Soil phosphorus constrains biodiversity across European grasslands

Abstract

Nutrient pollution presents a serious threat to biodiversity conservation. In terrestrial ecosystems, the deleterious effects of nitrogen pollution are increasingly understood and several mitigating environmental policies have been developed. Compared to nitrogen, the effects of increased phosphorus have received far less attention, although some studies have indicated that phosphorus pollution may be detrimental for biodiversity as well. On the basis of a dataset covering 501 grassland plots throughout Europe, we demonstrate that, independent of the level of atmospheric nitrogen deposition and soil acidity, plant species richness was consistently negatively related to soil phosphorus. We also identified thresholds in soil phosphorus above which biodiversity appears to remain at a constant low level. Our results indicate that nutrient management policies biased toward reducing nitrogen pollution will fail to preserve biodiversity. As soil phosphorus is known to be extremely persistent and we found no evidence for a critical threshold below which no environmental harm is expected, we suggest that agro-environmental schemes should include grasslands that are permanently free from phosphorus fertilization.

Species-rich grassland can persist under nitrogen-rich but phosphorus-limited conditions

“…However, an increase in P availability due, for instance to application of fertiliser or influx of nutrient-rich surface water will most probably lead to a further loss of species. In general our data lend experimental support to the view of Ceulemans et al (2014) that the general decrease of species numbers in the grasslands northwestern Europe is not only due to enrichment by N but also by P.…”

“…In practice this may mean that if P is added to a species-rich, P-(co)limited site, a strong loss of botanical diversity may occur, irrespective of effects of N. As P is highly immobile in soils this is most likely to occur in sites that are influenced by external supply of surface-water such as fens or mires. However, spreading of fertiliser dust (Ceulemans et al 2014) or chemical changes in the soil that increase P availability (e.g. acidification; Hinsinger 2001) may also play a role.…”

“…P enrichment may therefore be even more detrimental to plant species diversity than N enrichment (Wassen et al 2005). Ceulemans et al (2014), in a large-scale gradient study, showed a clear negative relationship between species number in grassland plots and P availability, independent of the level of atmospheric N deposition. Like the global carbon (Falkowski et al 2000) and nitrogen (Galloway and Cowling 2002) cycles, the phosphorus cycle has been accelerated by human activities during previous centuries, and probably even more strongly so (Wassen et al 2005), which would be a serious threat to biodiversity if P-limitation is a widespread phenomenon.…”

Last-Century Increases in Intrinsic Water-Use Efficiency of Grassland Communities Have Occurred over a Wide Range of Vegetation Composition, Nutrient Inputs, and Soil pH

“…Much of the extant ecosystem-scale variability of plant species richness and soil pH in temperate grasslands of Europe (Ceulemans et al, 2014) is included in the range of plot-scale plant species richness and soil pH at the PGE (which is reported in this investigation). The different long-term applications of fertilizer and lime over the past century have resulted in substantial changes in soil pH, species richness, and grass content on the experimental plots, but in most cases, within-plot changes over the study period considered here were comparatively small (Crawley et al, 2005;Silvertown et al, 2006).…”

Soil phosphorus fractionation as a tool for monitoring dust phosphorus signature underneath a Blue Pine (Pinus wallichiana) canopy in a Temperate Forest

“…However, the concentrations of Pi in soils underneath stemflow and throughfall were significantly higher than open field soil would result unique niches that will support more biodiversity on the forest floor. Bioavailable P concentrations in the soils have been implicated in controlling the biodiversity in natural ecosystems (Ceulemans et al, 2014).…”