Do they know it’s winter?

It’s nearly December and I find myself back at Low Barns running a couple of winter tree  identification sessions. We’ve run these before and each time we change things a little, but everything revolves around a quiz and a walk around the reserve, and they are always good fun. We start with an indoor session talking about … Continue reading “Do they know it’s winter?”

It’s nearly December and I find myself back at Low Barns running a couple of winter tree  identification sessions. We’ve run these before and each time we change things a little, but everything revolves around a quiz and a walk around the reserve, and they are always good fun.

We start with an indoor session talking about the basic features useful for identifying trees in winter, then look at a bunch of samples, drink lots of tea, then go hunting…

Around the reserve there will be found lots of tagged trees; lots of numbers that have to be matched to the quiz. Although the theme was identifying trees in winter I no longer worry about concentrating entirely on winter features. There’s little point in being skilled at identifying a tree on buds alone if there are no buds to be found. In an arboretum, or park, the lower branches of many trees are raised and buds may not be accessible. You need to work with the material available to you: are there any leaves, dead or otherwise, still on the tree? In mild winters there often is, and oaks often obligingly hang on to their leaves deep into winter, which is very handy for distinguishing Sessile and English oak.

Common Alder
a single defiant Alder leaf clings on into winter

Another good clue is to look down. Sweet Chestnut, especially mature old trees, often have a fantastically expressive fissured bark. Combine that with the distinctive buds sitting on little shelves on the stout twigs, and it’s a straightforward id. The Sweet Chestnuts at Low Barns don’t tick any of these boxes. It seems to think it’s a hazel and sprawls haphazardly through the understory with a non-descript bark and hard-to-find buds. It does, however, carpet the ground with a dense layer of distinctive leaves making confirmation of the id easy.

Low Barns has a lot of ash trees (Fraxinus excelsior), at least, for the time being. With Ash Dieback being in the news it was a topic of some discussion. The obvious parallel is with Dutch Elm Disease. But with the Taxonomy of English Elm (Ulmus procera) still unclear and the possibility that many if not all English Elms were genetically identical, it remains to be seen whether a similar fate awaits the Common Ash. A prolific self-seeder, perhaps Ash has enough genetic diversity somewhere in its distribution to cope with the attack. If large numbers of ash succumb to the disease we shall see some big changes in our woodland. Lots of standing dead timber, a fantastic habitat, and lots of light hitting the woodland floor. Interesting times ahead.

 

identifying trees in winter

I couldn’t say how many times I’ve driven along the Lanchester Road or run along the railway lines from Broompark without realising that just a short distance away lay Witton Dene. It’s one of the great attractions of County Durham that all over the region there are hidden pockets of tranquillity such as this just … Continue reading “identifying trees in winter”

Footpath to road
Footpath up to road from Witton Dene

I couldn’t say how many times I’ve driven along the Lanchester Road or run along the railway lines from Broompark without realising that just a short distance away lay Witton Dene. It’s one of the great attractions of County Durham that all over the region there are hidden pockets of tranquillity such as this just waiting to be discovered.

Fran Mudd from the Wild Woods Project had invited me to run a winter tree identification session for the Friends of Witton Dene. These can be a lot of fun. Since identifying trees in winter relies a lot on twigs and buds, a good approach is to collect bundles of samples from the area, mix them up with a bunch of photographs, take them somewhere warm and dry, ideally with tea, coffee and an inexhaustible supply of jaffa cakes, then encourage everyone to have a look at them in comfort.

Once the key features have been identified the new-found knowledge can be tested by heading outdoors and matching the samples to the trees. Some trees are easy to identify, and some aren’t. Some, like ash, can be easier to identify in winter than they are in summer as they have large, distinctive, sooty, ominous looking black buds in opposite pairs. They tend to be less conspicuous when the tree is in leaf.

black buds, opposite pairs
The unmistakable black buds of Common Ash

After our indoor session concentrating on the common species and their key features we headed outside for a wander and a quiz. It was a great morning but not without its puzzles.

There was a question about Horse Chestnut. Not the usual question about how it got its name, but more about how it got its buds. Its sticky buds. Horse Chestnut (Aesculus hippocastanum) has large reddish-brown sticky buds in opposite pairs. They are particularly noticeable over winter. So why are they sticky? Good question. I didn’t know the answer and used the response I heard Chris Packham use in his talk at the Gala theatre a few weeks earlier. He’d been asked about a housemartin with hairy legs. Why did it have hairy legs? Who could say, but there would be a reason. It’s expensive to make a leg hairy, or a bud sticky, and an animal or tree won’t do it without a good reason.

Hunting around, with assistance of the University of Google, was surprisingly fruitless. The question has been asked before and the hypothesis advanced usually involves predation; the tree protects itself from insects by trapping the insect on the sticky bud. It’s observable sure enough but doesn’t explain why lots of other trees manage to happily get through life without sticky buds. I’m sure there’s a reason, I just haven’t found it yet.

reddish buds on a sycamore
sun-ripened buds on a sycamore? Why are these buds not green?

The other puzzle I stumbled up on was the mysterious case of the sycamore with the reddish buds. During a visit in January I found a sycamore that had read the script and knew all the identification features it was supposed to have, except it decided to tint its southerly facing buds with a pinkish tint. This is common in Lime trees where the buds exposed to sun often have a reddish glow where the shaded side remain green. But I haven’t seen it in sycamore before. The north-south facing divide in the colour is so marked that it’s the only reason I can think for the difference.

The bleak midwinter will soon give way to spring and I shall nip back to Witton Dene sometime soon and quietly check my own answers, and see if there are any tree species I missed. Surely there’s some blackthorn hiding away in there …

The sickly katsuras, two months later

Time passes and I revisit the katsura trees. Thank you to David and Nadia for their comments about the similar sounding symptoms they’ve had. I’m none the wiser, sadly! According to Strouts & Winter frost damage from late or spring frosts can account for problems particularly on thin, vulnerable stems. That would fit, I suppose, … Continue reading “The sickly katsuras, two months later”

Time passes and I revisit the katsura trees. Thank you to David and Nadia for their comments about the similar sounding symptoms they’ve had. I’m none the wiser, sadly! According to Strouts & Winter frost damage from late or spring frosts can account for problems particularly on thin, vulnerable stems. That would fit, I suppose, except only one of my sapling katsuras was affected, the other, almost identical one, seems unaffected.

The only other katsura trees I know about locally are at Houghall Arboretum and Durham Botanic Gardens. I haven’t visited the botanic garden recently but the Houghall trees look fine.

But a closer examination of my own sickly katsura held a surprise. Scratching the bark in several places with my fingernail showed a bright green sapwood underneath. Next spring should be interesting.

I’ve uploaded some fairly large images (click on the thumbnails below) of the living and (apparently not so) dead trees.

 

The Katsura Tree

As the title of this blog might suggest, I have a particular fondness for the Katsura tree (Cercidiphyllum japonicum). I have three in the garden, all youngsters. One is getting on for 2 or 3 metres tall, has been in for a few years (planted Nov 2007), and is looking good. Around the corner in … Continue reading “The Katsura Tree”

As the title of this blog might suggest, I have a particular fondness for the Katsura tree (Cercidiphyllum japonicum). I have three in the garden, all youngsters. One is getting on for 2 or 3 metres tall, has been in for a few years (planted Nov 2007), and is looking good.

Cercidiphyllum japonicum
Healthy tree

Around the corner in the front garden there are a couple of tiny trees that I snapped up for a fiver each from Dawyck a couple of years ago. They are about 3 or 4 metres apart and have been absolutely fine since the day they were put in. I occasionally mulch with grass clippings or clear encroaching roses or beech from them, but all, in all, they’ve seemed happy.

But something has happened recently. The one on the right (click for a bigger picture) looks pretty healthy. Not a big tree but happy enough.

 

And then I walk about 3 metres along the flower bed to the next one. And it doesn’t look well at all.

Cercidiphyllum japonicum
Not a healthy tree

The mush you can see around the base is old grass clippings (no fertiliser, or weed and feed), and it is kept away from the base of the sapling. Same for the healthy one.

A closer look at the leaves shows them brown and mostly dead.

So, what is wrong with this picture? Why is one alive and apparently healthy, and one is dead, or nearly so? They are only a few metres apart and have no visible differences in light, soil or moisture.