Heathland Lichen Training Day in the New Forest Saturday 1 December 2012
This was a joint meeting held by the Hampshire Flora Group and the Wessex Lichen Group, with the aim of teaching basic heathland lichen identification and discussing their ecology. After all the rain we had had, the meeting was held on a cold sunny day, with a morning frost lifted by the sun at Plaitford Common in the north of the New Forest. Neil Sanderson led with Andrew Cross, Clive Chatters, Ginnie Copsey, Sara Cadbury, Sarah Ball and Janet Blizard attending, while Ollie the dog came along for the walk.
We met in the car park at Canada Common at SU2874 1773 at 10.30. As well as training, the meeting included recording 1km squares for the New Forest Heathland Lichen Survey. The area chosen is an area that has been grazed very short by the high numbers of stock turned out on the commons here for many decades. Heaths which have been short grazed for a long time on the New Forest can be very rich in the larger Reindeer Moss Cladonia species, with fire sensitive species such as Cladonia arbuscula prominent, as these short heaths can not be burnt. They tend to be poorer in the smaller lichens, which are promoted by cool fires on a fairly long cycle.
We started in 1km grid square SU2817, which is not a square allocated for full survey during the New Forest Heathland Lichen Survey. The survey intends to cover about 25% of the 1km grid squares containing heathland spread through the New Forest, with squares sampled previously having priority. In the Plaitford Common area three squares to the west were included, but not SU2817 or SU2818, crossed from the car park. The area to the east, on Canada Common (SU2817), is very heavy grazed and, as we discussed, possibly heavily trampled by people as well. It was not so short in the early 1990s and the lichen rich areas extended further east then. There certainly was an increase in the cattle numbers turned out here at this time. However, this might not be the whole story; the short heath allows people to walk everywhere, rather than be channelled along paths as occurs in slightly longer heath and trampling may be a additional issue.
As we crossed west, the lichens began to appear on drier heathery mounds (SU2818). These were not looked at I detail but I could not resist having a look at the better bits. The communities were dominated by Cladonia portentosa, but with some sprigs of the declining Cladonia arbuscula and just before we left SU2817, Cladonia gracilis, nicknamed The Giraffe. Open humus between the richest areas had patches of Pycnothelia papillaria, nicknamed Babyteeth. The latter is mainly a species of the burned heaths but does turn up in the short grazed heaths. It is declining and rare in lowland Europe beyond the New Forest. We also found the common acid bark leafy lichen Platismatia glauca. Occurrences of such species in lichen heath are a good indication of high quality lichen heath. Platismatia glauca itself has only been found on Plaitford Common during the New Forest survey so far.
Once into SU2718 we were into a square being fully recorded by the New Forest Heathland Lichen Survey and began to record properly. A crib for all the species seen, and others found on the New Forest, can be downloaded from this link. The short heath here had abundant Cladonia portentosa with Cladonia arbuscula, Cladonia gracilis and Cladonia uncialis frequent along with the common epiphyte Hypogymnia physodes. The brown Cetraria aculeata was also frequent but difficult to spot against the dark peaty soil. As well as the robust Cladonia arbuscula, the lighter built Reindeer Moss Cladonia ciliata var. ciliata also occurred occasionally along small amounts of Pycnothelia papillaria and Cladonia strepsilis. The latter typically found with Pycnothelia, and as also more widespread on the burned heaths and declining and rare in lowland Europe beyond the New Forest. Smaller cup and heathtail Cladonia species were present but not prominent. The heathland form of Cladonia squamosa var. subsquamosa, with a flaring glossy chestnut coloured cup was frequent as was Cladonia crispata. The latter, however, was not easy to identify until we reached less intensely grazed heath. Pixy Cups in the Cladonia chlorophaea agg, were tested with K/C and gave a nice flash of purple but were C–, indicating they were Cladonia cryptochlorophaea, the most widespread terricolous segregate of the group.
The east of the heath
At SU27680 18246 ±3m (Waymark 1423) there were traces of old holloways or diggings producing some uneven rutted ground; typically good hunting ground. Here the prize was a magnificent clump of the rare Cladonia zopfii. This species is easy to overlook for the common Cladonia uncialis but with the more silvery colour and the different branching angles giving a distinct jiz, which can used to spot it. It was already known to the north of this site on Plaitford Common, but this find suggested a large and more extensive population occurs at this site. The species is only known from the New Forest in England, but is more widespread in Scotland.
Cladonia zopfii
From here we carried on west and crested the ridge and had lunch in the shelter of a Gorse thicket. Over the ridge the grazing pressure and definitely the human trampling was reduced and the lichens in the short heath were taller and better developed. This quite corner was much more like the heathland was to the east in the 1990s. We were attracted towards a small but well developed seepage with valley bog vegetation (M21a), where wet heath at SU27488 18480 ±5m produced a smaller clump of Cladonia zopfii (Waymark 1424). In the bog it was too wet for lichens but a fine colony of the rare and declining moss Splachnum ampullaceum was spotted on some pony dung (Waymark 1425, SU 27411 18494), while on the bog edge was colony of the Endangered Marsh Clubmoss Lycopodiella inundata (Waymark 1426, SU 27412 18492). From the bog we cut through rich short heath with a similar lichen flora described above. At SU 27616 18591 (Waymark 1427) we crossed some deep holloways with a strong colony of the local liverwort Odontoschisma denudatum and added the lichens Micarea lignaria and Cetrelia muricata.
SU2719, Cladonia phyllophora & Marsh Clubmoss habitat
Having a good list from SU2718, we head back to the car park. A wander into the recently restored open mire habitat nearby to see how it was regenerating from the National Trust’s scrub clearance proved that it was still rather unstable and treacherous but it looked interesting. Some still green Blinks Montia material was presumably the perennial form Montia minor ssp. amporitana, which seems to be quite frequent in the Forest but needs mature seeds to be confirmed. Back on dry land we passed a Rowan with Mistletoe and a round barrow on the way back.
We recorded a total of 27 lichen taxa in the heathland, including a CCP index (total numbers of Cetraria, Cladonia & Pycnothelia species) score of 21 (including previous visits SU2718 now has a CCP score of 29). A CCP score of 15 or more is good.
The Species List
Downloads (Notes on identification of heathland lichens are given in the PDF & The KMZ file allowing the route to and waymarks be viewed in Google Earth)
