DOI: 10.5061/dryad.hdr7sqvx9
title: Data from: Anatomical trait variation across root orders shapes the distinct root economics space of herbaceous monocots and dicots

description: The trait-based root economics space provides a useful framework for
 understanding the nutrient acquisition strategies across species. However,
 it remains poorly understood how differences in anatomical features across
 root branching orders shape the root economics space. We measured
 order-based resource economics and anatomical traits of absorptive roots
 of 32 perennial herbaceous monocots and dicots in a temperate steppe and
 examined the trait coordination across root orders to gain insights into
 the nutrient acquisition strategies of herbaceous grassland plants. We
 found that differences in proportion of cortex in root cross-section and
 secondary growth drive variation in the root economics space across root
 orders of herbaceous species. In monocots, the absence of secondary growth
 resulted in comparably consistent trait coordination across root orders.
 Specifically, the gradient of root collaboration with arbuscular
 mycorrhizal (AM) fungal constituted the main dimension of root trait
 variation, mediated by the proportion of cortex in the root cross-section.
 In contrast, we found substantial variation in the trait distribution of
 dicots across root orders due to secondary growth. In lower-order roots of
 dicots, mycorrhizal colonization rates varied independently of specific
 root length, but were negatively associated with root nitrogen (N) content
 along a principal component axis. These relations seemed to be due to the
 alternative root symbiosis with nitrogen-fixing bacteria weakening the
 classic collaboration gradient within the root economics space.
 Importantly, our results demonstrate that the mycorrhizal colonization
 rates were more strongly correlated with the proportion of cortex than
 with root diameter in dicots. Consequently, secondary growth in
 higher-order roots of dicots turned the widely recognized trade-off
 between specific root length and mycorrhizal colonization rates into a
 positive correlation. Our study reveals the contrasting resource
 acquisition strategies of monocots and dicots across root orders,
 highlighting the fundamental role of root anatomical traits in shaping the
 root economics space. These findings provide valuable insights into how
 root anatomical traits predict plant strategies and set the foundation for
 exploring the potential influence of root anatomy on plant and ecosystem
 functions.
description: # Data from: Anatomical trait variation across root orders shapes the
 distinct root economics space of herbaceous monocots and dicots Dataset
 DOI: [10.5061/dryad.hdr7sqvx9](10.5061/dryad.hdr7sqvx9) ## Description of
 the data and file structure Order-based root morphological, chemical, and
 anatomical traits of 32 perennial herbaceous monocots and dicots in a
 temperate steppe ### Files and variables #### File:
 Data_Dryad-Zhou_et_al.-JEcol-2025.xlsx **Description:**  ##### Variables *
 Root diameter * Specific root length (m g ^-1^) * Root tissue density (g
 cm ^-3^) * Root nitrogen content (%) * Mycorrhizal colonization rates (%)
 * Cortex thickness: root diameter ratio (unitless)