DOI: 10.5061/dryad.8125b
title: Data from: Intraspecific variability and reaction norms of forest understory plant species traits

description: 1.Trait-based models of ecological communities typically assume
 intraspecific variation in functional traits is not important, though such
 variation can change species trait rankings along gradients in resources
 and environmental conditions, and thus influence community structure and
 function. 2. We examined the degree of intraspecific relative to
 interspecific variation, and reaction norms of 11 functional traits for 57
 forest understory plant species, including: intrinsic water-use efficiency
 (iWUE), Δ15N, 5 leaf traits, 2 stem traits and 2 root traits along
 gradients in light, nitrogen, moisture and understory cover. 3. Our
 results indicate that interspecific trait variation exceeded intraspecific
 variation by at least 50% for most, but not all traits. Intraspecific
 variation in Δ15N, iWUE, leaf nitrogen content and root traits was high
 (47-70%) compared with most leaf traits and stem traits (13-38%). 4. Δ15N
 varied primarily along gradients in abiotic conditions, while light and
 understory cover were relatively less important. iWUE was related
 primarily to light transmission, reflecting increases in photosynthesis
 relative to stomatal conductance. Leaf traits varied mainly as a function
 of light availability, with some reaction norms depending on understory
 cover. Plant height increased with understory cover, while stem specific
 density was related primarily to light. Resources, environmental
 conditions and understory cover did not contribute strongly to the
 observed variation in root traits. 5. Gradients in resources,
 environmental conditions and competition all appear to control
 intraspecific variability in most traits to some extent. However, our
 results suggest that species cross-over (i.e., trait rank reversals) along
 the gradients measured here are generally not a concern. 6. Intraspecific
 variability in understory plant species traits can be considerable.
 However, trait data collected under a narrow range of environmental
 conditions appears sufficient to establish species rankings and scale
 between community and ecosystem levels using trait-based models.
 Investigators may therefore focus on obtaining a sufficient sample size
 within a single set of conditions rather than characterizing trait
 variation across entire gradients in order to optimize sampling efforts.
description: Burton_etal_TraitDataWhole plant, leaf, stem and root trait data for 57 forest understory species from western Oregon, USA. Growth forms are: F = fern, G = graminoid (grasses, sedges and rushes), H = herbaceous forbs, LS = low clonal shrubs, TS = tall shrubs. GLI = gap light index (%). Total_pct_cover = total cover of understory vegetation surrounding specimen; soil__n = total soil nitrogen (%); CMD = climatic moisture deficit (mm); DELTA15N = Δ15N = δ15Nleaf - δ15Nsoil; iWUE = intrinsic water use efficiency (A/g); SLA = specific leaf area (mm2/mg); LNC = leaf nitrogen content (mg/g); Narea = leaf nitrogen per area (g/m2); LDMC = leaf dry matter content; leaf size (cm2); SSD = stem specific density (mg/mm3); SRL = specific root length (m/g).