequestration, water purification, nutrient cycling and climate regulation.
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Why are plantations still considered important?
In the twentieth century, many areas of ancient woodland were clear-felled and restocked with none-native conifers for timber production. These sites still retain critical remnant biological and cultural features including woodland specialists plans, relic deadwood, pre-plantation trees and archaeological remains. Features include lichens and bryophytes, invertebrate, seedbanks, rhizomes (i.e. latent plant materials) and soil profiles. They are often the last vestige of animals that cannot move easily through the landscape. Some of these plantations are now being transitioned back to native broad-leaves.
