Nature charity Plantlife is warning that air pollution, in particular a high atmospheric nitrogen level, is damaging the habitats of rare wildflowers across Wales.  High nitrogen levels favour plants such as brambles and nettles while most wildflowers prefer less rich conditions.  Plantlife say the increased nitrogen levels are substantially derived from intensive arable and livestock farming emissions of ammonia, and they can reach all parts of the country via rainfall.  Plantlife is calling for more regulations controlling ammonia emissions.