Excess atmospheric nitrogen poses a major threat to biodiversity across the UK, particularly through nitrogen deposition and associated eutrophication and acidification. These pressures alter ecosystem structure and function, affecting species composition, particularly in sensitive habitats. While the impacts of nitrogen on plant communities are well established, less is known about the consequences for higher trophic levels.
In 2022, Natural England hosted two PhD placements through the ACCE Doctoral Training Partnership to conduct rapid reviews of the current evidence on lethal, sub-lethal, and habitat-mediated impacts of air pollutants on higher trophic species. This review highlights key knowledge gaps and draws attention to the indirect effects of nitrogen on food quality, abundance, and plant chemistry, with cascading impacts on dependent species.
Acidification also contributes to higher trophic level ecological degradation by altering soil chemistry and reducing plant viability. Specialist species are found to be more vulnerable than generalists, yet significant gaps remain, particularly regarding impacts on mammals and long-term ecosystem function.
This evidence base could help to inform future research priorities in England and support broader public and stakeholder engagement with air quality as a critical ecological issue.