Why is planting trees any good anyway?
For our blog this month we welcome guest blogger David Jackson who is the Sustainability Project Coordinator for the Mid-Essex Hospital Services NHS Trust . He is also the NHS Forest Lead from Broomfield Hospital , which has seen many hundreds of trees planted under his watch.
Like all green plants, trees use photosynthesis to produce food; they do this through the conversion of carbon dioxide (CO2) into sugar, cellulose and other carbon-containing carbohydrates that aid in growth. Trees in fact have millions of years’ experience in this area, and through photosynthesis play a vital role in that carbon sequestration/uptake. Increasing their portfolio, trees likewise have an ability to store large amounts of carbon in their wood. In fact, one half of dried wood is carbon, meaning that trees can store a large amount.
Trees like humans do release CO2 from natural processes, such as respiration and decay, however a healthy individual can stores higher amounts of carbon than it releases.
Carbon uptake itself is complex; a number of factors can affect the rates of uptake; species, climate and location. However a younger and faster growing group of trees typically have higher annual sequestration rates.
One tree can therefore be a good carbon store, but combine this to the amounts also stored in soils and other vegetation, well that can be a huge amount. Why does all this matter? Having a healthy natural landscape is of major significance in helping to tackle the effects of climate change.
International agreements to regulate carbon emissions (Climate Change Act 2008 and Paris Agreement 2015 for example) recognise the importance of trees as carbon sinks, and emphasise the benefits of sustainable ‘tree’ management in carbon offsetting from human made emissions.
The NHS Forest seeks to play a part in the planting of trees in the UK by working with healthcare sites. Here the trees not only offer benefits in terms of the carbon they can store, but also in terms of improving air quality, as well as creating a more therapeutic wellbeing environment.
Broomfield Hospital, the main site of Mid-Essex Hospital Services NHS Trust (MEHT) and we are proud to manage two woodland areas in addition to other garden and green spaces on site. As part of the NHS Forest network, 100’s of new trees have been planted during the past 8 years.
We recently decided to try and calculate the amount of carbon sequestrated by our Trust trees; we likely have around 1,000 or so but 400 are surveyed each year due to proximity to walkways. This data, combined with several researched equations I managed to calculate the overall and per year carbon uptake (estimated of course). This 400 tree group has removed around 700 tonnes CO2 from the atmosphere over their current lifespan. That is around 5 tonnes CO2 offset per year. Considering these values do not include soil or vegetation carbon sink, the overall offset will be significantly larger, and can positively showcase the climate benefits from creating, and managing a natural space. We’re in the early stages, but this is in essence only one stepping stone into another quantifiable value of natural space.
If anyone is interested in calculating the carbon sink of their NHS Forest site you can get in touch with David on: David.Jackson2@meht.nhs.uk
Equally if anyone conducting research in this field is interested in doing further calculations around how the carbon sink value of forests, especially the NHS Forests, can be achieved, please also get in touch with David at David.Jackson2@meht.nhs.uk and and Makena at email@example.com .