title: Interspecific vs intraspecific patterns in leaf nitrogen of forest trees across nitrogen availability gradients.
abstract: Leaf nitrogen content (δ) coordinates with total canopy N and leaf area index (LAI) to maximize whole-crown carbon (C) gain, but the constraints and contributions of within-species plasticity to this phenomenon are poorly understood. Here, we introduce a game theoretic, physiologically based community model of height-structured competition between late-successional tree species. Species are constrained by an increasing, but saturating, relationship between photosynthesis and leaf N per unit leaf area. Higher saturating rates carry higher fixed costs. For a given whole-crown N content, a C gain-maximizing compromise exists between δ and LAI. With greater whole-crown N, both δ and LAI increase within species. However, a shift in community composition caused by reduced understory light at high soil N availability (which competitively favors species with low leaf costs and consequent low optimal δ) counteracts the within-species response, such that community-level δ changes little with soil N availability. These model predictions provide a new explanation for the changes in leaf N per mass observed in data from three dominant broadleaf species in temperate deciduous forests of New England. Attempts to understand large-scale patterns in vegetation often omit competitive interactions and intraspecific plasticity, but here both are essential to an understanding of ecosystem-level patterns.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Ray
authors.initials: R
authors.lastname: Dybzinski
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Farrior
authors.affiliation: Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH, 03824, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Ollinger
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Pacala
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D008027:Light; D008954:Models, Biological; D009511:New England; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D012987:Soil / Q000737:chemistry; D013045:Species Specificity; D014197:Trees / Q000145:classification / Q000502:physiology*
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: Evolutionarily Stable Strategy (ESS); Perfect Plasticity Approximation (PPA); White Mountains New Hampshire; foliar nitrogen (N); forest diversity; game theory; light competition; shade tolerance