Ptyxis Ecology - Our Botany Blog

Saturday, 14 June 2008

Small-white orchid and bluebell banks

The Weardale Gazette recently reported that "John O'Reilly excited himself by finding a rare plant in a meadow near Wolsingham". The rare plant in question was Alchemilla acutiloba which is not that rare in Weardale but is very rare elsewhere. Well, yesterday I 'excited myself'' even more by finding 8 spikes of small-white orchid Pseudorchis albida on a bank in the Holwick area of Teesdale. Out of about 450 meadows that I've surveyed so far this is only the 2nd time I have found it and the other time it was shown to me by Linda Robinson.

I surveyed this meadow on 5th June and was puzzled by this orchid spike in bud:

I assumed at the time that it was probably Platanthera chlorantha which is quite uncommon and a nice thing to find, but it didn't look quite right. The flower buds showed no sign of the elongated pedicels you would expect with greater butterfly-orchid but I thought that might just be because of the early stage of development. But the stem leaves seemed too big and the flower buds were very numerous and congested on the spike. I thought the stem leaves and overall shape of the spike was right for Pseudorchis but I doubted it was that because the plant was about 10 inches high already which I thought was too big and also because it is so rare around here.

So here it is in all its glory 8 days later:

It is not the most spectacular-looking species in the world but a nice find beacuse it is so uncommon and it usually indicates very nice habitat. One of the best things about it was that I told the farmer that I found it and he rang me back later on to ask how could he grow more of them on the bank!

I didn't take a proper habitat shot but you can see some of the associated species in this shot:

If you look closely you will see lots of leaves of Succisa pratensis and Hyacinthoides non-scripta, some Potentilla erecta and Conopodium majus a flowering stem of Festuca rubra, and STOP PRESS!..... I've just this minute noticed something with a spike of flowers in bud in the bottom right hand corner which I think is Persicaria vivipara - I will have to go back again to check that out.

This bank was quite large, about 15-20 metres top to bottom and about 100m long, the vegetation was fairly homogenous throughout. The dominant species were Devil's-bit scabious, bluebell, pignut, tormentil and creeping soft-grass. I was very puzzled as to what this would be in the NVC but I think I've worked it out now. One of the best places to look for Pseudorchis albida in upland hay meadows is apparently in U4c vegetation on banks (see my blogs from last year about banks in meadows). I think the vegetation above is a form of MG5c which grades into U4c depending on the soil characteristics. The main difference between the two is the grass component of the flora. MG5c has more of the broad-leaved bulkier grasses (here it had both Holcus species, Dactylis glomerata and Helictotrichon pubescens) and bulkier herbs like Centaures nigra, whereas the dominant grasses in U4c tend to be fine-leaved species like Festuca rubra and ovina and Agrostis capillaris.

Bluebells are a prominant feature of grasslands in meadows in Teesdale and in the Greta valley. In the NVC bluebell does not feature prominently in any of the tables describing the published grassland communities, so it has taken me a while to work out which communities are involved. Not far from the bank described above it occurs in another very large bank in vegetation with some similarities to the type of MG5c described above, except that in has some more typical acid grassland indicators like Galium saxatile and has a canopy of bracken. This 2nd type of vegetation is clearly a good match to U20a.

A third type of grassland where it occurs abundantly is almost identical to the U20a except that it has no bracken. So you could call this either 'U20a without bracken' or 'U4a with lots of bluebell'?

A forth type is quite common in narrow strips along the base of walls or along the lines where there used to be a wall within a field. This vegetation has clearly developed along these walls since they were erected and is not relict woodland vegetation. Usually the vegetation is overwhelmingly dominated by Holcus mollis and Hyacinthoides non-scripta, sometimes with the odd bit of Urtica dioica, Dactylis glomerata, Dryopteris filix-mas or Conopodium majus. This vegetation is an excellent match to W25a, except that there is no bramble or other woody species. Perhaps it is a stage in the development towards W25a!

It also occurs in more typical MG3 and the richer forms of MG6 that grade into MG3.

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Saturday, 7 June 2008

Eyebrights in old hay meadows

The hay meadow survey season has come around again. My job at this time of year is to survey lots of upland hay meadows in the north Pennines (the bits of the Pennines in Durham, Cumbria and Northumberland), to advise on their management and to find species-rich meadows to use as a source of 'green hay' for introducing seed to other meadows being restored nearby. Species-rich upland hay meadows ('MG3b' in the NVC) differ from southern or lowland meadows in having lots of wood crane's-bill and other northern montane species.

Wood crane's-bill in an upland hay meadow in Weardale

In a lot of the meadows the sheep have only been put out about 2 weeks ago and this week more and more species have been coming into flower. The meadows will probably be at their most colourful next week. The picture below shows a close up of a fairly common type of vegetation that we get in the north Pennines meadows. This is what I call MG6+. It is semi-improved and so lacks the special northern montane species. It is often quite herb-rich with more than 60% cover of herbs, but it is not really species-rich, being dominated by a few common species like red clover, buttercups, pignut, ribwort plantain and often a lot of yellow rattle. This vegetation is a bit too rich to fit in to standard MG6 and not rich enough to be called MG3 or MG5 so I call it MG6+.

Colourful MG6+ vegetation in a meadow in Teesdale

Just before the season started this year I got my eyebrights determined by the BSBI's eyebright expert Alan Silverside. My job gives me the opportunity to access lots of meadow on private land most of which may never have been visited by a botanist. So, it is worth making the effort to try to work out some of the critical groups or at least to collect specimens so that an expert can identify them.

Euphrasia arctica arctica

It seems that the eyebright I have been finding most frequently in these meadows is Euphrasia arctica arctica. This is an 'old hay meadow' specialist. Until a few years ago it was thought that this sub-arctic taxon (whose main stronghold is the Faroe Islands) was confined in Britain to Orkney and Shetland. However it turns out that it probably occured throughout the range of Euphrasia arctica in Britain (i.e. most of the northern half and upland areas in Britain) but has largely died out in most places due to both loss of old hay meadow habitat and being hybidised out by the more competitive, 'weedy' Euphrasia arctica borealis.

As with other eyebrights, hybrids are common which makes identification a bit of a nightmare! I can't distinguish between true Euphrasia arctica and hybrids so I collect specimens and allow the expert to identify them properly. In the field I can only split the upland hay meadow eyebrights into 2 main groups - The Euphrasia arctica types and the Euphrasia rostkoviana (officinalis) types which are much rarer. Last year I found Euphrasia rostkoviana montana (Euphrasia officinalis monticola) 4 times out of about 250 meadows surveyed. It has very large flowers for a Euphrasia and has long hairs with tiny glands on the end.

This is now a UKBAP species as it has suffered a massive decline and grows only in upland hay meadows which have themselves suffered a massive decline. Its current range in Britain is Wales, Yorkshire Dales, north Pennines, Cumbria and the Scottish Borders. Alan was delighted to see this again as there had been no authenticated records from the Pennines for about 30 years and he thought it may have gone completely extinct in the Pennines. I will be looking out for it carefully again this year.


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There's something else in the bog!

See our post of 19th January for pictures of amazing-looking testate amoebae taken by Chris Carter. Chris really wanted to find desmids (a type of unicellular alga with lateral symmetry) in the sphagnum samples but the samples I collected the first time were not from the right bit of the bog. So since then I have been collecting the most gungy, horrible-looking bits of sphagnum from bog pools. The more gungy they are the more excited Chris gets!

Here are some stunning photos of some of the desmids he has found in sphagnum samples from Widdybank Fell in upper Teesdale:

This next one is a testate amoeba rather than a desmid.

There is a method of assigning conservation value to mire sites based on the species of desmids that is used in the Netherlands. Using the first 3 small sphagnum samples Chris found 17 species (8 of which were red list) which already gives Widdybank fell a score of 6 out of 10. The pictures above are from 2 more samples collected recently and already Chris has found several extra species so this will result in an even higher conservation score from a very small amount of sampling.

The bog at Widdybank Fell is very species-rich and is well known for its conservation value for other groups of species. On my last visit Viola rupestris and Gentiana verna were flowering in the limestone grassland surrounding the bog and Minuartia stricta (at its only British site) was just about to flower in a flush. There was constant calling from golden plovers in the background and we almost stepped on a dunlin.

Viola rupestris growing on eroding sugar limestone at Widdybank Fell


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