Research
What is the urban forest?
Research Status:current
The urban forest comprises all the trees in the urban realm – in public and private spaces, along linear routes and waterways and in amenity areas. It contributes to green infrastructure and the wider urban ecosystem. It provides numerous benefits to human society and it does so in vast quantities.
Maintaining a healthy and diverse urban forest is critical to sustaining resilient delivery of these benefits, and requires understanding of the urban forest resource, including: species and age composition, distribution, and health.
Research to understand the urban forest focuses on:
Urban Forest Resilience
Sustainable Urban Forest Management
Healthy Communities
Urban tree canopy cover
Tree canopy cover has been measured in all urban areas in the UK. The area-weighted mean canopy cover was found to be 17.3%. The highest canopy cover, 80.4%, was found in a ward in the Epping Forest District, and the lowest, 0.0%, was found in central London.
Cooling by street trees
Street trees in Bristol have been found to cool the streets by several degrees during very hot weather. Analysis is ongoing, and this research will be developed to incorporate measurements of tree functions such as sap flow.
Novel tree species
The Novel Urban Tree Species Growth study began in 2018. Survey data for 41 tree species that have historically been underutilised in urban planting are being collected across five London boroughs. The aim of the project is to better understand the suitability of these ‘novel’ species for urban planting to inform future tree selection and help build resilient urban forests under our changing climate. Novel tree species in London continue to be monitored for their growth and vitality.
Regeneration Guidance for Tree Planting on Vacant and Derelict Land (VDL)
This work forms part of Defra’s ‘Discovery Phase 2’ project, which is supported by the Nature for Climate Fund (NCF). Forest Research will review and update existing VDL regeneration guidance, to reflect changes in policy legislation and practice; will lead the peer review of the Discovery Phase 2 outputs; and provide support to Defra and Forestry Commission VDL regeneration projects.
Climate-ready greenspaces
A successful sector engagement workshop was held in September 2023 which assisted in identifying the key climate-change-related risks to woodland creation and management on vacant and derelict land. Current work involves synthesizing existing evidence-based guidance for addressing the identified risks, followed by a research plan to address the guidance knowledge gaps.
Evaluation of the impacts of I-Tree eco surveys in the UK
A well-known effect of urbanisation is the warming of the local climate relative to surrounding rural areas, creating a phenomenon known as the ‘urban heat island’ (UHI). UHI intensity varies across a city and over time, but temperature differences may reach 9 °C in the UK. Factors that contribute to a UHI include the thermal properties, […]
Tree allometry describes the relationships between tree biometric variables, such as tree diameter, height and crown width. Understanding of these relationships helps urban foresters to assess many of the economic and ecological benefits (e.g. carbon storage, rainwater interception and regulation of temperatures) provided by trees, such as through the use of the urban forest management […]
Research into the sustainability of 12 urban forests across Great Britain, and recommendation of a framework to rate sustainability of urban trees.
This Research Report looks at a broad range of urban forest-based ecosystem services and disservices and, using a literature review, links their provision with four aspects of urban forests (physical scale, physical structure and context in terms of location and proximity to people and land use and ownership). A key objective of this report is […]