Wooded Ravines and Oceanic Species

Wooded Ravines and Oceanic Species

Oceanic plants rely on high levels of humidity throughout the year, so are typically found in upland areas and wooded ravines in hilly districts. Newry is bordered by three Mountain Ranges: The Mournes, The Ring of Gullion and The Cooleys.

Oceanic plants mostly come in the form of mosses and liverworts (Bryophytes), especially the latter. I have only recently become interested in bryophytes and I am still improving my ID skills, but I have come across some oceanic bryophytes which have a restricted range in Ireland. Examples include Plagiochila spinulosa (image below) that I found first in Ravensdale Forest Park on a mossy drystone wall, and then in a wooded ravine near Fathom Mountain. Other examples include Saccogyna viticulosa – a translucent and delicate liverwort which I have located in several places across the region.

Ravensdale Forest Park has several fantastic bryophytes, especially along the river glen. One particular ash tree which grows out of the rocky ravine is host to P. spinulosa, P. porelloides, Metzgeria conjugata and Frullania tamarisci (among other epiphytes). The pelt lichen Peltigera membranacae commonly grows on mossy tree trunks and branches in Ravensdale and adds to the oceanic feeling of the woodland.

However, not all oceanic plants are bryophytes. Filmy-ferns are a group of ferns found in humid areas with high rainfall. They look like mats of moss but are in fact ferns. I was very excited to find a population of filmy fern called Tunbridge Filmy Fern (Hymenophyllum tunbrigense) in a wooded ravine SW of Newry. It has been recorded in this area before, but due to its rarity, its exact location cannot be given in order to protect it. I worked out the location from cross-referencing and some guess work. I believe I found more colonies than previously seen by other botanists.

There are two species of filmy fern in the genus Hymenophyllum in Ireland, and H. tunbrigense is the rarer of the two. In fact, H. tunbrigense hasn’t been recorded in the Mournes since before 1930. These ferns require very sheltered conditions, typically in deep woodland in humid areas like the site in Newry. However, they will be found at the tops of mountains under boulders and in caves where wind scour is less of an issue. Ultimately, these ferns were probably more widespread across our mountains before large-scale removal of woodland. That being said, some oceanic plants thrive perfectly well in open conditions, with many even preferring it.

It is interesting to think of how much more widespread these plants were before intensive erasure of woodland, but it is vital that we protect these places and their amazing biodiversity.

Image: Plagiochila spinulosa colony from Ravensdale Forest Park