Temperate rainforest exists in Britain and almost nobody knows

Everything below about temperate rainforest comes from what actually happens rather than from what is supposed to.

A habitat defined by air, not trees

Temperate rainforest occurs where oceanic conditions produce persistent humidity and a narrow annual temperature range. Western coasts of Britain, Ireland, Norway, the Pacific north-west and parts of Chile and New Zealand all qualify.

The trees are ordinary; what makes it rainforest is what grows on them. What defines it is the spread of the rain rather than the total, since somewhere with heavy monsoon rain and a long dry season does not qualify while a cool coast with persistent drizzle and mist through most months does.

The interest is epiphytic

Lichens, mosses and liverworts coat trunks and branches in communities that need centuries of continuity and clean, damp air. Some species present in these fragments occur in very few other places globally. This is why a wood can look unremarkable and be internationally significant.

Epiphytes draw water and nutrients straight from the air and from what runs down the bark, with no roots in soil to buffer anything, which is exactly why they respond so sharply to air pollution and are used as indicators of it.

Fragments, not forest

What survives in Britain and Ireland is a scatter of small woods in steep valleys and along western coasts. Total area is a fraction of what the climate could support, most of it lost to grazing and clearance over centuries. Many fragments sit outside any designation that recognises them as rainforest specifically.

The loss was industrial before it was agricultural, because these woods were worked hard for charcoal, tanbark and oak coppice, and it was the sustained sheep grazing that followed which stopped them growing back.

The threats are mundane

Overgrazing prevents regeneration, so many fragments have a canopy and no young trees beneath it. Invasive rhododendron shades out the ground and epiphyte communities entirely.

Nitrogen deposition from agriculture and traffic damages lichens directly, which is invisible and cumulative. Tree disease now belongs on that list too, since several of these communities sit on ash as well as oak, and losing a generation of host trees removes the substrate whatever else is done for the site.

Restoration is slow and possible

Fencing to allow regeneration, rhododendron clearance and connecting fragments are the standard interventions. Results take decades because the epiphyte communities themselves are slow to colonise. Several long-term projects are now underway, and the concept has gained public recognition rapidly.

Rhododendron clearance is the part routinely underestimated, because it regrows from cut stumps and from a seed bank for years afterwards, so a site needs follow-up visits for most of a decade and a job abandoned halfway is money spent for nothing.

The exception is usually weather, which overrides most planning.

Telling rainforest from a merely mossy wood

Damp shade makes almost any western wood mossy; what marks out rainforest is the assemblage of lichens on bark and rock, not the depth of the moss underfoot. Ecologists use indicator groups for this — the lungwort lichens, script lichens and particular oceanic liverworts among them — because they need both long continuity and clean air, and disappear when either fails. A wood downwind of intensive agriculture can look luxuriant and have quietly lost its most sensitive lichens decades ago, which is why appearance alone is a poor guide.

On the ground the practical courtesy is to stay off the moss-covered boulders and fallen trunks, because a bryophyte mat that took decades to build is flattened by one boot.

The takeaway

Look at the bark, not the canopy. That is where the rainforest is.

Go slowly enough to notice, and most of this stops being advice and starts being obvious.