More evidence about the (really) positive role of trees. Government agency Natural England has published a report about the benefits of investing in the natural environment (MEBEI2). The report sets out evidence from a number of studies into the effects of natural infrastructure on health, wellbeing, work, productivity and climate change.
The importance of trees and woodlands, particularly in urban areas, was highlighted throughout the report. Some key points are:
- “Trees and plants can reduce the need for heating and cooling of buildings, and therefore lower energy costs.
- “Urban centres in particular may in future suffer from dangerous heat and air pollution. Some of the impact may be reduced by investment in the natural environment (particularly trees).
- “By increasing infiltration rates in forest soils, trees can have significant impacts on flooding, modelling since the O’Connell review in Pontebren in Wales suggests that in this context, a shelterbelt at right angles to the slope could reduce field scale flood peaks by 40%.
- “Urban forests intercept rain water and reduce peak run off… Test plots in Manchester demonstrated that over a year, the addition of a street tree could reduce stormwater runoff by between 50% and 62% in a 9 square metre area, compared with asphalt alone.
- “Trees can contribute to greater hydraulic roughness of floodplains, slowing water flow. Modelling around the River Parrett… found that floodplain woodland could slow water velocity within the woodland, increasing the water level by up to 270mm and increasing flood storage by 71%.
- “Green infrastructure makes a number of important contributions to local climate regulation… A single large tree can transpire 450 litres of water in a day which uses 1000 mega joules of heat energy, making urban trees an effective way to reduce urban temperature.
- “Modelling of the impact of trees on a two-storey office building in Scotland found that using trees as a shelterbelt could potentially reduce office heating energy use by 3.64 kilowatts per square metre of floor area (18.1 percent of total heating energy use)… from October to April.
- “Surveys across 26 different-sized cities in the USA found that shoppers reported being willing to travel further to visit, stay longer once there, and more frequently visit, business districts with trees.”