title: Changes in root architecture under elevated concentrations of CO₂ and nitrogen reflect alternate soil exploration strategies.
abstract: Predicting the response of fine roots to increased atmospheric CO₂ concentration has important implications for carbon (C) and nutrient cycling in forest ecosystems. Root architecture is known to play an important role in how trees acquire soil resources in changing environments. However, the effects of elevated CO₂ on the fine-root architecture of trees remain unclear. We investigated the architectural response of fine roots exposed to 14 yr of CO₂ enrichment and 6 yr of nitrogen (N) fertilization in a Pinus taeda (loblolly pine) forest. Root traits reflecting geometry, topology and uptake function were measured on intact fine-root branches removed from soil monoliths and the litter layer. CO₂ enrichment resulted in the development of a fine-root pool that was less dichotomous and more exploratory under N-limited conditions. The per cent mycorrhizal colonization did not differ among treatments, suggesting that root growth and acclimation to elevated CO₂ were quantitatively more important than increased mycorrhizal associations. Our findings emphasize the importance of architectural plasticity in response to environmental change and suggest that changes in root architecture may allow trees to effectively exploit larger volumes of soil, thereby pre-empting progressive nutrient limitations.
authors.affiliation: Department of Biology, College of Charleston, 58 Coming St, Charleston, SC, 29424, USA.
authors.forename: Katilyn V
authors.initials: KV
authors.lastname: Beidler
authors.affiliation: Ecology, Evolution, and Environmental Biology, Columbia University, 10th Floor, Schermerhorn Ext. 1200 Amsterdam Ave, New York, NY, 10027, USA.
authors.forename: Benton N
authors.initials: BN
authors.lastname: Taylor
authors.affiliation: Department of Biology, College of Charleston, 58 Coming St, Charleston, SC, 29424, USA.
authors.forename: Allan E
authors.initials: AE
authors.lastname: Strand
authors.affiliation: Department of Biology, College of Charleston, 58 Coming St, Charleston, SC, 29424, USA.
authors.forename: Emily R
authors.initials: ER
authors.lastname: Cooper
authors.affiliation: Department of Biology, College of Charleston, 58 Coming St, Charleston, SC, 29424, USA.
authors.forename: Marcos
authors.initials: M
authors.lastname: Schönholz
authors.affiliation: Department of Biology, College of Charleston, 58 Coming St, Charleston, SC, 29424, USA.
authors.forename: Seth G
authors.initials: SG
authors.lastname: Pritchard
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology*; D005308:Fertilizers; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology; D009584:Nitrogen / Q000494:pharmacology*; D028223:Pinus / Q000033:anatomy & histology* / Q000187:drug effects / Q000382:microbiology; D018517:Plant Roots / Q000033:anatomy & histology* / Q000187:drug effects / Q000382:microbiology; D012987:Soil / Q000737:chemistry*
chemical_list: D005308:Fertilizers; D012987:Soil; D002245:Carbon Dioxide; D009584:Nitrogen
keywords: Pinus taeda (loblolly pine); elevated CO2; fine-root architecture; foraging strategy; free-air carbon enrichment (FACE); nitrogen (N) fertilization