Woodland Watch – Week 20 – 31/07/2013

Well, another week, another walk in the woods and I can’t believe that we’re seeing signs of autumn emerging already. It seems like only yesterday I was walking through the woods with thick frost underfoot and no signs of growth, then we came through the spring and everything slowly started to emerge and grow, heading into a massive growth spurt in late spring and early summer. Where does the time go?!

So, the first sign of autumn approaching emerged before I even entered the woodland. On my way to the wood I passed a young horse chestnut tree (Aesculus hippocastanum). The horse chestnut is a broadleaf, deciduous tree, commonly found in the British landscape but actually non-native to the British Isles. The familiar Aesculus hippocastanum is a native of the Balkans, and believed to have been introduced to Britain in the 1500s.

The species doesn’t make up a significant component of British woodlands except in a select few cases in Britain. Mainly found along strees and in parks and gardens, there are horse chestnuts to be found dotted as individual trees, either planted or self seeded, in many woodland areas. In this wood, there are several large, mature horse chestnut trees growing towards the south of the site.

Undoubtedly the most exciting thing about the horse chestnut, especially for children is its seed, known more commonly as conkers and you can start to see the developing conkers inside their green spiny shells on the trees right now.

Developing conkers

Developing conkers

The horse chestnut has become naturalised in the UK and many people would think of it as a native British tree. The wood tends to be rather weak, so has never been widely used for timber or wood products, although its absorbent properties do make it ideal for fruit racks and storage trays as it keeps the fruit dry, preventing rotting. Extracts from the leaves including aescin or aesculin are marketed as herbal remedies because of their anti-inflammatory properties and the trees also have wildlife value with the nuts providing food for deer and other mammals and the flowers providing pollen for insects.

From personal experience I can also recommend using the leaves if you’re caught camping or wild cooking without washing up facilities. The leaves provide a useful lather for scrubbing dirty plates which has helped me on many occasions after a wild cooked meal!

Unfortunately, more recently, horse chestnuts have been a cause for concern as people have watched the leaves turn brown long before autumn. As tree surgeons we have lost count of the number of conversations we have had with people asking what they can do about their “declining” horse chestnut trees.

Rather than re-inventing the wheel here, i’ll point you to a very good Forest Research article about the leaf miner which is affecting horse chestnut trees:

http://www.forestry.gov.uk/fr/infd-68jjrc

The trees in the woodland have not escaped this pest and are showing clear signs of infestation with the leaves starting to turn brown. Larvae of C. ohridella mine within the leaves of horse chestnut, and the damage caused by large numbers of larvae can be striking. Up to 700 leaf mines have been recorded on a single leaf under favourable conditions. Severely damaged leaves shrivel and turn brown by late summer and fall early, well before normal leaf fall in the autumn.

Signs of leaf miner infestation on horse chestnut leaves

Signs of leaf miner infestation on horse chestnut leaves

Now, on to a happier note and from childhood games we move on to hedgerow fruits! Autumn is a wonderful time of year for foraging in the woodlands and I can remember many happy childhood days collecting blackberries and sloes with my family and friends. Although we’re not into autumn yet and I certainly wouldn’t want to wish the remaining summer days away, the hedgerows are starting to burst with early signs of food production.

A common hedgerow tree which we have looked at earlier in the season is the elder. The flowers have now gone and turned to young berries, clearly visible in the hedgerows, still green and yet to ripen but promising a good crop in the autumn.

Elderberries starting to develop ready for autumn

Elderberries starting to develop ready for autumn

From elderberry liqueur to elderberry jelly, there are a great variety of things to do with this wonderful fruit. Mixing it with sweeter fruits like blackberries and making into autumn pies and crumbles brings back wonderful childhood memories! I’ll keep you posted on recipes over the autumn!

Now then, on to something a bit more scientific…Although there’s a lot of science in making elderberry liqueur! Last week we looked at the spores developing on the ferns around the woodland and I said I would look into sporogenesis! My understanding is still pretty limited, but we’ll take a brief look!

Sporogenesis is basically a long word which means “the production of spores”, although the terms is also used to refer to the process of reproduction via spores. Reproductive spores are formed in many eukaryotic organisms such as plants, algae and fungi. If you’ve ever brought home a piece of King Alfred’s Cake fungus and left it on top of the stereo (as I once did) you’ll know the mess the spores make as they spread all over the surface!

Fern spores

Fern spores

Spores are distributed in many ways including by wind and by water. Organisms such as the puffball fungi dramatically expel their spores into the surrounding environment in order to reproduce. In ferns, the spores are expelled at a microscopic level and can be viewed in this video:

http://www.youtube.com/watch?v=-xF83pHEx6Q

For those of you interested in some more of the science behind sporogenesis I came across this video which explained it to me! Although not exactly a cinematic masterpiece, it will give you the basics!

http://www.youtube.com/watch?v=c6JNu0Vra-4

Lastly for this week, I wanted to look at a tree which has captured my attention many times walking through the woods. Take a look at this mature oak:

Oak tree with burrs up the main stem

Oak tree with burrs up the main stem

Burrs are commonly found on trees as a rounded outgrowth on a trunk or branch that has filled with small knots from dormant buds. These growths result from the tree undergoing some form of stress, which could be an injury, virus or fungus, among other causes.

The largest burrs have been recorded at 26 feet, occurring in coast redwoods in the US and can encircle the whole trunk where moisture is present.

They yield a very peculiar and highly sought after wood used by furniture makers, artists and sculptors. Every time I walk past this tree I would love to know what is going on under the bark and imagine the beautiful things you could make with the wood.

Well, that’s it for this week’s walk in the woods. I’m sorry it has taken a while to get to you, but the Treecreeper team have been so busy this summer! Join us soon for another walk in the woods!

Until then, enjoy your own walks and let us know how you’re getting on!

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