During the Terrific Scientific Trees Investigation, pupils counted, identified and measured the trees in and around their school grounds. Using these pieces of information, the pupils were able to estimate the amount of carbon stored in their trees and how much they are helping to tackle climate change.
Over 6,000 trees were counted during the investigation and more than 2,000 of them were measured and identified.
The average (median) number of trees per school was 30 – we were surprised to find that this was exactly the same for both urban and rural schools! Schools that described themselves as suburban (somewhere in between urban and rural) had the most trees, with a median average of 35 per school.
4% of schools unfortunately had no trees at all, but nearly 90% of schools had more than 10 trees on their grounds.
What kind of trees did the pupils find?
For schools in the countryside, birch was by far the most common type of tree to be found (11% of the total), followed by oak, cherry and willow. Whilst birch trees were also the most popular in urban schools (8% of the total), pupils in towns and cities found that sycamore and lime trees were the second and third most popular. The most common type of tree in suburban schools were cherry trees (12%), closely followed by field maples.
The children were able to identify 87% of the trees they surveyed. A further 11% were classified as having broad, flat leaves (broadleaf) or thin, needle-like leaves (needleleaf), only 2% of the trees surveyed could not be identified.
Across the UK, more than nine out of ten of the surveyed trees were broadleaf and less than 10% were needleleaf trees. In Scotland however, needleleaf trees were more common, making up 16% of all surveyed trees.
Whilst the most common trees across England were birch, most of the trees surveyed in Scotland were willow, and in Wales the most common trees were oak. In Northern Ireland, oaks, beech and elm were the most common trees.
How big were the trees?
The trees found on the school grounds came in a variety of shapes and sizes. Most of the trees surveyed were shorter than 10 metres. Two out of every five trees surveyed were taller than 10 metres, but only one in every 50 trees were taller than 20 metres.
The tallest tree was estimated to be 30 metres tall – that’s more than 3 times the height of an average house! But that’s small compared to the tallest tree in the UK, a mighty 60 metre tall fir tree!
The widest or thickest tree surveyed was over 5 metres in circumference – you would have to join hands with several of your friends to be able to hug that one!
We found that on average, trees measured in urban schools were slightly wider than those found in rural schools – this will be partly due to dominance of birch trees in rural schools which tend to be quite thin.
How much carbon do the trees store?
In total, the children estimated that the trees they surveyed contained around 550 tonnes of carbon (1 tonne = 1000 kilograms) – that’s over 2,000 tonnes of carbon dioxide. This is equivalent to the annual carbon footprint of 275 people living in the UK added together.
We found that on average the rural trees surveyed here were slightly smaller and therefore contained less carbon than those measured in towns and cities.
If we use the data collected by pupils during the Trees Investigation and extend this to all 25,000 primary schools in the UK, we would estimate that trees in UK primary schools have removed around 400,000 tonnes of carbon dioxide from the atmosphere over their lifetimes. That’s equivalent to the annual carbon footprint for around 55,000 people in the UK (the same amount of people who live in Kettering, Macclesfield, Loughborough or Canterbury).
Unfortunately, this is only 0.1% of the amount of carbon dioxide that is emitted by human activities in the UK every year [about 500 000 000 tonnes of carbon dioxide] – so we are emitting much more carbon dioxide into the air than our school trees can soak up.
As a result of Terrific Scientific, over 40, 000 trees have been planted in Kenya, Tanzania, Uganda and Madagascar. That means that for every school tree surveyed around twenty Terrific Tropical Trees are being planted! Head to the Terrific Tropical Trees website to follow their progress.
Tropical trees work much harder for the climate as they grow quickly and can reach very large sizes. The Terrific Tropical Trees projects will ensure that these newly planted trees are looked after for many years to come, taking carbon dioxide out of the air and helping to tackle climate change.