The clouds roll in, thick and grey. They send down a relentless deluge of heavy water-droplets to pound the canopy of trees above me. Leaves are soon saturated, coalesced raindrops thud down onto the woodland floor and rivulets trickle down trunks. Humidity rises rapidly, water vapour fills the air. No matter how dry the woodland has become, it takes very little time for the feeling of rainforest to return. But it’s not just a feeling. Our wood sits on the edge of one of the areas classified as temperate rainforest; it makes up a tiny part of the British Atlantic woodland, also known as the Celtic Rainforest. This kind of rainforest has a very restricted distribution globally, so the need to conserve and protect it is high; according to the Woodland Trust, Celtic rainforest is thought to be more threatened than tropical rainforest.
Temperate rainforest experiences a high annual rainfall with at least one and a half metres of rain falling in an average year. That rain is spread out reasonably evenly between the seasons so there are no extremes of wet and dry. Temperatures are mild and they too fluctuate only modestly over the year, with average temperatures of around ten degrees centigrade. Unlike tropical rainforest, temperate rainforests experience distinct seasons of around three months each and these rainforests tend to be found in locations half way between the poles and the equator. It is the influence of the sea which provides both the moisture for the high rainfall and the damping effect on temperature, keeping winter temperatures higher and summer temperatures lower than expected for the latitude. In the UK, this sea influence is provided by the Atlantic Ocean, hence it is the belt of woodland that runs down the West side of the country, from Scotland, through Cumbria, down through North and West Wales, to Devon and Cornwall, that makes up the mainland Celtic Rainforest, with additional areas in Northern Ireland across the Irish Sea.
Being an incredibly rare habitat could, in itself, provide a reason to conserve these rainforests, but the British Atlantic woodland is home to globally important species of lichen and bryophytes (simple plants including mosses and liverworts). Many of the lichens present are rare, and Plantlife International estimate these Celtic rainforests contain over half the European species of bryophyte, rivalling the cloud forest of the tropics for bryophyte diversity. It is a special experience to wander through these woodlands as the rain eases and the sun penetrates the canopy. There is a primal beauty in the drenched mosses sprinkled with glistening water spheres, the dripping ferns, the swollen lichens. The water haze in the air swirls in light shafts and you could be walking in the vast tracts of temperate rainforest found in Europe in ancient times. Now these rainforests are small and fragmented, but their essence still remains.
Just one day of heavy rain after the unusual dry weather has brought back the rainforest character of the wood. It emphasises to me again why our woodland needs to be protected. The Celtic rainforests are evermore under threat with the pressures brought by climate change, tree disease and invasive, non-native species. As the moss and lichens are reinvigorated with the rain, I have a renewed awareness that rainforests are not just exotic far-away places, that conservation is needed right here on my doorstep. It reminds me again how special this woodland is and how we need to ensure its survival into the future.