Steve Masters, Dorset Wildlife Trust’s ecologist, shines a light on the often-forgotten miniature realm of the important bryophyte
Image: Steve Masters
Have you ever perched on an old log in the wood, only to find yourself enveloped within a sumptuous rug of moss? Or, paddling in a river, wondered at the creeping green sheets adorning the exposed rocks?
Around 1,000 species of bryophytes are found in the UK – representing 58 per cent of the total European species. As such, they contribute significantly to our biodiversity: they are in fact the second most diverse of the world’s plant groups (angiosperms – flowering plants – are the most diverse group).
Bryophytes include mosses, liverworts and hornworts. They are the ancient organisms likely to have first arisen from green algae around 450 million years ago in the Ordovician period, a time of expansion for multi-cellular organisms.
To identify and understand bryophytes, we need to get up close and personal with them, in some cases microscopically. The leaf structures of mosses and liverworts are often only one cell thick, with a whole host of structures which aid them in photosynthesis and water conservation. Some liverworts take the form of sheets of green fingers creeping across rocks, or miniature necklaces hung about trees.
Mossy romance
The life-cycle of bryophytes sets them apart from other plants. It is two-staged: the leafy part (gametophyte) produces male and female structures which then combine to make a sporophyte. The sporophyte produces spores in a distinctive capsule, which are then dispersed and develop into a new leafy part. Another amazing ability is that of reproducing asexually, which many species do either by simply shedding part of their leaf structure or via specific structures which are shed. Both these and the capsules are beautiful structures, rivalling those of any flowering plant.
Bryophytes play a key role in ecosystems across the UK, in many different habitats from grasslands to wetlands to woodlands. In each of these habitats, they often create favourable micro-habitats for other species – for example, conserving water for young seedlings in arid environments, thereby helping vegetation to establish. They help shelter invertebrates, the recyclers of our ecosystems, and create the perfect terrestrial habitats for amphibians. Mosses also provide the ideal cosy nest material for birds and small mammals to hunker down.
They are integral components of some of our most precious habitats, such as peat bogs, in our fight to combat climate change. Among the main components of peat bogs are sphagnum mosses, and they perform three essential functions. Firstly, along with other plants, they form the storage vessel in which the carbon is locked. Secondly, they help to hold water within the bog, and thirdly, due to their chemical interactions with the nutrients around them, they create an acidic environment which reduces the decomposition of the plant material, ensuring the locked-in carbon is not released. Without the sphagnum moss component of these communities, the function of peat bogs to store the 500 billion tonnes of carbon they do worldwide would be severely impacted.
Moss hunting
Dorset Wildlife Trust nature reserves offer the opportunity to discover an amazing array of bryophytes: whether during an autumnal woodland walk, a bright winter wander across a grassland or a damp dabble in a heathland mire. Why not try finding big shaggy-moss at Bracketts Coppice, cow-horn bog-moss at Winfrith Heath or swan’s-neck thyme-moss at Kingcombe Meadows, and wonder at the mysterious world of bryophytes. If you’re lucky, maybe you’ll find the moss cushion at the bottom of The Faraway Tree’s slippery slip!
Did you know?
Sphagnum mosses have been used by humans for centuries. Native Americans used them to line their children’s cots and carriers, where it acted as a natural nappy due to its absorption abilities – twice that of cotton wool.
The moss also played a key role in medicine, particularly during the First World War. Its chemistry creates a mild acidity with antiseptic properties which, combined with its abilities to absorb, made it useful as a wound dressing.
