Forest Research have now provided us with the results of their analysis of the OneOak tree’s leaf area.
After taking the spectacular images of the tree canopy with the hemispherical camera lens (see post of September 18th), they used special software to calculate how much of the sky was visible underneath the tree.
Leaf Area Index analysis software
Leaf Area Index or LAI is the ratio of total upper leaf surface of vegetation divided by the surface area of the land on which the vegetation grows read more. Forest Research calculated that the LAI for OneOak was 1.4.
LAI values can range from 0 (no cover) to 6 (dense forest cover). Apparently our result of 1.4 is quite low for a mature broadleaved woodland. Scientists will now use this value in future calculations of the tree’s biomass.
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Children from Bladon C of E Primary School visited the OneOak tree this week.
We are measuring the circumference of the tree so we could find the age of it. We had a long measuring tape to go round it. Euan and Madeleine.
Will found a caterpillar on a leaf. We found a tree which has been cut down and Jake found it and we liked to climb on it too. Ben and Jake.
When we were being scientists we worked out the height of the tree and I stung my hand on a nettle Ouch! Joseph.
We are playing the listening game. And we have to shut our eyes and hold our hands up. And shut our fingers and listen to as many noises as we can. And every time you hear a noise put your finger up. We had lots of fun at the oak tree!!! We heard a plane, wind, foot steps, breath, birds, talking, leaves rustling, Mrs Thorne saying Megan shut your eyes!!!. That’s it! By Szymon & Charlotte BYE
We caught insects and put them in tubs. Then we each got a magnifying glass and had a close up look at them. We found a spider, caterpillar and a slug. Ben B & Jake M.
Bladon Primary and the OneOak tree
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We have received some stunning images of the canopy of the OneOak tree. These were taken when Forest Research scientists visited the tree last week to measure it.
Hemispherical image of the OneOak tree canopy
Using a fisheye lens fitted to a digital camera, they took hemispherical images looking up into the tree canopy. This produced a complete circular image taking in 180 degrees field of view.
The picture here is one of many taken by the scientists. Back in their laboratory they joined these all together to form a complete picture of the canopy from all angles. They then used special software that calculated the proportions of light and leaves. This gives us the Leaf Area Index.
The Leaf Area Index is used to calculate the biomass of the tree. Read more here.
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We met at the tree with Jenny and Mhairi from the Oxfordshire Forest School Service this week.
We are delighted to announce that the Oxfordshire Forest School Service will be a partner in the OneOak project, and that Mhairi MacGillivray-Edwards, an experienced Forest School Leader, will be leading the school visits to the OneOak tree during September and October.
Some 300 children from Years 3 & 4 of six primary schools will be visiting the OneOak tree over the next few weeks. We look forward to reading about their experiences in the woodland and what they think of the tree and our project. We hope that they will join in the blog and post their work on our schools gallery page.
Mhairi and the OneOak tree
Forest Research scientists measure the OneOak tree
Matt and Ian from Forest Research visited the tree today. They work with the government research agency as scientists specialising in tree measuring or ‘mensuration’.
Matt brought along a hemispherical camera – basically a normal camera fitted with a fisheye lens. A fisheye produces a picture that takes in an amazing 180 degrees field of view. We will be posting some the images that were taken with the fisheye on the website soon. Images taken looking up at the canopy will be analysed with special software that will calculate the leaf area index – effectively a measure of how much sky is visible between the leaves. This will be used to calculate the biomass of the tree.
Ian used some other equipment to measure tree height, timber height, crown width and stem diameter. Below is a picture of Ian using a hypsometer – this uses pythagoras to calculate (from a known distance from the tree + the the angle to the top of the tree) the total height of the tree. Look carefully at the photograph and you can see the distance to the tree is 36.3m. The tree measurements below it are the three different angle readings to the top of the tree. These will average at about 22.6m. However, after more readings from all directions, the final height of the tree has been estimated to be 23.9m.
We had estimated that the tree was 17.5m. We now know that we were quite inaccurate (or it grew 5+ metres in one year!). We look forward to receiving the detailed results from our friends at Forest Research, and will post them here in the OneOak blog, and on the web pages when available. You can read more on our Tree Facts & Figures page.
A hypsometer being used to measure tree height
Our thanks to Ian and Matt and to Forest Research.
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Planning the OneOak felling
We held a meeting at the OneOak tree today. Foresters Paul Orsi and Nick Baimbridge of Blenheim Estate met with Sylva to discuss everything that needs to be done. From how the tree will be felled, to where we will site the toilets for our guests who will come to watch the tree felling at the public launch of the OneOak project.
This time of year the bluebells, that were so beautiful when we first found the tree, are long gone and the bracken is waist high. We met to discuss how we should best fell the tree from a forestry point of view. Also, because we hope many guests will come to watch the tree being felled, we need to start planning carefully so that everyone will be able to see the tree yet be safe!
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We are delighted that the OneOak project is now underway. The project website has been launched, and work with our six partner primary schools in Oxfordshire is now well underway. About 300 school children will be visiting the tree this term and will be working with us on the project in many different ways – how exciting! A huge thank you to everyone who has helped us get to this point, with special thanks to the team at Blenheim Palace.
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