Building a better foundation: improving root‐trait measurements to understand and model plant and ecosystem processes

Abstract

SummaryTrait-based approaches provide a useful framework to investigate plant strategies for resource acquisition, growth, and competition, as well as plant impacts on ecosystem processes. Despite significant progress capturing trait variation within and among stems and leaves, identification of trait syndromes within fine-root systems and between fine roots and other plant organs is limited. Here we discuss three underappreciated areas where focused measurements of fineroot traits can make significant contributions to ecosystem science. These include assessment of spatiotemporal variation in fine-root traits, integration of mycorrhizal fungi into fine-root-trait frameworks, and the need for improved scaling of traits measured on individual roots to ecosystem-level processes. Progress in each of these areas is providing opportunities to revisit how below-ground processes are represented in terrestrial biosphere models. Targeted measurements of fine-root traits with clear linkages to ecosystem processes and plant responses to environmental change are strongly needed to reduce empirical and model uncertainties. Further identifying how and when suites of root and whole-plant traits are coordinated or decoupled will ultimately provide a powerful tool for modeling plant form and function at local and global scales.

The Responses of Forest Fine Root Biomass/Necromass Ratio to Environmental Factors Depend on Mycorrhizal Type and Latitudinal Region

“…Global information on fine root traits is particularly important to advance our understanding and to predict plant and ecosystem processes under changing environmental conditions (McCormack et al, ). The fine root B/N ratio in forest ecosystems combines many important ecological processes including production, mortality, and decomposition of fine roots and can be served as a powerful metric for identifying the absorptive capacity of fine root systems (Persson & Stadenberg, ; Zang et al, ).…”

Maintaining connectivity: understanding the role of root order and mycelial networks in fine root decomposition of woody plants

“…In a global analysis of fine root traits, Iversen et al (2017) found that evergreen and deciduous broadleaf trees from temperate ecosystems had lower average C:N values when compared to needleleaf woody plants from the same ecosystem. It has been demonstrated that fine roots of deciduous tree species decompose more quickly than those of coniferous species (Mao et al 2011;Tong et al 2012).…”

“…To predict how decomposition will respond to environmental changes, recent literature has emphasized the use of trait-based approaches and the need for measurements that directly connect fine root traits to forest C and nutrient cycling (Iversen et al 2017;McCormack et al 2017). Fine root chemical and morphological traits vary across ecosystems and plant taxa, which in turn influences rates of decay as litter quality is a product of both the chemistry and structure of decomposing tissues (Dornbush et al 2002;Birouste et al 2012;Prieto et al 2016).…”

Does plant biomass partitioning reflect energetic investments in carbon and nutrient foraging?

“…Particularly for studies that did not involve grasses, we found that TBCA tends to exceed RMF (log RMF/TBCA ratio <1) to greater degree in younger plants (<2 months). We hypothesize that this results from mass‐based root respiration rate declining as roots age (McCormack et al, ; Volder, Smart, Bloom, & Eissenstat, ). The overall lower root respiration rate of grasses (Tjoelker et al, ) may be why grasses as a group do not show the same ontogenetic trends in the RMF‐TBCA relationship as other species.…”