Photo courtesy of Google Images.
As trees photosynthesise they use carbon dioxide (CO2) from the atmosphere with water from rain or irrigation and nutrients from the soil to form carbohydrates, which make up the tree’s biomass, but how much carbon is made by a tree in this process? Researchers at Ecometrica have worked it out!
The amount of carbon stored by a tree depends on its size, which in turn is influenced by factors, such as species, local environmental conditions and the way it is managed. In an attempt to find a simple answer to this question, researchers at Ecometrica have broken down approximately how much carbon is stored in each element of a typical tree (the branches, the leaves, the stem and the roots) by percentage for a quick and simple calculation.
They used standard forestry practices to estimate the amount of carbon contained within the stem, branches, roots and leaves of a mature sycamore (Acer pseudoplatanus), found near their office in Edinburgh, with a diameter of 52 cm and a stem height of 12 m.
First they measured the various parts of the tree and, from these measurements; they calculated their volumes, which were then used to calculate the biomass (mass of living matter in plant tissues):
- The radius of the stem at 1.3 m above the ground (r1 = 26 cm) and at the top of the stem (r2 = 20 cm), and
- The height of the stem (h = 12 m)
They used known relationships between the biomass of the stem and the biomass of roots, branches and leaves to estimate the total biomass of the tree:
- Stem volume was estimated using the equation for the volume of a truncated cone:
which gave an estimated stem volume of 2.0 m3
- The wood density of sycamore is approximately 620 kg/m3, so using the equation:
Mass = Density × Volume
the stem biomass was 1243 kg, or approximately 1.2 tonnes
- The biomass of the roots, branches and leaves of a sycamore tree are known to be around 26%, 11%, and 1% of the total biomass, respectively. These proportions were used to estimate the total biomass of the tree without having to dig up roots or cut down branches.
In summary, the sycamore tree had a stem with a biomass of 1.2 tonnes, roots of 0.5 tonnes, branches of 0.2 tonnes and leaves of 0.02 tonnes, giving a total biomass of 2 tonnes.
The carbon content of woody matter (stem, branches and roots) and that of leaves is approximately 50% of their biomass. Multiplying the total biomass by the proportion of that biomass which is carbon gives an estimate of the total amount of carbon stored in the tree, which in this case was exactly 1 tonne! Each tonne of carbon equals to approximately 3.67 tonnes of CO2.
Link to Ecometrica paper.
Tree biomass percentages (approximate). Photo courtesy of Ecometrica.
No wonder the rules of the Kyoto Protocol and of the United Nations Framework Convention on Climate Change say forestry can generate a sink for greenhouse gases that can contribute to meeting the national commitment to emissions reductions, as explained in a review paper by Jandl et al., 2007, published in CAB Reviews.
A search of the CAB Abstracts database using the terms forests and carbon sequestration gave over 4000 records.
R.Jandl, L.Vesterdal, M.Olsson, O.Bens, F.Badeck, J.Rock (2007). Carbon sequestration and forest management. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2007, 2, No. 017, 16 pp.
Ecometrica (2011). A one tonne carbon tree.
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Is one ton carbon contained by any species of tree locked up 3.67 tonnes of carbon dioxide from the atmosphere???
Yes, one ton of carbon stored in any tree is equivalent to approximately 3.67 tonnes of atmospheric CO2.
What is the regression model for Q. semicarpifolia for above ground biomass calculation?
If you want to calculate the above ground biomass for Q. semicarpilfolia you can follow the method I described in my blog, i.e. measure the radius of the stem in cm(r1) the radius at the top of the stem (r2), and the height of the stem in metres (h); and estimate the tree volume using the equation for the volume of a truncated cone given in the blog. The wood density of oak is 590 – 930 kg/m3, depending on how dry it is; then use the equation: Mass = Density × Volume to calculate the biomass. Hope this helps!
I am wondering that how can we relate the annual tree ring increment with biomass increment? I have data of annual ring increment but cannot convert it into biomass, So is there anyone can help me???
Very informative post and a definite must read for anybody who is interested in how tree’s create and produce carbon dioxide, keep up the good work, I will definitely recommend this to my readers.
Again as I said on the previous post wonderful and informative post on how tree’s create and store carbon dioxide, I really am enjoying these posts please keep them coming
Great info on the photosynthesise and carbon dioxide. Thank you, great article!
Hope this could inspire people not to cut down the trees but instead will encourge them to protect and contribute in their growth, for better global climate. This scientific research will help to design the industrial area too.
Loved this, Thank you.
Thanks again for the blog.Really looking forward to read more. Much obliged.
Very interesting, Further should be conducted, I would personally like to see more.
How can you have a mass of Co2 higher than the mass of the actual tree? :s
Each tonne of carbon equals to approximately 3.67 tonnes of CO2 taken out from the atmosphere. The reason you have a mass of CO2 absorbed by a tree which is higher than the mass of the actual tree is that the CO2 molecule is not made of just carbon; it also contains two oxygens for each carbon; and only the carbon part of CO2 is absorbed and therefore counted as part of the tree biomass. I hope this answers your question.
Then why does the Kyoto Protocol encourage countries to cutdown natural forest and replant them? I mean, take a look at Guyana. They cannot participate in carbon credit scheme because their forests are not replanted. Shouldn’t it be opposite way around? What I heard is when a tree breaks down, stored carbon escapes, making the Protocol a bit hypocritical 🙁
Thank you for your input Yuri. Here is the link to a review paper which discusses the issues related to forest management and C sequestration. I hope it will help to answer your question. http://cabiblog.typepad.com/hand_picked/files/PAV2017.pdf
Hello! I’m at work browsing your blog from my new apple iphone! Just wanted to say I love reading through your blog and look forward to all your posts! Carry on the outstanding work!
Hello, where can I find the densities of different trees in the uk please?