Grassland futures in Great Britain – productivity assessment and scenarios for land use change opportunities

To optimise trade-offs provided by future changes in grassland management, spatially and temporally explicit estimates of grassland productivity 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) at 1 km2 resolution for the whole UK. The effects of climate change, rising atmospheric [CO2] and technological progress on baseline DMYs were used to estimate future grassland productivities (up to 2050) for low and medium CO2 emission scenarios of UKCP09. UK baseline productivities (1970-1980) of 10.5, 7.9 and 2.6 t/ha were extrapolated to benchmark productivities (2010) of 12.5, 8.7 and 2.8 t/ha on temporary, permanent and rough-grazing grassland, respectively. By 2050, grassland productivities under medium emission scenario is 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 grasslands areas for Great Britain in 2010 the GIS-modelled distributions of grassland productivity and total availability of biomass were shown at 1 km2 grid. Assuming that optimal N application could close existing productivity gaps of ca. 40% there are a range of management options available that could deliver additional biomass availability or spare some grasslands for provision of other ecosystem services.