Ptyxis Ecology - Our Botany Blog

Tuesday, 23 September 2008

It doesn't exist until I've seen it!

In my favourite film, 'Down by Law', Jack and Zac share a prision cell and really dislike each other. At one point they have another argument and Jack says to Zac (or maybe it was Zac to Jack), "from now on as far as I'm concerned, you don't exist". Zac (or maybe it was Jack) wants to sound tough so he says "yeh, well you don't exist either".

I was out surveying on Tuesday on a remote bit of blanket bog in Kielder with Julia who is from Quatemala. We found this lizard and Julia was very pleased as she had never seen a reptile in the wild in Britain before. She said "now I believe that reptiles exist in Britain". That struck a chord with me because there are many species that I didn't believe existed until I saw them for the first time.

In my twenties I was (still am) a very keen birdwatcher, but for some strange reason it took me years to see my first little grebe. I did lots of birdwatching and went to lots of the right places to see little grebes in the Lee Valley near where I lived at the time. Even though I knew very well what they looked like from looking at pictures it was really difficult for me to believe that they really existed until I actually saw one. Since then I've seen them loads of times but I always get a great kick out of seeing them every time now!

Other species I still don't believe exist include: scaup, wood warbler, garden warbler (probably have seen or heard these but not realised it), pine marten, Carex aquatilis, Bryum caespiticum and of course many many millions more!

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Wednesday, 17 September 2008

Dwarf birch on an English hill

Last week I was doing some 'condition assessment' of blanket bog sites in Northumberland for as part of a nation-wide survey for Natural England. We have to use a ridiculous method which can't possibly tell you what condition the bog is in, but that's another story! One day on a very remote site in Northumberland, my co-surveyor Fiona came back to the car at lunch time with a twig of Betula nana (dwarf birch) in her hand. I couldn't believe my eyes and got very excited as I knew there were only 2 native sites for it in England. When I say 2 sites I really mean 2 bushes (ok, one of the sites has 2 tiny bushes quite close together). I also knew that one of the sites was somewhere in the Northumberland hills but I thought the chances of Fiona stumbling upon that site by accident in such a remote place were extremely slim.

Well believe it or not that's exactly what happened. What are the chances of that happening? neither of us had any idea that the plant was on the site. The site we were surveying is about 7 or 8 miles from the nearest public road and covers about 3,000 hectares. Professor George Swan (who wrote the 'Flora of Northumberland' originally found the plant on this site in 1973 new to south Northumberland. There is a very old record from north Northumberland but nobody has refound it there for a very long time.

Here's another map from BSBI's website showing its British (and lack of Irish!) distribution. I believe that the 2 records in Lancashire are of introduced plants. There is quite a scattering of records in the central highlands and the north of Scotland. This is an artic-alpine species whose core range is really in the artic and boreal zones.

I couldn't resist including another photo of Tetraplodon mnioides (see the entry of 13 August 2007). I think this is probably my favourite moss now - its definitely one of the most colourful species. It is still quite uncommon in Northumberland. There are only 16 records for it in VC67 - south Northumberland overall but I've found it 3 times in just over a year. I guess this probably means that it is increasing, but who knows really?

I've always found it growing on dead sheep before, but this time there were 5 seperate small clumps on the forestry road leading up to the Betula nana site. I guess it must have been growing on deer dung here.


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Saturday, 6 September 2008

Northern hawk's-beard

I've always thought it very strange that the common names of so many plants are named after parts of animals. Hawk's-beard, hawkbit, hawkweed, cat's-ear, and ox-tongue all look confusigly similar. There are lots more - dog's-tail, cat's-tail, squirrel-tail, mare's-tail, rat's-tail, mouse-tail, hare's-tail, horse-tail, fox-tail, buck's-horn, crane's-bill, stork's-bill, adders-tongue, hart's-tongue, weasel's-snout, ox-eye, bird's-eye, hare's-ear, mouse-ear, lamb's-ear, buck's-beard, goat's-beard, old man's-beard (yes we're animals too!), dog's-tooth, dragon's-teeth (does dragon count?), oxlip, bird's-foot, hare's-foot, crow-foot, colt's-foot, cock's-foot, goose-foot, cockspur, larkspur, parrot's-feather, etc. Unfortunately dog's-dibble is no longer in common usage. One plant is even named after 2 animals, mouse-ear hawkweed. Sometimes these names are helpful when trying to remember which plant it is but most of the time they are not helpful. How many people know what a hawk's beard looks like and even if they did, would they spot the resemblance to the plant? I guess the real reason is that after most plants have been named its difficult to think up original names for new plants so the plant namers start to clutch at straws.

But anyway, back to northern hawk's-beard, or if you prefer (as I do) Crepis mollis - much simpler! I've had a good year for Crepis mollis this year. Here's a picture of it taken by my colleague Rebecca last year near Nenthead in the Cumbrian pennines.

Yes, I know it just looks like a load of dandelions, but it really is a very special plant - honest! Its particularly relevant for me as its main habitat is upland hay meadows which is what my day job is all about and I live right in the centre of its British distribution in south-west Northumberland.

This map from BSBIs website shows its distribution in Britain. The darker coloured dots (there are not very many of them) are records from recent years. Not only is it a scarce and very loclaised plant in Britain, but it has also declined a lot in recent decades due to agricultural intensification.

As my job in summer involves lots of surveying in upland hay meadows, I'm always on the look out for it. Also, this year it was chosen as one of the species in BSBIs threatened plants survey so I've been looking for it in some of the sites where it was recorded a long time ago. Although I couldn't find it in a few of these places, it is hanging on in a good number of its old sites in this part of the world. My colleague Fiona Corby also managed to find 2 new sites for it in Allendale including one on a large herb-rich bank with upland hay meadow type vegetation which had about 500 plants of Crepis mollis on it. This was particularly good news as we think this could well be the biggest population left in the country. The landowners are pleased that they have it and are willing to try to do the right things to conserve it which is also good news.


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More bog desmids from Widdybank Fell

Chris Carter continues to find some amazing-looking desmids in the gungy bits of Sphagnum I've been sending him from Widdybank Fell. Last time I sent him just 2 bits of Sphagnum and he has been busy for months finding more and more species of these microscopic algae in amongst the Sphagnum - and he's not finished yet!

Here are some of his latest finds -

There is a Dutch method of assessing the conservation value of wetland sites using desmid species called the Coesel method. Based on what Chris has found so far from just 5 small samples of Sphagnum from Widdybank Fell, the site now has a score of 8 or 9 out of 10. I'm sure its only a matter of time before it reaches 10 out of 10.


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A mountain stream in Regent's Park??

The shot below shows a water feature in the 'nature study' area of Regent's Park in central London. On a recent bryophyte survey we did for the park this was one of the few habitats we found with a well-developed bryophyte community. The sheltered water feature creates a suitable humid environment for several species that otherwise occur only sparsely in the area.

However the biggest surprise was finding Racomitrium aciculare sitting on rocks by the 'stream'. This species has never been recorded in Middlesex before and is very uncommon in south and east England as you can see from this distribution map from the NBN website.

In the north and west of Britain you can almost gaurantee to find it on rocks by any upland stream, but this habitat is absent from most of lowland Britain.

The neat round cushions with the white hairs sticking up in the picture above are Grimmia pulvinata which is a very common species on rocks and walls everywhere. Racomitrium aciculare is the more straggly dark green plant in the middle of the top of the picture, with a few more shoots on the top right.

The main focus of the survey was to look for bryophyte epiphytes (plants that grow on trees). These were fairly sparse and mainly confined to a small number of species. Many epiphytic species cannot live in areas with high athmospheric pollution. In recent decades particulate air pollution associated with coal fires has almost gone and as a result in recent years several epiphytic species have been sucessfully recolonising areas they have been missing from for a very long time. However most truly urban areas still have relatively few epiphytes.

The picture above shows the most common type of epiphyte community we found, comprised mainly of the lichens Physcia adscendens and Xanthoria parietina, with a little of the moss Orthotrichum diaphanum. Most Orthotrichum species are epiphytes and Orthotrichum diaphanum is the one that is most tolerant of air pollution.

On a small number of trees the bryophyte element of the epiphytic community was more developed but it usually consited of just Orthotrichum diaphanum and Rhynchostegium confertum. Interestingly, their were occasional cushions of both Tortula muralis and Grimmia pulvinata on the trees. These species normally grow on walls or rocks and only rarely grow on trees, but something about the tree habitat in London makes them behave differently.

There are many London plane trees in London parks and at first glance these would seem to be unpromising habitat for epiphytic species as the trees shed their outer bark in small patches very regularly. This habit allows the trees to cope with polluted areas better than most other tree species as every time the bark is shed it results in a fresh clean new bark free from grime, helping the tree to breathe easier. It turned out that London plane is in fact the best tree species for bryophytes in central London (apart from elms which are much less common). The epiphyte community is often fairly well developed on the base of the larger trees where the bark is no longer shed so regularly. The texture and chemistry of the bark must make the suface more suitable for epiphytes than the other tree species.


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