Britain once supported a temperate rainforest covering roughly a fifth of its land surface. This woodland, an estimated 4.6 million hectares, stretched from Cornwall to the Scottish Highlands along west-facing slopes and river gorges. The climate there, mild with heavy Atlantic rainfall, allowed oaks, mosses, lichens, and ferns to grow in dense, interconnected layers. Today, less than 1% of Britain’s land still holds this habitat. More than 98% of the original forest is gone.

The loss was not a single event. It happened gradually over roughly 800 years. From the Bronze Age through the medieval period, the canopy was felled for farmland, charcoal, shipbuilding timber, and the tanning industry. No single generation saw the landscape in its original state. Each successive generation worked from a baseline that was already reduced. By the end of the industrial era, the continuous forest was broken into hundreds of disconnected fragments.

The clearance itself did not trap the system. A cleared hillside can regrow, but what followed made recovery difficult. Without canopy cover, rainfall hit exposed soil and ran off rather than soaking in. Channels cut into the ground, and the soil thinned and compacted. Even if the felling had stopped entirely, the forest could not easily return because the soil it needed had already been washed away.

Later pressures compounded the problem. Post-war agricultural policy paid farmers per head of livestock, and grazing densities rose across the uplands. The removal of predators meant deer populations grew without natural limits. Young oak and hazel seedlings were eaten before they could establish themselves. The remaining trees, some several hundred years old, continued to stand, but nothing grew up beneath them. The woodland aged without replacing itself.

From 1919 to the 1980s, the Forestry Commission planted non-native conifers such as Sitka spruce and lodgepole pine on large areas of ancient woodland. These plantations occupied the same soil and climate that once supported rainforest. Their dense rows of acidic needles replace the layered native canopy and support little of the life that once inhabited the forest floor.

An additional pressure came with the arrival of Rhododendron ponticum. Introduced in the 1760s as a garden plant, it spread into the wild. It thrives in the same wet, mild conditions as the native rainforest. It forms dense thickets that block sunlight, and its leaf litter is toxic to native seedlings. It filled the gaps left by felling and grazing and sealed the remaining forest fragments shut.

Air pollution also took a toll. Ammonia and nitrogen oxides from farming and vehicle exhaust changed the chemistry of the air. The mosses, lichens, and liverworts that define a temperate rainforest take their nutrients directly from the air, and by the 2020s, 95% of UK woodlands exceeded safe levels of nitrogen deposition for these species.

The remaining fragments became too small and too isolated to function as connected systems. Specialist species such as the horsehair lichen were reduced to only two known sites. The genetic diversity within each fragment narrowed over time. The fragments were no longer parts of a forest. They were isolated biological islands.

The turning point came in 2020, when environmental researcher Guy Shrubsole began surveying the gorges of the Southwest. He found stands of moss-draped oak and liverwort-coated boulders that were not catalogued by any map. These areas were not recognised as rainforest in policy or planning. Shrubsole launched a crowdsourced mapping effort and published a book in 2022 that classified the fragments as temperate rainforest. Within 18 months, England, Scotland, and Wales each produced their first national strategy for temperate rainforest recovery.

The practical work of restoration involves several methods. In Scotland, Forestry and Land Scotland used a technique that injects herbicide directly into the stem of rhododendron plants. This kills the plant at the root without spraying the surrounding soil or harming nearby lichens. In Wales, the Celtic Rainforest project has treated over 500 hectares of invaded woodland using the same method.

Deer populations are being managed through coordinated culling across whole river catchments. In some areas, livestock have been replaced with Highland cattle and ponies, whose grazing helps break up compacted soil without stripping every young sapling. The aim is not to remove all herbivores, but to reduce grazing pressure below the level where young trees can survive their first decade.

The remaining fragments are also being expanded. Conventional planting has begun around Wistman’s Wood on Dartmoor to double the footprint of that 4-hectare remnant. Cumbria Wildlife Trust purchased 3,000 acres of upland at Skiddaw in the Lake District with plans to plant 300,000 trees. In late 2023, heavy-lift drones were used on Bodmin Moor to scatter 75,000 native seeds across 11 hectares of inaccessible ravines.

The financial framework has also changed. In 2023, the insurance company Aviva committed £38.9 million to a 100-year rainforest restoration programme covering over 1,700 hectares. Carbon finance allows landowners to replace grazing income with long-term payments for growing native woodland. This is intended to fund the restoration over decades rather than the usual three-to-five-year grant cycles.

The results so far are early but measurable. Forestry and Land Scotland treated 1,226 hectares of rhododendron in the 2024–25 season, 41% above target. Wales treated 540 hectares. Borrowdale’s 721 hectares were declared a national nature reserve in May 2024. Community teams on the Isle of Raasay achieved rhododendron clearance above 90% across 160 hectares. Those gains remain a fraction of what is needed. The seeds scattered over Bodmin Moor need decades to become trees and a century to become forest. Lichens may take generations to colonise new canopy.

A 2024 climate study in the journal Earth’s Future suggested that up to 68% of the world’s remaining temperate rainforest could become too hot and dry to survive by 2100. Britain, kept wet and mild by the Atlantic, is projected to remain one of the more stable zones. The country holds less than 1% of the Earth’s land surface, but its conditions could support between 6 and 9% of the world’s future viable rainforest habitat.

The restoration process will take a long time. An oak planted today will not mature for 200 years. The moss and lichens that once defined these woodlands will take generations to return to new growth. The people currently doing the work will not see the finished forest. That is not a limitation of the project. It is the expected timescale of the repair. For the first time in eight centuries, the condition of Britain’s rainforest is moving in the opposite direction.