Posted by: lensweb | December 6, 2017

Bennerley Bryophytes

Bennerley Viaduct is a disused railway viaduct spanning the Erewash Valley between Awsworth in Nottinghamshire and Ilkeston in Derbyshire. It is set to be restored and incorporated into a newly formed cycle-path by Sustrans. The area underneath the viaduct has three settling ponds which were used to neutralise water run-off from the industrial site entering the River Erewash. The extensive brownfield site nearby is currently a haven for wildlife.20mbpf.jpg

Today we came looking for bryophytes –  mosses and liverworts.

  • Liverworts have a thin, leathery body that grows flat on moist soil or, in some cases, the surface of still water, the leaves have no central vein. Liverworts have oil bodies which may give them a distinctive smell, and they have long cells called elaters which absorb water to aid spore release .
  • Mosses have an erect shoot bearing tiny leaf-like structures with a central vein which are arranged in spirals. They have no oil bodies or elaters.

They have a similar life cycle click here

In addition bryophytes may spread by fragmentation, or formation of gemmae or bulbils. Dispersal tends to be over a short distance, they are vulnerable and need connectivity.

Bryophytes have no lignin or conducting tissue so are very small, but they are very important to help ecosystems perform effectively by filtering and retaining water, stabilizing the ground and removing CO2‚ from the atmosphere. Unlike flowering plants, they have no cuticle or waterproof layer so water and minerals are directly absorbed.  This makes them good indicators of pollution but tends to restrict them to damp environments where they may form an association with mycorrhizal fungi. Eutrophication, increased nitrogen from the air and from water run-off marmelises bryophytes, brambles grow and shade them out but if pollution decreases bryophytes increase as recently the air has become less acid epiphytic bryophytes can now be found growing on tree bark as epiphytes.

Nottinghamshire has a new bryophyte recorder Margaret Crittenden who is keen to find the good sites for bryophytes fill in the blank piece of the jigsaw which is Nottinghamshire on the National Atlas, so we went to look at the Bennerley site.

Currently Nottinghamshire has recorded 224 of the 753 UK species of moss, and 63 of the 296 UK species of liverwort. Recording bryophytes is a winter activity and amateurs can contribute to the recording effort and may well record a species new for the county. A copy of the Mosses and Liverworts Field Guide is essential and you really need a x20 hand lens to see this minute world of very pretty organisms. Unthwarted by footpath closure we enjoyed a walk down the Nottingham Canal to the Bennerley site.

In the lead-in woodland, Frullania and Metzgeria liverworts coated willow trees in green slime. Centipedes of Hypnum crawled up the cracked birch trunks, Lophocolea swarmed at the base. Dark green furry globes of Orthotricum (or was it Ulota?)  had lodged in the fissured elder bark. Elder is an especially good host so old elder should not be ‘weeded out’.

The golden tips of Aulocomnium palustre with red-brown hairy arms reaching to the water, attracted our attention to the Gilt Brook. It was a wonderful splodge through the soft spongy colonies of Sphagnum and Polytrichum. We tried to decide if the individual fronds of sphagnum had the appearance of a drowned kitten?  Well being was factor 20 as we appreciated the fine filigree  fronds of Thuidium tamariscinum and we discovered delicate Calypoegia, Riccardia and Lophocolea liverworts in the drawdown line of the rusty brown brook.

Bright green pointed arrow tipped shoots of Calliergonella cuspidata  were ubiquitous by the settling ponds. A sign of a good meadow, the yellow green shoots of Pseudoscleropodium purum have a stout, fat appearance, at the tip of the stem and new branches, the crowded points of the leaves protrude like a miniature crown. ‘Our old friend’ Rhytidiadelphus squarrosus is distinctive in the way the limey leaves bend back at a right angle to the red stem giving shoots a star-like appearance. There was also plenty of two very common mosses, Brachythecium rutabulum and a great deal of ‘I’m afraid it is Kindbergia praelongum again’.

The exciting cement outlet from the settling ponds to the River Erewash had a good display of fruiting acrocarps some with gemmae, tiny green balls on the leaves and some with bulbils fatly nestling in the leaf base. Acrocarps are tiny and difficult to identify but Margaret rose to the challenge. These seem better able than pleurocarps  to cope with  drier conditions as could the tiny Christmas trees of Polytrichum juniperinum,  a very pretty moss.

In the shaded environment underneath the giant shoes of the viaduct, little lettuce leaves of Pellia endivifolia edged the marshy pools. Plagiomnium undulatum, with wavy leaves, it’s (tall for a moss) stems up to 15 cm long and branched, like a tiny tree in grassland. Steep banks of coal measures clay supported combed furry carpets of Amblystegium serpens and shiney sheets of tiny fern-like Fissidens, so grateful these have been cleared of bramble by the Bennerley Friends.   Bryum capillare bulging green nerves to a hair point on blue brick stamped in Derby.

Dicranum scopare formed green cushions in a patchwork of Bryums. An alien invader, a pioneer of bare peat, formed dark green almost black carpets on the industrial apron. Multitudinous sporing capsules of  Campylopus introflexus curve and twist on a swan’s neck seta or stalk. Black carpets seem frosted due to the white leaf point.  

Barbula, Didymodon, Plagiomnium, Schistidium, Tortula, Syntrichia the poetry of mosses, why do  the Latin names persist? It seems bryophytes are species who have been given the most awkward of long winded common names and the Latin names have a commonality so that we all know what we are talking about. There is no doubt that post-industrial or brownfield sites are productive for bryophytes.  Nature reserves and nature corridors are important refugia for bryophytes. The UK hosts two-thirds of European bryophyte species and they are rare globally, so we have a burden of responsibility to look after them.

Marion Bryce 5 December 2017


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