Sunday, November 28, 2010

Architecture in the Snow

A snowfall has a wonderful tendency to turn pieces of natural architecture into something magical....

... and to sprinkle a bit of magic over man-made architecture.

Hogweed stems
Durham Cathedral from Observatory Hill
Lunchtime today

Thursday, November 25, 2010

A Walk in the Bishop's Park

Today's Guardian Country Diary describes a visit to the Bishop of Durham's deer park at Bishop Auckland. The bishops have lived in Auckland Castle for over 800 years and for much of that time the park provided resources like venision and timber, but now it's simply a beautiful and tranquil place to visit at any time of the year, but especially so in autumn. It's just five minutes walk from the busy centre of the market town of Bishop Auckland.....and a much-loved natural resource for all who live in the area.
The River Gaunless flows through the park and would have been a source of fish for earlier generations of clergy who lived here, but now its home to kingfishers (that occasionally breed here) and dippers. When I first visited, 35 years ago, there were water voles here too, that I used to tempt out of their bank-side burrows with apple cores, but they are long gone, sadly.

Bishop Trevor's bridge spans the Gaunless and if you're lucky you can sometimes catch a glimpse here of a kingfisher flashing past underneath.

The park is famous for its mid-18th. century Gothic Revival deer house, where clerics could picnic...

...and where the deer herd was fed and could shelter from severe North-Eastern winters.
Originally the arcades around the outside would have been roofed over - you can see the sloping roof line on the end wall in this photograph.
The cloister arches provide a frame for some of the park's magnificent trees, including the beeches on the steep bank of the Gaunless, where landslips have pitched some trees into the river in recent years.
The ancient trees are one of the park's finest features. This is a magnificent sweet chestnut, whose stout bole seems to be melting into the soil under its own weight ...

... and this is one of several decaying sweet chestnuts that have been on their 'last legs' for the thirty-odd years that I've been coming here, and will probably still be producing new shoots long after I'm gone.

As Oliver Rackham, the noted authority on woodlands once observed, there's only one thing more useful than a live tree and that's a dead tree. Old beeches like this have been slowing crumbling away for decades as bracket fungi digest them, and provide a home for all sorts of beetles and sundry insects that in turn attract woodpeckers - of which there are many (green and greater-spotted) in the park.
I haven't identified these toadstools yet, but there was a perfect ring of them around an old hawthorn earlier this month and...

... these Russula atropurpurea appear every autumn under a magnificent Scots pine....
... while oyster mushrooms Pleurotus ostreatus favour the decaying beeches

With so many different trees here, the autumn colour is spectacular: this is hawthorn, with elm in the background ...

... and this is Scots pine and European larch, evergreen and deciduous conifers respectively.

From the highest point in the park the view over the tree canopies is magnificent and the view...
... across to the west takes in the Newton Cap viaduct, which once carried stream trains (what a magnificent sight that must have been!) but now carries a road. The River Wear flows underneath the arches.
These are the homes of the Bishop's other parishioners. There are well over 200 of these hemispherical meadow ant nests on the south facing slopes of the parkt - so many that this ant metropolis is easily visible on Google satellite maps. At a very conservative estimate, I'd say that somewhere around one million ants live here in summer and you can almost always find green woodpeckers visiting these mounds for a meal.

There has been alarming news recently that the Church Commissioners are contemplating the sale of Auckland Castle (the Bishop's palatial residence) and with it the park. Understandably, this has raised great public concern about future access to the park and the fate of its trees and wildlife. The idea of the palace and park being acquired by, perhaps, some hotel chain or multinational corporation that would restrict access and - God forbid - 'tidy-up' the park and its venerable trees is too depressing to contemplate.

For further Guardian Country Diary posts click here

Sunday, November 21, 2010

A Tree-Spotter's Guide to Bark: Part 4

The success of London plane Planatus x hispanica as a street tree owes a lot to its propensity to slough off flakes of bark frequently, shedding pollutants along with it - and leaving an attractive abstract pattern of pastel coloured patches.

Marooned in a sea of of concrete and asphalt and assailed by exhaust fumes; it's a small miracle that plane trees like this not only survive but thrive in the urban jungle.
On a sunny day, it's pretty obvious how redwoods got their name. This is the giant sequoia Sequoiadendron giganteum, a species that was introduced into Britain in 1853. The bark is incredibly thick, soft and fibrous and, it is said, has been adopted as a roosting site by treecreepers that hollow out small depressions where they spend the night. Where did treecreepers roost before 1853, I wonder? The tree is sometimes known as Wellingtonia, named after the Duke of Wellington who died the year before it was introduced, but attempts to formalise this name as Wellingtonia gigantea - an act of imperialistic arrogance - upset the Americans. It was, after all, their tree so they countered with the name Washingtonia, to commemorate their national hero.... but there was already a palm species with the same name. Thankfully, it turned out that it was a cousin of the coast redwood Sequoia sempervirens and so could also be called Sequoia, circumventing any further taxonomic squabbling. It became Sequoiadendron in 1939, when detailed examination revealed that it was sufficiently distinct to be placed in a genus of its own. 

Horse chestnut Aesculus hippocastanum becomes flaky with age but isn't easily shed - so it often acquires a veneer of green algae on the northern, shady side of the trunk.
Elder Sambucus nigra rarely lives long enough to develop tree proportions but when it does the deeply fissured corky bark can be very attractive.
When common hawthorn Crataegus monogyna grows as a tree, rather than as a regularly cut hedgerow shrub, it tends to branch from low down from an early age and this produces a trunk that resembles vertical branches welded together - which is what they are, I suppose.

For more information on tree identification click here

Friday, November 19, 2010


I found this exquisite little purple toadstool on my lunchtime walk in Durham today, growing beside the footpath near Blaid's Wood to the south of the city. I'm pretty sure it's a violet webcap Cortinarius violaceus (unless anyone out there knows better???). Without doubt the most intensely purple pigmented toadstool I've ever seen. It doesn't have much of a 'web' but what remains of it is the white patch on the flank of the cap and the wispy white threads around its rim.

For pictures of fungi on this blog click here

Thursday, November 18, 2010

A Tree-Spotter's Guide to Fruits and Seeds: Part 7

I've always been partial to pickled walnuts and the key thing to remember if you are going to pickle them is to time the harvest just right, before the coat of the developing seed inside begins to become woody, which you can test by pushing in a long needle. The soft outer fruit wall produces a black dye (which is why pickled walnuts are black) and after you've harvested them your hands go black too - it can take a couple of days for the dye to fade from your skin.

These are sitka spruce Picea sitchensis cones, which are often at the top of the tree and out of camera range, but this tree was growing on a cliff ledge and the cones were at eye level from the top of the cliff. Like so many conifers, sitka spruces are attractive trees when they are given space to develop their natural shape but all too often they are only seen crowded into dense commercial plantations. The tree a native of the west coast of North America, from Alaska to Northern California.

In comparsion to sitka spruce, the 4 cm.-long cones of giant redwood Sequoiadendron giganteum are diminutive and the seeds are minute - only about three millimetres across, including their papery wing - which is remarkable when you consider that the tree that they produce grows to a height of 100 metres and lives for over 3000 years.

The cones may be small but they do have an interesting pattern on the end of their scales........

... and are quite decorative when they ripen.

A familiar sight on the streets of the capital in winter - leafless branches of London plane Platanus x hispanica decorated with the dangling, ball-shaped fruits that break up to release small hairy seeds. The tree's only real link with London is that it's the commonest street tree there - it's actually a hybrid between Oriental plane Platanus orientalis from eastern Europe and north west Asia and the American plane (aka American sycamore) P. occidentalis. In nature the parents of the hybrid are separated by the Atlantic Ocean but they hybidised when they were grown together in Europe (possibly first in Spain - hence hispanica). The offspring of the union is a vigorous and pollution tolerant urban tree that rarely seems to be planted in the countryside.

For more on tree identification click here

Sunday, November 14, 2010

A Tree-Spotter's Guide to Bark: Part 3

Few trees reveal the way in which patterns in bark are formed as clearly as the white poplar Populus alba. It's upper branches are clad in smooth pale grey bark, but mid-way down the tree it develops a series of splits, as though the tree has been attacked with a pick, where the bark begins to split under the strain of the swelling circumference of wood underneath. Here and there (towards the right of this photo, for example) you can see places where the splits begin to join up, to form fisssues until...

... near the base of a tree of medium age - perhaps 40 years old - the bole of the tree is covered in fissured bark, with those pick-marks barely visible on raised patches of smoother bark. As the trees age and approach the end of their lives....

...the fissures become deeper and the wonderfully textured character of the bark becomes apparent.

The bark of a mature sweet chestnut Castanea sativa bears this very distinctive pattern of branching and rejoining ridges. In many old trees the whole trunk appears to be twisted, so the pattern spirals up the trunk. 

Auckland Park in Bishop Auckland, County Durham, is home to several magnificient old sweet chestnuts with elephantine boles .....

... including this one which sits on a pediment of roots that seem to melt into the soil.

For more information in tree identification click here

Tuesday, November 9, 2010

Shaggy Scalycap

It has been a wonderful autumn for fungal forays around here. We found this fine cluster of shaggy scalycaps Pholiota squarrosa growing around the base of a moribund beech tree in the Bishop's Park in Bishop Auckland on Sunday.

The scales that cover the cap and stipe of this species are distinctive. It is supposed to taste of radishes. I'm content to take the field guide's word for that - it's not edible.

Sunday, November 7, 2010

Last survivors

Despite the fact that we've had several frosts, there are still some wasps around, congregating on the flowers of ivy that provide a last chance for them to find nectar.

I found this wasp, which I think is a tree wasp Vespula sylvestris, crawling over the ivy flowers just as the rising sun melted the frost on the grass.

The dense covering of hairs on the wasp's body must provide some insulation against low temperatures, and it probably spent the night under the glossy, waterproof leaves of the ivy plant, which provides an overwintering site for all manner of invertebrates.

For more on the curious back-to-front life cycle of ivy, flowering in autumn and producing fruits in spring, click here.

Saturday, November 6, 2010

A Tree-Spotter's Guide to Bark: Part 2

The grey-brown bark of alder Alnus glutinosa isn't particular distinctive - unlike the wood within. Freshly-felled alder wood turns a startling shade of red, although this quickly oxidises to a pinkish-brown. Understandably, the blood-like shade of the cut timber gave rise to many superstitions but didn't stop the coppicing of the tree for the production of high quality charcoal for gunpowder. Alder wood lasts exceptionally well if it's kept permanently wet or submerged - not surprising really, considering the tree's propensity for growing on riverbanks that frequently flood - and it was sometimes used for piles in bridge construction and also for the soles of clogs.

Wild cherry or gean Prunus avium bark is easily recognised by the long horizontal scars (lenticels) that run across the trunk. These are areas of porous bark that allow gas exchange for the living tissues below that generate new wood each year. Cherry bark also has a tendency to peel away in narrow strips around the circumference of the tree.

From a distance silver birch Betula pendula bark is dazzling white when it catches the sunlight, but a closer look reveals subtle shades of pink, orange and brown showing through from the bark tissues just below the surface. At this stage in the tree's life the birch bark peels away, sometimes in large sheets, as the diameter of the trunk expands (and so is ideal for birch-bark canoes) but as the tree ages....

-- the bark splits vertically, separating the white bark into flakey patches between deep fissures.

For more information on tree identification click here