Trees in urban landscapes play a vital role in making our cities more sustainable.
Our cities are expanding rapidly, and this expansion should only take place with a proper land planning strategy, otherwise it will result in damaging effects on forests, landscapes and green spaces in and around our cities. But trees in urban landscapes can help to mitigate some of the negative impacts and social consequences of urbanisation, thus making our cities more resilient to change.
Here are the ways trees in urban landscapes can help make our cities more sustainable.
They produce oxygen
Trees produce oxygen, an element which is fundamental to our existence on this planet!
In a single season, one mature leafy tree can produce enough Oxygen to allow 10 of us to breathe. This is most important of all in densely populated and polluted areas like cities, with average Oxygen levels expected to be at least 6% lower.
Trees act as ‘carbon sinks’
Trees play an important role as what we call ‘carbon sinks’. This is the storing of carbon as part of the carbon cycle and is a key part of helping to mitigate the effects of climate change.
In a year, a single mature tree can absorb up to 48 pounds of carbon dioxide. It’s thought that globally our forests absorb 40% of man-made CO2 emissions before it reaches our outer atmosphere where it can trap more heat. Because of their size and density, trees are much better at this than smaller plants.
It’s estimated that 2,367,000 tonnes of carbon are stored in London’s trees alone, with an estimated value of £6.1 billion to the capital and £130 million in wider benefits.
Trees in urban landscapes clean our air
It’s well known that trees absorb Carbon Dioxide from the air, but that’s not the only air-purifying they get up too. Trees also soak up a surprising range of other pollutants and toxins generated by human activity. These include nitrogen oxides, ozone and sulpher oxides. They also filter fine particles such as dust, dirt or smoke out of the air by trapping them on leaves and bark. In the modern world, this is more vital than ever; air pollution – particularly in urban areas – means the air we breathe is reaching (or exceeding) toxic levels.
While all trees do this, the most successful ones are those suited to their location, require little management, or have long lives and are more disease resistant.
They help protect us from flooding
Did you know a single mature, leafy tree can absorb up to 450 litres of water through its roots every day? In addition, trees also capture rainwater on the surface of their leaves. Roots also reduce soil erosion in the ground and slow the filtration of water into our city drainage networks.
This is particularly important in cities where a large proportion of surface is made up of impermeable materials, such as paving or tarmac. When we get a sudden downpour, this can quickly cause flash flooding if the water has nowhere to go. This has become known as stormwater management and has seen the rapid rise of sustainable urban drainage systems, known as SuDs.
Trees have a cooling effect
While trees absorb water, they also release it as water vapour through ‘transpiration‘. Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. As this vapour emits it produces a cooling effect to the immediate area. Trees in urban landscapes also provide shade for the ground and buildings, resulting in further cooling and less energy usage.
The average overall cooling effect of a single, mature tree is equivalent to 10 air conditioning units running for 20 hours a day! This cooling helps against the urban heat island effect, which can cause temperatures in a city to be an average of 7 degrees higher.
Trees in urban landscapes support wildlife
Trees are, of course, an important species in their own right and an integral cog of urban wildlife. They provide a source of food and habitat to a host of other species in our urban environments – bats, birds, badgers, insects, plants, fungi and mosses – the list goes on! London is home to quite an array of wildlife, as explored in our recent insight Wildlife & Habitats in London’s Landscapes.
They support our mental health & wellbeing
It’s not all about the physical environment. Trees also help us with our ability to cope mentally with life in a concrete urban environment. Being around nature – and specifically trees – has proven to reduce the levels of cortisol in our brains. This is otherwise known as the stress hormone. Lowering this can help to reduce the symptoms of anxiety and stress.
Trees also have the knock-on effect of encouraging physical activity. We’re more likely to leave our homes, go outside and exercise if there are welcoming trees and inviting green spaces.
Trees don’t live forever
Most of the trees we see in our cities today are here thanks to our ancestors who planted them as long as 100 years ago. Whilst there is debate whether trees die of ‘old age’, specialists agree that they don’t live forever. Eventually trees deteriorate to a state where they could pose a threat in an urban setting.
The challenge we face now is that replacement trees are unlikely to be as mature as their predecessors. It takes many years for a tree to reach the level of maturity where it is bringing its maximum benefits to us. So if we don’t increase the rate of tree planting soon, we may have a long wait until we have more established trees to replace the aging tree population.
The power of the urban pull
80% of us are now living in urbanised environments and there are no signs of this slowing down. Quite the opposite in fact. It is projected that the increase in urbanisation, along with expected global population growth, could result in another 2.5 billion people in urban populations by the year 2050. Urban sprawl is certainly taking over.
Trees have been part of the natural landscape since time began. Humans have lived alongside them since the beginning, and we have a deep, innate desire to be around them (even if you aren’t aware of it).
Valley Provincial have been greening London with outstanding landscapes and planting displays for over 40 years. If you are looking to work alongside an established, experienced landscaping contractor please contact our team of experts today.