Birmingham i-Tree Report

The urban forest within and around Birmingham is a vital resource, providing numerous benefits to the people who live, work and visit the city. The ecosystem services highlighted within this report are just some of the benefits the urban forest provides. This study captures an immediate snapshot of the urban forest at the time the data was collected, in relation to the plots sampled.

The purpose of this report is to provide clear, concise information on the urban forest resource as a means to assist decision making on urban forest management.

Key findings include:

• There are nearly 1.13 million trees across Birmingham - equivalent to 0.9 trees per person and 42 trees per hectare. Tree cover was estimated at 15% with shrub cover at an estimated 11.8%.
• 74 species of tree were recorded across the Birmingham study area. The most common tree species are; Silver Birch with an estimated 125,000 trees, Sycamore with an estimated 102,000 trees, and Holly with an estimated 94,200 trees.
• Birmingham’s trees and shrubs have the potential to remove approximately 80 tonnes of air pollution every year with an associated value of £6.42 million. These pollutants include sulphur dioxide (SO2), particulate matter (PM2.5) and nitrogen dioxide (NO2).
• Birmingham’s trees reduce surface water runoff by over 481,000 m³ per year. This volume is equivalent to over 192 Olympic swimming pools of surface runoff being averted every single year, a service worth an estimated £776,000 in avoided water treatment costs.
• In total, the trees store around 419,000 tonnes of carbon and sequester 12,800 tonnes of carbon annually, with associated values of approximately £407 million and £12.5 million respectively.
• The amenity value of the trees was calculated to be £25.3 billion, as determined using a CAVAT valuation approach.
• There is a good distribution of both semi-mature and mature trees, however there are very few large senescent (ancient) trees. Managing trees to ensure they reach their full potential, namely in their stature is important, as large trees generally provide far more benefits than small trees.

The recommendations from this study include:

• Continue to plant a wide diversity of species (with due consideration to local site factors) to replace the future loss of ash, and reduce the likelihood of severe impact from any given pest or disease outbreak and/or the impacts of climate change.
• Aim to retain large, mature trees wherever possible (as large trees generally provide the most benefits) - make them part of new developments rather than lose them.
• Continue new planting to maintain a healthy tree size diversity in Birmingham in order to avoid significant losses in ecosystem service provisions in the future, whilst addressing lack of canopy and unequal distribution of the urban forest.
• Carry out a Tree Planting Opportunity Mapping study to target prioritised areas and optimise resources. This can facilitate additional planting alongside main roads, and join up/fill in gaps within the existing urban forest to enhance wildlife corridors and the connectivity of pathways and cycle lanes through green infrastructure. Tree equity analysis at neighbourhood level can also be incorporated to target areas that lack canopy cover, particularly in areas with high deprivation and which experience poor air quality, surface flooding, limited existing green space, heat stress or lack of shade.