A starting guide to root ecology: strengthening ecological concepts and standardising root classification, sampling, processing and trait measurements

Abstract

I.Introduction: continuing to face up to root ecology's challenges 975 II.Semantics: defining concepts for better understanding and communication 977III. Species-level vs ecosystem-level measurements 978

Lessons Learned from the Studies of Roots Shaded from Direct Root Illumination

“…Studying the adaptation of root system architecture under toxic growth conditions, including salt stress and drought, is crucial as the availability of unpolluted soil and water for crop production continuously decreases, leading to devastating crop losses [ 93 , 96 , 97 , 98 ]. To study plant stress responses in soil, Rhizotrons, also known as Rhizoboxes, are used, which still allow monitoring of root growth under controlled conditions [ 42 , 96 , 99 , 100 ]. Results obtained from DGR are more comparable to studies done on soil compared to LGR.…”

“…This demonstrates the importance of performing basic research under more natural conditions to allow a smoother transition of findings into applied science. Furthermore, Rhizotrons are commonly used to examine the interaction of roots with the rhizosphere, which is very sensitive to light, and most studies have been conducted on roots grown in soil [ 100 , 102 ]. Therefore, recent attempts to study biotic interactions with the root, which can be beneficial or threatening, include the use of transparent artificial soil for DGR, which in turn will allow a more detailed study of root growth adaptation at the cellular level under more natural conditions [ 103 , 104 ].…”

Formation and Development of Taproots in Deciduous Tree Species

“…Commonly, the classification of roots is based on the position of emergence, and the recognition that most of the functional traits of root systems as a whole are directly related to this location ( Zobel and Waisel, 2010 ; Zobel, 2011 ; Freschet et al, 2021b ). Primary roots in tree seedlings, known also as a taproots, develop from the central embryonic root – the radicle, forming the central axis of a root system ( Zobel and Waisel, 2010 ; Wang et al, 2014 ; Freschet et al, 2021b ).…”

On the Below- and Aboveground Phenology in Deciduous Trees: Observing the Fine-Root Lifespan, Turnover Rate, and Phenology of Fagus sylvatica L., Quercus robur L., and Betula pendula Roth for Two Growing Seasons

“…However, for pragmatic reasons and because of unofficial convention, roots are usually defined on a morphological basis. For example, roots with a diameter below 2 mm are usually defined as fine-roots, while lignified (i.e., woody) roots with a diameter above 2 mm and secondary development are usually defined as coarse roots [2]. Fine-roots are therefore Forests 2021, 12, 1680 2 of 27 considered to be non-woody, short-lived, and of main importance for a tree's resource uptake (often mediated through microbial interaction), while coarse roots are considered to live longer and be of main importance for a tree's stability and resource transportation [3][4][5].…”

“…Roots with a diameter below 0.5 mm may then be considered mostly absorptive roots with a primary or secondary structure, while roots with a diameter between 0.5 and 2 mm may largely be considered woody transport roots [6,7]. Roots of the same diameter sometimes have a different branching structure (i.e., primary or secondary roots) or function [2,8,9]. Apart from resource uptake, resource transportation, and physical stabilization, roots can also store nutrients and carbohydrates or act as sensors for exterior conditions [10][11][12][13].…”