Notice how pine decreases after 5500 BC.
This correlated with the initiation of peat formation at this time (5500 - 3000 BC).
During the Sub-Boreal stage, peat depth increases, pine is almost totally disappeared.
Weeds (e.g. bracken), heathers and grasses appear and increase in population after 5500 BC.
The Sub-Atlantic saw a rapid growth of peat in the colder, wetter climate. Heather populations increased.
The increase of grass and bracken pollen from the Sub-Atlantic to the present indicates widespread clearing of forests with pastoral and arable farming becoming increasingly popular.
