title: Root structure-function relationships in 74 species: evidence of a root economics spectrum related to carbon economy.
abstract: Although fine roots are important components of the global carbon cycle, there is limited understanding of root structure-function relationships among species. We determined whether root respiration rate and decomposability, two key processes driving carbon cycling but always studied separately, varied with root morphological and chemical traits, in a coordinated way that would demonstrate the existence of a root economics spectrum (RES). Twelve traits were measured on fine roots (diameter ≤ 2 mm) of 74 species (31 graminoids and 43 herbaceous and dwarf shrub eudicots) collected in three biomes. The findings of this study support the existence of a RES representing an axis of trait variation in which root respiration was positively correlated to nitrogen concentration and specific root length and negatively correlated to the root dry matter content, lignin : nitrogen ratio and the remaining mass after decomposition. This pattern of traits was highly consistent within graminoids but less consistent within eudicots, as a result of an uncoupling between decomposability and morphology, and of heterogeneity of individual roots of eudicots within the fine-root pool. The positive relationship found between root respiration and decomposability is essential for a better understanding of vegetation-soil feedbacks and for improving terrestrial biosphere models predicting the consequences of plant community changes for carbon cycling.
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Roumet
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS - Université de Montpellier - Université Paul Valéry Montpellier - EPHE, 1919 Route de Mende, 34293, Montpellier Cedex 5, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Birouste
authors.affiliation: INRA, UR 874, UREP, Grassland Ecosystem Research, 5 Chemin de Beaulieu, 63039, Clermont-Ferrand, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Picon-Cochard
authors.affiliation: INRA, UMR AMAP, Boulevard de la Lironde, 34398, Montpellier Cedex 5, France.
authors.forename: Murielle
authors.initials: M
authors.lastname: Ghestem
authors.affiliation: Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors.forename: Normaniza
authors.initials: N
authors.lastname: Osman
authors.affiliation: INRA, UR 874, UREP, Grassland Ecosystem Research, 5 Chemin de Beaulieu, 63039, Clermont-Ferrand, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Vrignon-Brenas
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Forestry, Guangxi University, Nanning, Guangxi, 530004, China.
authors.forename: Kun-Fang
authors.initials: KF
authors.lastname: Cao
authors.affiliation: INRA, UMR AMAP, Boulevard de la Lironde, 34398, Montpellier Cedex 5, France.
authors.forename: Alexia
authors.initials: A
authors.lastname: Stokes
mesh_terms: D002244:Carbon / Q000378:metabolism*; D019069:Cell Respiration; D016014:Linear Models; D018517:Plant Roots / Q000033:anatomy & histology* / Q000502:physiology*; D025341:Principal Component Analysis; D013045:Species Specificity
chemical_list: D002244:Carbon
keywords: economics spectrum; eudicots; fine-root traits; graminoids; nitrogen; plant diversity; root decomposability; root respiration