Valuing Improvements in Biodiversity Due to Controls on Atmospheric Nitrogen Pollution

Atmospheric nitrogen pollution has severe impacts on biodiversity, but approaches to value them are limited. This paper develops a spatially explicit methodology to value the benefits from improvements in biodiversity resulting from current policy initiatives to reduce nitrogen emissions. Using the UK as a case study, we quantify nitrogen impacts on plant diversity in four habitats: heathland, acid grassland, dunes and bogs, at fine spatial resolution. Focusing on non-use values for biodiversity we apply value-transfer based on household's willingness to pay to avoid changes in plant species richness, and calculate the benefit of projected emission declines of 37% for nitrogen dioxide (NO2) and 6% for ammonia (NH3) over the scenario period 2007-2020. The annualised benefit resulting from these pollutant declines is £32.7 m (£4.4 m to £109.7 m, 95% Confidence Interval), with the greatest benefit accruing from heathland and acid grassland due to their large area. We also calculate damage costs per unit of NO2 and NH3 emitted, to quantify some of the environmental impacts of air pollution for use alongside damage costs for human health in policy appraisal. The benefit is £103 (£33 to £237) per tonne of NO2 saved, and £414 (£139 to £1022) per tonne of NH3 saved.