Camden i-Tree Inventory Report

Camden is a borough in North-West London, its southern reaches forming part of central London.

Home to sprawling street markets, world-famous music venues, first class museums and theatres, and a thriving alternative cultural scene, Camden is one of London’s most popular tourist sites. Camden’s trees are generally recognised and appreciated by their presence and stature in the townscape, but society is often unaware of the many benefits that trees provide to those living in our towns and cities.

In 2017, Treeconomics, in collaboration with Forest Research, reformatted and assessed Camden Council’s tree inventory using Eco. A total of 25,890 trees were measured as part of the report.

The main driving force behind climate change is the concentration of carbon dioxide in the atmosphere. Trees can help mitigate climate change by storing and sequestering atmospheric carbon as part of the carbon cycle. Since about 50% of wood by dry weight is comprised of carbon, tree stems and roots can store up carbon for decades or even centuries.  Over the lifetime of a tree, several tons of atmospheric carbon dioxide can be absorbed.

Overall, the publicly owned trees in the Camden inventory store 10,830 tonnes of carbon – a service valued at a huge £691,300.

Carbon sequestration was also calculated from the predicted growth of the trees based on field measurements of the tree, climate data and genera specific growth rates within Eco. This provides a volume of tree growth. This volume is then converted into tonnes of carbon based on species specific conversion factors and then multiplied by the unit cost for carbon.

Treeconomics determined Camdens’ inventory trees to annually sequester 207 tonnes of carbon per year, with a value of £48,483.  Of the entire tree species inventoried, the Plane species store and sequester the most carbon, adding 72 tonnes every year to the current Plane carbon storage of 5410 tonnes.

Surface run-off can also be a cause for concern in many areas as it can contribute to flooding and is a source of pollution in streams, wetlands, rivers, lakes, and oceans. During precipitation events, a portion of the precipitation is intercepted by vegetation (trees and shrubs) while a further portion reaches the ground. Precipitation that reaches the ground and does not infiltrate into the soil becomes surface runoff, particularly in urban areas with a large extent of impervious surfaces. However, trees are very effective at reducing surface runoff. Existing trees in Camden divert an estimated 6,700 cubic meters of storm water runoff away from the local sewer systems each year. This is worth £10,200 each year in avoided stormwater treatment costs.

The tree population within Camden generally has a good species and age diversity, with 258 species recorded during the study. This will provide some resilience from possible future influences such as climate change and pest and disease outbreaks. In terms of structural diversity, however, the Plane species have the largest proportion of trees in the larger size classes, and all other tree species are poorly represented. Camden is highly dependent on this single species for the delivery of ecosystem services (13% of population, and 34% of all carbon stored in the trees). Camden would benefit from having a greater proportion of larger trees, of other species, in order to build resilience into its tree population.

Nonetheless, the public benefit of Camden’s existing trees is clear – at least £199,000 in environmental services, and £234,202 in total annual benefits, each year. The challenge now is to ensure that policy makers and practitioners take full account of Camden’s trees in decision making. Not only are trees a valuable functional component of our landscape, they also make a significant contribution to peoples quality of life.