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Abstract: Urban green space and particularly the tree canopy have been highlighted as offering a mitigation potential against atmospheric particulate pollution. In this paper current and future particulate (PM10) deposition to the urban tree canopy of the Greater London Authority (GLA) was estimated. A modelling approach was used based on the Urban Forest Effects Model (UFORE) and a modified version. Here we give evidence showing that these deposition models can be adapted to run from annual mean meteorological and PM10 concentration data, thus providing a methodology to examine future scenarios. Depending on the modelling approach, the urban canopy of the GLA is currently estimated to remove between 852 and 2121tonnes of PM10 annually; representing between 0.7% and 1.4% of PM10 from the urban boundary layer. Estimates of PM10 removal which take into account a planned increased in tree cover, from the current 20% to 30% of the GLA land area, suggest deposition of 1109–2379tonnes (1.1–2.6% removal) by the year 2050. The evidence provided here suggests that the targeting of tree planting in the most polluted areas of the GLA and particularly the use of street trees which have the greatest exposure to PM10, would have the greatest benefit to future air quality. The increased deposition would be greatest if a larger proportion of coniferous to broadleaved trees were used at such sites. [Copyright &y& Elsevier]

To optimise trade-offs provided by future changes in grassland use intensity, spatially and temporally explicit estimates of respective grassland productivities are required at the systems level. Here, we benchmark the potential national availability of grassland biomass, identify optimal strategies for its management, and investigate the relative importance of intensification over reversion (prioritising productivity versus environmental ecosystem services). Process-conservative meta-models for different grasslands were used to calculate the baseline dry matter yields (DMY; 1961–1990) at 1 km 2 resolution for the whole UK. The effects of climate change, rising atmospheric [CO 2 ] and technological progress on baseline DMYs were used to estimate future grassland productivities (up to 2050) for low and medium CO 2 emission scenarios of UKCP09. UK benchmark productivities of 12.5, 8.7 and 2.8 t/ha on temporary, permanent and rough-grazing grassland, respectively, accounted for productivity gains by 2010. By 2050, productivities under medium emission scenario are predicted to increase to 15.5 and 9.8 t/ha on temporary and permanent grassland, respectively, but not on rough grassland. Based on surveyed grassland distributions for Great Britain in 2010 the annual availability of grassland biomass is likely to rise from 64 to 72 million tonnes by 2050. Assuming optimal N application could close existing productivity gaps of ca. 40% a range of management options could deliver additional 21 ∗ 10 6 tonnes of biomass available for bioenergy. Scenarios of changes in grassland use intensity demonstrated considerable scope for maintaining or further increasing grassland production and sparing some grassland for the provision of environmental ecosystem services. [ABSTRACT FROM AUTHOR]