DHBlog012 · A report by Jon Crewe (Chair of the Dorset Flora Group)
Early in 2022 the Dorset Flora Group made contact with Ben Wallbridge of Dorset Council with a view to discussing plant recording on the Avon Heath Country Park. Park staff have made records over the years and have monitored some of the rarer plants in known locations. These include Ophioglossum azoricum (Small Adder’s-tongue), Dianthus armeria (Deptford Pink) and orchid populations on one or two fields in the South section of the park. There does not seem to have been a sustained recording effort in recent years.
The park has undergone substantial felling of mature pines which has created bare ground with recovering vegetation cover. Committee members from the Dorset Flora Group met with Ben for a walk around some of the North Park sections and agreed that there was scope to look at felled areas for pioneer heathland species. The park has annual cattle grazing over parts in the autumn and winter and this has maintained some interesting short-turf acid grassland, as well as opening up areas of mature heath. There is a pond and some less permanent water features in wet areas, with a small compartment classed as wet heath.
We agreed that Dorset Flora Group members would make monthly visits over the course of the season; I would lead these on a weekday. While this isn’t ideal for working members, the group probably has more retired members, or part time workers. Park staff would also be involved with a view to staff and their volunteer team members receiving some informal botany training. We were hoping that some of the East Dorset based members would be able to join in, given that driving distance may stop people joining Saturday field trips to the more western parts of Dorset.
Dates were agreed for each month from April to July; these were usually the third Wednesday of the month. The field trips were publicised to all Dorset Flora Group members but attendance was low, possibly due to the weekday timing. We did manage to cover all of the north park and had some interesting finds.
April 20th with Robert Sharp, Rex Bale and Rebekah Bisset (Becks) from the Ranger Team
This was a walking session, trying to visit all of the 17 compartments that Dorset Council have mapped in North Park. Rex had run around them all in earlier days but we found that we weren’t quite as fast as that. We made a fairly full circuit in a long morning and decided to leave a few compartments for another day. One aim was to roughly classify each compartment into broad categories such as dry heath, acid or other grassland, wet heath, recently felled woodland, scrub and so on. This worked quite well, although most compartments were a mix of more than one habitat. The notes were useful for planning future recording, because it allowed us to focus on areas of the same habitat. The few compartments missed were recorded on an additional visit, adding five more species to the 58 recorded on the first visit. These included Carex flacca (Glaucous Sedge), Carex panicea (Carnation Sedge) and Carex pilulifera (Pill Sedge), Polygala serpyllifolia (Heath Milkwort) Melampyrum pratense (Common Cow-wheat) and Viola riviniana (Common Dog-violet). Nothing very unusual but already we were seeing more variety in the “dull dry heath” than we had expected.
24th May with Robert Sharp and Phil Smith
This was the day chosen to look for Small Adder’s-tongue; we decided to have a good look at other habitats first – leaving something to look forward to perhaps! The track along the south-east edge of compartments 16 and 12 seemed to have a slightly more varied flora than other track edges, possibly through some imported alkaline substrate, although this is guesswork. The Deptford Pink site is in this area. Plants found included Aira praecox (Early Hair-grass), Erodium cicutarium (Common Stork's-bill) Festuca ovina (Sheep's-fescue), Isolepis setacea (Bristle Club-rush), Ornithopus perpusillus (Bird's-foot) and Potentilla erecta (Tormentil). We eventually found our way to the compartment where we expected to find the Small Adder’s-tongue and searched – and searched! Phil Smith and I more or less gave up and headed off to find lunch. I returned to where Robert Sharp was patiently hunting to hear that he had found the elusive plant – and eventually we noted around 150 specimens spread across a small area of acid grassland, mostly close to the scrubby edges of the compartment. We later found a new site for the species in similar habitat to the North, with about 30 slightly larger plants in similar marginal habitat.
22nd June with Robert Sharp
This visit found the site already suffering with the persistent hot, dry conditions. We were pleased to see a great deal of Parentucellia viscosa (Yellow Bartsia) in the grassland at the Western end of the park; this is locally present around the East Dorset heaths but not often seen. We were also pleased to see the Deptford Pink in early flower, with immature shoots evident in several places and over 50 plants visible. Another elusive heathland plant, Cuscuta epithymum (Common dodder) almost tripped us up as we walked a narrow path through the heather. Crassula tillaea (Mossy stonecrop) and Lotus subbiflorus (Hairy birdsfoot-trefoil) were other additions to the list. Marco Marsango joined us from the Ranger team to look at the new site for the Small Adder’s-tongue, which was almost invisible in the dried up turf by this time.
20th July with Tony Fulford
The drought was well established at this point and we only stayed for a morning circuit of the site. The Deptford Pink was in full bloom and we were pleased to locate Radiola linoides (Allseed), on an overgrown path near to a dried up pond. This was the site of an earlier record for Lythrum portula (Water-purslane).
21st September with Robert Sharp
This visit had the dual aim of late season plant recording and a look at damper areas for bryophytes – Robert’s winter passion! We looked at the Deptford Pink enclosure to find it long gone but did note that the Allseed site had many more plants along the track than previously seen, so this track is one to watch for other heathland track rarities in the future. We reached the permanent pond in the East of the site where Robert photographed a liverwort that was exposed in the drawn down mud at the water’s edge. This has subsequently been confirmed as Riccia huebeneriana (Violet Crystalwort), a first for vice county 11 and not seen in vice county 9 (Dorset) since 1937. After that highlight we checked a few other potentially damp areas on our return but the only new find in the still dry margins was more Water-purslane.
This was an interesting focus on a site which does not appear very promising at first glance but has much to offer. We hope to return to the South section of the park for more recording next year; there are some different habitats in the land south of Boundary lane and perhaps more new finds await! Visit dates will be announced on the Facebook page, WhatsApp group and via the Dorset Environmental Records Centre website – see local groups / Dorset Flora Group.
Many thanks to everyone that came along for the recording days and to the Park Rangers for their help and company on occasion.