Tag Archives: Fraxinus excelsior

Local Histon Lichens

A closer look at the trees and branches, live and otherwise, in my local meadow which I posted about recently, revealed large quantities of lichen. I’d seen it there before but never really paid it sufficient attention so a couple of weekends ago I decided to rectify this shabby state of affairs.

To my highly untrained eye there didn’t seem to be more than 4-5 species but the ones that were there were present in abundance. There are four basic  morphologies of lichens: they are crustose – the flat ones which form very thin layers, foliose – form leaf like structures but where the leaves lie flat and don’t protrude far from the surface of the substrate, fruticose – have longer branched structures and can look like small shrubs and lastly squamulose –  have horizontal, scaly, overlapping lobes and look rather like some fungi I’ve seen growing on dead wood.


A grey/green crustose species and a fruticose species, the yellow one.

Lichens can be extremely sensitive to pollutants, and as a rule of thumb the foliose species are generally more sensitive and are only found in places where the environment is clean and free of fumes and other chemical pollutants. Consequently the species I find in my local patch, being close to a big town, are of the crustose and fruticose varieties. Sensitivity to pollutants can cut both ways though, those susceptible to acid pollution will obviously suffer in a low pH environment, but others which have a high demand for nitrogen can really benefit from pollution by agricultural fertilisers.

The ones I found were all growing on the surface of live deciduous trees and dead branches and the trees in the meadow are predominantly ash and oak. I’m not going to try to identify the different species here because I don’t have the requisite expert knowledge to unambiguously name lichens, but I plan to do some reading and observing and I’ll post again if I find out what they are. Even though I don’t know the species I think their colours and structures render them particularly photogenic.

The ‘thallus‘ (main body) of the yellow lichen above has the leafy structures of a fruticose species surrounding round saucer shaped structures which are called ‘apothecia‘ and are the reproductive machinery of this lichen. Within the apothecia are tiny structures called ‘paraphyses‘ and these surround the ‘asci‘ from which the fungal spores are generated. Masses of this yellow species covered many trees and fallen branches in the meadow.


Another fruticose lichen which has the leafy structures but no reproductive apothecia – I’m assuming it’s another species and not a different stage in the life cycle of the yellow one


The grey/green species here is definitely a different one. It has some erect leafy and spiky parts and it appears to have apothecia which are more cup shaped

The fungal spores produced from the asci are microspcopic and dispersed on the wind and it is a matter of conjecture how they manage to settle on the requisite species of alga to form a new lichen.

Some species can reproduce both the fungal and the algal part simultaneously by growing structures called ‘lobules‘ or ‘isidia‘ which basically consist of outgrowths of the thallus of crustose or foliose lichens which break off and are dispersed by wind and water. Or there are structures calles ‘soredia‘ which are algal cells enmeshed in a bundle of fungal ‘hyphae‘ (threadlike structures of fungal cells) which are similar to the middle part of the body, the ‘medulla‘.

If anyone out there knows the names of these lichens or has any other snippets of lichen related information please leave a comment as I’d be very interested to hear them.

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Crystallised countryside

After the snow at the beginning of February, last weekend the temperatures in this part of the world plummeted to a wintry -12C creating a cold crystalline landscape.

So here are some pictures from the frost bound south Cambridgeshire countryside:

Ash saplings and brambles festooned with ice crystals on the shaded north side. The sun had already stripped the south side bare of frost

It was still early in the morning so the sun was low in the sky and created ghostly scintillations as it reflected from showers of dancing frost crystals dislodged by wafts of icy breeze.

As I walked my footsteps made loud cracking and crunching sounds but when I stood still it was completely silent. No cars, no birdsong, just the sound of the breeze. It was absolutely beautiful.

The rays of the sun couldn’t reach the grass stems so they remained coated with crystals through the day

Giant burdock

The burrs of the burdock (Arctium lappa) normally provide seeds for goldfinches to feast on but today they were twice their normal size and weighed down by a thick coating of frost.

Where have all the birds gone?

There are virtually no birds in my garden at the moment, and they have been conspicuous by their absence all through the autumn. This appears to be a more widely observed phenomenon as reported on BBC’s Countryfile, and the RSPB have been seeking to reassure people who are concerned by the apparent dearth of birdlife visiting their gardens that it’s simply due to the abundance of suitable food still accessible in the countryside, and whenever possible that’s where the birds prefer to be.

I can vouch for the disappearance of the small birds from gardens. Apart from the occasional blackbird and blue tit  (and a jay last week – the first one I’ve ever seen in my garden!) very few birds are availing themselves of my feeders. If this is happening in your garden the best thing to do is to keep your feeders clean and put a small amount of feed in so any passing birds recognise your garden as a source of food and can stop to refill if they need to. But it looks as thought the cold weather is starting to arrive here in Cambridgeshire so garden bird numbers may well increase in the near future.

So last weekend I ventured to the fields on the edge of Histon to see if they are still in residence. The hedges and fields were well populated with goldfinch (Carduelis carduelis, Dansk: stillits) and chaffinch (Fringilla coelebs, Dansk: bogfinke), great tit (Parus major, Dansk: musvit) and long tailed tit (Aegithalos caudatus, Dansk: halemejse) and green woodpeckers were abundant too. I don’t know if the numbers of green woodpecker (Picus viridis, Dansk: grønspætte) I see are representative of national trends but they seem to be numerous here in Histon, also where I work on Cambridge Science Park and today I was at the RSPB reserve at Fen Drayton near St Ives and there were good numbers there too. Two birds that I haven’t seen recently in the numbers I’d expect are dunnock and greenfinch – I hope that’s because they’re out in the countryside and it doesn’t reflect a decline in overall numbers.

I talked in my post a couple of weeks ago, Forests and Fungi, about how I’ve been inspired to look for other ways of photographing nature rather than simply taking traditional portrait shots. Rowleys Meadow which is on the edge of Histon, has mature ash trees (Fraxinus excelsior) on the periphery which are laden with ash keys and as a result there are thousands of young ash saplings:


Brown grass stems merge with the taller, thicker, silver stems of the ash saplings

And this presented a good opportunity to capture some abstract nature images. I like the way the low, bright sunlight creates a vertical pattern of silver and shadow as it illuminates hundreds of young ash trees

Back to birds, as well as our regular winter residents migrants from Scandinavia are much in evidence, redwing (Turdus iliacus, Dansk: vindrossel), and fieldfare (Turdus pilaris, Dansk: sjagger):


A lone fieldfare perched in a tree after gorging on a blackthorn bush laden with sloe berries

Small flocks of fieldfare can be seen and heard making there distinctive and diagnostic call, and the flocks will get bigger if the weather does turn wintry. Last winter, which was brutally cold here and in Scandinavia, huge numbers of waxwing (Bombycilla garrulus, Dansk: silkehale) arrived in the UK from Norway, but due to the much warmer weather I don’t think we’ll see them here in quite such abundance this year, which is a real shame because they are indeed spectacular:


Waxwing – it’s around the size of a starling and the colours are amazing

Histon has a resident rook colony (Corvus frugilegus, Dansk: sibirisk allike) who have their rookery in the tall trees adjacent to the church and are a constant source of aerial entertainment. They were feeding in a field along Guns Lane, which runs from Histon to Ely, as I wandered along it and this one took exception to my presence and flew over squawking at me as it went,

I took the hint and moved on, heading home. But a little further along Guns Lane I paused when I heard the quiet and delicate song of a flock of long tailed tits. So I stood still and they went about their routine in trees about 10m away. I really like these diminutive, gregarious, birds and I love trying to photograph them, which can be challenging as they are very small and they never settle in any one place for very long. But I managed to get this series of shots which I’m rather pleased with:

Even though the weather is pleasantly mild at the moment, I prefer winter when it’s cold, so I’m hoping it will start to behave as it should and these delightful little birds come back to feed in my garden!

9th January birdwalk

The weather on the 9th was dominated by two features: bright warm sunshine and a biting northerly wind. They were combining to make some brisk but very pleasant walking weather so I spent the morning exploring Guns Lane and fields north of Histon. Rowleys Meadow was very quiet, apart from the occasional blue tit (Cyanistes caerulius) or wood pigeon (Columba palumbus) and numerous unidentified gulls gliding over. Unusually, the only interesting sightings were a song thrush (Turdus philomelus), a pair of magpie (Pica pica) and a flock of hundreds of fieldfare (Turdus pilaris) which drifted over the field east of the Meadow – none of which were close enough to photograph.

Not long after emerging from the Meadow and turning  north up Guns Lane the situation changed dramatically and the hedges were full of birdlife.  Blue tit and great tit (Parus major) were busy looking for food and a pair of bullfinch (Pyrrhula pyrrhula) emerged from the hedge heading northward just as a small flock of approximately 15 fieldfare descended into a tree  in front of me, remaining in situ until I was directly underneath, in pole position for some photographs:

A pair of fieldfare, and…

…a single one

Shortly after taking these pictures and moving on, a second pair of bullfinch rose  out of the hedge. They may have been the same ones as earlier, but I’ve seen bullfinch here on numerous occasions lately so I’m hoping there are more than one pair in residence.

Having turned off the Lane and walked along the south side of a mature hedge containing some big old oak (Quercus robur) and ash (Fraxinus excelsior)  trees, I was admiring the perfect symmetry of a woodpecker hole around 5m up an oak tree when I noticed an insect emerge from it. It turned out to be a honeybee (Apis mellifera):


A lone honeybee entering a woodpecker hole casting its shadow on the threshold

And several more toing and froing in the sunshine. I love the texture and colours of this gnarled old oak tree

I was surprised to see so much honeybee activity on a freezing cold January morning. The south facing hedgerow was sheltered from the wind and  I think the bright sunshine had warmed up the tree sufficiently to waken the bees from their winter slumber. I was hoping they had sufficient stocks of honey to fuel them through their brief awakening before the cold forced them back into hibernation.

I carried on around the field looping back to Cottenham Road in Histon. The terrain on this route included alot of grassy scrub with patches of brambles and other low arboreal scrub consisting predominantly of hawthorn. A green woodpecker (Picus viridis) rose out the grass and dipped over the field to take cover in a tree and a group of five yellowhammer (Emberiza citrinella), which had been feeding on the ground, rose up and headed into another old oak tree which I’d passed by a couple of hundred metres back.  As I about-turned to try to get a photo they upped sticks and returned to their original location on the ground where, where their amazing camouflage rendered them completely invisible even from a distance of about 5m, As I approached so close they again flew into the same old tree and as their place on the ground and the tree were a fair distance apart I  decided not to disturb them again.

The landscape here looked as though it will be rich with birdlife in the Spring and Autumn so I’ll hopefully report more sightings as the year progresses