Decreasing nitrogen deposition rates: Good news for oligotrophic grassland species?

Several studies have found that increased nitrogen (N) deposition leads to a decline in species richness semi-natural grasslands, mainly due the loss of typical nutrient-poor soils. However, after reaching peak around 1990, N has decreased Europe over last 30 years. In this study, we investigated changes number and composition grasslands during period declining deposition. To end, compared data from first survey (2001-2005) 147 grassland sites Switzerland with those third (2011-2015). We further analysed vegetation development specific hay meadow 1992 2013. grassland, total cover graminoid decreased, while oligotrophic increased. At sites, at still high levels it tended increase low deposition, i. e. below critical load for The large decrease strong inclination. Thus, results study indicate reduction emissions had measurable positive effect on diversity these grasslands. Most surveyed appear be quite resilient against they do not shift an alternative state dominated by few competitive species, recovery as result seems possible, especially steep slopes. Furthermore, underlines importance regular management semi-natural, unfertilised, low-productivity maintain species.