Bryophyte report on visit to Chedington Woods

Chedington Woods

Andrew Branson | 1-3-2023

Bryophyte report on visit to Chedington Woods

I surveyed an area of steep north-facing woodland along the southern edge of Chedington woods. These are mapped as Wyke Coppice (Compartment 8) and Flaxley Coppice (Compartment 3) and are shown as wooded on the 1901 OS Map. The geology is Gault Clay, a type of mudstone, which is transitional from the acidic Upper Greensands of Crook Hill, to the more calcareous Frome Clay. The Frome Clay forms the bulk of the slopes of Flaxley Coppice. There are a few springs on the slopes and the area above the ride edge at the entrance to Wyke Coppice is noticeably flushed (see below). The drainage ditch beside the ride at the bottom of the Flaxley Coppice slope still had running water despite the recent dry weather. The wood appears to be W8 ash-field maple woodland, with some large oaks, hazel, occasional holly, and presumably planted beech. Interestingly, a few large alders were along the top edge of the wood, indicating possible areas where there is a perched water table, presumably a result of the geological transition. The slopes have large areas of conifer plantation (Norwegian Spruce and others).

I walked mostly along the top edge of the wood and, lower down, along the main ride. The bryophytes along the top edge of the wood, particularly where there had been disturbance and the soils had become leached, are those typical of neutral to slightly acid conditions. This community includes species such as Mnium hornum, Dicranella heteromalla, Fissidens bryoides, Pseudotaxiphyllum elegans and Polytrichum formosum. On some decaying oak stumps where the conditions were more humic, there were more specialist species such as Orthodontium lineare, and occasional Pleuridium acuminatum. The epiphytes on the ash and field maple were mostly common species of basic bark, such as Homalothecium sericium, Neckera complanata and N. pumila, Zygodon conoideus and Pulvigera lyellii (this especially on the larger trees), as well as ubiquitous species such as Hypnum andoi, Isothecium myosuroides, and Frullania dilitata. On some upturned stumps (these are often interesting as they provide a habitat for species of well-drained, steep and sometimes shaded surfaces, unlike the surrounding soil) in Wyke Coppice I found a species of Weissia (a small moss that has narrow, parallel-sided leaves that curl up into a tight ball when dry) that is probably Weissia brachycarpa subspecies brachycarpa. However, I need to have mature capsules to be sure, so have a small clump growing at home under a cold frame to see if I can get the plant to mature. If it is this species, that will be a significant record, as it has been recorded in Dorset only a half a dozen times before. It is a specialist of moist, slightly acid clay soils. We shall see. Over much of the site, the ground flora was characterised by species typical of neutral to slightly basic soils. The vascular plants testify to this, with much ramsons and pendulous sedge, and also with bluebells and wood sorrel picking out the more acid areas. Bryophytes, such as Calliergonella cuspidata and Eurhynchium striatum, also indicate these conditions, and are common throughout.

Near the ride at the bottom, I had a look at some of the decaying conifer logs in the shaded plantations. Here I found some plants of Sematophyllum substrumulosum (Bark Signal-moss). This was first found in Dorset near Wootton Fitzpaine in 2017 and, just a few years later, has become almost an expected species to find in this habitat. Until recently, it was considered a very rare plant in the British Isles, found only in southern Ireland, the Isles of Scilly and one site in Sussex. It was thought of as a Macaronesian species found only on the Atlantic coast and island groups such as the Canaries and Azores. But recently it has spread rapidly, perhaps as a result of climate change. It produces large numbers of capsules, which has probably helped its spread. Beside the ride in a hollow were some decaying remains of an old oak, and here there were a few plants of more humid acid substrates. These include the lovely little liverwort Cephalozia curvifolia, often a deep golden orange colour, with arching leaves along the stem. Until recently, it was named Nowellia curvifolia after John Nowell, a 19th-century Lancashire hand-loom weaver. He was a highly accomplished field bryologist who discovered several species new to Britain, and Sir William Hooker offered him a post at Kew, However, he preferred to remain in Lancashire. Also growing on the oak was a small patch of another liverwort, Lepidozia reptans, with its distinctive three-toothed leaves, looking like tiny claws.

As is often the case with bryophytes, the wetter areas were the most interesting. In some of the sheltered wet flushed areas above the ditch, there are some patches of the attractive Hookeria lucens (Shining Hookeria). This translucent species, with rows of flattened leaves, has strikingly large cells., which can easily be seen with a hand lens. It is named in honour of the same Hooker that invited Nowell to work at Kew. It is a plant of slightly acid wet places and has a scattered distribution in Dorset.

The left-hand bank as you enter Wyke Coppice is flushed with calcareous water and has an interesting community. This includes a number of calcicoles, such as the liverworts Pellia endiifolia and Riccardia chamedryfolia, as well as Ctenidium molluscum (Chalk Comb-moss) and Campylium protensum (Dull Starry Feather-moss), mixed with the more common Calliergonella and Eurhychium mentioned earlier. The Ctenidium and Camplylium are more often found on unimproved, humid, chalk and limestone grassland, so it is quite rare to find them along a woodland edge. Also growing here is the small ‘forklet-moss’, Dicranella howeii. This has only recently been recognised in the UK and we are now finding that it is widespread on calcareous habitats. The total number of species recorded for this section of the wood is 72.

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The top ridge of Flaxley Coppice.

Sematophyllum substrumulosum (Bark Signal-moss), growing on a rotting conifer log. A big name for a small moss.

Cephalozia curvifolia, with its unusual golden leaves, growing with Lophocolea bidentata (green plant in the centre) on a decaying oak stump.

The calcareous flushed bank at Wyke Coppice.

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