Functional composition has stronger impact than species richness on carbon gain and allocation in experimental grasslands

PLoS One. 2019 Jan 31;14(1):e0204715. doi: 10.1371/journal.pone.0204715. eCollection 2019.

Abstract

Numerous experiments have shown positive diversity effects on plant productivity, but little is known about related processes of carbon gain and allocation. We investigated these processes in a controlled environment (Montpellier European Ecotron) applying a continuous 13CO2 label for three weeks to 12 soil-vegetation monoliths originating from a grassland biodiversity experiment (Jena Experiment) and representing two diversity levels (4 and 16 sown species). Plant species richness did not affect community- and species-level 13C abundances neither in total biomass nor in non-structural carbohydrates (NSC). Community-level 13C excess tended to be higher in the 16-species than in the 4-species mixtures. Community-level 13C excess was positively related to canopy leaf nitrogen (N), i.e. leaf N per unit soil surface. At the species level, shoot 13C abundances varied among plant functional groups and were larger in legumes and tall herbs than in grasses and small herbs, and correlated positively with traits as leaf N concentrations, stomatal conductance and shoot height. The 13C abundances in NSC were larger in transport sugars (sucrose, raffinose-family oligosaccharides) than in free glucose, fructose and compounds of the storage pool (starch) suggesting that newly assimilated carbon is to a small portion allocated to storage. Our results emphasize that the functional composition of communities is key in explaining carbon assimilation in grasslands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biodiversity*
  • Carbon Isotopes / analysis
  • Carbon Isotopes / metabolism*
  • Grassland*
  • Nitrogen / metabolism
  • Plant Leaves / chemistry
  • Plant Leaves / metabolism
  • Poaceae / chemistry
  • Poaceae / metabolism*
  • Soil / chemistry*
  • Sugars / metabolism

Substances

  • Carbon Isotopes
  • Soil
  • Sugars
  • Carbon-13
  • Nitrogen

Grants and funding

The Jena Experiment is funded by the German Research Foundation (FOR456/1451). N. Buchmann and D. Bachmann acknowledge funding of the Swiss National Science Foundation (315230E-131194). This study benefited from the CNRS human and technical resources allocated to the ECOTRONS Research Infrastructure as well as from the state allocation “Investissement d’Avenir” AnaEE-France ANR-11-INBS-0001. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.