Ramsons carpets

Two recent woodland trips provided the inspiration for this post on ramsons (Alium ursinum). The first trip was an afternoon recce for some uncommon woodland flora when a visually compelling ramsons carpet was chanced upon in less than ideal lighting. Another location identified and added to the seemingly ever lengthening 'to visit under more idealised lighting' list.

To increase the chances of finding ramsons carpets an appreciation of their ecology is useful and a Hungarian research paper provides some useful insight into the habitat requirements amongst other things:

"In spite of its broad distribution across continents, and its occurrence as a weed, the species cannot be considered as a generalist. Several authors have classified it as a habitat specialist, having a rather narrow range of ecological tolerance (Grime et al. 1988, Kevey 1977, Rychnovská and Bednář 1998). A. ursinum is particularly sensitive to the availability of water. It requires a mesic soil, which is well-drained. Both drought and waterlogging are unfavourable (Csiky et al. 1999, Grime et al. 1988, Kevey 1977, Rychnovská and Bednář 1998, Trémolières et al. 2009, Tutin 1957). Sufficient humidity in the air is also crucial for survival (Kevey 1977, Kovács 2007)."

"The species strongly prefers the forest floor; it can rarely be found outside of a forest (Grime et al. 1988), only in some places with high, evenly distributed precipitation (Tutin 1957) or along rivers or streams (Kevey 1977)." 

"The plant requires a nutrient-rich soil (Tutin 1957)"

"A. ursinum is sensitive to the pH, missing from base-poor sands and mor soils (Tutin 1957). Falkengren-Grerup and Tyler (1993) demonstrated experimentally that mor (pH 3.6) inhibited the production of new roots. Tutin (1957) estimated the tolerated pH range from 5.5 to 7.9; Grime et al. (1988) narrowed it to 6–7.5" 

Extracts taken from Oborny, B., Botta-Dukat, Z., Rudolf, K. and Morschhauser, T., 2011. Population ecology of Allium ursinum, a space-monopolizing clonal plant. Acta Botanica Hungarica, 53(3-4), pp.371-388.

Ransoms are an indicator species of ancient woodland and some online detective work cross referencing national ancient woodland inventories e.g. Wales and England, against a relevant geology map will identify candidate sites of ancient woodland overlying calcareous bedrock. It is then a case of recceing the candidate woods.

The second trip was one made specifically to photograph a riparian carpet of ramsons within the Lower Wye Valley AONB on a rare day with overcast skies, the weather in May, thus far, has been mostly clear blue skies and sunshine. The woodland is designated as ancient semi natural and has outsize coppice stools of alder, ash, wych elm and hazel with a ground flora community of ancient woodland indicator species.

A spring woodland trip

A forecast of heavy overnight rain with clearing skies, negligible wind and the chance of mist, was the inspiration to set the alarm clock for a dawn outing. A bluebell wood recced on an evening visit a few days before would be the destination.

Wild boar foraging

Entering the wood just before sunrise and it became apparent that a) there was no ground mist, nor indeed any other type of mist and b) a sounder of wild boar had descended en masse to forage in the bluebell carpet in the area of wood that I wanted to photograph. Sigh. There were no signs of leaves or flower stalks sans bulbs, the boar seemed interested in something else and the bluebells collateral damage. Taking stock of the situation and the overnight rain had enlivened the mosses, wetted the leaf litter and the wind was negligible, so Plan B would be a visit to a scowles woodland 10 minutes drive away and hopefully the flora would be in flower.

Ramsons carpet

On the drive to the scowles wood I passed by patches of ground mist on fields and on the walk in there was a ground mist in the meadow adjacent to the wood. No mist in the wood though and reinforcing my view that woods have their own microclimate. Nevertheless there was some nice mist filtered light over a ramsons carpet and also deeper into the wood.

The Ransoms whilst in full flower at the wood edges were only beginning to flower in some parts of the wood where beech trees had leaf flushed well before the other canopy trees of lime and ash.

In the scowles where yew forms the understorey then it's the domain of bryophyte communities and just a few vascular plants.

It did appear to my eyes that where a canopy gap allowed morning sunlight onto the woodland floor there was a noticeable increase in woodland plants.

The light all too quickly became too harsh for effective photography and the remainder was spent investigating the wood for less common plants and enjoying the chorus of bird song.

Spring woodland flower recce.

A weather forecast of light wind and leaden skies favoured a recce for signs of spring flowers in two local woodlands: one a scowles woodland ~200m a.s.l and the other a Lower Wye Valley woodland ~100m a.s.l. The scowles woodland has gentle slopes underlain by Carboniferous limestone and shales with calcareous soils whilst the Wye valley wood is on a steep slope underlain by Devonian sandstone, mudstone and quartz conglomerate with a range of soil pH from acidic to mildly calcareous.

Ransoms carpet

The scowles woodland flowering was disappointing with only the odd primrose (Primula vulgaris) and carpets of dog's mercury (Mecurialis perennis) in full bloom, sadly dog's mercury is the most unphotogenic of spring wildflowers. Although carpets of ramson (Allium ursinum) leaves hinted at some potential for a future visit later in spring.

An oddity was the scarlet elf cup (Sarcoscypha cocinea) fungus which normally appears in February was still evident in the 1st week of April.

 The Wye Valley wood provided more floral interest with lesser celandine (Ficaria verna), primroses, dog's mercury (Mecurialis perennis), early dog violets (Viola reichenbachianas) and wood anemones (Anemone nemorosa) in flower. Wood sorrel (Oxalis acetosella), bluebells (Hyacinthoides non-scripta), lords and ladies (Arum maculatum) and ransoms were not in flower.

The wood anemones provided the necessary photographic inspiration. and a welcome break in the cloud allowed sunshine to briefly illuminate the woodland and an image made with some warmth to finish the trip.

Both woodlands had west facing aspects, the difference in flowering between the two woods is possibly due to the ~100m height difference with marginally colder temperatures on the more exposed and elevated scowles woodland and/or the prevalence of drier and warmer soils in the Wye Valley wood on steeper slopes.

Lichens of ancient deciduous woodland

There is something compelling about native woodland where twigs, branches, and trunks are mantled with epiphytic flora. The juxtaposition of lichens, liverworts, mosses and polypody ferns creates a visual kaleidoscope of patterns and colours when walking through these unique woodlands. The complexity is not just visual but also on an ecological level where similar adjacent trees can have widely divergent epiphytic flora with one tree dominated by liverworts and mosses, whilst an adjacent tree has crustose and leafy lichens and another has mosses and leafy lichens. This apparent random distribution of species, as far as I am aware, is the exploitation by species of microhabitats determined by humidity/light levels/bark character/air pollution level etc. Whilst mosses and liverworts create their own unique primordial atmosphere in a woodland, the patina of 'hoary' lichens generates the atmosphere evocative of antiquity.

Oak woodland with a diverse assemblage of epiphytic lichens ~ Coille Dhubh,  Shieldaig Forest

Early 19th century oak plantation with a poor assemblage of epiphytic lichens ~ Nagshead Plantation, Forest of Dean.

It just so happens that some lichens are indicative of ancient old growth woodland, identified by the commendable detective work of ecological historians and a significant amount of survey work incorporating careful observations of habitats. In many areas of the British Isles, lichens of old woodland are glacially slow to colonise new woodland and this is illustrated from studies in the New Forest, where 200-300 years was sufficient time for most lichens to recolonise undisturbed woodland. Although the ancient dry bark lichen community (Lecanactidetum premneae) requires 400 years to recolonise after clear felling. The ecological impact of clear felling woodland in the 17th Century is only now being rectified.

The Revised Index of Ecological Continuity (RIEC) developed in 1976 lists 30 indicator lichens to grade the ‘ancient woodland’ interest of deciduous woodlands throughout the whole of Great Britain and Ireland :
1. Anisomeridium ranunculosporum
2. Arthonia vinosa 
3. Biatora sphaeroides (Current Taxon Name: Mycobilimbia pilularis)
4. Catinaria atropurpurea 
5. Cresponea premnea 
6. Degelia atlantica/or Degelia plumbea/or Parmeliella triptophylla 

Degelia sp. (atlantica?) and Lobaria pulmonaria on a mature Ash tree ~ Sleat, Isle of Skye

7. Dimerella lutea
8. Enterographa crassa 
9. Lecanographa lyncea 
10. Lobaria amplissima
11. Lobaria pulmonaria

Tree lungwort (Lobaria pulmonaria) ~ Coille Dhubh, NW Highhlands, Scotland

12. Lobaria scrobiculata
13. Lobaria virens

Green satin lichen (Lobaria virens) - Loch a' Mhuilinn SAC

14. Loxospora elatina
15. Nephroma laevigatum
16. Pachyphiale carneola
17. Pannaria conoplea
18. Parmotrema crinitum
19. Peltigera collina
20. Peltigera horizontalis
21. Porina leptalea
22. Punctelia reddenda
23. Pyrenula chlorospila/or Pyrenula macrospora
24. Rinodina isidioides
25. Schismatomma quercicola/or Pertusaria pupillarisv
26. Stenocybe septata
27. Sticta limbata

Sticta limbata ~ Meirionnydd Oakwoods SAC

28. Sticta fuliginosa/or Sticta sylvatica
29. Thelopsis rubella
30. Thelotrema lepadinum

A formula has been developed to rank the degree of ecological continuity of woodland from the species density of REIC lichens in a square kilometre of woodland:

• 15 or more RIEC lichens and there is "clear evidence of an ancient woodland with a long history of ecological continuity; the woodland has never been clear-felled or extensively coppiced, although trees may have been felled on a selective basis".
• 10 - 14 REIC lichens indicates there is "strong evidence of ecological continuity". 
• 6 - 9 RIEC lichens indicates there is "evidence of some degree of ecological continuity".
• 0 - 5 RIEC lichens indicates "no indication of ecological continuity; the woodland is either a plantation or has been clear felled and regenerated, or coppiced."

There are a number of caveats with the RIEC as it assumes levels of air pollution have not negatively impacted on the lichen population, was based largely on those Lobarion or Lecanactidetum communities found in the New Forest and lowland English parklands and some lichens are geographically restricted.

Screenshot of a map showing areas where each Lichen Index for Ecological Continuity for deciduous woodlands is appropriate http://www.britishlichensociety.org.uk/about-lichens/indices-ecological-continuity-woodland-epiphytic-lichen-habitats

Since 1976 further insights into lichens and their habitats has been been elucidated with indices developed to cater for regional distributions and rating the conservation value of woodland:
New Index of Ecological Continuity (NIEC)
West of Scotland Index of Ecological Continuity (WSIEC)
Eu-Oceanic Calcifuge Index of Ecological Continuity (EUOCIEC)
East of Scotland Index of Ecological Continuity (ESIEC)
West Ireland Index of Ecological Continuity (WIIEC)

Tree lungwort (Lobaria pulomaria),  Green satin lichen (Lobaria virens) and Bark barnacle lichen (Thelotrema lepadinum)  on a mature oak ~ Tower wood, Killarney National Park 

Many of my local woods in the Forest of Dean and Wye Valley are designated as ancient in origin and sadly clearly demonstrate the effects of historic air pollution AND adverse woodland management. Centred on a coalfield and downwind of the Bristol and South Wales coalfields the area has been subjected to pollution from coal burning associated sulphur dioxide emissions and 'acid' rain. The woodland management has seen extensive coppice management for charcoal and then conversion to broadleaf and evergreen plantations. The Nagshead Plantation in the Forest of Dean illustrates the slow rate of lichen recolonisation, it was clear felled and replanted with oak in the early 1800's and a Forestry Commission handbook on lichens (1989) records that the Nagshead Enclosure has no lichens indicative of old woodland and 16 other epiphytic lichens. The same handbook has a listing for old growth oak woodland with glades in the New Forest with an impressive 20 REIC lichens and 300 epiphytic lichens recorded.

Bark barnacle lichen (Thelotrema lepadinum) indicator of 'Old woodland', Speech House Oaks SSSI, Forest of Dean

Consulting the NBN Atlas indicates that the Speech House Oaks SSSI is the richest area in the Forest of Dean for REIC lichens:

• Anisomeridium ranunculosporum
• Arthonia vinosa
• Cresponea premnea
• Enterographa crassa
• Loxospora elatina
• Porina leptalea
• Schismatomma quercicola
• Stenocybe septata
• Thelotrema lepadinum

None of which are macrolichens, which means you need to get up very close with a hand lens to see any detail and then some competence to then identify them. Which is why there is only one image of the bark barnacle lichen to illustrate the Speech House Oaks SSSI REIC community. Taking an interest in the lichens at least provides an opportunity to appreciate the micro-habitats of woodland and an insight into their ecological continuity.

Shades of green

Persistent rain and almost negligible wind provided the necessary inspiration and motivation for a late spring photography trip to a scowles woodland. Whilst I have written about the benefits of rain wetted surfaces elsewhere in this blog, an additional bonus of heavy rain is the dampening effect on the surprisingly large and diverse resident population of biting insects, that would have otherwise made photography purgatory.

The tree species tally was impressive : beech (Fagus sylvatica), oak (Quercus spp.), ash (Fraxinus excelsior), cherry (Prunus avium), rowan (Sorbus aucuparia), wych elm (Ulmus glabra), holly (Ilex aquifolium), yew (Taxus baccata, field maple (Acer campestre), hazel (Corylus avellana),  hawthorn (Crataegus spp), birch ((Betula spp.), large leaved lime (Tilia platyphyllos), small leaved lime (Tilia cordata) and wild service (Sorbus torminalis). Some trees were derelict coppice stools of considerable girth indicative of a long life span.

Having exhausted my supply of dry micro fibre towels, I made my way back to the car and chanced upon a Greater Butterfly Orchid, the first I have ever seen in a woodland and the end to a satisfying outing.

A Pembrokeshire bluebell wood

A weekend away in Pembrokeshire to catch up with friends and it is reasonable to suggest that the date was timed to coincide with the display of bluebells in Coed Tŷ Canol National Nature Reserve. I had last visited the Tŷ Canol woodlands at the end of March 2015  and this was my first visit in the month of May. Saturday dawned to a forecast of high wind and clear skies, sigh, nevertheless I had time for a recce to Tŷ Canol and ascertained that the woods were as atmospheric as ever, most of the sessile oaks were in leaf and bluebells were in flower, the harsh lighting and wind meant any meaningful photography was limited to recording the ground flora.

Enchanters nightshade, wood sorrel, hard fern, buckler fern and  bluebells.

On Sunday I persuaded Nic that we should visit Tŷ Canol on the journey home, coincidentally the weather was more photographically promising with lighter winds, showers, over head cloud with breaks for sunshine. The weather was amenable to making images of woodland in contrasting lighting with the quiet light of overhead cloud and intermittent sunshine allowing sunlit dappled woodland.

A far better appreciation and insight was gained into the habitats within Tŷ Canol with flora in leaf/flower denoting associations with deep shade, water logged ground, flushes and dry soils. The lichen and bryophyte communities for which Tŷ Canol is renowned for were once again pondered and once again a mental note made to make the effort to investigate these further. Nic summed up Tŷ Canol  perfectly in describing it as a 'special place' and 'nourishment for the soul'.

Asturias trip report - 2

Next up on the itinerary was a stay at the Hotel rural Los Riegos in the Redes Natural Park run by two biologists : Sergio and Paloma. Their knowledge, guidance and insight was invaluable, which meant we undertook some excursions that otherwise would have been overlooked and consequently we extended our stay from 2 to 4 nights. After unpacking there was time for a late afternoon excursion and enquiring about a suitable walk in old woodland with spring flowers, Paloma recommended one and provided a map.

Veteran beech pollards

The walk was along old trackways in places lined with beech pollards, through predominantly beech woodland. The size of some pollards and coppice stools indicated a great age to the trees and a long history of woodland management. Natural regeneration was evident with a mix of age ranges of saplings to young trees and in places dead wood was being conserved as a habitat resource, the woodlands appeared to be managed for conservation too.

Beech woodland

The trees provided a habitat for communities of bryophytes and lichens, that might interest a specialist.

Some of the woodland flora was familiar from the UK.

Wood Sorrel (Oxalis acetosella)

Whilst other flora was not so familiar and Dog's tooth violets once again put in an appearance.

Hollow-root is classified as a neophyte in the UK.

Hollow-root (Corydalis cava )

It was a surprise to stumble upon St Patrick's Cabbage in a beech wood ~1,200 metres asl, the first indication was a group of emerging plants and then an actual specimen ready to flower. St Patrick's cabbage is part of the Lusitanian flora an enigma in plant distribution.

St Patrick's cabbage (Saxifraga spathularis)

St Patrick's cabbage (Saxifraga spathularis)

It was a good interesting walk and did not require a huge amount of imagination to see the potential for Autumnal colour.

The next day a walk was selected for its geology, geomorphology and scenery, starting from Caleao to the Desfiladero de los Arrudos.  Surrounding Caleao are a patchwork of small fields that appeared to be farmed in a traditional manner, some fields were being manured.

A landscape of traditional small scale farming

A trackway of some age.

View over farmland to the outer gorge cutting through limestone/dolostone lithologies

Downstream of the gorge is an extensive alluvial fan of boulders, many imbricated and deposited when the stream capacity of the palaeo-Arrudos dropped exiting the gorge. The size of the boulders indicate an event(s) where extremely high volumes of water flowed through the gorge. The boulder deposit had subsequently been colonised by woodland with many trees pollarded or coppiced.

One interesting flower was Angel's Tears, a native daffodil whose distribution seemed to be intimately associated with the underlying bedrock geology.

Angel's Tears (Narcissus triandrus)

In the main gorge there was compelling evidence for comparatively recent rock fall debris free from mosses, overlaying older rock fall debris colonised by mosses.

Rock fall debris chronology

The main gorge is formed from the Arrudos cutting down through steeply inclined beds of sedimentary rocks, predominantly almost pure quartz sandstones with occasional beds of shale. The depth of the gorge and the contrast between the gorge sides with ragged outcropping beds on one side and 'smooth' bedding plane surfaces on the other, is dramatic and visually impressive.

Desfiladero de los Arrudos - highly inclined bedding planes

Desfiladero de los Arduous

Outcrop of intensely fractured quartz sandstone - possibly associated with a fault/thrust plane?

The excursion up into the Desfiladero de los Arduous was good and it was another location that would be best visited in the Autumn.