title: Increased plant growth from nitrogen addition should conserve phosphorus in terrestrial ecosystems.
abstract: Inputs of available nitrogen (N) to ecosystems have grown over the recent past. There is limited general understanding of how increased N inputs affect the cycling and retention of other potentially limiting nutrients. Using a plant-soil nutrient model, and by explicitly coupling N and phosphorus (P) in plant biomass, we examine the impact of increasing N supply on the ecosystem cycling and retention of P, assuming that the main impact of N is to increase plant growth. We find divergent responses in the P cycle depending on the specific pathway by which nutrients are lost from the ecosystem. Retention of P is promoted if the relative propensity for loss of plant available P is greater than that for the loss of less readily available organic P. This is the first theoretical demonstration that the coupled response of ecosystem-scale nutrient cycles critically depends on the form of nutrient loss. P retention might be lessened, or reversed, depending on the kinetics and size of a buffering reactive P pool. These properties determine the reactive pool's ability to supply available P. Parameterization of the model across a range of forest ecosystems spanning various environmental and climatic conditions indicates that enhanced plant growth due to increased N should trigger increased P conservation within ecosystems while leading to more dissolved organic P loss. We discuss how the magnitude and direction of the effect of N may also depend on other processes.
authors.affiliation: Division of Biology, Imperial College London, Silwood Park SL5 7PY, United Kingdom. michael.perring03@imperial.ac.uk
authors.forename: Michael P
authors.initials: MP
authors.lastname: Perring
authors.forename: Lars O
authors.initials: LO
authors.lastname: Hedin
authors.forename: Simon A
authors.initials: SA
authors.lastname: Levin
authors.forename: Megan
authors.initials: M
authors.lastname: McGroddy
authors.forename: Claire
authors.initials: C
authors.lastname: de Mazancourt
mesh_terms: D017753:Ecosystem; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D063245:Plant Development; D010944:Plants / Q000378:metabolism
chemical_list: D010758:Phosphorus; D009584:Nitrogen