10 May 2013

Measuring the age of Oak trees

Ardd Fotaneg · Botanic Garden

A beautiful sunny day after a fabulous May Day bank holiday.  So a debate as
to what clothes to discard, then off up towards the biomass centre with lots
of botanical interest on the way.  Of course, not only in the Garden but
everywhere you looked there were Dandelions, with their splendid
golden-yellow heads.  But no clocks – the seed heads.  Why? Well, although
Dandelions attract insects and other pollinators, for nectar and pollen,
most varieties are self-pollinating.  Then, once that has occurred, they
drop their heads and close up to avoid being eaten by cattle then, when they
are ready they shoot up with the familiar clock seed heads.  The air could
be filled with them this year.

Another flower that was now out in abundance was the Ladies Smock, or Cuckoo
plant and visitors coming up the Broadwalk would have also seen a few
Cowslips.  Way back in the 50’s it was nothing unusual to see whole meadows
of these flowers.

A couple of weeks ago we had spotted two old oaks – indeed one of them is
little more than a dead stump.  But they stand out from all the other trees
by virtue of their girth.  So how old were they?

There is a rough way of measuring the age of oak trees, which is to put a
tape measure around the trunk at a height of about 1.5m.  This we did and
the result was a little under 15ft.  Using the ready reckoner from the
Woodland Trust this works out at around 250 years old.  It was a sapling at
the time of the Battle of Waterloo.  There are, apparently a few other old
trees around Waun Las of similar age.  Intriguing though to know why these
two were where they were.

[nggallery id=334]

A less welcome plant which we had previously noted around the Garden is the
Horsetail or Snakegrass.  It is the only living genus of an entire class,
equisetopsida which dominated the undergrowth of late Paleozois forests. The
stalks arise from rhizomes that are deep underground and almost impossible
to dig out. Below they are shown growing through the Science lab car park
tarmac.  But nearby and in various other places we spotted this lovely
little Geranium.

[nggallery id=333]

Up on the hill beyond the Science Lab the occasional Bluebell, a
Tortoiseshell butterfly, the occasional OrangeTip – and birdsong.  We had
already heard the ‘last weeks’ Blackcap still singing away in the trees
behind the marquee and out on the hill above the boar we could hear another
Blackcap and a Garden Warbler.  They have very similar songs, but the Garden
Warbler is much shorter.  Some say that the Blackcap’s song is better than
the Nightingale and that many of the places in Wales where there are
references to Nightingales should really be about Blackcaps.

A couple of weeks ago ten Dormouse nest boxes were placed in the coppice at
the edge of the Garden at the spot where we had found nibbled Hazel nuts.
There were no sign of activity in these boxes which is hardly surprising
given the recent cold weather.  If the weather is really not to their liking
they can just curl up and sleep through it all – for maybe eighteen months!

[nggallery id=331]

Going back down on the path towards the Boar we found clusters of bright
yellow/orange eggs on the undersides of dock leaves.  The latter having
holes indicating the presence of the adult Beetles.  These eggs, which look
very much like those of the Large White Butterfly which are so familiar to
gardeners, are those of the Green Dock Beetle, a shiny Beetle around 4 – 7mm
in length with a metallic shimmer, which, depending on the light, can be
gold green, blue, purple, violet, or red.

[nggallery id=332]

Thanks to John James for his photos and if any volunteer or member is
interested in joining us, or even starting something similar on a different
day, then send an email to Colin Miles – also if you see or photograph
anything exciting in the Garden.  If you click on any of the images in these
blogs, or anywhere else you will see a larger picture.