Data from: Fine root morphology is phylogenetically structured but nitrogen is related to the plant economics spectrum in temperate trees

1. Plant functional traits have revealed trade-offs related to
life-history adaptations, geographical distributions, and ecosystem
processes. Fine roots are essential in plant resource acquisition and play
an important role in soil carbon cycling. Nonetheless, root trait
variation is still poorly quantified and rarely related to the rest of the
plant. 2. We examined chemical and morphological traits of 34 temperate
arbuscular mycorrhizal tree species, representing three main angiosperm
clades (super-orders asterid, magnoliid and rosid). We tested to what
extent fine root chemical and morphological traits were correlated
similarly to the leaf economical spectrum (LES) or were structured by
ancestral affiliations among species. 3. Root traits did not display the
same trade-offs as leaves (e.g. specific root length was not correlated
with root N, whereas specific leaf area was correlated with leaf N).
Moreover, 75% of below-ground traits were phylogenetically structured
according to Pagel's λ and Abouheif's Cmean autocorrelation
tests, as opposed to 28% of above-ground traits. Magnoliids showed
thicker, less branched roots than asterids or rosids, but rosid roots
exhibited lower N and higher non-acid-hydrolysable (e.g. lignin) content
than other species. In contrast, leaf traits did not differ significantly
among super-orders. At the whole-tree level, chemical traits such as
nitrogen tissue content and lignin content were correlated between above
and below-ground organs. 4. The distribution of root traits in woody
temperate trees was better explained by shared ancestry than by the
nutrient content and structural trade-offs expected by the LES hypothesis.
Root chemistry and morphology differed substantially among species
belonging to different super-orders, suggesting deep divergences in
resource acquisition strategies among major angiosperm groups. Although we
found partial support for the idea of whole-plant integration based on
corresponding nitrogen content across all organs (i.e. a plant economics
spectrum), our study stresses phylogenetic affiliation as the primary
driver of root trait distributions among angiosperms, a pattern that could
be easily overlooked based solely on above-ground observations.