DOI: 10.5061/dryad.4vc2n
title: Data from: Fine root tradeoffs between nitrogen concentration and xylem vessel traits preclude unified whole-plant resource strategies in Helianthus

description: Recent work suggests variation in plant growth strategies is governed by a
 tradeoff in resource acquisition and use, ranging from a rapid resource
 acquisition strategy to a resource-conservative strategy. While evidence
 for this tradeoff has been found in leaves, knowledge of root trait
 strategies, and whether they reflect adaptive differentiation across
 environments, is limited. In the greenhouse, we investigated variation in
 fine root morphology (specific root length and tissue density), chemistry
 (nitrogen concentration and carbon:nitrogen), and anatomy (root
 cross-sectional traits) in populations of 26 Helianthus species and sister
 Phoebanthus tenuifolius. We also compared root trait variation in this
 study with leaf trait variation previously reported in a parallel study of
 these populations. Root traits varied widely and exhibited little
 phylogenetic signal, suggesting high evolutionary lability. Specific root
 length and root tissue density were weakly negatively correlated, but
 neither was associated with root nitrogen, providing little support for a
 single axis of root trait covariation. Correlations between traits
 measured in the greenhouse and native site characteristics were generally
 weak, suggesting a variety of equally viable root trait combinations exist
 within and across environments. However, high root nitrogen was associated
 with lower xylem vessel number and cross-sectional area, suggesting a
 tradeoff between nutrient investment and water transport capacity. This
 led to correlations between root and leaf traits that were not always
 consistent with an acquisition–conservation tradeoff at the whole-plant
 level. Given that roots must balance acquisition of water and nutrients
 with functions like anchorage, exudation, and microbial symbioses, the
 varied evidence for root trait covariation likely reflects the complexity
 of interacting selection pressures belowground. Similarly, the lack of
 evidence for a single acquisition–conservation tradeoff at the whole-plant
 level likely reflects the vastly different selection pressures shaping
 roots and leaves, and the resources they are optimized to obtain.
description: Population collection
 sites and USDA National Genetic Resources Program (GRIN) accession numbers
 for populations of 26 Helianthus species and Phoebanthus
 tenuifolius.Population collection
 sites and USDA National Genetic Resources Program (GRIN) accession numbers
 for populations of 26 Helianthus species and Phoebanthus tenuifolius grown
 in a common garden.DatasetS1.xlsxNumber of replicate seedlings used for analyses of fine root traitsNumber of replicate Helianthus and Phoebanthus tenuifolius seedlings per population used for analysis of root morphology, chemistry, and anatomy in each year of the study and pooled over the entire study.DatasetS2.xlsxLeast-squares means for fine root traits in populations of 26 Helianthus species and Phoebanthus tenuifolius.Least-squares means for fine root traits in populations of 26 Helianthus species and Phoebanthus tenuifolius.DatasetS3.xlsxNative site characteristics for populations of 26 species of Helianthus and Phoebanthus tenuifolius, representing a subset of the data reported in Mason and Donovan (2015).Native site characteristics for populations of 26 species of Helianthus and Phoebanthus tenuifolius, representing a subset of the data reported in Mason and Donovan (2015).DatasetS4.xlsx