Defining the fundamental units of bryophyte conservation.

“As a phylogenetic taxonomist working on bryophytes (mosses, liverworts and hornworts), I feel I have a responsibility to be a tireless advocate for the underappreciated importance of these organisms and a sound understanding of their evolutionary relationships in a conservation science world that’s often dominated by ecology and large fauna,” says Dr Neil Bell. “My work involves recognising and defining the fundamental units of conservation – species and higher taxa – in a way that reflects evolutionary processes and ultimately underpins the identification of genuine rarity, endemism and threat status.

Beautiful bryophytes

“Bryophytes have an image problem! Scotland’s rainy, temperate-oceanic climate, although very familiar to us, is actually rather unusual globally and able to support plants that aren’t found in many other parts of the world. Yet because most of our flora has arrived since the end of the last glacial period, our vascular plants are not as diverse as they otherwise might be. Because bryophytes are generally very good at dispersal, however, as well as being particularly well-suited to our rare cool oceanic climate, Scotland’s native bryophyte flora is of genuinely global significance and almost certainly our most valuable botanical asset.

“In terms of biodiversity, many bryophyte species have their main European distributions in our western temperate rainforests or our wet montane heaths. Meanwhile on the ecological front, Sphagnum moss is almost single-handedly responsible for creating and maintaining peat bogs, one of the most important carbon sinks globally and one that we really need to look after if we are to have any hope of reining in runaway climate change.

“A recent focus of my research has been the oceanic liverwort heath community (previously known by the rather uninspiring name ‘mixed northern hepatic mat’). This spectacular assemblage of relatively large and often very attractive liverwort species is found on sheltered, north and east facing slopes in the hills in the wettest parts of the north and west of the country. Most of these species have very limited and highly disjunct global distributions. For example, some have their only non-Scottish populations in in the Himalayas and on a few oceanic islands widely scattered around the world, while one is apparently disjunct between Scotland, Ireland, Central and South America and sub-Saharan Africa! By analysis of molecular sequence data and careful herbarium taxonomy we can tease apart these distributions to discover whether they represent populations of the same species (and if so, how and when the Scottish populations arrived), or different species entirely. This is critical for informing conservation priorities, as the rarity and total distribution of a species clearly has a major impact on its global IUCN threat status and the relative effort we devote to its protection and active management.

A white man sitting in a mountain environment, wearing a red jacket and multicoloured woolly hat, smiling at the camera and holding a bryophyte in his hand
Dr Neil Bell

“I’m interested in applying spatial phylogenetics to the British and Scottish bryophyte floras. This involves, for example, identification of areas with large amounts of bryophyte phylogenetic diversity – not just areas with large numbers of species, but places where these species represent a disproportionately large part of the evolutionary tree (because they have fewer close living relatives). The true uniqueness of the Scottish bryophyte flora lies not so much in the total number of species we have (although that rivals anywhere else in Europe), but in what it represents as a diverse assemblage of distinct evolutionary lineages with different biogeographical histories, all adapted to our very special temperate oceanic climate.

From medieval history to evolutionary history

Many bryologists reach the subject by a convoluted route, although mine was more than usually meandering as my first degree was in medieval history! Discovery of a dog-eared copy of Steven Rose’s The Chemistry of Life on a girlfriend’s bookshelf in my mid-20s, combined with a growing passion for the Scottish hills, reignited my interest in biology, my favourite subject at school alongside history. This led on to survey work for the Scottish Wildlife Trust, Open University courses, an MSc at the Royal Botanic Garden Edinburgh, and eventually a PhD at London’s Natural History Museum on the evolution of pleurocarpy (the key innovation that underpins the growth form of creeping, multiply-branched mosses).

“After that I worked at the Museum of Natural History in Helsinki, Finland for nine years, including on the phylogeny and evolution of the moss family Polytrichaceae and on southern temperate pleurocarpous mosses, before returning to Scotland seven years ago.

“Applying phylogeny and taxonomy in a conservation context often involves walking a narrow path between an academic ideal and the needs of end-users. Most British bryologists are focused on recording and monitoring, and many strongly dislike the inevitable name changes that accompany phylogenetic discovery. It’s necessary to have names (for higher-level groupings as well as for species) that reflect natural entities in order to recognise, characterise and conserve them, but I’m quicky taken to task by my friends in the British Bryological Society for any taxonomic changes I can’t convince them are truly necessary! Working closely with other conservation scientists, public bodies and amateur societies is critical for achieving this balance between academic systematics and taxonomy as a practical tool for representing and quantifying biodiversity.”

Dr Neil Bell is a Bryologist at the Royal Botanic Garden Edinburgh. His work is supported by the Scottish Government’s Rural and Environmental Science and Analytical Services Division. He is editor-in-chief of The Journal of Bryology, a role that keeps him continually involved with bryologists around the world working on many different aspects of the subject. Find out more here.

This post is part of a series showcasing Scotland’s innovative, high-impact research supporting biodiversity conservation, in partnership with Scottish Government and NatureScot. Read the rest of the series here.

Further reading

Bell, N.E., et al. 2015. Delongia gen. nov., a new genus of Polytrichaceae (Bryophyta) with two disjunct species in East Africa and the Himalaya. Taxon 64: 893—910.

Coudert, Y., et al. 2017. Multiple innovations underpinned branching form diversification in mosses. New Phytologist 215(2): 840—850.

Bell, N.E. & Ignatov, M. 2019. Placing the regionally threatened moss Orthodontium gracile in the big picture – Phylogeny, genome incongruence and anthropogenic dispersal in the order Orthodontiales. Molecular Phylogenetics and Evolution 134: 186—199.

Flagmeier, M., et al. 2020. Globally rare oceanic-montane liverworts with disjunct distributions: evidence for long-distance dispersal. Biodiversity and Conservation 29: 3245—3264.

Bell, N.E., et al. 2021. The diversity of the Polytrichopsida – a review. Bryophyte Diversity and Evolution.

Van Rooy, J., et al. 2021. Notoligotrichum synonymised with Atrichopsis (Polytrichaceae, Bryophyta), with two new species from South Africa. Taxon 71(1): 11—24.