Urban meadows as an alternative to short mown grassland: Effects of composition and height on biodiversity

There are increasing calls to provide greenspace in urban areas, yet the ecological quality, as well as quantity, of greenspace is important. Short mown grassland designed for recreational use is the dominant form of urban greenspace in temperate regions but requires considerable maintenance and typically provides limited habitat value for most taxa. Alternatives are increasingly proposed, but the biodiversity potential of these is not well understood. In a replicated experiment across six public urban greenspaces we used nine different perennial meadow plantings to quantify the relative roles of floristic diversity and height of sown meadows on the richness and composition of three taxonomic groups – plants, invertebrates and soil microbes. We found that all meadow treatments were colonised by plant species not sown in the plots, suggesting that establishing sown meadows does not preclude further locally determined grassland development if management is appropriate. Colonising species were rarer in taller and more diverse plots, indicating competition may limit invasion rates. Urban meadow treatments contained invertebrate and microbial communities that differed from mown grassland. Invertebrate taxa responded to changes in both height and richness of meadow vegetation, but most orders were more abundant where vegetation height was longer than mown grassland. Order richness also increased in longer vegetation and Coleoptera family richness increased with plant diversity in summer. Microbial community composition seems sensitive to plant species composition at the soil surface (0–10 cm), but in deeper soils (11–20 cm) community variation was most responsive to plant height, with bacteria and fungi responding differently. In addition to improving local residents’ satisfaction, native perennial meadow plantings can produce biologically diverse grasslands that support richer and more abundant invertebrate communities, and restructured plant, invertebrate and soil microbial communities compared with short mown grassland. Our results suggest that diversification of urban greenspace by planting urban meadows in place of some mown amenity grassland is likely to generate substantial biodiversity benefits, with a mosaic of meadow types likely to maximise such benefits

Urban meadows as an alternative to short mown grassland: effects of composition and height on biodiversity

There are increasing calls to provide greenspace in urban areas, yet the ecological quality, as well as quantity, of greenspace is important. Short mown grassland designed for recreational use is the dominant form of urban greenspace in temperate regions but requires considerable maintenance and typically provides limited habitat value for most taxa. Alternatives are increasingly proposed, but the biodiversity potential of these is not well understood. In a replicated experiment across six public urban greenspaces, we used nine different perennial meadow plantings to quantify the relative roles of floristic diversity and height of sown meadows on the richness and composition of three taxonomic groups: plants, invertebrates, and soil microbes. We found that all meadow treatments were colonized by plant species not sown in the plots, suggesting that establishing sown meadows does not preclude further locally determined grassland development if management is appropriate. Colonizing species were rarer in taller and more diverse plots, indicating competition may limit invasion rates. Urban meadow treatments contained invertebrate and microbial communities that differed from mown grassland. Invertebrate taxa responded to changes in both height and richness of meadow vegetation, but most orders were more abundant where vegetation height was longer than mown grassland. Order richness also increased in longer vegetation and Coleoptera family richness increased with plant diversity in summer. Microbial community composition seems sensitive to plant species composition at the soil surface (0–10 cm), but in deeper soils (11–20 cm) community variation was most responsive to plant height, with bacteria and fungi responding differently. In addition to improving local residents’ site satisfaction, native perennial meadow plantings can produce biologically diverse grasslands that support richer and more abundant invertebrate communities, and restructured plant, invertebrate, and soil microbial communities compared with short mown grassland. Our results suggest that diversification of urban greenspace by planting urban meadows in place of some mown amenity grassland is likely to generate substantial biodiversity benefits, with a mosaic of meadow types likely to maximize such benefits.N/

26. The Validity of Student Course Evaluations: An Eternal Debate?

Student evaluation of courses and teaching at universities remains a highly contentious and divisive topic. Emotions and anecdotal evidence can overrule conclusions drawn from research on the validity and design of course evaluations. However, even amongst researchers, there is significant disagreement on the efficacy of course and teaching evaluations. This paper explores this ongoing dialogue through the medium of a parliamentary debate drawing from the breadth of current research on course evaluations

Ozone photochemistry during the UK heat wave of August 2003

A wide range of chemical and physical parameters have been observed over the course of a severe Europe-wide air pollution episode in August 2003. Detailed surface observations made at the rural perimeter edge of London, U.K. indicated significantly elevated levels of primary VOCs, ozone (>110ppb), other photochemical by-products such as PAN, HCHO, and higher oxygenates but not NOx. Reactive organic tracers in combination with surface Doppler wind radar and back trajectory analysis have been used to establish that initial rapid morning rises in O3 during the episode were caused by entrainment of air from aloft, polluted on regional scales from mainland Europe. Total VOC reactivity to OH approximately doubled during this episode, with similar distribution between functional groups, but showing a temperature dependant exponentially increasing contribution from biogenic isoprene (max 1.2 ppbV). In addition to entrainment of regional air pollution, ozone formation rates within the U.K. boundary layer on the day of observation have been determined using measured peroxy radicals in combination with other chemical data. Under episodic conditions total peroxy radicals in excess 120pptV were observed in late afternoon with strong correlation to a later and higher peak in ozone when compared to non-episodic conditions. During the daytime under episodic conditions alkyl peroxy radical formation was dominated by PAN thermolysis, whose afternoon lifetime averaged only 18.3 min, but which was sustained at a concentration greater than 750 pptV. Low episodic wind speeds resulted in a relatively small possible spatial footprint for emissions of reactive precursors to PAN, and a strong correlation between isoprene and PAN production rate suggest this species may have contributed to the later afternoon increases seen in surface O3