title: Quantifying species composition in root mixtures using two methods: near-infrared reflectance spectroscopy and plant wax markers.
abstract: Understanding of plant interactions is greatly limited by our ability to identify and quantify roots belonging to different species. We proposed and compared two methods for estimating the root biomass proportion of each species in artificial mixtures: near-infrared reflectance spectroscopy (NIRS) and plant wax markers. Two sets of artificial root mixtures composed of two or three herbaceous species were prepared. The proportion of root material of each species in mixtures was estimated from NIRS spectral data (i) and the concentration patterns of n-alkanes (ii), n-alcohols (iii), and n-alkanes +n-alcohols combined (iv). For each data set, calibration equations were developed using multivariate statistical models. The botanical composition of root mixtures was predicted well for all the species considered. The accuracy varied slightly among methods: alkanes < alcohols = alkanes + alcohols < NIRS. Correlation coefficients between predicted and actual root proportions ranged from 0.89 to 0.99 for alkanes + alcohols predictions and from 0.97 to 0.99 for NIRS predictions. These two methods provide promising potential for understanding allocation patterns and competitive interactions.
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, UMR 5175, 1919 route de Mende, 34293 Montpellier Cedex 5, France. catherine.roumet@cefe.cnrs.fr
authors.forename: Catherine
authors.initials: C
authors.lastname: Roumet
authors.forename: Catherine
authors.initials: C
authors.lastname: Picon-Cochard
authors.forename: Lorna A
authors.initials: LA
authors.lastname: Dawson
authors.forename: Richard
authors.initials: R
authors.lastname: Joffre
authors.forename: Robert
authors.initials: R
authors.lastname: Mayes
authors.forename: Alain
authors.initials: A
authors.lastname: Blanchard
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Brewer
mesh_terms: D000473:Alkanes / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D018533:Biomass; D005233:Fatty Alcohols / Q000032:analysis*; D018517:Plant Roots / Q000737:chemistry / Q000145:classification*; D013045:Species Specificity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D014885:Waxes / Q000737:chemistry*
chemical_list: D000473:Alkanes; D015415:Biomarkers; D005233:Fatty Alcohols; D014885:Waxes