Understanding deep roots and their functions in ecosystems: an advocacy for more unconventional research

Pierret, Alain; Maeght, Jean‐Luc; Clément, Corentin; Montoroi, Jean Pierre; Hartmann, Christian; Gonkhamdee, Santimaitree

doi:10.1093/aob/mcw130

Cited by 235 publications

(146 citation statements)

References 102 publications

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“…52% for temperate coniferous forests, and 65% for temperate deciduous forests, possibly partly because of the deeper soil layers covered by Jackson et al (1996, i.e. more than 2 m soil depth in some of the studies included in the analysis) where still considerable fine-root mass may be present (Maeght et al 2013;Pierret et al 2016).…”

Section: Discussionmentioning

confidence: 95%

Fine-root trait plasticity of beech (Fagus sylvatica) and spruce (Picea abies) forests on two contrasting soils

et al. 2016

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Aim The fine roots of trees may show plastic responses to their resource environment. Several, contrasting hypotheses exist on this plasticity, but empirical evidence for these hypotheses is scattered. This study aims to enhance our understanding of tree root plasticity by examining intra-specific variation in fine-root mass and morphology, fine-root growth and decomposition, and associated mycorrhizal interactions in beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst.) forests on soils that differ in resource availability. MethodsWe measured the mass and morphological traits of fine roots (i.e. ≤ 2 mm diameter) sampled to 50 cm depth. Fine-root growth was measured with ingrowth cores, and fine-root decomposition with litter bags. Mycorrhizal fungal biomass was determined using ingrowth mesh bags. Results Both tree species showed more than three times higher fine-root mass, and a ten-fold higher fine-root growth rate on sand than on clay, but no or marginal differences in overall fine-root morphology. Within the fine-root category however, beech stands had relatively more root length of their finest roots on clay than on sand. In the spruce stands, ectomycorrhizal mycelium biomass was larger on sand than on clay. Conclusions In temperate beech and spruce forests, fine-root mass and mycorrhizal fungal biomass, rather than fine-root morphology, are changed to ensure uptake under different soil resource conditions. Yet enhancing our mechanistic understanding of fine-root trait plasticity and how it affects tree growth requires more attention to fine-root dynamics, the functional diversity within the fine-roots, and mycorrhizal symbiosis as an important belowground uptake strategy.

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Section: Discussionmentioning

confidence: 95%

Fine-root trait plasticity of beech (Fagus sylvatica) and spruce (Picea abies) forests on two contrasting soils

et al. 2016

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“…For example, deep rooting (Davidson et al, ; Markewitz, Devine, Davidson, Brando, & Nepstad, ) and deep soil water extraction in tropical forests are important mechanisms to sustain growth during the dry season (Restrepo‐Coupe et al, ; Wu et al, ). A number of studies suggest that deep root systems are not restricted to trees and shrubs in arid/semiarid and seasonally dry forests (e.g., Pierret et al, ). Thus the role of deep root water uptake across ecosystems may have been underestimated (Pierret et al, ).…”

Section: Discussionmentioning

confidence: 99%

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

et al. 2020

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The depth distribution of soil water contributions to plant water uptake is poorly known. Here we evaluate the main water sources used by plants at the global scale and the effect of climate and plant groups on water uptake variability and depth distribution. The global meta‐analysis is based on isotope data (δ2H and δ18O) extracted from 65 peer‐reviewed papers published between 1990 and 2017. We applied a new direct inference method to quantify the overlap between xylem water and soil water sources used by plants. The median overlap between xylem water and soil water at different depths varied between 28% and 100%, but they were generally >50%. The shallow (0‐10 cm) soil water overlap with xylem water was largest in cold regions (100% ± 0%) and lowest at tropical sites (about 28%). Conversely, the median overlap between xylem water and deep soil water was largest in the arid and the tropical zones (>75%) and much smaller in the temperate and cold zones. Our results suggest that the isotopic composition of xylem water reflects mostly the signature of shallow soil water (<30 cm) in the cold and the temperate zones, whereas in the arid and the tropical zones, plants appear to exploit water in deeper soil layers. Our novel, simple statistically‐based direct inference method performed well in determining these differences in water sources, and can be applied more widely to isotope‐based plant water uptake studies.

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“…Q. robur, however, produces a deep root system that reaches into low levels of groundwater (Boratyński and Bugała 2000). Indeed, taproots make oak tree growth less dependent on surface soil layers that tend to dry out, and limit overexploitation of the resources present in a narrow soil profile (Cavender-Bares and Bazzaz 2000; Pierret et al 2016). The inability of a tree species, such as Q. robur, to regenerate a pruned taproot (Ogijevskij and Popova 1954) may be essential for the optimal acquisition of nutrients and water [see Maeght et al 2013 and literature cited therein].…”

Section: Discussionmentioning

confidence: 99%

Functional response of Quercus robur L. to taproot pruning: a 5-year case study

Mucha

Jagodziński

Bułaj

et al. 2018

Annals of Forest Science

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& Key message Quercus robur seedling mass was affected more by planting density than by taproot pruning. Root pruning enhanced stem biomass at the expense of roots in later growth stages. Alteration of biomass allocation due to nursery practices may result in greater susceptibility to injury and death of the seedlings under unfavorable environmental conditions. & Context Plants adjust their growth and modulate the resource allocation in response to applied treatments and environmental conditions. & Aims The aim was to examine how taproot pruning in seedlings grown at different densities affected long-term growth of Quercus robur. & Methods Seedlings, sown as acorns at two planting densities, with or without pruned roots were harvested in the second, fourth, and fifth years of growth. The effect of root pruning on biomass allocation was determined by measuring leaf, stem, and root mass fractions; carbohydrate concentrations in the roots; and C/N ratios. Specific leaf area and root length were also determined to assess morphological adaptations to growth conditions. Handling Editor: Andreas BolteContribution of co-authors Joanna Mucha: participated in the experiment, analyzed the data, and wrote the first draft of the manuscript. Andrzej M. Jagodziński: contributed substantially to revisions. Bartosz Bułaj: contributed substantially to revisions. Piotr Łakomy: contributed substantially to revisions. Adrian Marek Talaśka: contributed substantially to revisions. Jacek Oleksyn: contributed substantially to experimental design and revisions. Marcin Zadworny: acquired funds for the implementation of research, coordinated the research project, supervised the experiment, and contributed substantially to experimental design and revisions. & Results Total seedling mass was affected more by planting density than by taproot pruning. After 4 years of growth, root mass fractions were lower and stem mass fractions were greater in seedlings planted at a higher density. Five-year old root-pruned seedlings also had a lower root mass fraction and higher stem mass fractions than unpruned seedlings. Specific root length was not affected by root pruning or planting density. & Conclusion Decrease of relative root biomass with simultaneous increase of stem biomass may be a long-term consequence of taproot pruning of Q. robur, and the effects may manifest years after the seedling stage. Electronic supplementary material

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Understanding deep roots and their functions in ecosystems: an advocacy for more unconventional research

Cited by 235 publications

References 102 publications

Fine-root trait plasticity of beech (Fagus sylvatica) and spruce (Picea abies) forests on two contrasting soils

Fine-root trait plasticity of beech (Fagus sylvatica) and spruce (Picea abies) forests on two contrasting soils

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

Functional response of Quercus robur L. to taproot pruning: a 5-year case study

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