Evidence suggests that at the start of the Mesolithic period when the ice sheets retreated from England 10,000 years ago, they left a landscape in the High Weald of scrub tundra with areas of birch-pine woodland. Summers became at least as warm as today and plant communities dominated by grasses and sedges were accompanied by dwarf-shrub heath. Other plant species appeared but herbaceous and dwarf-shrub heath communities seem to have remained dominant. Plants like heather cannot survive the dense shade of high forest and may have originally evolved in unwooded areas including sea cliffs or land at higher altitudes. Grazing, burning and cutting trees by settlers from pre-Roman to Early Modern times of on the soils of the Ashdown Forest area would have favoured a mixture of Heathers, grasses and trees, much as today.
Wild horses, wild pigs, aurochs (wild cattle), moose, red deer and roe deer spread from continental Europe and grazed here and were hunted, perhaps more easily in the more open and relatively treeless areas that probably persisted for many centuries. However there were clearly enough trees for fuel when the Iron Age began around 750 BC. Details of Iron Age activity on the Forest can be found on the history pages.
The survival of today's plant assemblage and habitat known as heathland is the legacy of hundreds of years of pastoral activities of our Commoners. Their Rights of Common entitled them to firewood, animal bedding (bracken and heather) and grazing by cattle and working horses. This land use on nutrient-poor soils prevented development of woodland, controlled Bracken dominance and favoured species that had some competitive advantage under this regime. At the height of Commoner activity in the late 19th Century, entitlements for Rights of Common were fiercely contested.
The activities and numbers of farming Commoners since the Second World War diminished so much that the condition and extent of heathland declined at the expense of scrub and semi-natural woodland. Aerial photographs from 1947 show only 7% woodland cover; this increased to 40% by 2000. In England, only one sixth of the heathland present in 1800 now remains. By 1990, the Misbourne Valley was almost entirely impenetrable scrub with tall gorse.