Sunday, 31 January 2016

A Natural History of Highfield Moss, Lowton

I've been visiting Highfield Moss at Lowton since the early 1980's, primarily as a botanist, lured to the site annually by the enigmatic and nationally rare marsh gentian and a host of other local rarities such as sundews and sphagnums. The moss first came to my attention in a weekly column in the Daily Post by the Merseyside naturalist the late Eric Hardy. I was living in Newton-le-Willows at the time and very much wanted to move the county boundary half a mile to the east in order to claim the moss for Newton and Merseyside. Far from receding, this feeling grew even stronger in later life when I became secretary of the St Helens Wildlife Recording Group and I wanted the moss in St Helens! Ironically in 2015 I moved to Lowton and am now happy for the Site to stay put!

In 2010 I wrote a scientific report on the impact of aspect on the diversity of plant communities at the moss and in 2012 my MSc dissertation was a study of the potential influence of altitude on morphological variants in Common sedge Carex nigra which included a collection of samples from Highfield Moss (with the permission on Natural England).

This blog post is really just a pulling together of lots of information that I have collected on the moss from many visits, and much of this is scattered elsewhere across the blog. Some of the technical information I have taken off the original SSSI designation from the Natural England website, available here. All of the photographs used here are my own, and with one or two exceptions were all taken at Highfield Moss.

Where I have mentioned NVC community types, this is my opinion based on what I know about the flora present, but these shouldn't be taken as absolutely accurate since I have not conducted a full NVC survey at the site. Opinions given about the current state of the habitats present are my own and are based on personal observations and are not based on any formal long term study.

I have carefully avoided using the title "The Natural History of Highfield Moss". "My Version of the Natural History of Highfield Moss" might have been more appropriate. The report does not include whole orders of animals and plants, so it is by no means comprehensive. I have produced this report for no other reason than it seemed an entertaining thing for me to do. Hopefully though it is interesting and informative.

Highfield Moss
Highfield Moss is a Site of Special Scientific Interest in Lowton, on the border of Greater Manchester and Merseyside, bisected by the Liverpool to Manchester railway line. It was notified as a SSSI in 1986 and is a small site of 21 ha, underlain by Triassic Scythian Sherwood sandstones. The Site can be divided into three sections of habitat (units).

Mixed valley mire
The southern most section is mixed valley mire which is the best remaining example of the raised mires which once covered large areas of lowland Greater Manchester and Merseyside. This area includes a small Sphagnum lawn, Molinea mire, wet heath, tall fen, marginal ditch vegetation and open pools.

Several sphagnums occur on the sphagnum lawn, including Sphagnum pappilosum, S. palustre, S. fimbriatum and S. fallax. Also here, round-leaved sundew Drosera rotundifolia and Cranberry Vaccinium oxycoccus.

Box 1. Plants of the Sphagnum lawn
Sphagnum fallax Sphagnum fallax
This species is variable but is tyically green. This specimen is most likely a male plant because it has a contrasting darker tip to the capitula. Compare this to the superficially similar Sphagnum palustre below. Specimens which are very submerged often appear darker green than those which are in drier situations. Wetness and shade can alter the colour of sphagnums.
Sphagnum fallax Sphagnum fimbriatum
An over abundance of Sphagnum fallax can be an indicator of a degraded bog. I don't think that this is the case at Highfield Moss.
Sphagnum palustre Sphagnum papillosum
Sphagnums are grouped into six different sections. This species and the next are in section "sphagnum". The five sphagnums in this section look quite a lot different to species in other sections because the shape of the leaf is distinct. Once you're aware of this difference it's easy to see that S. palustre is quite different to male plants of S. fallax (above). This is one of the most important peat building sphagnums and its prescence and abundance can be an indicator of the health and functionality of a bog or mire.
Round-leaved sundew Drosera rotundifolia Cranberry Vaccinium oxycoccus

The Molinea mire is dominated by purple moorgrass Molinia caerulea and wavy hair-grass Deschamsia flexuosa with common cottongrass Eriophorum angustifolium and hare’s-tail cottongrass E. vaginatum common in places. This community seems to most closely resemble NVC community M25a Molinia caerulea-Potenilla erecta mire Erica tetralix sub community and typical of that community, bryophytes here are represented by hummocks of Polytrichum commune interspersed with Sphagnum fallax. Sedges include star sedge Carex echinata, Carnation sedge C. panicea and common sedge C. nigra, whilst rushes are represented by soft rush Juncus effusus and jointed rush J. articulatus. 

Box 2. Plants of the Molinea mire
Purple moor grass Molinea caerulea
Polytrichum commune
Vast swathes of this grass cover the moors throughout the UK and in M25 Molinea mire such as this it is overwhelmingly abundant. This photograph was taken in summer when the grass can have this purplish sheen. This is one of my favourite bryophytes, well grown, large hummocks are unmistakable and can cover large areas. Each shoot can be around 1cm diameter and can be up to 40cm long. They don't grow that big in M25 Molinea mire but it is still an impressive species at the Moss.
Common cottongrass Eriophorum angustifolium Hare's-tail cottongrass Eriophorum vaginatum
This and the next species are by far the commonest cottongrasses in the UK. Of the two, common cottongrass prefers much wetter situations. Notice that this species has 3-7 "cotton buds" on each stem. This cottongrass is easily distinguishable from the last because it only has one "cotton bud" on the end of each stem. It prefers drier situations, and an overabundance can be an indicator of a degraded bog.
Cross-leaved heath Erica tetralix Star sedge Carex echinata

The open pools provide good habitat for a number of odonata species, including the locally scarce black darter Sympetrum danae. Other species include common hawker Aeshna juncea, emperor Anax imperator, black-tailed skimmer Othetrum cancellatum, four-spot chaser Libellula quadrimaculata, emerald damselfly Lestes sponsa and large red damselfly Pyrrhosoma nymphula.

This unit is considered to still be in favourable condition, though eutrophication caused by run off from adjacent farmland is a constant threat.

Box 3. Odonata
Black darter Sympetrum danae Emerald damselfly Lestes sponsa
Black-tailed skimmer Othetrum cancellatum Large red damselfly Pyrrhosoma nymphula
I first saw this species on the moss in 2003 and it may well be a recent colonist. Black-tailed skimmers have expanded their range northwards during the past couple of decades and were first recorded in St Helens in 2000.

Acidic marshy grassland
When the railway cutting was dug across the Site around 1830, an earthmound was created 30m south of the railway running parallel to the line. The area north of this earthmound is acidic marshy grassland on glacial deposits of sand and gravel. This area is dominated by purple moor grass and is the major stronghold in North-west England for the rare marsh gentian Gentiana pneumonanthe and is one of only two sites in Manchester for petty whin Genista anglica. Cross-leaved heath Erica tetralix, ling Calluna vulgaris, Goldenrod Solidago virgaurea and Devil's bit scabious Succisa pratensis also occur here.

This unit is declining due to a thick sward of Molinia and the build-up of a thick Molinia litter between the tussocks, and this has resulted in a significant reduction in both the number of flower spikes and the extent of the population of marsh gentian since the site was designated a SSSI.  Indeed the largest area of acidic marshy grassland which is to the north of the railway line seems to have completely lost its population of Marsh Gentians, where there were previously up to 50 flower spikes in the mid 1980s. The species now seems confined to the small strip between the railway line and the railway earth mound (personal observations and  records). The apparent spread of ling and decline of cross-leaved heath is another indicator of the drying out of this unit. 

Assignment of an NVC community type is difficult with this unit without undertaking a survey, but it seems to be most likely a drier sub community of M25, perhaps M25b Molinia caerulea-Potenilla erecta mire Anthoxanthum odoratum sub community.  

Box 4. Plants of the acidic marshy grassland
Common sedge Carex nigra Marsh gentian Gentiana pneumonanthe
Here in full flower. The top two (orange) spikes are the male flowers, the bottom two (white and yellow) spikes are female.
Pill sedge Carex pilulifera Devil's-bit scabious Succisa pratensis
Petty whin Genista anglica Ling Calluna vulgaris
Goldenrod Solidago virgaurea Purple moor grass Molinea caerulea 
Photographed here in South Wales, the pale colour of the dead leaves in winter gives moorland the name "white moor".

Unimproved acidic grassland
The earth mound itself is unimproved acidic grassland. Wavy hair-grass dominates, and mat-grass Nardus stricta, sweet vernal-grass Anthoxanthum odoratum, tormentil Potentilla erecta and heath-bedstraw Galium saxatile are also abundant. Bracken Pteridium aquilinum occurs on the western and northern edges of the site and there is a small stand of pedunculate oak Quercus robur and gorse scrub, dominated by common gorse Ulex europaeus, but also including western gorse Ulex gallii. Bryophytes in this unit include Hypnum jutlandicum, Pseudoscleropodium purum and Dicranium scoparium, whilst rushes include heath rush Juncus squarrosus and field wood-rush Luzula campestris. This community most closely fits NVC community U5 Nardus stricta-Galium saxatile grassland.

This unit is considered to be still in favourable condition, though there is concern over the dynamics of change towards more species-poor Molinia and bracken. Both of these species are well represented and likely to spread in response to dryness and burning.

Box 5. Plants of the unimproved acid grassland.
Mat grass Nardus stricta Wavy hair grassDeschampsia flexuosa
The dominant species in this type of grassland, mat grass is easily identifiable when in full flower as it is in this photo, and even dead flower heads have a distinctive look. The wirey leaves feel rough if you run your fingers along them. This is one of the wiry leaved grasses which can be quite difficult to identify when not in flower, but when in flower it's quite distinct with purple stems and two florets per spikelet. This plant was photographed in South Wales.
Dicranium scoparium Hypnum jutlandicum
Pseudoscleropodium purum Rhytidiadelphus squarrosus
Western gorse Ulex gallii

Birds at Highfield Moss
Although I have visited the moss primarily as a botanist, I am also a birder and have inevitably recorded a number of species over the years. The site is also watched regularly by other local birders and sightings are reported on the Manchester Birding blog. Highfield Moss holds a suite of farmland birds including tree sparrow  Passer montanus, yellowhammer Emberiza citrinella, corn bunting Emberiza calandra, skylark  Alauda arvensis, linnet Carduelis cannabina and grey partrdige Perdix perdix. Snipe Gallinago galllinago are common in winter and a host of migrant birds are recorded on spring and autumn migration. Buzzard Buteo buteo, sparrowhawk Accipiter nisus and kestrel Falco tinnunculus are common, with occasional visits from peregrine Falco peregrinus, hobby Falco subbuteo and short-eared owl Asio flammeus in the correct season.

Box 6. Habitats at Highfield Moss
Molinea mire and bog pool. Molinea mire and unimproved acid grassland
This is looking at the south from the earth mound. The railway is 30m behind us. Looking east along the earth mound which is on the left of the photo, with the railway line a further 30m to the left. This photograph was taken in January and you can see the "white moor" of the Molinea mire on the right two thirds of the photograph.

Threats to the site
Threats to the site have already been touched on. Eutrophication, drying and burning are the main threats, especially on such a small site. In 2015 a program of re-wetting the Site began.

Tuesday, 26 January 2016

A few bryophytes from Pennington Flash

I feel I've neglected the bryophytes recently, so with a bit of time to spare today I decided to have a look through some mosses and liverworts I collected at Pennington Flash recently. All of these are common, the blue tits and dunnocks of the bryophyte world, but it was nice to get my eye in again and remind myself of some bryophyte field characters.

Brachythecium rutabulum. Abundant, grows in woodland at the flash, on tree trunks and stumps. Easily recognisable due to its pale tipped shoots. Note the dark brown sphore capsules. The shape and colour of the capsules can be diagnostic when identifying bryophytes.

Amblystegium serpens. A very fine moss with tiny leaves. This specimin is growing on the fence near Tom Edmondson hide.

Cryphaea heteromalla. Grows on the barks of trees and is a very distinctive moss, with its capsules on short seta and all along one edge.

Hypnum andoi. One of the distinctive plait mosses, growing on trees.

Kindbergia praelonga. One of the commonest mosses in the UK, it grows on trees and stumps at the Flash. This and all of the mosses above are pleurocarps, i.e. they have branches coming from a central stem. In the case of Kindbergia praelonga the branches are easy to see, they makes the moss look like it has fern like fronds, but in other species pleurocarps can have very short branches which are not so obvious (e.g. some of the Hypnum species). Bryophytes which aren't branched (or are very sparsely branched) are called acrocarps (e.g Ulota crispa below).

Syntrichia intermedia, typically grows on stonework with this plant on the "pier" near Horrock's hide.

Orthotricum affine. Grows on branches, in this case grey poplar.

Ulota crispa on ash tree.

Ulota crispa under the microscope. Note the capsules.

Mertzgeria furcata. This is a liverwort, i.e. a bryophyte but not a moss. It grows on trees.

Saturday, 23 January 2016

Horsebere Flood Alleviation Pool and some other stuff

Today we headed south west, into Gloucestershire to look for the penduline tits which have recently been at Horsebere Flood Alleviation Pool on the east side of the city. We found the place easily enough, straight down the M6 / M5 to junction 11 then onto the A40 / A417 for a couple of miles and park in the layby opposite the Premier Inn. Even better, the birds were showing well when we arrived, a bit of a relief because they have been prone to disappearing for a couple of hours at a time. I say showing well, good decent views through the scopes and not bad through the bins, but not good enough for photography for me, and nowhere near as close as the birds we saw last year in Devon. After watching them for about 20 minutes, they flew high and away over the Premier Inn.

This was our cue to leave because we had other places to get to, including our next stop, Slimbridge WWT just 16 miles to the south. Wildfowl numbers had picked up since our last visit in November, and there were now 150 European white-fronted geese and 140 Bewick's swans (though we only saw about 68). Also here, five Greenland white-fronted geese, six common cranes, peregrine, female scaup, 600 golden plover  and thousands of wigeon, teal and lapwings. A very impressive spectacle. The Greenland white-fronted geese were with their European counterparts and weren't quite so easy to pick out as I expected. They were clearly darker birds with a more powerful orange bill compared to the pink billed Europeans, and when the flock took off they looked larger birds, but not a lot in it to my eyes.

Having seen these birds so well and so quickly, we decided to head back to Gloucester for another look at the penduline tits, and I was glad we did. Once again we were lucky because the birds had been missing for nearly two hours since we left them, but by the time we arrived back they had also returned. This time they were a little closer but spent most of their time out of view and right down at the base of the bulrushes, only occasionally popping into view. A real pain in the backside! However, eventually one did climb a little higher and I got excellent scope views before both birds flew into a hawthorn bush near the layby. They were a bit more distant here but stayed on full view for a couple of minutes allowing us to get a good look at them. Still not great for photography though.

We could have hung around longer and probably could have got some good photos eventually, but we wanted to try for the overwintering hoopoe in Staffordshire at Hinksford. Our luck held again and we  dropped right onto the bird showing at less than 10m, albeit largely obscured by long grasses. Eventually though it flew and landed for a few minutes on the fence at fairly close range, before flying again further away. An excellent end to the day.

Year: 139 (Penduline tit, hoopoe etc.)

Penduline tits.

Horsebere Flood Alleviation Pool.

Bewick's swan.


Common cranes.


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