Our University of Leeds tree trail was created in collaboration with the United Bank of Carbon to celebrate the massive value of trees to campus life. The trail highlights the value of hosting a range of species and the results of the i-Tree project - in which academic staff and volunteers calculated the total carbon stored by campus trees (over 500 tonnes!). We hope you enjoy the trail!
Directions are available via Google Maps here or by following the instructions below, starting from the back of the Leeds University Union building. We expect the trail will typically take 40-60 minutes.
Not following the trail in winter? If the trees have leaves they might be hard to recognise from the photos here. Click here for leaves!
1 - Chainsaw Carving
Our tree trail starts at the back of the Leeds University Union building, where a carved wooden sculpture stands between pathways. Until 2018, this carving was a living ash tree but, when the tree began to die, the university decided to turn it into a work of art.
It might seem a little strange to start a tree trail with something dead but, in nature, death for a tree is just the beginning of new life. When left in place, dead wood provides a habitat for lots of insects and fungi, which then also feed our campus birds!
This artwork was carved by local artist Shane Green, using a chainsaw and taking inspiration from the winning entries of a competition run by the university sustainability service. The competition's winning entry was from mathematics student Joely Holder. Joely's design included imagery for the concepts of sustainability and international living, including the recycling symbol, books, flowers, an owl (from the Leeds coat of arms), and even the Parkinson building! How many can you spot on the carving?
2 - Black Walnut
Species: Juglans nigra | Carbon stored: 440 kg | Rate of carbon storage: 25 kg/year
Outside the Esther Simpson building stands the second tree of our trail: a black walnut tree! When the Esther Simpson building was designed, this tree featured heavily in the planning process. Instead of cutting it down to extend the building or to make access to the site easier for large construction vehicles, we prioritised keeping this tree healthy and in place.
After the building was complete, we added bat roosting boxes to the tree and three bee towers on a nearby patch of grass to help boost biodiversity in the area.
Black walnut trees were originally taken from North America and introduced to Europe in the 1600s. While the nuts are still growing (before the shells harden!) walnuts provide an excellent food resource for squirrels and birds on campus.
Historically, people have used these trees in a variety of ways, including crafts (the seeds produce a dark dye) and medicine. Specifically, the chemical compound 'juglone' is found in black walnut husks and can be used to prevent bacterial and fungal infections. Scientists have also suggested that juglone may be useful in prevention and treatment of cancer, although the evidence for this remains limited.
3 - Sycamore
Species: Acer pseudoplanatus | Carbon stored: 4978 kg | Rate of carbon storage: 66 kg/year
Mount Preston Street is home to some of our biggest trees on campus. Amongst them is the third tree on our trail: a giant sycamore tree with a whopping five tons of carbon stored inside it! That's approximately the same carbon emitted by brewing 330,000 cups of tea - or 845,000 if you don't take milk!
With three stems from a single base, the Mount Preston Street sycamore is our widest tree on campus. As well as capturing carbon, mature trees like this produce lots of food for wildlife so it's vital that we protect them as much as possible. Sycamores are attractive to caterpillars and aphids, which then feed other insect species and birds. Sycamore seeds, known as samaras, also provide food directly for birds and small mammals, as well as being culturally beloved for their helicopter-like spinning when they fall from trees or are thrown into the air.
Sycamores are a native European species but are thought to have been introduced to the UK in the 1500s by the Tudors. Because sycamores are typically tolerant of high winds and pollution, they are now used commonly as street trees in towns and cities and as windbreaks on more open land.
4 - London Plane
Species: Platanus x acerifolia | Carbon stored: 3059 kg | Rate of carbon storage: 78 kg/year
Chancellor's Court is a great place to see some campus biodiversity and is home to many beautiful trees, as well as the university's Sustainable Garden. We think the London plane tree at Chancellor's Court deserves particular attention though as one of our best trees for flood prevention on campus. Every year, the leaves and branches of the London plane catch 2,400 litres of rainfall before that water has a chance to form puddles or flow downhill to cause flooding!
Urban environments are much more at risk from flooding than rural areas because so much of the land is covered by materials like concrete and asphalt, which don't let rain sink into the ground. Instead, rainfall in urban areas is likely to flow quickly over the land surface, causing floods. Adding green spaces to campus helps rain sink into the soil and trees like our London plane are particularly good at flood prevention because of their high surface area; every raindrop wetting a branch or leaf is water not flowing to floods!
London plane trees have a short but interesting history! They were first created less than 400 years ago in a London tree nursery, where a natural pollination caused an unintentional hybrid to be created, mixing the Oriental plane (Platanus orientalis) and the American sycamore (Platanus occidentalis). Since then, they have become the most common trees in London, thanks to common planting in the 1700s. Their continuing popularity is in part due to their high resistance to pollution, allowing them to thrive in busy cities, where other planted species might struggle.
5 - Dawn Redwood
Species: Metasequioa glyptostroboides | Carbon stored: 832 kg | Rate of carbon storage: 12 kg/year
As you emerge from the passage that cuts through the E.C Stoner Building, dawn redwood trees tower high above you. It’s hard to believe that less than a hundred years ago we thought they were extinct! Fossils of dawn redwoods had been found dating back 150 million years to the Mesozoic Era but it wasn’t until the 1940s that we found one that was still alive!
In 1941, Kan Duo (A botanist working in the Sichuan-Hubei region of China) found a huge tree that shared many traits with the dawn redwoods in the fossil record. Although he never attempted to publish his findings, similar samples were collected in 1943 by another botanist, Wang Zhan. Unfortunately, World War II prevented those samples from being properly identified until 1946 by Professors Zheng Wanjun and Hu Xiansu at Nanjing University. After the species was officially recognised, the Arnold Arboretum of Harvard University commissioned an expedition to collect seeds from the tree and we were lucky enough to get some of those seeds delivered to Leeds. Those seeds grew up to be the trees you see on campus today!
Dawn redwoods are one of just three redwood species in the world. Their cousins, the giant redwoods (Sequoia giganteum) and coastal redwoods (Sequoia sempervirens), live in North America and share a similar reddish bark. As you might expect of species living on different continents however, there are also some big differences between them. Our dawn redwoods are still growing and could eventually reach over 60 metres tall but they are absolutely dwarfed by their cousins - giant redwoods are the tallest species on Earth and grow up to 126 metres tall! Dawn redwoods might not be as big as their cousins but they do have a special skill: in winter they can drop their leaves, allowing them to live further north and at higher altitudes than their evergreen cousins.
Luckily, we have a few giant redwoods growing along the same road as our dawn redwoods (marked ❹ on the map above) so you can try to spot some of the differences for yourself!
6 - Japanese Maple
Species: Acer palmatum | Carbon stored: 162 kg | Rate of carbon storage: 13 kg/year
This variety of Japanese maple is prized for its unusual, stripy, greenish bark and is just one of hundreds of cultivars from the species, each produced to fit different aesthetics. In Japan, these trees have been cultivated for centuries but were only exported around the world more recently, in the 1800s. Unlike many trees along this trail, the Japanese maple is primarily ornamental and will only grow to around 10m tall. Because of this, it won’t capture a huge quantity of carbon in its lifetime. Sometimes however, it is important to simply enjoy the beauty of trees, without requiring them to be the biggest or the most useful.
7 - Common Lime
Species: Tilia x europea | Carbon stored: 900 kg | Rate of carbon storage: 28 kg/year
Opposite the front of the University Union building is a green space, shaded by common lime trees. Trees in social spaces provide shade on sunny days and shelter on rainy ones, making the campus a much nicer place to be. Staff and students alike will often sit out on the grass here in summer, enjoying this patch of green in the middle of campus.
Despite sharing a name in English, common lime trees are not closely related to the green citrus fruits we use in cooking. Their shared name is a coincidence as the citrus gets its name from French, sharing an origin with lemons. The name of common lime comes from the old English term 'lind', meaning flexible, which refers to the quality of their wood. The flexibility of common lime wood has made these trees well suited for traditional hedge laying in some areas, as well as ornamental training of the trees to decorative shapes. Once cut, lime wood is ideal for carving and doesn't warp - a reason why many piano keys are still made from lime today! Most lime trees you see out and about will be ornamental however, not grown for timber!
Unlike their citrussy counterparts, common lime trees are native to the UK and help to support the wildlife on campus, especially pollinators like bees! By supporting populations of insects like aphids and caterpillars, these trees provide a valuable food source for larger animals too.
8 - European Ash
Species: Fraxinus excelsior | Carbon stored: 1284 kg | Rate of carbon storage: 36 kg/year
The European ash tree on Lifton Place has been part of campus life for decades. If you look closely, you will see thousands of staples stuck into its bark where the tree has been used as a notice board for social events over the years. While people often think of trees as objects within the environment or as being beneficial for wildlife, we often forget the direct roles they can play in society and how we interact with them day-to-day.
European ash trees, like this one, account for 8% of all trees on campus, storing 61 tonnes of carbon! Sadly though, ash trees in the UK are at high risk from diseases and pests. In particular, ash dieback is a fungus (Hymenoscyphus fraxineus) that was introduced to the UK in the early 90s and is expected to reduce our native ash population by as much as 80%! While we do everything we can on campus to protect these trees, it is important that we consider which species might be most resilient to harm in the future when we plant new trees on campus, as well as which species can provide similar benefits for the wildlife that ash trees currently support.
9 - Sycamore
Species: Acer pseudoplatanus | Carbon stored:
1243 kg | Rate of carbon storage: 42 kg/year
Although we try to not to cut back our big campus trees, sometimes a trim is necessary to keep them healthy and to make sure the people and buildings around them are safe.
Back in 2018, when our carbon data were collected as part of the i-Tree project, this sycamore held over a tonne of carbon! Unfortunately however, its size was becoming dangerous for the roads, paths, and buildings nearby. To avoid accidents and damage, the difficult decision was made to prune the sycamore back to its trunk - a process known as pollarding. We won't know exactly how much carbon this tree still holds until another census of campus trees is conducted but we're excited to watch all the new growth as it recovers after pruning. You can already see lots of fresh branches emerging, supporting local wildlife, capturing carbon, and sustaining the tree, now without any risk to passers-by. Trees can recover from a lot of disturbance if managed with care and understanding.
10 - European Beech
Species: Fagus sylvatica | Carbon stored: 2577 kg | Rate of carbon storage: 69 kg/year
Like many of our largest trees on campus, the biggest beech tree can be found in St. George’s Field. It stands over 25 metres tall and almost a metre wide. As well as holding 2.6 tonnes of carbon, this beech is great at cleaning the air on campus. Every year it scrubs almost a kilogram of pollution from the air (833g of nitrogen dioxide, 80g of sulphur dioxide, and 47g of PM2.5 particulate matter), which could otherwise lead to lung disease and production of acid rain in urban environments.
Beech trees can grow over 40 metres tall (the tallest native tree in the UK is a 45 metre beech in Derbyshire!) and can live for over 300 years, making them key players in the long term stability and success of ecosystems. Beech leaves are loved by caterpillars and the seeds are eaten by mice, squirrels, and birds, amongst other wildlife. If you watch carefully enough, you are sure to spot something living up in the branches.
11 - White Willow
Species: Salix alba | Carbon stored:
5177 kg | Rate of carbon storage: 49 kg/year
The white willow of St. George’s Field is our final stop on the trail. Until recently, it held over five tonnes of carbon, but damage from high winds has caused it to lose some big branches. Although it might not be as big as it once was, the white willow is still one of our campus giants. Just look at how wide its trunk is!
Old and damaged trees are vital habitat for lots of campus wildlife so this white willow will continue to play a big role in St George's Field for years to come, while younger trees grow up around it! Like the chainsaw carving at the beginning of our trail, dead wood in the old willow is really just the beginning of new life as insects and fungi begin to make their homes. One of the special things about St George's field is that it contains trees at a variety of life stages, making it the perfect place to host diverse species of wildlife, each with slightly different needs.
We hope you have enjoyed our campus tree trail. If you have just completed the marked route, you might like to take some time exploring the rest of Saint George's Field. To find out more about individual trees, we recommend taking a look at the map below. By navigating the different layers of the map, you can discover data on the species, carbon storage and sequestration, and pollution removal for each tree. Alternatively, St George's Field is a wonderful place to relax for a while - our trail has been full of information so now might be the perfect time to rest your brain and simply enjoy the trees around you. There will always be plenty more fun tree facts to learn about in the future!