A British Ecological Society Special Interest Group
by Sally Eaton
Rainforest ecology is a fascinating subject, and despite the associated long haul flights, sure-fire tropical diseases, and long term planning required, tropical rainforests remain one of our better studied ecosystems. Temperate rainforests on the other hand remain little known and under studied (a WOS search revealed just 1,370 results for ‘temperate rainforest*’ as opposed to 20,998 for ‘tropical rainforest*’), despite having far fewer of the unpleasant side-effects.
Aside from the obvious presence of trees, just how similar are these ecosystems? Despite their latitudinal differences, temperate rainforests, have two main features in common with tropical rainforests; unsurprisingly one of these is their rainfall and the second is their high levels of biodiversity. Looking into this second feature, it may be surprising to discover that it is the diversity of their cryptogamic epiphytes (lichens, bryophytes and ferns) in particular that these two ecosystems share (DellaSala et al. 2011). [editor’s note: definitions of temperate rainforest vary, but closed canopy forest with >100 mm precipitation per month is reasonable, Alaback (1991) is often used for Americas]
Temperate rainforests are globally rare, thus one of the joys of working in Scotland is that we have some of the best examples of this ecosystem in all of Europe. The relatively low levels of air pollution, coupled with a long historic continuity, ensure that the pockets of ancient woodland that cling to the west coast of Scotland harbour amazing arrays of epiphytic lichens and bryophytes.
One of my all-time favourite examples is Glen Creran, a mixed deciduous woodland that hugs the slopes of a sea loch, lying between Oban and Fort William in Argyll. Once under the canopy of this seemingly modest woodland, the jewel like epiphytic community gives away its aspirations to be something greater than a standard NVC W9 woodland, and magnificent specimens of the Lobarian community can be viewed from the footpath that snakes through its lower slopes. In addition, rare butterflies such as the Pearl Bordered Fritillary can be found fluttering in clearings, and the occasional otter can be seen pottering along the loch shore.
Despite the treasures within, and the comparative ease of making a visit, the enchantment of these Celtic rainforests remain a relative secret. I believe that we need to make more of a fuss of these unassuming spaces, after all, the riches they harbour can be just as fascinating as that of their tropical cousins.
DellaSala, D. 2011. Temperate and Boreal Rainforests of the World: Ecology and Conservation. Island press, Washington DC.
Alaback, PB. 1991. Comparative ecology of temperate rainforests of the Americas along analogous climatic gradients. Revista Chilena de Historia Natural 64:399-412 . PDF.
What’s your favourite forest? Let us know!