Beaulieu Heath West, New Forest, 25 August 2012
This meeting aimed to explore an area of heathland which had been much disturbed by a WWII airfield. The concrete runways had been removed and returned to common grazing but leaving ground enriched with lime from the broken concrete. The sites of the old runways have developing calcareous grassland with scattered lumps of concrete, where I expected more mobile downland species and to learn some concrete weeds, a habitat I have rather ignored. There was also plenty of unexplored heathland adjacent where specialist heathland species were expected.
We met at SU3572 0043, on a sunny if windy afternoon with the threat of heavy showers. Led by Neil Sanderson with Sara Cadbury, Ginnie Copsey, Eric Clement, Tara Dempsey, John Norton, and Richard Reeves attending. We started off on grassland developed on the ripped up runways and dispersal areas. The first species of interest spotted near the car park was a Cladonia taxa that I am still working out exactly what it is (Way Mark 3500-01, SU35734 00412). It has large flat basal squamules with turned up ends, which are green on top and bright white underneath; these are very similar to Cladonia humilis. The podetia are similar shape to Cladonia humilis; short and wide, with a corticate base. The fine soredia of Cladonia humilis on the upper podetia and inside the cup, however, are replaced in this taxa by coarse corticate granules/schizidium. The spot tests are different with Pd + red and K – as opposed to the Pd + red and K + yellow reactions of Cladonia humilis. Previously I put this down as Cladonia pocillum, but this has brown basal squamules, which are much more appressed (links to pictures) and appears to be confined to more calcareous substrates than are found in the New Forest. This taxa seems to match Cladonia hammeri, which would be new to Britain, and I am waiting for conformation by TLC. [Note, initial TLC tests at the Natural History Museum have ruled out both Cladonia hammeri and Cladonia pocillum but not Cladonia pulvinata, also new to Britain, but more tests are to be run, NAS 1/4/2013]. It appears local but widespread on moderately base rich brown field habitats in at least southern England.
Cladonia hammeri or Cladonia pulvinata?, specimens from other sites
Bits of broken concrete about the car park provided practice in identifying common concrete lichens, with Caloplaca oasis identified, the main Caloplaca holocarpa segregate on concrete. We then crossed over to the site of the main eastern runway. The lime rich soil left behind after the concrete had been ripped up has been colonised by a open grassland with many lime loving vascular plant species more typical of downland. These include mats of Thyme Thymus polytrichus and Thymus pulegioides, along with Stemless Thistle Cirsium acaule, Salad Burnet Sanguisorba minor, Fellwort Gentianella amarella and Kidney Vetch Anthyllis vulneraria. Other species of interest were Autumn Lady’s Tresses Spiranthes spiralis, just coming into flower, and Lesser Centaury Centaurium pulchellum. There were also large mounds of the lime loving moss Ditrichum gracile. Among these downland herbs is a smattering of typical downland lichens. These included abundant Cladonia rangiformis, Collema auriforme, some Cladonia furcata subsp. subrangiformis and lots more Cladonia hammeri. More scattered was Bacidia bagliettoana, with rare Cladonia cariosa (NS) (Way Mark 3500-05, SU35509 00453), Leptogium schraderi, Leptogium tenuissimum (NS) (Way Mark 3500-02, SU35593 00370) and Placidium squamulosum (Catapyrenium squamosum) (Way Mark 3500-03, SU35581 00373). The latter was new to the New Forest heaths.
Runway grassland, habitat and lichens
After recording a length of the runway site, we turned west in the the heathland. Adjacent to the runway was a belt of herb rich heathland and tall Gorse. This was too productive to have any terricolous lichens but the rich vascular plant flora included a hybrid between the Vulnerable RDB Pale Heath Violet Viola lactea and the common Dog Violet Viola riviniana at SU3545 0050.
Beyond this was more open heath with little Gorse. This is under a controlled burning cycle with most of the heath described below last burned in about 2004 from Google Earth, but the southern bit walked over at they end of the day older than this. I did not expect this to be very lichen rich. The lower terraces in the New Forest typically have a layer of brickearth (loess) over the plateau gravel producing more fertile heaths with lower lichen diversity, except on the plateau edges where the brickearth has been eroded. Into the heath however the diversity started to get quite high (Way Mark 3500-06, SU35356 00467), with Cladonia strepsilis, Pycnothelia papillaria frequent, occasional Micarea lignaria var. lignaria and a little sterile Cladonia callosa (NS). The heath was open with poor heather growth and although the grass Bristle Bent Agrostis curtisii was frequent, its growth was also poor (high Bristle Bent cover normally suppresses lichen diversity), producing very open heath. This very rich heath continued right through the area of heath we traversed. As this was very atypical of the area, after the meeting I had a look at some 1946 aerial photographs and the explanation became clear. During the war the heath was mown along the runway margins (the herb rich heath with Gorse) but between the runways the heath was bulldozed leaving much bare ground (as a fire prevention measure or to smooth the ground for over running planes?). The resulting recolonised heath was still very different from normal low terrace heath.
Heathland: 1946 aerial photograph, habitat & lichens
Into the rich area at Way Mark 3500-07 (SU35300 00458) Cladonia subcervicornis and Micarea leprosula were found along with confusing material the same size and look as Cladonia subcervicornis but with brown upper parts. Wet in the field the large squamules were flat on the ground, but latter dried in the lab the under sides curled over showing snowy tips grading the grey - brown bases. The thalli had some small podetia, which were narrowly conical with shallow cups. The possibility of Cladonia firma went through my mind, but the soil was more acid than the first Cladonia firma habitat in the New Forest, which was in habitat similar to the runways. At this site this "brown Cladonia subcervicornis" was growing withCladonia strepsilis, Cladonia subcervicornis and Pycnothelia papillaria. Back in the lab, however, I did get a week K + yellow reaction at the junction between the cortex and the medulla, so it seems to be Cladonia firma, but I will get a TLC done to check. [Revisiting the site it may be that this material simply is brown Cladonia subcervicornis. At this site the brown material appeared to grade into normal blue-grey C. subcervicornis; brown C. subcervicornis is not described in any sources I have looked at. As the two lichens have the same chemistry, it is not clear exactly how to easily separate them if C. subcervicornis can be brown. There is a second site which has a better candidate for real Cladonia firma, where similar material grows in very base rich ground with species such as Salad Burnet Sanguisorba minor. This material has the squamules a bit more dissected but not nearly dissected enough to be Cladonia cervicornis s. str. NAS 7/8/2013]
The back threatening cloud to the north west of us then clipped as and gave us a short rain shower. We were lucky, further north this was a cloud burst that refilled my water butts. Once passed over, we moved into more rich ground (Way Mark 3500-08, SU35283 00456), where we added some special New Forest species: Cladonia cornuta, Cladonia grayi (NR) (until then Cladonia cryptochlorophaea (NS) had dominated) and Cladonia phyllophora NT (NS). North east of this we found a disturbed linear strip that had shown up on Google Earth (Way Mark 3500-09, SU35248 00499). This proved to be a level area with slightly base enriched soil. From the 1946 aerial photograph, this looks to have been a hollow way filled in for safety reasons. Here we found some pure plants of the Vulnerable RDB vascular plant Viola lactea, with the lichen Dibaeis baeomyces forming sheets on open flat ground, a fine population of Cladonia phyllophora NT (NS) and some Cladonia rei NT (NR) on the side of a hole. There was more Micarea leprosula and the under recorded Micarea viridileprosa (NS). More Cladonia firma was spotted, this time in more expected habitat, of slightly enriched soil. The burning sensitive Cladonia uncialis appeared in small quantity, this very open area probably gets jumped by the controlled fires.
Cladonia firma?
Finally back on the site of the perimeter road a boulder of concrete provided a few more records, including some fine Xanthoria calcicola.
Xanthoria calcicola on concrete
In total we recorded 60 terricolous and saxicolous species, with the CCP index (Cetraria/Cladonia/Pycnothelia papillaria index) scoring 25, a good but not outstanding total for the Forest. A richer total would require more heathland habitats, such as short grazed unburned heath, or hollow ways with steep banks, but a lot of very good records were made. The heath with Cladonia firma certainly requires more work.
Species List
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