Across western Britain and Ireland, you can find patches of damp and misty woodland draped in a cover of green lichens, mosses and liverworts. Increasingly referred to as temperate rainforests, these unique ecosystems harbour the largest concentration of oceanic lichens and mosses in Europe, including some found nowhere else on Earth.
Now at a fraction of their previous coverage, many are asking whether Britain should be doing more to protect and expand the areas it has left. But what actually are these rainforests of Britain – and how can we save them?
What are temperate rainforests?
Temperate rainforests, unlike their tropical counterparts like the Amazon, are found in cooler climates which intersect with an oceanic zone, leading to the most well-known characteristic of rainforests – high rainfall.
They exist in several areas across the world including the Pacific Northwest of the US, southeastern Australia and New Zealand, as well as western Britain and Ireland. The key thing about all these locations is that their humid climates are permissive for “a whole bunch of really special little things to grow on the trees”, says Rebecca Yahr, lichen biodiversity scientist at the Royal Botanic Gardens of Edinburgh (RBGE).
These include mosses, lichens, liverworts, and other fungi, she says, many of which can only grow there.
“It’s this incredibly rare and unique set of species that all occur together,” says Yahr.
“Every bough is covered with an intricate mosaic of different colours, different textures, with spots, with speckles, with floppy places, with red spots, just all these crazy things.”
In Britain, these humid woodlands are found in several locations down the west coast, including in Scotland, the Lake District, Wales and the southwest of England. Here, a mix of the local microclimate and a position on the western seaboard where relatively warm, moist, air flows in creates ideal conditions for the rainforests to thrive.
“We have this sort of special set of climatic conditions that exist almost nowhere else,” says Yahr. “It's really very unusual where we have these forests.”
There is now a rising focus on the rainforest properties of these woodlands and the unique ecosystems they host. It might surprise some to hear that Britain has a rainforest.
In fact, temperate forests have long been considered as part of the broader term 'ancient woodland', says David Rickwood, the Woodland Trust’s site manager for several temperate rainforests in Devon including Fingle Woods. The terms Atlantic Oakwood forests or Celtic rainforests also refer to similar things. “[Temperate rainforests] are not that well defined,” says Rickwood. “And I think that is due to happen.”
How can we save them?
Britain once supported far larger expanses of temperate rainforest, but centuries of tree felling and land-use change has reduced them to small fragments. Temperate rainforests are also rare globally, says Yahr. In fact, the conditions for them occur in less than 1 per cent of the planet’s land, with 15 per cent of this occurring in Europe.
A “saving grace” for Britain’s rainforests is that most of the best examples are in places in the highlands, in the west coast of Scotland, says Yahr, which have seen both low impact of management and clean air due to their position with regards to local ocean currents. Other parts of Europe with potential for rainforest have been decimated by pollution, she adds.
Several groups are now working to protect or restore temperate rainforests in Britain, including the Alliance for Scotland's Rainforest, RSPB, Plantlife, the Woodland Trust, and the Atlantic Woodland Alliance.
Invasive species, especially the common Rhododendron, Rhododendron ponticum, are among the largest threats. This popular garden plant is at its optimal habitat zone exactly where the temperate rainforest zone lies, says Yahr. “Where it grows, it completely shades out the understory, and prevents anything else from coming in.” Removing it and keeping it out is extremely labour intensive.
Grazing by deer also poses a huge issue in Scotland. Further south, regenerating conifer and other non-native tree species is an additional problem, says Rickwood. “In most of my sites [in Devon] we're gradually removing the conifer and allowing the native species to regenerate.”
A rising effort in Britain aims to expand and connect existing patches of these rainforests together, says Yahr, while balancing people's use of the land. Networks are needed so organisms have corridors to move – especially in the face of a changing climate.
However, many of the species found in temperate rainforests are slow to move, raising the risk they may fail to keep up with the rate of change of where woodlands that might sustain them may be in the future, adds Yahr.
One way to overcome this is to experiment with translocations.
“We move them around and see how they do,” says Yahr. “They're not too bad as experimental subjects to be moved, and they seem to survive in some places.”
As other areas of Britain are subject to climate change, areas of temperate rainforests in deep valley systems could become even more important as reservoirs of biodiversity, says Rickwood.
What’s crucial is for these projects to have the long timeframes they need to regenerate naturally – including when it comes to funding, adds Rickwood. “A grant might exist for five years, but you can't do it in five years. You've got to have a 20-to-30-year timeframe.”
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