title: Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species.
abstract: Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders.
authors.affiliation: Ecology, Department of Biology, University of Konstanz Konstanz, Germany ; Department of Biology, Institute of Plant Sciences, University of Bern Bern, Switzerland.
authors.forename: Lidewij H
authors.initials: LH
authors.lastname: Keser
authors.affiliation: Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen Nijmegen, Netherlands.
authors.forename: Eric J W
authors.initials: EJ
authors.lastname: Visser
authors.affiliation: Ecology, Department of Biology, University of Konstanz Konstanz, Germany.
authors.forename: Wayne
authors.initials: W
authors.lastname: Dawson
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Yao-Bin
authors.initials: YB
authors.lastname: Song
authors.affiliation: School of Nature Conservation, Beijing Forestry University Beijing, China.
authors.forename: Fei-Hai
authors.initials: FH
authors.lastname: Yu
authors.affiliation: Department of Biology, Institute of Plant Sciences, University of Bern Bern, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Fischer
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Dong
authors.affiliation: Ecology, Department of Biology, University of Konstanz Konstanz, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: van Kleunen
keywords: invasion ecology; multi-species comparison; nutrient heterogeneity; phenotypic plasticity; pre-adaptation; root morphology