Air phyto-cleaning by an urban meadow – Filling the winter gap

Urban areas are characterised by polluted air which endangers the health and quality of life of city dwellers. Among the dangerous air contaminants is particulate matter (PM) and one of the main sources of PM in urban areas is road traffic. Studies have already shown that the air can be phyto-cleaned by plants, especially trees and shrubs. However, for safety reasons, planting trees and shrubs in some places is problematic, e.g. close to roads. These locations are usually occupied by lawns, which are plant communities of low ecological value. Unfortunately, too little attention has been paid so far to urban meadows. Therefore, this study (i) investigated for the first time the phyto-cleaning potential of an urban meadow all year round, including autumn–winter period, and (ii) compared the efficiency and mechanisms of PM phyto-cleaning by an urban meadow and lawn during the vegetative season. Plant material was harvested from urban meadow (in June, August, November and March) and lawns (in June and August) located by a busy road in Warsaw (Poland). PM was analysed in two categories (surface PM and in-wax PM) and two size fractions (fine: 0.2–2.5 µm, coarse: 2.5–10 µm). The results obtained suggested that accumulation of PM by urban meadow is possible even out of vegetative season. In autumn and winter, even though the meadow plants were physiologically not active, they still participated in air phyto-cleaning. Urban meadow phyto-cleaned air most effectively in summer when the vegetation was fully developed, and least effectively in autumn. During the vegetative season, the urban meadow accumulated more PM than lawns, mostly due to the greater height and complex structure. Therefore, urban meadow would appear to offer an promising solution to problem of phyto-cleaning of urban air in the immediate vicinity of roads throughout the year.