Thursday, October 23, 2014

Under the skin of a sycamore


Thursday's Guardian Country Diary is about the remarkable range of small invertebrates that live under the flaking bark of old sycamore trees.























When the bole of an old sycamore tree expands the old rigid bark cracks and begins to curl at the edges, while ....























.... a fresh, new layer of bark forms underneath. It might not look very attractive but these bark flakes, some as large as a slice of toast, take a long time to fall off and while they are still attached harbour a remarkable fauna of small invertebrates underneath. Here's a selection, most of which I've yet to ID.



































Millipedes, a hatched moth pupa and some unidentified cocooons 






















Lots more millipedes - these were just a few from under two bark scales - if this sample is representative there must have been hundreds sheltering under the bark of this tree
















A minute scarlet mite



















A rather beautiful little money spider, Gonatium rubens























A huddle of earwigs ....























... that raised their tail forceps in defence when they were suddenly exposed to the light. Male left, female on the right.




































A spider that lives in a silken tent under the bark























Lots of slugs in areas where the bark is permanently damp, where rain water trickles down the tree trunk ..























.... together with snails ......























...... and woodlice















Another moth pupa, that looks as though it hatched successfully.


Sycamore sits low in the league table for tree foliage that supports insect biodiversity - a 1961 research paper on the subject found only 15 species, compared with the 284 hosted by oak (click here for details). But a quick look under the flaky bark of old sycamores casts them in a more favourable light, as a sheltered habitat for a host of invertebrates. 

The few examples shown here were just from a height that I could reach - there may well be a different array of species higher up the trunk and the hosted species most probably vary depending on the aspect (sunny & south facing or shaded & north-facing). Moisture must play a role too because there are well defined runnels where rainwater flows down the trunk from the branches and the bark there is always moist and often very wet. All in all, flaking sycamore bark is probably quite a complex habitat, with many interesting interactions between species that inhabit it.


10 comments:

  1. I will have to investigate myself. Thanks once again.

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    1. Amazing what lurks under flaky bark!

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  2. Goodness, what a surprising amount of creatures.

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    1. Probably many more if they were thoroughly surveyed

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  3. Now I am looking at my old teak tree with the flaky bark with respect!

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    1. I bet it has much more exotic creatures under its bark, lotusleaf!

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  4. Great set of photos and finds, i love things like this, finding as many interesting things in one small area. Once again it shows us all how important trees are..
    Amanda

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    1. I know what you mean Amanda, my favourite wildlife sites are those that I go back to and get to know really well, in depth.

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  5. I become quite animated when people say sycamores aren't of value in the British landscape for wildlife. As your posting shows they are (admittedly when mature). And; having a base rich bark, are superb for mosses, ferns, lichens and bryophytes. I know of a 250 year old sycamore in north Wales which has the only colony of a rare lungwort in the country, since a second sycamore which also had it nearby was felled because it was old and may have fallen on a passing sheep. Superb trees and once they're mature as you say their layered bark is awash with invertebrates. Lovely posting.

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    1. Thanks! Totally agree about the value of sycamore. have often watched blackcaps picking off the aphids from under the leaves in spring and summer. There are some magnificent old sycamores around too. Very variable trees - some have very scaley bark that comes off in large longitudinal flakes. May be time for a really close study of the tree and a reappraisal of its value - especially as it's likely to replace ash in some places.

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