Data from: Multi-dimensional patterns of variation in root traits among coexisting herbaceous species in temperate steppes

1. Characterizing patterns of variation in plant traits across species and environmental gradients is critical for understanding performance of species in ecosystems. One-dimensional pattern of variation has been demonstrated in leaf traits, which is known as the leaf economic spectrum. However, it is unclear whether such a spectrum exists for root traits.
2. For roots of 15 species from temperate grasslands, we determined respiration rate, relative growth rate, lifespan as well as 10 morphological, chemical and anatomical root traits. We further evaluated pairwise and multiple-trait relationships by the Pearson’s correlation and principle component analysis including phylogenetic contrasts.
3. We found that root functions were related to three clusters of variation. Root respiration rate and relative growth rate were positively correlated with average root diameter, but they were negatively correlated with specific root length. In contrast, root lifespan was not correlated with average root diameter, but it was positively correlated with specific root length. These results are inconsistent with the presumption of the root economic spectrum.
4. The principle components analysis revealed a multi-dimensional pattern of variation in root traits among the 15 coexisting herbaceous species. Moreover, species within the same phylogenetic clades tended to have similar root trait syndromes. Most of the root traits exhibited a significant phylogenetic signal.
5. Synthesis. Our results do not support a one-dimensional root economic spectrum in the coexisting herbaceous species of temperate grasslands. In contrast, the pattern of variation in root traits was multi-dimensional. We further demonstrated that species in different phylogenetic clades possess diverse root trait syndromes for efficient resource acquisition. Our findings provide a next step in understanding root functions and plant strategies in temperate grasslands.