title: Functional diversity of leaf nitrogen concentrations drives grassland carbon fluxes.
abstract: Little is known about the role of plant functional diversity for ecosystem-level carbon (C) fluxes. To fill this knowledge gap, we translocated monoliths hosting communities with four and 16 sown species from a long-term grassland biodiversity experiment ('The Jena Experiment') into a controlled environment facility for ecosystem research (Ecotron). This allowed quantifying the effects of plant diversity on ecosystem C fluxes as well as three parameters of C uptake efficiency (water and nitrogen use efficiencies and apparent quantum yield). By combining data on ecosystem C fluxes with vegetation structure and functional trait-based predictors, we found that increasing plant species and functional diversity led to higher gross and net ecosystem C uptake rates. Path analyses and light response curves unravelled the diversity of leaf nitrogen concentration in the canopy as a key functional predictor of C fluxes, either directly or indirectly via LAI and aboveground biomass.
authors.affiliation: CNRS, Ecotron - UPS 3248, Campus Baillarguet, 34980, Montferrier-sur-Lez, France.
authors.forename: Alexandru
authors.initials: A
authors.lastname: Milcu
authors.forename: Christiane
authors.initials: C
authors.lastname: Roscher
authors.forename: Arthur
authors.initials: A
authors.lastname: Gessler
authors.forename: Dörte
authors.initials: D
authors.lastname: Bachmann
authors.forename: Annette
authors.initials: A
authors.lastname: Gockele
authors.forename: Markus
authors.initials: M
authors.lastname: Guderle
authors.forename: Damien
authors.initials: D
authors.lastname: Landais
authors.forename: Clément
authors.initials: C
authors.lastname: Piel
authors.forename: Christophe
authors.initials: C
authors.lastname: Escape
authors.forename: Sebastien
authors.initials: S
authors.lastname: Devidal
authors.forename: Olivier
authors.initials: O
authors.lastname: Ravel
authors.forename: Nina
authors.initials: N
authors.lastname: Buchmann
authors.forename: Gerd
authors.initials: G
authors.lastname: Gleixner
authors.forename: Anke
authors.initials: A
authors.lastname: Hildebrandt
authors.forename: Jacques
authors.initials: J
authors.lastname: Roy
mesh_terms: D044822:Biodiversity; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D017753:Ecosystem; D018515:Plant Leaves / Q000737:chemistry; D010944:Plants / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D002244:Carbon
keywords: Apparent quantum yield; Ecotron; Jena Experiment; Rao's quadratic entropy; biodiversity-ecosystem functioning; gross primary productivity; net ecosystem productivity; nitrogen use efficiency; plant species richness; water use efficiency