Canopy science

When was the last time you climbed a tree?  I expect the last time for most of us was as children – climbing the biggest tree in our garden or in the local park.  So when I heard that some students from Plymouth University would be climbing up into the oak canopy at Yarner Wood to study the diversity of life there, I had to find out more.

When I spoke with the tutors from Plymouth University I learnt that they were no strangers to working in the tree canopy and they would be teaching the students over the next few days.  In fact they had honed the tree climbing techniques they would use at Yarner, studying the canopies of the giant trees found in Malaysia and Borneo.  In Borneo the trees can reach up to 80 metres, significantly higher than the oak trees at Yarner! They would also be using some unconventional methods to collect invertebrates, they had modified a garden leaf blower, reversing the air flow so they could suck invertebrates out of the tree and they hang pitfall traps high up in the branches.  This was the first year they would make their research base so close to home, for the last few years Plymouth students have been visiting the Trees for Life project in Scotland.  At least they would not have the midges to contend with here!

On just their second day of climbing, I joined a small group of slightly apprehensive students, to learn more about their canopy research.  We set off deep into the woods to find one of their 6 study oak trees.  The base of the tree was already a mini research lab, another student was studying the role oak trees have in adding nutrients to the woodland floor.  While the students set up their climbing gear I took a look at the apparatus – there were ‘hammocks’ to collect the leaf litter and frass (insect poo) falling from the tree and bottles to collect rain water. You can click on the pdf to read more – Yarner poster.

With her harness fastened and safety ropes secured, Maia was ready to climb.  We watched as she slowly raised herself right up into the tree’s canopy. She used a small quadrat to make a mini plant survey to record the lichens, mosses and ferns living in this elevated position, and for species she did not recognise she took a small sample, which she sent fluttering down to the ground crew in a paper bag!  With a variety of probes, she also measured temperature, humidity, light levels and the pH of the bark to fully understand the conditions for life in the canopy.  This would be repeated at 3 different heights within the tree.

I was intrigued to hear that students also use a hemispherical camera to take photos looking up into the canopy.  The photos are analysed in the lab to measure the light coming through the canopy at different heights in the tree.  The results are beautiful in themselves…

KODAK Camera
Students use photos from a hemispherical camera to measure the light coming through the tree canopy. The finger is pointing north!

It was fascinating to see the exciting and ingenious methods the students were using to study the rare Western oak woodland here in Yarner Wood.  After all the fun of tree climbing, inevitably there will be the challenging task of identifying, analysing and drawing conclusions from all the data they have collected.  Many hours in the lab and the library!  We hope to share some of their results on the blog…

Words and pictures by Kate Smith, The Woodland Trust
With thanks to Plymouth University’s Biological Science and Environmental Science courses for sharing this work and for the use of the hemispherical photo 





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