The Cambridge Canopy Project: preparing a city for a changing climate
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By Dr Matthew Ling, Project Lead, Cambridge Canopy Project
By 2050, it is estimated that nearly 70% of the global population will live in urban areas. As such, we need to plan, adapt, and prepare our urban environments to be fit for purpose for their residents. Urban centres, by their nature, are predominated by engineered, built, or grey solutions. Whilst this building and engineering is often remarkable, evermore technologically advanced, and facilitates our modern ways of living, it can also bring about a host of unplanned problems. Asphalt and concrete in particular, are impervious to rainfall, causing rapid runoff, and absorb and store heat from solar irradiation, causing localised heat attenuation – often referred to as the urban heat island effect. An overreliance on these materials, coupled with a climate that is projected to expose the UK to more frequent hot, dry summers, suggests that we need to explore alternative approaches for our urban environments.
Cambridge City Council has recognised the important role green infrastructure can have in addressing some of these issues. In 2019 the Council declared both climate and biodiversity emergencies, committing to tackling both through its actions and decisions. In 2019 Cambridge City Council also joined a project consortium to pilot a range of green infrastructure solutions to help adapt to climate change. This led to the launch of the Cambridge Canopy Project, the green infrastructure focus of which, is trees.
The Cambridge Canopy Project seeks to help the City adapt to a changing climate by cultivating a resilient urban forest with increased tree canopy cover. Specifically, this will be achieved through a 2% increase in tree canopy cover (17% rising to 19%) by the 2050’s. The main objectives of the project are: contributing to, and encouraging, increased levels of tree planting and protection; and, making a measurable contribution to the sustainability of the City’s urban forest.
More and more, people are coming to realise the huge range of benefits we receive from trees, and just how valuable they can be in our changing climate. Some of the more obvious factors include shade, fruit, and timber provision, and carbon sequestration for example. Whereas, some of the less well-known benefits include positive influence on primary school educational attainment, reduced levels of violent crime, and increased mental well-being, including less marked ADHD (Attention Deficit Hyperactivity Disorder) in children.
There is a huge wave of momentum and enthusiasm behind tree planting at the moment, as demonstrated in the 2019 UK general election, which saw all of the main political parties making ambitious manifesto commitments around increased tree planting efforts. For example: the Labour Party, 2 billion trees to be planted by 2040; the Green Party, 700 million trees by 2030; and, the Conservative Party, 30 million trees planted per year by 2024. With trees so firmly in the public psyche, the time really is now for the Cambridge Canopy Project to seize the momentum and engage with the City’s residents.
Average tree canopy cover across cities in the UK is approximately 8%; at 17%, Cambridge is already doing quite well, and has the feel of a leafy and green city. But canopy cover across the City is not evenly distributed, with some wards being comparatively poorly provided for (ranging from 12.8% to 22.6%). As a result, not everyone will realise the range of benefits flowing from trees. The project will therefore seek to prioritise planting in these areas to ensure that, in the decades ahead, the urban forest will cater for everyone on some level. Other specific measures the project will focus upon include proposing a number of ‘shadeways’ where pedestrians and cyclists will be able to commute and travel on paths and roads with substantial levels of shade provided by tree canopy cover. To achieve this, greater numbers of street trees will be planted, alongside selection of larger species that will cast more shade.
These factors in combination, are intended to make Cambridge as well suited as possible for its residents and visitors under climatic conditions in the years ahead which will be hotter and drier, and with more frequent and intense storm and rainfall events. Having a larger and more resilient urban forest with greater canopy cover will positively contribute to the alleviation of many of the effects realised through climate change.
The greatest challenge for the project in terms of achieving its aims, will be to engage with the public in such a way that they are moved into action. Cambridge is a relatively small city council with limited land on which to plant additional trees. Of the total land area of the city, only 13.5% of it falls under Council ownership; with 77% being privately owned. Analysis indicates that within the private land ownership group there are approximately 44,000 houses with gardens in the city. Through engagement, outreach, and awareness raising activities it is hoped that at least 12,500 of these will plant one new tree in their gardens.
A core principal exists in arboriculture, that of ‘the right tree in the right place’. Cambridge City Council employs a team of highly skilled and knowledgeable tree officers that oversee all things tree related. Being able to draw upon this expertise ensures that the right tree is always selected for each planting location, based on size, micro-climatic and environmental conditions, and any nearby constraints or stresses. With this same approach, it is possible to find a tree to suit almost any sized garden. The project will develop guidance to help residents select and plant a tree to meet their needs.
By collectively realising the benefits provided by trees and the urban forest, and taking action to help grow and maintain it, Cambridge’s residents can help to make the City more robust, self-sustaining, and prepared for the future impacts of climate change.
You can also keep updated via our Twitter account: https://twitter.com/CamCanopyProj.
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