title: Phosphorus resource partitioning shapes phosphorus acquisition and plant species abundance in grasslands.
abstract: Species diversity is commonly hypothesized to result from trade-offs for different limiting resources, providing separate niches for coexisting species1-4. As soil nutrients occur in multiple chemical forms, plant differences in acquisition of the same element derived from different compounds may represent unique niche dimensions5,6. Because plant productivity of ecosystems is often limited by phosphorus7, and because plants have evolved diverse adaptations to acquire soil phosphorus6,8, a promising yet untested hypothesis is phosphorus resource partitioning6,9,10. Here, we provided two different chemical forms of phosphorus to sown grassland mesocosms to investigate phosphorus acquisition of eight plant species that are common in European grasslands, and to identify subsequent patterns of plant abundance. For the first time, we show that the relative abundance of grassland plant species can be influenced by soil phosphorus forms, as higher abundance was linked to higher acquisition of a specific form of phosphorus. These results were supported by a subsequent isotope dilution experiment using intact grassland sods that were treated with different inorganic or organic phosphorus forms. Here, 5 out of 14 species showed greater phosphorus acquisition in the inorganic phosphorus treatment, and 4 in the organic phosphorus treatments. Furthermore, for the species used in both experiments we found similar acquisition patterns. Our results support the hypothesis of phosphorus resource partitioning and may provide a new mechanistic framework to explain high plant diversity in phosphorus-poor ecosystems6,11-13. As world biodiversity hotspots are almost invariably related to phosphorus limitation8,11,12, our results may thus also be key to understanding biodiversity loss in an era of ever-increasing nutrient enrichment14.
authors.affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Tobias
authors.initials: T
authors.lastname: Ceulemans
authors.affiliation: Isotope Bioscience Laboratory - ISOFYS, Department of Applied Analytical and Physical Chemistry, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Samuel
authors.initials: S
authors.lastname: Bodé
authors.affiliation: Soil and Water Management, Department of Earth and Environmental Science, University of Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Jessica
authors.initials: J
authors.lastname: Bollyn
authors.affiliation: Department of Physiological Diversity, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, 04318 Leipzig, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.|Institute of Biology, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle (Saale), Germany.
authors.forename: Stanley
authors.identifier: 0000-0002-3404-9174
authors.initials: S
authors.lastname: Harpole
authors.affiliation: Soil and Water Management, Department of Earth and Environmental Science, University of Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Kristin
authors.initials: K
authors.lastname: Coorevits
authors.affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Peeters
authors.affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Kasper
authors.initials: K
authors.lastname: Van Acker
authors.affiliation: Soil and Water Management, Department of Earth and Environmental Science, University of Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
authors.forename: Erik
authors.initials: E
authors.lastname: Smolders
authors.affiliation: Isotope Bioscience Laboratory - ISOFYS, Department of Applied Analytical and Physical Chemistry, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Pascal
authors.initials: P
authors.lastname: Boeckx
authors.affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium.
authors.forename: Olivier
authors.identifier: 0000-0002-4287-8511
authors.initials: O
authors.lastname: Honnay
mesh_terms: D044822:Biodiversity; D017753:Ecosystem; D005060:Europe; D065948:Grassland; D019684:Magnoliopsida / Q000502:physiology*; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism*; D011156:Population Density
chemical_list: D010758:Phosphorus