What the trees tell us

Photo by Maxwell Ayamba
Photo by Maxwell Ayamba

Story by Maxwell Ayamba

English language students from Sheffield College Fir Vale Centre and pupils at Byron Wood Primary Academy school pupils took part in an Open Air Laboratory (OPAL) Explore Nature air survey around Osgathorpe and at Byron Wood’s “forest school”.

Air pollution locally is up to two and a half times the legal limit and is responsible for up to 500 deaths each year in Sheffield. Dangerously high levels of nitrogen dioxide have been recorded around the city as part of a community monitoring scheme, with the Council recently initiating an Air Aware campaign to highlight the dangers of traffic fumes.

The Council’s air monitoring scheme is very technical but the Sheffield Environmental Movement (SEM) is using bioindicators such as lichens and black tar spots on sycamore trees to raise awareness visually among school pupils and college students.

SEM use lichens found on tree trunks to estmate the amount of nitrogen-containing air polluton at the survey site, calculated by the Air Polluton Index. The lower the Air Polluton Index the higher the amount of nitrogen-loving lichens compared to the amount of nitrogen-sensitve lichens. Another guide to polluton is the Tar Spot Index, as tar spots are caused by fungal infecton found less in areas of high polluton .